tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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But...
First things first.
First, here's a series of pics of the lens and cell. The cell appears custom made, but it seems like a decent machine job. The lens doesn't move in the cell by much at all. I set it on top of a plastic sourcream tub (or whatever it was) so I could lower the cell from the lens as you see in the pic after I took out the retaining ring.
There are a few small chips out of the edge of the lens. Most of these are covered by the retaining ring, but the one you see that's been marker'd out in black is about 1/2" into the field from the retaining ring.
The cell is unpainted, so the main reason I took it apart was to squirt some flat black on it to help cut down reflections off that shiny aluminum.
But when I got it apart, I noted the two "3"s printed on it, with arrows. These aren't in line and aren't pointing in the same direction. The guy who gave me the lens/cell about 5 years ago has passed away, so I don't know whether it was assembled incorrectly, or if this alignment is a result of some testing!
And finally, as I design a means of holding it in the plywood tube I'm about to make, which way is the sky? Both outer surfaces are convex, but the lens on top in the picture is thinner at the edge than the other. I presume that this is the biconvex element that goes skyward, but if someone knows different, by all means tell me! 
The spacers between lenses are tape of some kind. The two lenses are stuck together with them. Otherwise, I'd gently lift the top element off and determine this for myself. Probably, I'll have to do that anyway, if the lenses aren't aligned properly here.
Anyway, first pic. Next, I'll go back outside and double check the FL before I cut any wood.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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2:
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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In both pics, the "3"s with arrows are visible. In the upper element, it's on the left side, with the arrow pointing down. in the lower element, it's on the right, with the arrow pointing up.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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Tim,
The arrows should line up so the heads are pointing at each other. They are indications of were the wedge in the the elements cancel each other and the biconvex element is the crown and faces the sky.
You should have between 5 to 10 thousands clearance around the diameter of the elements vs the ID of the cell. If the cell is too tight it will pinch the optics when it cools and it also cause one to easily chip the edges trying to get it in and out the cell.
Does the metal lip on the inside of the cell have three raised areas at 120 ° apart ? If so, these areas should be aligned with the foil spacer between the lens elements so that you get even pressure when the retail ring is applied.
The lens should have a slight rattle when you place it in the cell and give it a light shake. Check it in two direction that 90° apart. Either the elements or the cell might not be perfectly round. My friend's 6" Schupmann had a cell that was out of round and was pinching the optics. The lens rattled just fine in one direction but was very tight in the other. Opening up the cell made a huge difference in the images.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I'll go outside and check!
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Dave:
The lens elements weren't hard to get apart. So I have the arrows pointing toward one another now.
The cell fits better (feels like a few 'thou gap after I rotated it about 90 degrees from where it was). There are no shims on the surface against the back element (4th surface). I could probably scare up some thin cardboard shims or something. Any paritcular recommendations?
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
But...
First things first.
First, here's a series of pics of the lens and cell. The cell appears custom made, but it seems like a decent machine job. The lens doesn't move in the cell by much at all. I set it on top of a plastic sourcream tub (or whatever it was) so I could lower the cell from the lens as you see in the pic after I took out the retaining ring.
There are a few small chips out of the edge of the lens. Most of these are covered by the retaining ring, but the one you see that's been marker'd out in black is about 1/2" into the field from the retaining ring.
The cell is unpainted, so the main reason I took it apart was to squirt some flat black on it to help cut down reflections off that shiny aluminum.
But when I got it apart, I noted the two "3"s printed on it, with arrows. These aren't in line and aren't pointing in the same direction. The guy who gave me the lens/cell about 5 years ago has passed away, so I don't know whether it was assembled incorrectly, or if this alignment is a result of some testing!
And finally, as I design a means of holding it in the plywood tube I'm about to make, which way is the sky? Both outer surfaces are convex, but the lens on top in the picture is thinner at the edge than the other. I presume that this is the biconvex element that goes skyward, but if someone knows different, by all means tell me!
The spacers between lenses are tape of some kind. The two lenses are stuck together with them. Otherwise, I'd gently lift the top element off and determine this for myself. Probably, I'll have to do that anyway, if the lenses aren't aligned properly here.
Anyway, first pic. Next, I'll go back outside and double check the FL before I cut any wood.
-Tim.
Tim before you attempt to seporate the two elements...DON'T!
The 3 three's may have originally been placed there for alignment...and over time someone may shifted the two elements to correct for aberrations.
Let things be alone. After you mount the cell..do a star test and see if the elements have shifted or not.
If the spacers are *sticky* this may be to hold them in place at that inclination.
Good luck...and remember to post your progress on my yahoo site too..... 
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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Tim,
I use Kapton tape for shims, both along the back rim and three tabs along the slide, that will minimize metal to glass contact.
Take the lens and place it under monochrome light if you have it or if you don't use an Engery Saver type bulb. You should see interference rings between the two elements. They should appear perfectly round when viewed from looking straight down on the elements. If the rings are off center, then that usually indictates that one of the spacers in thicker then the others.
You said that the spacer were tape ? If so then they don't sound like the stock spacers and maybe the wrong thickness. Jaegers is still around under Jaegers Jr. They might know the correct thickness of the spacers.
The "right" way to set the spacing is to set the lens up in double pass autocollimation mode and look at the correction in green light, then adjust the spacing for the least amount of spherical abberration.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Rob:
Oops, I already moved them. But since I have the pics from where they were before, I could move them back.
Dave:
I have compact fluorescent lights in my shop. Will those work?
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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OOo!
I just tried that with the compact fluorescents, and it WORKS!
The rings are there, and seem to be perfectly concentric, but how many should there be? Seems there's thousands of them.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Okay, I just tried it again with the lenses oriented like they were in the pic above (there were shadows of the shims still visible to help me do that), and the rings are way off center.
They're right on center with the arrows aligned, though. The shims look like they have a weak adhesive on one side, and they're all regularly sized - 1/4" long by 3/4" wide.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
Rob:
Oops, I already moved them. But since I have the pics from where they were before, I could move them back.
