Click here if you are having trouble logging into the forums
Privacy Policy |
Please read our Terms
of Service | Signup and
Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User
mtb54703
sage
Reged: 11/12/08
Posts: 204
Loc: Eau Claire, WI
|
|
I purchased a pair of GT100/45s about year ago. Of course one of the first things I did was try and see how much magnification I could get out of them with a pair of 9mm EPs. I know others have had success with shorter length EPs but I couldn't get the images to merge. For the most part I thought it might just be me as even using the OEM EPs or my 19mm extra flat field EPs it would take a second or two for my slow brain to produce a single image.
One night a couple months back I was playing with the binos out in my driveway. The 19mm extra flat EPs have the typical security groove. My fix was to wrap all the way around the very top of the EP barrel with a single layer of .003" teflon tape. The EP then required just a little push to seat into the focuser. That night I hadn't pushed the right EP in completely so it had a little slop. I don't recall what I was looking at but I went to adjust the focus on the right barrel a bit and when I bumped the EP I noticed the images separate in my view. I needed to push the EP in the direction of 10 o'clock to get the images to come back together. Then I look away from the binos for a bit. When I returned to looking through the binos while still lightly pressing against the EP I found that it didn't take the 1-2 seconds for the images to merge - I instantly saw one image when I looked into the binos. I started playing around with the other EPs with similar results. I think I had finally proved to myself that the binoculars where not quite collimated.
For the record I did try all the tricks (way back originally and now), such as rotating the EP while holding the focuser - none of those made any difference.
I contacted Zach at Garrett Optical and he said no problem - they would check them. But he also offered to send me some instructions on how to do the collimation myself. He said the worst I could do would be to make them worse and in that case they would still correct them for me under warranty.
I received the instructions and decided to give it a try. I took one turret off and saw how nicely the collimation push/pull screws were secured I decided I didn't want to attempt it myself after all. I finally got around to packing them back into their original shipping containers and sent off to Zach.
I did take some pictures of the "innerds" - will post them once I find where I copied them to. Some might find them interesting. I did measure the prism aperture when I had the one turret off but I didn't write it down - arg!
They should be back soon - will need to follow up when they do arrive.
Thinking about the prism aperture - I'm curious about the new 100mm binos from Orion with respect to that. I recall some discussions about the aperture on the GT100s limiting the longest EP that made sense to use as well as prism cut off in general. I've also noticed the GT100s do present some flaring (I think would be the correct term) when a bright star is just outside the field of view.
--------------------
18" F/4.11 AstroSystems Telekit under construction
Meade 12" Lightbridge
Garrett 100mm F/5.3 45º Binocular Telescope
Vixen Foresta 7x50
Chippewa Valley Astronomical Society
|
Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1393
Loc: Carson Valley, Nevada, USA
|
|
I would hope that after Cory is done with the GTs they'll be in fine shape, Mike.
It's kind of a hassle removing the turret, making an adjustment and then replacing the turret to check if you went the right way or not. With a little patience, though, collimation can be done just fine in the comfort of your home. I look forward to your pictures.
I've collimated a couple of Miyauchi Saturn IIIs which I'm pretty sure are just like your GTs. It doesn't even take half an hour once you're familiar with the operation. At least you know you can give it a go if you need to!
If there's any chance you could scan a copy of the collimation instructions and PM them to me I'd be greatly obliged. I'm curious if they copied Miya's prism tilt convention exactly; I suspect that they did.
Good luck,
Rich V
--------------------
Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
|
beachchairbill
professor emeritus
Reged: 11/06/08
Posts: 505
|
|
MTB,
Beachchairbill will be very interested in seeing the pictures of the inside of the GBT barrells to see if they look any thing like the ones that I have.
Also, would not turning bothe barrels closer to your nose remove the double image. I have the same problem when the barrels are spread two far apart?.
Please tell me how you took the pictures of the inside of the barrels as I would love to show my cracked inner tube to everyone.
Looks like Zach is going to receive a call from me as well.
Beachchaitbill
|
mtb54703
sage
Reged: 11/12/08
Posts: 204
Loc: Eau Claire, WI
|
|
Quote:
MTB,
Beachchairbill will be very interested in seeing the pictures of the inside of the GBT barrells to see if they look any thing like the ones that I have.
Going to disappoint you on that one - I only took off the turret cover - there's was still a prism (or two) before the barrel.
Quote:
Also, would not turning bothe barrels closer to your nose remove the double image. I have the same problem when the barrels are spread two far apart?.
I definitely played with the IPD as well.
Quote:
Please tell me how you took the pictures of the inside of the barrels as I would love to show my cracked inner tube to everyone.
Ouch. I wouldn't think displaying to the world would help much in getting it fixed, rather it would be better to just contact Zach/Gary and let them take care of it.
