Rich V.
Post Laureate
Reged: 01/02/05
Loc: Lake Tahoe area, Nevada, USA
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Re: Tinkering Beachchairbill
[Re: EdZ]
#4067953 - 09/23/10 12:01 PM
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Agreed, Ed, this was more about the process of checking and aligning the binocular, not the particular misalignment of Bill's specimen. By looking at his photos, both barrels were misaligned in the same direction by a similar amount.
As to his final alignment, I suggested his using his higher magnification eyepiece set for the exact reason you bring up above; it's easier to be critical with more magnification.
Also, as has been pointed out numerous times before, the nature of the misalignment (convergent vs. divergent) makes a big difference as our eyes naturally try to "cross" when the axes converge (relative to the eye) but they are far less, if at all, capable of correcting the divergent condition by going "wall-eyed". I think many folks settle with a bit of convergent misalignment simply because it's so natural for the eyes to automatically correct for this. Still, over time, the eyestrain can become bothersome.
Rich V
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beachchairbill
Pooh-Bah
Reged: 11/06/08
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Re: Tinkering Beachchairbill
[Re: EdZ]
#4068244 - 09/23/10 02:18 PM
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Rich V.
A slap in the hand - ooch. Only kidding.
EdZ just what I needed at this point and here is why. Last night after the Thunder and Lighting passed by everything was looking good so I decided to perform the final adjustment. I checked the 20eps at the moon and I was very happy with the view. I did not get a chance to look at Jupiter as the Thunder Storms rolled in.
When the storm cleared I decided to put the 8.9 Sieberts in and take a look at Betelgeuse. As expected a double image, however it was not that far away. Made several adjustments and bingo both merged together. Yes I was finished, however, not so fast as I decided to put my Mead Zoom 8x24 in for a final view and end the night a 3:30 AM. At 24mm I had double image again. What! Now I was fustrated and decided not to go to bed until the 20eps were back on the money again. That took an additional 15 minutes. I went to bed knowing that I was at least right on with 20MM and the views were beautiful.
Rich V. I appreciate your advice and staying with me on this long thread and I am trying to do the same thing from the back side which is the grasshopper side.
EDZ, I will print all of this material out so that I can absorb all that you have written and will glue a dime to a lamp post if I have to at 100 yards. I appreciate all of your advice and only hope that I can apply it.
Bill C when do I get out of grasshoper status?
Thank you
BB
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EdZ
Professor EdZ
Reged: 02/15/02
Loc: Cumberland, R I , USA42N71.4W
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Re: Tinkering Beachchairbill
[Re: beachchairbill]
#4068300 - 09/23/10 02:46 PM
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Hmmm,
once merged at a higher power, there is no logical reason why it would appear not merged at any lower power, EXCEPT
if the eyepieces chosen to perfrom the merging adjustment do not sit right when inserted into the housing and are themselves tilted causing what appears to be misalignment but is in reality sloppily fitting eyepieces.
OR
if the eyepieces chosen for the lower power do not sit right when inserted into the housing and are themselves tilted causing what appears to be misalignment but is in reality sloppily fitting eyepieces.
edz
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: Tinkering Beachchairbill
[Re: EdZ]
#4068418 - 09/23/10 03:46 PM
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EdZ is correct. If the eyepieces are made correctly and seat correctly without wobble, there is no reason collimation should get worse at lower power.
The following instructions are useful if you don't have a comparator...
When assessing mis-collimation, center the target, and then move your eyes back from the eyepieces at least several inches. By doing this, you hugely shrink the field of view and the resulting 'tunnel vision' better allows to see any offset. Here's why...
When your eyes are some distance away from the eyepieces, your field of view is defined by the very small (and out of focus) exit pupils. The farther back you move, the smaller the FOV becomes, and the more sensitive the test--up to a point.
If the eyepieces have been set correctly to your interpupillary distance, the two exit pupils will merge into one when your eyes are aligned parallel, as when looking at an infinitly distant target. The key is to make sure your eyes are nicely relaxed and thereby keep the exit pupils merged. If necessary, slightly tilt your head left or right if the exit pupils appear offset vertically.