Dave:
I have compact fluorescent lights in my shop. Will those work?
-Tim.
Dave is giving you steller advice...but I would be a bit more cautious. Dave mentioned that Jaegers may not have used tape(sticky) back spacers and they may have been placed after the fact. And like Dave also mentioned a double pass autocolimation will reveal the spherical rings you are looking for to optimize spherical aberrations. this may have been done and this may be an indication why the spacers are what they are and that the arrows do not line up.
Nothing is set in stone...so check the current alignment before you *THINK* you need to make changes to it. There might be reasons why things are the way they are.
There is pleanty of time to realign the arrows and set the elements up as they theoretically should be.
Good luck.
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
Okay, I just tried it again with the lenses oriented like they were in the pic above (there were shadows of the shims still visible to help me do that), and the rings are way off center.
They're right on center with the arrows aligned, though. The shims look like they have a weak adhesive on one side, and they're all regularly sized - 1/4" long by 3/4" wide.
-Tim.
Excellent! You just figured it out.
It appears the 2 elelements have shifted and the test revealed that. I would have done the monchromatic light test before and determined the current alignment. You just did it the other way around. Good and it proved very successful...
See..how much a little education can reveal....?
Now you know a bit more on how to align and even test your objectives elements alignment.
This is the best kind of way to educate yourself...and it didn't harm a thing.
Dave is to be warmly thanked for his acute attention. 
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Rob and Dave:
I took this pic of the rings with my iPhone (love 21st century technology!). Obviously, I couldn't hold the phone exactly on axis, but I got a lot closer than I could with my haid. The ghost rings are due to reflections viewed off axis.
How does this look? (other than the obvious grunge from the spacers and the dirt that's enhanced by the technique and my stretch of the image!)
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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The two black blobs near the edge at top and lower right are where the bigger chips have been inked out.
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Quote:
Okay, I just tried it again with the lenses oriented like they were in the pic above (there were shadows of the shims still visible to help me do that), and the rings are way off center.
They're right on center with the arrows aligned, though. The shims look like they have a weak adhesive on one side, and they're all regularly sized - 1/4" long by 3/4" wide.
-Tim.
Excellent! You just figured it out.
It appears the 2 elelements have shifted and the test revealed that. I would have done the monchromatic light test before and determined the current alignment. You just did it the other way around. Good and it proved very successful...
See..how much a little education can reveal....?
Now you know a bit more on how to align and even test your objectives elements alignment.
This is the best kind of way to educate yourself...and it didn't harm a thing.
Dave is to be warmly thanked for his acute attention.
Rob
And you know what? I get all goose-bumpy with excitement doing this kind of stuff! Like I got when I looked through Dave's and others' schupmans at Stellafane 2 years ago.
I'm going to dig up that old Telescopics 8" mirror kit that I "started" 37 years ago and finish it when i get the chance. And if this refractor performs well enough on the planets, maybe I'll try to make one myself! (a schupman, that is).
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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KevinP
super member
Reged: 06/25/07
Posts: 170
Loc: Edmonton
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Quote:
Take the lens and place it under monochrome light if you have it or if you don't use an Engery Saver type bulb. You should see interference rings between the two elements. They should appear perfectly round when viewed from looking straight down on the elements. If the rings are off center, then that usually indictates that one of the spacers in thicker then the others.
- Dave
I don't mean to hi-jack this great thread, but this quote caught my eye.
My 80mm lens came without index marks, so I marked them as they sat in the box and try to keep them aligned when I fit them to the cell. Can I assume this technique works for smaller lens sets also? I am almost ready to mount the lens permanently and it would be nice to have everything aligned as close as possible before hand.
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Kev
Sketches
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Antares 200 mm / f5
ATM 82/700 refractor in progress
Bushnell 10x50
Celestron 15x70
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Kev:
I just tried to do the same thing with a couple of 3" lenses, and can't see the rings. ONe's an f/6 and the oher's an f/15.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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We're getting things mixed up here. First the alignment marks, what was done was the thickness of each element was measured and the high and lows spot on each found. The alignment marks are the high spot on one and the low spot on the other. When they match up the wedge in each element cancels. If you have a lot of wedge a star turns into a tiny spectra and a small amount makes star astigmatic.
Second the interfernce test. This is to determine if the air gap between the two elements is the same. The wedge in the elements and the air gap are not 100% related to each other. You can have the wedges off set in the element and with air gap spacers being the same thickness get perfectly concentric rings.
The interference test doesn't work on all lens. The reason is that either the air gap bewteen the two elements is too large and/or the two inner radii are different. From the picture of your 6" f/15 your only see rings in the middle, that is because only at that area are the two lens close enough for them to form. It also indicated that the radii are somewhat different. If they were close or the same, you would rings form across the complete surface if the spacing was close enough. Back to figuring another Schupmann objective.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Thanks Dave for the explanation!
Okay, I managed to determine the focal length by setting the lens in its cell on the picnic table outside and viewing a distant hill (about 1.5 miles away) with a 28mm RKE. This came out to 86". So, allowing for some focuser travel and 2" star diagonal backfocus, plus distance inside the support for the cell (that will be incorporated into the dewcap), I get a tube length of 78". A convenient length. I would rather err on the side of too short, because I didn't with my 6" f/10, and I can't use 2" star diagonals with it (until I cut it shorter, that is). I can always add a block behind the focuser to bring it out more if needed.
I'm going to start cutting a pattern for the baffles, then the baffles, then the tube slats for the nonagonal tube.
Speak now or forever hold your peace! (especially if you think I'm about to screw up!) 
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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Tim,
I would double check the focal length on the Moon or the Sun. Even though the hill was a couple of miles away it wasn't at infinity and that will make a difference in the focal length at infinity. I'm a little surprised you came up with 86" vs something closer to, or actually greater then 90" since the lens is suppose to by f/15. Lens maker are usually really good at hitting radii or the performance of the lens will greatly surface. Usually the focal length is off by no more then 1% or less. Also since the hill wasn't at infinity, the focal length you measured is longer then what it will be when the lens is focused on an object that is really at infinity. Are you sure you had crown element facing skywards ?