--------------------
18" F/4.11 AstroSystems Telekit under construction
Meade 12" Lightbridge
Garrett 100mm F/5.3 45º Binocular Telescope
Vixen Foresta 7x50
Chippewa Valley Astronomical Society
|
mtb54703
sage
Reged: 11/12/08
Posts: 204
Loc: Eau Claire, WI
|
|
Found the picture I took of the binos with the turret covers removed. My intention was to do a photo essay of the collimation process, but as I said, the collimation screws looks so locked down I didn't want to mess them. I thought I had taken a picture of the back side of the turrent as well (there was a prism attached there to it) but evidently I didn't before I re-assembled.
Now the next thing someone is going to ask me is if I measured the opening that is seen. I did, I wrote it down, but I can't find the notes. For some reason .789 comes to mind. But there was also a bracket around the prism on the turret, and it to had a similar size hole, as well as the that can be seen looking down the focuser hole. I guess the one that matters is the one seen in the picture since its probably the first one the light cone passes through.
--------------------
18" F/4.11 AstroSystems Telekit under construction
Meade 12" Lightbridge
Garrett 100mm F/5.3 45º Binocular Telescope
Vixen Foresta 7x50
Chippewa Valley Astronomical Society
Edited by mtb54703 (11/04/09 07:43 PM)
|
pcad
Carpal Tunnel
Reged: 01/17/05
Posts: 1767
Loc: Connecticut
|
|
I may be incorrect, but I think the turret prism is similar to a rhomboid prism that just shifts the image laterally. The image erection prisms are inside the 45° housing.
The big binos with the "tuna fish can" under each ocular have the image erection prisms in the "can".
--------------------
Peter
Telescopes 25 - 318 mm
Binoculars 15 - 88 mm
Microscope 50x - 1000x
|
Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1393
Loc: Carson Valley, Nevada, USA
|
|
To show the similarity, here's a picture of the Miya version (note there is no goop on the screws):
--------------------
Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
|
Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1393
Loc: Carson Valley, Nevada, USA
|
|
Here's the rhomboid turret prism:
--------------------
Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
|
Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1393
Loc: Carson Valley, Nevada, USA
|
|
Quote:
I may be incorrect, but I think the turret prism is similar to a rhomboid prism that just shifts the image laterally. The image erection prisms are inside the 45° housing.
The big binos with the "tuna fish can" under each ocular have the image erection prisms in the "can".
I think you're correct, Peter, the Miya Saturn, Galaxy and clones use a Schmidt roof prism with rhomboid turrets. The Saturn II is different, probably using a semipenta prism and Porro II turrets (the "tuna can")  .
Rich V
--------------------
Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
|
pcad
Carpal Tunnel
Reged: 01/17/05
Posts: 1767
Loc: Connecticut
|
|
Phase corrected Schmidt roof prisms? Sorry, couldn't help myself. 
--------------------
Peter
Telescopes 25 - 318 mm
Binoculars 15 - 88 mm
Microscope 50x - 1000x
|
pcad
Carpal Tunnel
Reged: 01/17/05
Posts: 1767
Loc: Connecticut
|
|
Something else bothers me about the Schmidt prisms. I don't think a Schmidt prism alone could account for the shift medially of the optical axis. I'm guessing there's another prism with the Schmidt roof prism in the 45 deg housing. Perhaps another rhomboid or something.
--------------------
Peter
Telescopes 25 - 318 mm
Binoculars 15 - 88 mm
Microscope 50x - 1000x
|
Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1393
Loc: Carson Valley, Nevada, USA
|
|
Quote:
Something else bothers me about the Schmidt prisms. I don't think a Schmidt prism alone could account for the shift medially of the optical axis. I'm guessing there's another prism with the Schmidt roof prism in the 45 deg housing. Perhaps another rhomboid or something.
Peter, the 45° Schmidt roof flips the image 180°, as far as I can tell.
Take a look at these prism ray images; the 45° Schmidt roof is about 3/4 of the way down the page. I don't profess to be a prism expert!
http://www.tecplusplus.de/ManualLu/prisms.htm
Rich V
--------------------
Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
|
mtb54703
sage
Reged: 11/12/08
Posts: 204
Loc: Eau Claire, WI
|
|
Quote:
Here's the rhomboid turret prism:
If memory serves me right - this photo looks very similar to the underside of the GT100 turret.
--------------------
18" F/4.11 AstroSystems Telekit under construction
Meade 12" Lightbridge
Garrett 100mm F/5.3 45º Binocular Telescope
Vixen Foresta 7x50
Chippewa Valley Astronomical Society
|
pcad
Carpal Tunnel
Reged: 01/17/05
Posts: 1767
Loc: Connecticut
|
|
Thanks Rich, I had lost the link to that prism page. Although it's not noted on that page, 45 deg Schmidt roof prisms provide full image reversal so that it provides a correct image through the eyepiece. It bends the optic axis by 45 deg, but doesn't shift it laterally. Something else is doing that.