Now when you get your target into the tiny field of view you'll have the handy reference of the (single, merged!)field circle against which to gauge offset. This makes sure that you don't inadvertently allow your eyes to swivel differentially and thereby merge the target image, for if you do so, the exit pupils will immediately appear as two overlapping circles.
Make sure in the end that you see only one field circle while the target is merged, of at least very nearly so. Don't bother starting at low power; go straight to the highest power you have.
Until I make my own comparator, I will ALWAYS do this. And with my MkII right-angle bino, I'm doing this every time I swap the 50mm and 60mm objective barrels. (But by having externally accessible knobs--three for each barrel, this takes only a couple of minutes.
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beachchairbill
Pooh-Bah
Reged: 11/06/08
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Re: Tinkering Beachchairbill
[Re: GlennLeDrew]
#4068662 - 09/23/10 05:38 PM
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Thanks Ed and Glen
I hope to be able to check everything tonight, however it looks like the clouds are moving a while. might have something to do with it as I was working in the dark. Maybe I did not set the focuser screw back properly.
Will take notes tonight step by step.
I need to print out the last couple of pages so that I can absorb all of your great ideas.
Beachchairbill
I used the 8.9mm Sieberts and then the Meade 8x24 Zoom that
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daniel_h
Carpal Tunnel
Reged: 03/08/08
Loc: VIC, Australia
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Re: Tinkering Beachchairbill
[Re: beachchairbill]
#4068790 - 09/23/10 06:42 PM
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Bill is there much diff in eyepiece size between Meade & sievert could it be they are slightly off & therefore this represents a small change in IPD?
I presume you had them sitting flat & snug.
At the Bino course at high mag it's so easy to see the diff in minutes or degrees between two diff IPD- it might look ok visually but it's 30 mins
this way & 20 mins that way when you change IPD
Bill you you rotate both sets of eyepieces in the ep holders or are you using just one ep & swapping it between barrels I amguessing you are using both ep's does rotating eps make any difference
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: Tinkering Beachchairbill
[Re: daniel_h]
#4068879 - 09/23/10 07:37 PM
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Daniel,
Small changes in IPD will cause at most only a tiny change in collimation. For example, let's assume a 2 arcminute miscollimation. If the turret could rotate a full 360 degrees, the target would trace a circle having a radius of 2' (4' diameter). So we can see that if the turret is rotated only a few degrees when making a minor IPD adjustment, the target would trace out a similarly small portion of an arc. This would always be much smaller than the existing radial offset (it would require a turret rotation of 1 radian, or 57 degrees in order to effect a rotational offset equal to the radial offset.
In case anyone has the impression that even with perfect collimation a change in IPD will cause mis-collimation, then disabuse yourself of the notion. With the light emerging from the two eyepieces mutually parallel, the only thing that is altered when changing the IPD is illmination, due to exit pupil clipping. Even if the IPD is altered so much that barely any light is getting into the eyes, the images will still be collimated.
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daniel_h
Carpal Tunnel
Reged: 03/08/08
Loc: VIC, Australia
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Re: Tinkering Beachchairbill
[Re: GlennLeDrew]
#4069081 - 09/23/10 09:17 PM
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With perfect collimation IPD changes will have no effect but I am presuming bill is aligning his glass at one ipd. 2 arc mins would show no noticeable but I am guessing if he is seeing two versions of the one star he must be off by more than 2 arc mins - that is must be closer to 20-30 arc mins though some eyes will detect smaller differences than others
Edited by daniel_h (09/23/10 09:31 PM)
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beachchairbill
Pooh-Bah
Reged: 11/06/08
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Re: Tinkering Beachchairbill
[Re: GlennLeDrew]
#4069103 - 09/23/10 09:29 PM
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Hi everyone,
Here is a double hmmmm, hmmmm.
Are you ready for this
Sometimes a double image and then sometimes not. Used Jupiter as my target and used the 20mm Meade, 8x24 Meade Zoom set at 24mm and the Siebert 8.9mm. I interchanged these eps frequently and had double images with all of them.