I calculated that if the lens had 90" Fl at infinity and the hill was really 1.5 miles away, the focal plane should be at 90.9". ( Correction, it should be 90.085", Thanks Mike)
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
Edited by DAVIDG (07/02/09 10:31 PM)
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Mike I. Jones
Carpal Tunnel
Reged: 07/02/06
Posts: 1571
Loc: Fort Worth TX
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Actually the focal plane shift for a 90" EFL paraxial lens imaging at 1.5 miles is 0.085" (image distance is 90.085"). Think you left out a zero 
Mike
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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Quote:
Actually the focal plane shift for a 90" EFL paraxial lens imaging at 1.5 miles is 0.085" (image distance is 90.085"). Think you left out a zero
Mike
Thanks Mike, sure did drop a zero.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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hehe
Okay, well I only got so far as to cut out my baffle/bulkheads, I haven't cut the walnut plywood yet.
It's marvelous out tonight, so I will set up again after dark.
Hey, downtown LA has all kinds of lights and is about 7 miles in a straight line from my hilltop. How bout I try that?
I like it because I can set up horizontally.
-Tim
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Oh, by the way...
My 6" f/10 has a 54" tube. The cell is mounted recessed in the sky end, and I have a University Optics 2" focuser on the other end. That thing is almost identical to a Meade 680, so it's about 4" high by itself, and with another 3.5" added (needed) for a 2" diagonal, I'm right up around 61.5" from the center of the lens.
I'll still give it a check tonight, though.
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Okay, sighting on downtown lights, I get 89 inches from the back of the cell to the base of the RKE 28mm the stop where it goes in the focuser).
THe cell is 2.5" wide, so if the objective is considered in the middle of that, then I get 91.25" focal length, or f/15.2. If f is measured from the rear of the achromat, then the FL is 89", or f/14.8.
Safe to assume f/15 and build accordingly?
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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I would say it's a f/15 and build to that focal length. By the way you can put those lights from LA to good use. You can get a good feel for the spherical correction of the lens by looking at a Mercury street-light as far away as possible. Use a green eyepiece filter and ronchi grating with at least 100 lpi. The mercury line at 546nm will be isolated by the green filter and that is were your lens should be corrected it show no spherical abberation so with three ronchi lines showing they should be nice and straight.
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
I would say it's a f/15 and build to that focal length. By the way you can put those lights from LA to good use. You can get a good feel for the spherical correction of the lens by looking at a Mercury street-light as far away as possible. Use a green eyepiece filter and ronchi grating with at least 100 lpi. The mercury line at 546nm with be isolated by the green filter and that is were your lens should be corrected it show no spherical abberation so with three ronchi lines showing they should be nice and straight.
- Dave
Now that's a slick trick Dave.
Too bad I don't have any street lights close by... 
No...that's a good thing.
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Well, I'm definitely making this up as I go along!
I was going to use this "workbench" to lay up the tube slats, but it's so hot out there that the 1/4" plywood will likely warp out of shape if I do...
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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So, I just used it to cut the plywood to the length of the tube, plus a quarter inch or so for trimming.
It's Walnut plywood, but it's got mdf as a core, which I didn't notice when I brought it home. This means I need to be pretty careful working with it, lest I go through the thin veneer while working on it.
I had bought a new carbide blade for my table saw, and ripped the slats on it, with a 20 degree bevel (9 sided tube).
Yesterday, I made these "bulkheads/baffles" out of some 3/4" chinese plywood scraps I had laying around. I decided to use these instead of some 1/4" plywood, so I'd have some strength for things like rings and/or tube weights and guide scopes, and I'm spacing them every 12" just so I'll remember where they are when the tube is together!
But I quickly remembered the good old days when I made my 8" Springfield tube this way... The imprecision of making the bulkheads means I'm going to wind up a little big as I wrap the slats around them, or worse, a little small. So, I plan to tape up 5 of the 9 sides first, and see if the bulkheads will fit without either spreading the sides apart or leaving a gap on the inside between the bulkheads and slats.
If they do (either thing), I'll cut them into "gussets" so I get a good fit at all the corners.
I numbered every facet of the bulkheads and each side so I know where everything goes. Now, I'm going to go out there and glue up the first 5 sides.
Here's a pic of the baffles and the pattern I made them from, on my neatly-kept saw table!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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plyscope
sage
Reged: 11/23/06
Posts: 326
Loc: Perth, West Australia
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Looking good Tim.
A trick I used was to make a pattern from thin sheet metal and then clamp all the baffles and pattern together and sand the sides of the baffles down to the metal edge of the pattern. The baffles were close enough in size then that the tube sides were all equal.
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Andy
6" f15 refractor
90mm f16.7 refractor
Edited by plyscope (07/03/09 05:33 PM)
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Andy:
That's a good suggestion. I may try that as opposed to cutting my baffles up. On the other hand, if I cut them into thirds, maybe they'll all happily fit without any additional sanding.
Here's the first 5 slats taped up:
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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And here's where I dry-labbed them together with the first baffle. Already, there's error before I get to the last slat on the left, and the next one on the right is going to have issues as well...
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hm....
I sanded these to the tracing of the pattern on a 12" disk sander. I wonder if I were to just take all the baffles and sand the line off, if that would be enough for it all to fit?
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I think I'll go and tape up the remaining 4 sides so I can lay them on top of the other 5 with the baffle in place. then I'll try sanding that baffle to where it fits, and when it does, go for it with the rest of them!
-T
im.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Last dry lab clampup before I pour glue over everything!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Glue in the grooves!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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First "half" glued up.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Now, I'm pretty sure I don't have any flat black paint that I can brush on. Only spray cans.
May have to hop in the Model A and head off to the hardware store for some.