--------------------
Peter
Telescopes 25 - 318 mm
Binoculars 15 - 88 mm
Microscope 50x - 1000x
|
Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1393
Loc: Carson Valley, Nevada, USA
|
|
I understand what you were referring to now, Peter, there must be an additional prism making that inward shift ahead of the 45°. Perhaps another rhomb? That's a lot of reflections!
I sure wish there was more information available about these binoculars. It would be great so see one in pieces spread out on a table! I sure don't want to go any deeper into them than removing a turret and collimating, personally.
Rich V
--------------------
Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
|
beachchairbill
professor emeritus
Reged: 11/06/08
Posts: 505
|
|
Rich V,
Goop on the screws is not so bad, I found it on the stop lenses as well. I cleaned that mess up with Q-Tips.
MTB,
Thanks for the great pictures and you were right to stop at that point. I will call Zach by the end of the week and see what he has to say about my little crack as well.
Beachchairbill
|
Michael Cox
member
Reged: 12/24/08
Posts: 49
Loc: Barstow, CA
|
|
MTB:
I also have a GT100/45 bino that I purchased this past April from Garrett Optical so that my wife and I could have a quick cool down scope. My wife can not seem to see through my single EPs on my NexStar's so this bino was an attempt to allow her to see and enjoy some of the night sky. Since day one, I have had problems with the image showing a double stacked image and thought the problem was EP related. Since I also have several pairs of Televue Plossl EPs I gave them a try thinking they might correct the double image issue. Like you I also rotated the EPs to see if it would correct the problem without any success. Tonight after reading your post, I made one more attempt to use this bino and looked at both the Moon as well as Jupiter and each image appeared as a double image stacked one on top of each other. The only way to correct it was to push on the EP and then both images would become a single image once again.
Based on reading your problems, I also believe I have a collimation issue and will be calling Garrett Optical tomorrow to request service for my bino.
I am so glad that I am a member of Cloudy Nights, my education is ongoing and it is great to have others who have already gone through the same thing share their experience with others.
Michael
--------------------
Michael Cox
Member High Desert Astronomical Society
Nexstar 8SE (For At Home Viewing)
NexStar 6SE (Grab & Go)
|
mtb54703
sage
Reged: 11/12/08
Posts: 204
Loc: Eau Claire, WI
|
|
Just curious if others with more experience with binos feel that my assesement in determining mis-collimation make sense?
BeachchairBill asked about the IPD distance. Tilting one EP is in essence changing the IPD ever so slightly, but it could also be better aligning the EP with the light cone correct? This is not something that can be done on binos with fixed EPs, so it seems like a plausible test to me.
Also, does it make sense that what I believe was only a slight mis-collimation was more apparent when viewing the night sky than during daytime use?
--------------------
18" F/4.11 AstroSystems Telekit under construction
Meade 12" Lightbridge
Garrett 100mm F/5.3 45º Binocular Telescope
Vixen Foresta 7x50
Chippewa Valley Astronomical Society
|
EdZ
Professor EdZ
Reged: 02/15/02
Posts: 14728
Loc: Cumberland, R I , USA42N71.4W
|
|
I don't know about your assessments, or the severity of any misalignments, but
Alignment on stars will ALWAYS show error more readily than anything viewed in daytime. Star alignment is the most critical test you can give a binocular. At the powers achievable in interchangable eyepiece binoculars, there is very very little room for any misalignment at all. In these binoculars, allowable misalignment will not be measured in arcminutes, it will be measured in arcseconds.
edz
--------------------
Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
|
BillC
on a new path
Reged: 06/04/04
Posts: 2237
Loc: Washington, USA
|
|
"allowable misalignment will not be measured in arcminutes, it will be measured in arcseconds."
Slowly but surely the short, fat guy is losing his place as resident curmudgeon. Oh, well, "they say that all good things must end someday . . .
Chad & jeremy, 1964
Cheers,
Bill
--------------------
William J. Cook, Chief Opticalman, USNR-Ret.
Founding Editor, Amateur Telescope Making Journal
20-year vet. of Captain's Nautical Supplies, Optics Dept. Mgr.
Optics Machanic, WG11-3306, Ft. Lewis, Tacoma,WA
Yata, Yata, Yata . . .
|
|
10 registered and 18 anonymous users are browsing this forum.
Moderator: EdZ
Print Thread
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Thread views: 363
|
|
|
|
|
|
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
[Re: 