I also had no double vision as well and have had double vision go to single vision while looking through the ep. I did find that if I removed the eps and put them back in it would fix the double image. Sometimes it would take three times before it went back to single mode. Most double images came from the 8.9mm, however when working properly I was able to see three bands on Jupiter as well as three moons. The Harvest Moon was sharp and very very bright.
Could this be caused by loose screws and that is why most of them were hot glued?
BB
Edited by beachchairbill (09/24/10 01:01 AM)
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daniel_h
Carpal Tunnel
Reged: 03/08/08
Loc: VIC, Australia
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Re: Tinkering Beachchairbill
[Re: beachchairbill]
#4069114 - 09/23/10 09:35 PM
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Perhaps something is loose, Is the prism firmly seated are the collimation screws max'd out on in travel & so the prism is pushed as far as it can go & thus small bumps of the whole unit are shifting the prism ever slightly ( we have had this come up in class - we had to take out the prism, secure tightly & start again to get good collimation
Did you look at the prism are they cemented tight? Good luck
Edited by daniel_h (09/23/10 09:37 PM)
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Rich V.
Post Laureate
Reged: 01/02/05
Loc: Lake Tahoe area, Nevada, USA
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Re: Tinkering Beachchairbill
[Re: daniel_h]
#4069182 - 09/23/10 10:09 PM
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Bill, I don't know what to tell you; you must be certain the eyepieces are not the problem.
You must also make sure that the prism has been locked down by the pull screws after you have adjusted the push screws.
I'm copying what I said earlier in this thread about the mechanics of the prism system:
Quote:
Understand that the prism is actually resting on the tips of the push screws creating a three point suspension. The larger pull screws just hold the prism tight against those three points.
Have you made sure that the pull screws you backed off so you could turn the push screws were re-tightened? Otherwise the prism will be loose and won't hold collimation. Just checking.
If you're sure the prisms are locked down but the collimation doesn't hold between eyepiece changes then I'd suspect something is amiss with the insertion of the eyepieces in the holders.
Rich V
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Gordon Rayner
Carpal Tunnel
Reged: 03/24/07
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Re: Tinkering Beachchairbill
[Re: Rich V.]
#4069415 - 09/24/10 01:05 AM
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Bill might be able to use his expanding-mandrel style HoTech SCA laser . It can expand to eliminate any loose fit in the eyepiece holder. That might serve to confirm or refute loose eyepieces as a cause of trouble.
Interchangeable eyepieces for a binocular instrument add problems to an already (hopefully) delicately balanced and adjusted system, If it has been designed to allow tweaking the alignment in real time ( fewer than 3 minutes?) it might be worth the trouble for some, if one ignores aberration balance upsets which may/may not be objectionable.
A JTII style rhomboidal beam-combining comparator, or its equivalent, is a big help in rapid error assessment and adjustment. I lent one to the owner of a big reflecting binocular at an RTMC convention. He tweaked away a horizontal error in little time.
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KennyJ
The British Flash
Reged: 04/27/03
Loc: Lancashire UK
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Re: Tinkering Beachchairbill
[Re: Gordon Rayner]
#4069512 - 09/24/10 02:59 AM
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From where I'm sitting there seems to be too much swapping and changing of eyepieces taking place BEFORE the FACT of the instrument being TRULY COLLIMATED has been established beyond reasonable doubt .
Kenny
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EdZ
Professor EdZ
Reged: 02/15/02
Loc: Cumberland, R I , USA42N71.4W
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Re: Tinkering Beachchairbill
[Re: KennyJ]
#4069626 - 09/24/10 06:19 AM
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Quote:
From where I'm sitting there seems to be too much swapping and changing of eyepieces taking place BEFORE the FACT of the instrument being TRULY COLLIMATED has been established beyond reasonable doubt .
Kenny
I agree.
The simplest method is to align at the highest power. It is a given that the eyepiece used must fit properly and not induce any uncertainty. Once achieved at highest power, it will be properly adjusted for any and all lower powers.