I do have some satin house paint, but it's latex. if I thought the rustoleum would stick to it, I'd brush that on, then spray down the tube once it's all together to knock down the "highlights". But I'm pretty sure it won't stick.
-tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hah! Found some. A quart of flat rustoleum.
So, here I am painting the inside of the first half.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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And here I've turned it over and taken the tape off.
I did it now, when the glue's only had about 45 minutes to dry, because I wanted to be able to wipe the excess off if any got between the tape and the wood. And I used a water-soluble glue so I could get it off if I needed to.
but I didn't need to!
Gosh, wood looks so good!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Now, I've got a problem, but it's not a huge one.
I set the remaining 4 sides, with the tape holding them together, on top. And I've got about a 3/32" gap left over when I put one side against the bevel on the glued-on side.
So, I'm going to have to do what I did with my Springfield tube. And that is to put the remaining 4 sides on one at a time, and cut a new one for the last side that's just a tad wider than the rest to fill the gap. That'll be easier than trying to sand the bulkheads when they're in place. And I have enough of the plywood left over to do it.
I'm going to try to do that before I close up for tonight, so it'll be dry and ready for polyurethane tomorrow.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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That is looking great and coming along very well.
I'm only assuming you will paint the inside that is finished first before you glue the other half(that has been painted beforehand) together...?
Pretty stiff tube...and I'm assuming pretty light too.
Thanks for posting/
Rob
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www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hi Rob:
Yes, I'm painting the remaining sides as I tape them up and get ready for gluing.
Since I've decided to lay them up one at a time, I found I can file off the high corner on the bulkhead that's holding the plywood corners apart. If I'm lucky, I can get them all to fit tight. Only two more to go!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here's the 2nd to the last getting glued up and ready to swing into place:
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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DAVIDG
Carpal Tunnel
Reged: 12/02/04
Posts: 1985
Loc: Hockessin, De
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Tim,
Really looks great and really fast work. You'll be observing in no time. Get your 'scope finished so you can meet us back on Breezy Hill next month !
- Dave
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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics
Engineering = Taking what you have and making what you need.
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
Here's the 2nd to the last getting glued up and ready to swing into place:
Well holy moly man.....You're movin out. Don't rush things just for us. Is the temp up high there and so the glue is drying fast? You're moving out for sure.
How you gonna fix the cell to the wood baffle?
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Tim,
Really looks great and really fast work. You'll be observing in no time. Get your 'scope finished so you can meet us back on Breezy Hill next month !
- Dave
Boy, I'd sure love to go back to Stellafane! but unless I flew, I can't justify that much time off this year.
Do you think they'd let me carry that OTA on the plane? 
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Quote:
Here's the 2nd to the last getting glued up and ready to swing into place:
Well holy moly man.....You're movin out. Don't rush things just for us. Is the temp up high there and so the glue is drying fast? You're moving out for sure.
How you gonna fix the cell to the wood baffle?
Rob
Well, the glue sets up in about a half hour or so. Won't be good and dry for a day, though.
I ended up packing it in before making that last slat. Sun went down, so it was already about 8:30.
I plan on making plywood rings to hold the cell, with thin ones on either side of it to keep it in. One of those will be removable to get the lens and cell out. And then the dewshield will live outside that.
I'm hoping I can get most of the OTA done this weekend, but fittings and stuff may take a bit longer.
One thing that'll help is that I plan to use polyurethane to finish the tube, and it dries very fast. I should be able to put about 3 coats on in an hour or two.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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NHRob
Post Laureate
Reged: 08/27/04
Posts: 3148
Loc: New Hampshire
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Tim,
Awesome work! Do you plan to use water-based urethane?
Rob
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Rob
**********************
Canon 12x36 IS binos
TEC-140: #433 on CGEM
Faworski orthos (7,10,16.7mm)
stuff ...
no free time ... lots of clouds !
" Life is what happens to you while you're busy making other plans" !!
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Yep. Probably Varathane floor urethane, as I have some left over from my 12.5" Cass tube.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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clintwhitman
Caveman
Reged: 01/01/07
Posts: 2425
Loc: ValVerde CA(SoEasyaCavemanCanD...
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Tim Awsome wood monster scope... Wow you should bring it to Mount Pinos on Aug 14th for the Second Anual Classic Star Party!!!!! You have to be there this time!!! (aveman
After looking at the post for a while I was wondering if you did a ray trace drawing for the light path? 
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Clint&Debbie Whitman (aveman
1960s 6"F15 Jaegers-Unipons by John Pons on a Byers 812, 1947 4" F15 TINSLEY, 1965 10" F8 CAVE, 1950 5CM & 6.5CM Nippon Kogakus (the twins), 1960s UNITRONS a 152 restored a 160 numbered green lens original mint a 114 original 50s mint, 1950s UNITRON M100 100mm F15 OTA, WO 80mm Florite, ASTROPHYSICS 155 EDFS on LOSMANDY G11, a bunch of Tascos,Sears Mayflowers The list goes on Add infinitum.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hi Clint:
I may try to do that August thang this time!
I didn't do any ray trace, just made sure that the light cone gets through with a 3" circle where the focuser mounts, so there's no vignetting and the drawtube has someplace to go.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here's the last slat all glued up and ready to swing into place. I did have to make a new one that's about 3/32" wider than the rest, and then had to use a power plane to shave off some where it's too tight. The adjacent sides aren't quite parallel, but the plane let me get the last slat in with a pretty decent fit.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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And here it is in place. I had to really tension the tape across the last gap to pull it really tight, since I can't get the little clamps in there anymore.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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While that dries, I'll scribble up something for a cell support, and then a dewshield to go over it.
I'm going to try to make the cell adjustable.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
While that dries, I'll scribble up something for a cell support, and then a dewshield to go over it.
I'm going to try to make the cell adjustable.
-Tim.
Man that looks great Tim. I luv the wood..it will be very sheak and beautiful when done.
One thing if I may add(Not to be critical or nothing).
But I always wonder why folks build their scopes with such abrupt back plates? there you have this wonderful tube going along then....Bamn! Flat back and then the focuser.
I think it would be slick if you turned on your lathe(If you have one) a nice piece that dropped down the tube size a bit..then you attached the focuser. I would think a nice hectagonal piece about 4~5" long the same shape as your tube but tapered. Then the focuser.
Now I know.. you have already built the tube with the focal legth of the objective in mind and at this point it is too late. When I built my 10"f/16 OTA..I knew.. that that 12" tube would have to come to an end and have an enormous back plate. I intentionally built up the focuser body to be 6" OD and then the collimation ring that connects the focuser to the backplate was 8"OD. With this incromental stepping...the large tube didn't look so *bulky* when it came to an end. It kinda *steps down* to the EP.
Anyway....in no way was I criticizing your project..it is awesome and very well built...and very beautiful.
I guess that's just me talking...I try to do things differently.
I can't wait to see your solution for the adjustible cell and its attachment to the OTA......
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Well, I do plan to cover that chinese plywood on the end. I may make a 9-sided backplate using the walnut plywood, or I may use solid stock. But I probably didn't leave enough backfocus to add much of a step-down to it.
My cell support so far is quite ugly! But it'll be out of sight, and painted black, so maybe it won't be so bad!
I can't find my walnut-colored wood glue. I need to fill a gap in that last corner, and the regular glue is going to look like snot when it dries!
-Tim.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here it is, sanded and ready to poly!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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And here it is, 2 coats later.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I love the walnut grain.
It's pretty hot out today, and though I put the 2 coats of poly on in the shade of the garage, it kind of went on heavy, and I got some runs!
Dries very fast, though, so I 'spect I'll be going back over it with fine sandpaper, then a couple more coats.
I wanted to get it covered to protect the wood while I continue working on it. 'Specially, when I go to spray the inside with flat black to catch things like the sawdust from adjustments and the glue drips from laying the last couple sides on. I don't want overspray on the wood. it'll be a lot easier to sand off the polyurethane than off the wood!
Still need to finish the cell, dewshield and back plate. Then it's fitting everything, making rings for it and a dovetail plate so I can put it on one of my tak mounts (either the NJP or the EM-500, I figure).
-Tim
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
I love the walnut grain.
It's pretty hot out today, and though I put the 2 coats of poly on in the shade of the garage, it kind of went on heavy, and I got some runs!
Dries very fast, though, so I 'spect I'll be going back over it with fine sandpaper, then a couple more coats.
I wanted to get it covered to protect the wood while I continue working on it. 'Specially, when I go to spray the inside with flat black to catch things like the sawdust from adjustments and the glue drips from laying the last couple sides on. I don't want overspray on the wood. it'll be a lot easier to sand off the polyurethane than off the wood!
Still need to finish the cell, dewshield and back plate. Then it's fitting everything, making rings for it and a dovetail plate so I can put it on one of my tak mounts (either the NJP or the EM-500, I figure).
-Tim
Good night Nurse! Tim...you work at warp speed. I love expedient progress.
Will your dew cap be the same shape or will it be round? Possibly brass......Hmmm....or copper
Beautiful...just beautiful....
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Rob:
Here's the dewcap:
Same shape, but about 10" across instead of 8".
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Compared to putting the tube together, this was a cinch!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here's the "cell cell" because it's the cell that holds the cell that holds the lens!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I painted the cellcell parts black before i put everything away so I could get cleaned up for a bbq at my daughter's house.
The thicker ring is for the lens and cell to fit in, and the thinner ring screws on as a retainer to keep the lens from falling out.
I still need to make the back plate for this, which will probably be round, and wide enough to epoxy nuts into for the cell adjustment screws. It'll have a hole similar to the thin ring above, to keep the lens from falling out the other side.
The sky end of the tube will have a matching "plate" for the adjustment screws to come at the cell support from the back. I'll make the adjustments, and then the dewshield will be screwed on, also from the back (through holes in the plate on the OTA). These screws will go into blocks glued onto the inside of the dewshield, which I still need to make.
I'll probably poly the dewshield before I paint the inside, as it was way too easy to get little drops of black paint on the outside of the OTA while I was working on it. I got them all off, but it'll be easier if they can't soak into the wood.
Then it's the rings and saddle dovetail. I might actually be able to do that tomorrow, although I need to clean up the house after "bachin' it" for the past 2 weeks while my wife and son have been out of town.
I won't be "finished" with it, though. Just maybe able to toss it together to see how it performs!
Just don't hold me to it!
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
I painted the cellcell parts black before i put everything away so I could get cleaned up for a bbq at my daughter's house.
The thicker ring is for the lens and cell to fit in, and the thinner ring screws on as a retainer to keep the lens from falling out.
I still need to make the back plate for this, which will probably be round, and wide enough to epoxy nuts into for the cell adjustment screws. It'll have a hole similar to the thin ring above, to keep the lens from falling out the other side.
The sky end of the tube will have a matching "plate" for the adjustment screws to come at the cell support from the back. I'll make the adjustments, and then the dewshield will be screwed on, also from the back (through holes in the plate on the OTA). These screws will go into blocks glued onto the inside of the dewshield, which I still need to make.
I'll probably poly the dewshield before I paint the inside, as it was way too easy to get little drops of black paint on the outside of the OTA while I was working on it. I got them all off, but it'll be easier if they can't soak into the wood.
Then it's the rings and saddle dovetail. I might actually be able to do that tomorrow, although I need to clean up the house after "bachin' it" for the past 2 weeks while my wife and son have been out of town.
I won't be "finished" with it, though. Just maybe able to toss it together to see how it performs!
Just don't hold me to it!
-Tim.
I need to clean up the house after "bachin' it" for the past 2 weeks while my wife and son have been out of town.
OH I see now...you've been on a mission...you actually had a time frame to (git er done) in....
I completely understand that. Once mommas home your time has thus become divided...and late nights burning the midnight oil...are gonna be over..
Now I understand the expeditiousness of your build..... 