I've read so many potential places for some error in the process here, that I'm not sure any description could be interpreted by the readers here to conclude what is going on.
edz
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beachchairbill
Pooh-Bah
Reged: 11/06/08
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Re: Tinkering Beachchairbill
[Re: EdZ]
#4070832 - 09/24/10 04:34 PM
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EDZ,
I just completed your 100 yard dime test today and will report on it later. Just received an emergency phone call, must go.
Beachchairbill
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: Tinkering Beachchairbill
[Re: beachchairbill]
#4070937 - 09/24/10 05:10 PM
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BB,
Be aware that the parallax at 100 yards is several arcminutes. For instance, if we take the objective spacing as 125mm, the parallax would be 4.7 arcminutes. At, say, 40X, the apparent separation would then be 188 arcminutes, or 3.1 degrees--a rather large displacement that you absolutely would NOT want to collimate out. This is why collimation as done in this fashion is best performed with a really distant target, at optical infinity being best, naturally.
***Added in edit***
If you were to collimate on a 100 yard distant target until the image nicely merged, then when focused on the sky the images would be significantly divergent, requiring your eyes go walleyed in a Marty Feldman-esque manner.
Edited by GlennLeDrew (09/24/10 05:13 PM)
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EdZ
Professor EdZ
Reged: 02/15/02
Loc: Cumberland, R I , USA42N71.4W
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Re: Tinkering Beachchairbill
[Re: GlennLeDrew]
#4070982 - 09/24/10 05:34 PM
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Glenn,
have you ever had a pair of 100mm binoculars that you could NOT use to view an object at 100yd.? I haven't.
I don't disagree that aligning images on stars is the better method. I perform ALL conditional alignment on stars. But I will also add, all binoculars I've ever used 70,80,85 and 100mm, when used to observe at 100yds a USAF target as small as a 4 arcseconds, are perfectly merged.
edz
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: Tinkering Beachchairbill
[Re: EdZ]
#4071202 - 09/24/10 07:31 PM
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EdZ,
They were nicely merged because at the large parallaxes engendered by close target distances, the eye can easily 'cross' to accommodate for the displacement. For example, look at any stereo microscope. Their optical assemblies necessarily have to converge dramatically due to the really near subject distance, the barrels being tilted with respect to each other by at least near to 10 degrees.
For that matter, we've evolved to be able to cross our eyes even more than this when examining any very close object. At 10" distance and eye separation of 2.5", the parallax is over 14 degrees.
So out of a 50+ deg. AFoV, a few degrees of lateral inward displacement poses no difficulty whatsoever, and indeed merging is so automatic the observer will probably not be aware his eyes are crossing to any degree whatsoever.
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daniel_h
Carpal Tunnel
Reged: 03/08/08
Loc: VIC, Australia
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Re: Tinkering Beachchairbill
[Re: GlennLeDrew]
#4071228 - 09/24/10 07:47 PM
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I agree glen 100 yards isn't a big distance perhaps bill could look how much focused travel he has between 100 yards & infinity. If it's close he will be alright if not he may need a more distant target
Now if he get get some parallel light rays to test on he will be cooking with gas ( as we say here in Oz or sweetest if you're in OK)
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beachchairbill
Pooh-Bah
Reged: 11/06/08
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Re: Tinkering Beachchairbill
[Re: daniel_h]
#4071394 - 09/24/10 09:28 PM
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Hi everyone,
At mid day today, I measured off 100 yards from the front of my building which wound up right in front of a NYC Greenway pole. I glued the silver dime to the pole just above eye level and went back to my ruled off starting point.
For those of you who are interested the date on the dime was 1989 R with a picture of Kenny on the face.
After setting up the GBT, I used my Meade 4000 Series 20mm eps or 26.5x for my first view. They were spot on with no double image. I repeated this process at 15mm or 35.3x, 10mm or 53x and again at 8mm or 66.2x with no double images.
I then used the Siebert 8.9mm eps and to my surprise I did see a double vertical where the dimes over lapped each other. Kenny you devil. This did not happen again as I repeated this process several times.
If I pulled my eyes away from the eps about 4 to 6 inches I would see double images with the right side being down and the left side being up. Not sure if this means anything.
I will set up for viewing tonight and see if their are any changes.
Kenny only in fun.
Beachchairbill
Beachchairbill
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