No..actually..I'm very impressed with your wood working skill and very timely assembly.
It's gonna be beautiful.
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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It hit me as I woke up this morning...
...where am I gonna put this thing? 
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
It hit me as I woke up this morning...
...where am I gonna put this thing?
-Tim.
Dude.....You had better work that one out quick....
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Okay, I still haven't figured out where to put this thing!
But I'm making more progress...
Here's the "flange" glued onto the sky end of the tube. This is sized to fit inside the end of the dewshield, so that the edges of the Finnish plywood aren't visible.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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The flange is made of two 1/4" pieces glued and clamped together, so it's 1/2" thick and a gazillion plies, for strength.
Here's the cell progress. I've got the backplate of the cell glued onto the rest now, waiting for the glue to dry.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Finally, the dewshield interior. I glued this piece in as a stop and mounting surface for the backplate of the cell 9the unpainted part above.
The backplate and cell fit inside the dewshield behind this part.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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johnnyha
Pooh-Bah
Reged: 11/12/06
Posts: 1081
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Quote:
It hit me as I woke up this morning...
...where am I gonna put this thing?
-Tim.
I think you can make a convincing argument that this is a sculptural work of art that can be hung up on a wall in the house. Then put a few sturdy racks on the wall to cradle it. Hey it looks fantastic by the way I had been thinking of doing this, it's nice to see another one underway and NINE sides!
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Johnny
Spicewood, TX
Sherman Oaks, CA
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hi Johnny:
Yeah, I don't know why it looks better to me to have a corner opposite a flat, but it does.
Years ago I tried making 12-sided tubes out of 1/4" plywood. But I found that the more sides, the harder it is to control "twist". And of course, the greater number of cuts and masking tape, glue and the lot.
Okay, now to go out and make a backplate and attach a focuser!
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Okay, more stuff...
I just mounted the dewshield and cell onto the tube. No optics yet, and I still need to paint the inside of the diewshield black.
It should have mounted flush with the "plate" on the end of the tube, but it isn't. Possibly my screws are holding it out (come to think of it, that must be it!).
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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From the back.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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Star Gazer94
member
Reged: 12/20/08
Posts: 12
Loc: Altoona, Wisconsin
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That looks absolutely beautiful!
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http://astronomyking.wordpress.com/ (a work in progress)
Meade ETX-125AT w/ tripod (my new baby)
Homemade 6" Dobsonian
60 mm Bushnell Refractor (not used anymore)
Orion 17mm Stratus
TMB 7mm Planetary Eyepiece
Homemade 11mm RKE
Meade 4000 26mm Super Plössl
Edmunds Scientific RKE 28mm
Homemade 19mm plossl
Olympus E-510
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Thanks!
Okay, I'm toast! Feet hurt, back hurts, stomach's growling!
I did put the lens in and have achieved first light!
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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sighting along tube to downtown LA.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here's a closeup of the JMI focuser on a temporary back plate.
I'm using a 1 1/4" star diagonal here, and the focuser's out about 1 ", so I wasn't too far off when I measured things the other day. But I'm not sure I won't have a problem reaching focus with a 2" diagonal in. The building I was looking at is about 6 or 7 miles away, so there may be a bit of in-travel needed for true infinity.
If need be, i'll saw a bit off the tube and make a tapered block for the focuser as Rob suggested.
Now, gotta go wash off all that sawdust!
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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plyscope
sage
Reged: 11/23/06
Posts: 326
Loc: Perth, West Australia
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Well done Tim.
It looks fantastic and I am amazed at how quickly you have progressed. Looking forward to hearing more about your observing experiences and mounting etc.
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Andy
6" f15 refractor
90mm f16.7 refractor
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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It's probably going to be a while, as next week I think I'll be working on the house.
Probably the single most effective factor in getting this far so fast with it is that I've sort of been designing the tube ion my haid on my way to work and back for months now. And it's similar to tubes I've made before.
For my last 9-sided tube, I drew all kinds of plans on the computer, but when i started this one, i realized I didn't have a computer when I built my Springfield in 1981. So, I looked up my old drawings and went that route.
They're really awful drawings, but they help me keep track of what I'm doing as I go. I write the dimensions on the drawings as I make them or change them. So the end result is more a combination of what's in my head and what I've written down. They're about as far from patterns as you can get!
Best thing is that they don't take long to draft up.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Tim......That looks totally awesome!
And in near record time too. My kind of working...I want to gust get in there and *bust* it out too. I worked very fast on my 10"f/16.......I just don't have my objective yet. 
Kinda like that train that was built over the Alps..when the track was laid they didn't even have a train that could make the journey....but they built the track anyway knowing that someday the train would be invented....
You could always set it up as a decorative wooden collum in the livingroom and tell mamma it is for shear asthetics.
Na...she might want to put a potted plant on top of it....
Just tell her the truth...you were working on the house and you found it in the attic..
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Well, it's pretty obvious!
I still couldn't figure out where to put it when I was done, so it's on the dining room table!
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Quote:
Well, it's pretty obvious!
I still couldn't figure out where to put it when I was done, so it's on the dining room table!
-Tim.
Just take it...and be the better for it..
She'll probably fall in love with it too...it's awesome!
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
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drshr
professor emeritus
Reged: 06/09/08
Posts: 672
Loc: Darwin, Australia
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Magnificent!
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Doc
14" F5 DOB.
APM 8" F6 Achro.
APM 105mm F6.2 CF APO.
120/F8.3
150/F5
80/F6.25ED
25x100 Binos.
To affect the quality of the day, that is the highest of arts.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hokay, I managed to squeeze off a couple hours this afternoon to make me some temporary rings to use to mount this thing on my NJP tonight (hopefully), so I can try it out.
I got up around 5 this morning and gee-whizzed Jupiter through my NP101is, and the seeing was SO GOOD I just have to have the 6" ready to try tomorrow morning!
Anyway, here are a couple progress pics:
Lens in "cell cell":
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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And here are the rings, just sitting on the tube. The aluminum and poplar thingy in the background against the tube is a dovetail plate I made. It's only 12" long, but it'll do for this trial. I plan to glue up the rings double, so they'll be 1.5" wide, then screw into them to mount the dovetail.
The temporary back plate and focuser are on the right:
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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The "final" mounting system, I'm reckoning, will be about 2 feet long, and have places to mount a couple of barbell weights toward the focuser end so that I can minimize the arc that the focuser swings when moving the scope around.
Okay, back to work!
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Okay, try not to laugh!
I'm definitely going to need weights on the focuser end of the tube!
But I got it together, collimated the focuser (will worry about the lens another time), and so it's ready for the dark.
When Jupiter's up, I should be able to sit on the grass and observe!
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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2
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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KevinP
super member
Reged: 06/25/07
Posts: 170
Loc: Edmonton
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Tim, that really looks fantastic. Congratulations on a beautiful scope.
--------------------
Kev
Sketches
------------------
Antares 200 mm / f5
ATM 82/700 refractor in progress
Bushnell 10x50
Celestron 15x70
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Thanks, Kev!
I've still got a lot of things to do and change, but I've got a couple of long trips coming up, some vacation, and so it'll probably stay like this until sometime in mid August.
I'm hoping to start staring at my eyelids early tonight, so I can get up around 4 or so for Jupiter. Going to leave the scope set up all night. It's been pretty warm and dry here, and it's in my backyard. I don't think anybody will mess with it.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Tim...that is so awesome...so awesome..beautiful...beautiful.
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
|
tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Well, I've officially gee-whizzed Saturn with it!
Very nice. Almost no false color, but it is there at high mags. Very nice contrast, even though Saturn was only up about 35 degrees when I started.
The real test will come in the morning when I try imaging Jupiter with it using a Pt Grey Flea2 16-bit color digital video firewire camera and Astro IIDC on the mac.
With the 6" f/10, there's just too much false color to get a good color balance on jupiter, so I always shot in green monochrome with it. I'm curious whether I'll have to do that with the f/15.
It was kind of funny viewing with the eyepiece end hanging so far back from the saddle! When i switched from Saturn to the double double, I was only about a foot and a half off the ground, and had to squat on the slope next to the scope. I should have set up farther from the edge! But I've got good polar alignment, so I'm not going to mess with it now...
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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rwiederrich
Goldfinger
Reged: 11/17/05
Posts: 8300
Loc: Bremerton Washington
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Well...come on Tim..take some pix so we can see what you're talking about....
Rob
--------------------
www.goldmtobservingcenter.com
A great place for amateur astronomers, and ATM's to come and enjoy their hobby.
http://tech.groups.yahoo.com/group/HomemadeRefractorTelescopes/ My homemade refractor group.
www.vimeo.com/6014031
|
mikey cee
Post Laureate
Reged: 01/18/07
Posts: 3507
Loc: bellevue ne.
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Tim....I kinda' like that 9 sided look over the traditional octagon.....much more pleasing to the eyes.  Mike
--------------------
7x35 and 10x50 sears tower binocs, 3" f/10 edmunds reflector, 2.4" f/11.7 manon refractor, 6" f/8 jaegers refractor, "The 8 Ball" 8" f/13.3 brandt refractor, 3" f/15.8 sans&streiffe refractor, 3.1" f/15 selsi refractor(towa 339), 2.4" f/15 sears refractor, selsi 30x30mm spyglass, criterion 5-draw 25x45x75x spyglass(1957), 4.25" f/14.8 tasco 20te.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here are some pics I took this morning while imaging jupiter:
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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too (and that's Jupiter, live, on the laptop)
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
Edited by tim53 (07/12/09 10:09 AM)
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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three
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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fore
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here's the setup I got the best image scale from:
William Optics 0.8x focal reducer/field flatener, 2x shorty barlow (really, just the barlow was too big, without- too small), Point Grey Research color Flea2 firewire camera.
-Tim
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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Mike I. Jones
Carpal Tunnel
Reged: 07/02/06
Posts: 1571
Loc: Fort Worth TX
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Tim,
Which FLEA2 camera did you get? Point Grey has them in 7.4um, 4.65um and 3.75um pixel sizes. We have some at work and I've been wanting to take one home and try it on my scopes. At your focal ratio of f/15 the 7.4um array is probably best matched to the optics, and has the highest sensitivity of the three. Either the 7.4um or 4.65um cameras would work well with my 16" f/6 Newt.
Mike
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56 mirrors, lenses, 16" f/6 Newt, 6" f/10 refractor, TOA-130S, Tinsley 5" f/15 Mak, 6" f/4 RFT, Coronado PST. Still to build: 24" f/10 Modified Dall-Kirkham, 10" f/26 Mak, 8" f/12 apo, spectrohelioscope, Herrig, Schupmann, and others.
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mikey cee
Post Laureate
Reged: 01/18/07
Posts: 3507
Loc: bellevue ne.
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Tim....I'm lost here. Is that scope that lens heavy or is it more convenient to get the eyepiece locale closer to your work? Also did you knock off your chimney and then cap it? Nice looking home there. Mike
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7x35 and 10x50 sears tower binocs, 3" f/10 edmunds reflector, 2.4" f/11.7 manon refractor, 6" f/8 jaegers refractor, "The 8 Ball" 8" f/13.3 brandt refractor, 3" f/15.8 sans&streiffe refractor, 3.1" f/15 selsi refractor(towa 339), 2.4" f/15 sears refractor, selsi 30x30mm spyglass, criterion 5-draw 25x45x75x spyglass(1957), 4.25" f/14.8 tasco 20te.
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Tim,
Which FLEA2 camera did you get? Point Grey has them in 7.4um, 4.65um and 3.75um pixel sizes. We have some at work and I've been wanting to take one home and try it on my scopes. At your focal ratio of f/15 the 7.4um array is probably best matched to the optics, and has the highest sensitivity of the three. Either the 7.4um or 4.65um cameras would work well with my 16" f/6 Newt.
Mike
Mike:
This one's the Flea2 with 1032x776 4.65 micron pixels. I tend to use this one more than my Flea 640x480 with the 7.4 micron pixels because it's easier to pick a ROI and get a larger range of possible image scales. I've compared them, and when they're at the same scale on planets (requiring different barlows on same scope), the sensitivity is the same.
Also, with Astro IIDC, you can bin COLOR, though you have to change the R and B gains to balance things. I've been wanting one of the bigger chip Pt Grey cameras. Unfortunately, the one I'd want is the Grasshopper with the Exview HAD chip in it (same as the DSI III Pro), and it's something like 2600 bucks!
Here's one of my Jupiters from this morning. I'm still processing, so this might not be the best. In addition to the optical train above, I had a Baader contrast booster in the system. Without it, there's still too much CA for planetary color imaging. But at least I can get good color balance with it on the f/15, whereas I can't with the f/10.
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Tim....I'm lost here. Is that scope that lens heavy or is it more convenient to get the eyepiece locale closer to your work? Also did you knock off your chimney and then cap it? Nice looking home there. Mike
Mike: Yep, it's heavy at the lens end. The wood components are actually quite light. Probably a lot lighter than an aluminum tube would have been.
That chimney has been cut off for as long as any of the neighbors can remember. I'm guessing the Long Beach earthquake of 1933, but I have no particular reason for picking that date. The other two were cut off after the Sylmar quake.
When we were rebuilding our house after the roofer set it on fire in 2001, we looked into having the chimneys rebuilt to match pics (of the other two, this one there are no pics of that we've found... ...yet). We were quoted upwards of $100K, so it's not going to happen soon!
-Tim. 
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Here's one with just the 2x shorty barlow in place, resized to 800x602 pixels
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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Mike I. Jones
Carpal Tunnel
Reged: 07/02/06
Posts: 1571
Loc: Fort Worth TX
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Looks great! Try making a composite shot through a few different narrow-band filters rather than a white-light shot. Focus at each different wavelength with a Bahtinov mask. That's a sharp lens at any one wavelength or correct pair of wavelengths between F and C, just not all of them together. Blue and violet focus farther away from the lens, so the image scale actually increases slightly and has to be compensated for when making the composite image.
Love the King Crimson avatar. I wore the grooves off that LP back in the 70's. You know that Fripp tours with the California Guitar Trio now, right?
Mike
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Quote:
Well, it's pretty obvious!
I still couldn't figure out where to put it when I was done, so it's on the dining room table!
-Tim.
Just take it...and be the better for it..
She'll probably fall in love with it too...it's awesome!
Rob
Well, I was struggling with where to put the scope when I take it down, and my wife made the suggestion that I set it up in the living room on the NJP!
This way, I can cogitate on how to rig up tube weights after I get home from work!
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
Edited by tim53 (07/12/09 08:28 PM)
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Quote:
Looks great! Try making a composite shot through a few different narrow-band filters rather than a white-light shot. Focus at each different wavelength with a Bahtinov mask. That's a sharp lens at any one wavelength or correct pair of wavelengths between F and C, just not all of them together. Blue and violet focus farther away from the lens, so the image scale actually increases slightly and has to be compensated for when making the composite image.
Hi Mike:
Well, I got up this morning about 5am (starting to get light) and plugged the scope in and attached my Meade DSI Pro III with filter bar to the scope for some filtered imaging tests (via Nebulosity on the mac) like you suggested, changing focus for each color. I was still rather groggy, though, and the coffe wasn't ready until I was well into the imaging sequence, so I forgot to put the IR block filter back on the nosepiece. So IR was getting into the RGB filtered images. I did notice a wider range of "good" (but not great) focus with the green and blue filters (duh!), but I'd have to repeat the experiment in a lot more awake condition for the results to be meaningful.
...and unfortunately I took the scope down to set up again in our living room, because it looks like it'll be about a month before I can spend much time again on the project.
Until then, I'll likely do any imaging I get time for either with the NP101is, my good ol' Orange tube C-8, or the Nexstar 9.25 GPS.
Quote:
Love the King Crimson avatar. I wore the grooves off that LP back in the 70's. You know that Fripp tours with the California Guitar Trio now, right?
Mike
Yep. I'm a big fan of Fripp, but especially the early King Crimson stuff. The later stuff isn't quite as cool.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I should ad that I've tried this with the 6" f/10 before (though not with a monochrome camera and filters, but with Bayer on-chip RGB filtered color cameras), where I shot video sequences in red, green, then blue monochrome mode, refocusing for each. At that f/ratio, I found the blue channel to be way too soft, even at "best" focus. To be fair, though, I should try that again with the DSI (and the IR blocker!), because the red and blue pixels are only a 1/4 of the total number in a bayer color camera.
-Tim.
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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I reprocessed that Jupiter picture I posted above. I think this is more better:
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"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
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Jim Curry
sage
Reged: 10/29/07
Posts: 431
Loc: Maine
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Tim:
I've been silently following this thread. Fantastic workmanship. This last photo of Jupiter is great, too. As far as tube weights go you might consider some weights extended from the saddle to keep from overloading the tube. Weights at the end of long rods, I'm sure you've seen them on some classic scopes.
Jim
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Vixen 140 refractor
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tim53
Pooh-Bah
Reged: 12/17/04
Posts: 1421
Loc: Highland Park, CA
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Hi Jim:
That's an interesting thought... sort of "Zeiss-like", though they also mounted the Griffith 12" on an inverted fork mount.
For my 6" f/10, I simply attached short dowels big enough to fit inside standard barbell weights to the tube, then put on the weights, followed by fender washers and screws into the dowels. But those weights are only 2.5 pounds apiece. I'll likely need a pair of 5 pounders for the f/15!
-Tim.
--------------------
"We`re just waiting looking skyward as the days come down.
Someone promised there`d be answers, if we stayed around."
-Orchestral Maneuvers in the Dark, "The Romance of the Telescope"
|
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