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scottjan
member
Reged: 12/03/06
Posts: 91
Loc: Tullahoma,TN
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I am looking at an Olympus OM-1
The camera has MD on the lower front any idea what MD
means?
Any help Thanks
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Scott
Celestron C8newt
Meade 70 AZ
60mm Bushnell Refractor
15x70,7x35 binos
32,20,12.5 Plossl,4mm uo abbe,42mm 2"gso superview
17mm Hyperion,8mm TMB
spc900nc,OM-1
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Happy-Idiot
Carpal Tunnel
Reged: 04/06/06
Posts: 1791
Loc: 3rd Rock
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OM-1MD (MD standing for Motor Drive), on which a motor drive can be attached with no modification.
Brian
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Brian
A small scope that gets used often is a better investment than a big scope that stays in the closet.
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scottjan
member
Reged: 12/03/06
Posts: 91
Loc: Tullahoma,TN
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Thanks Brian
I thought that might be it but just wanted a second opinion
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Scott
Celestron C8newt
Meade 70 AZ
60mm Bushnell Refractor
15x70,7x35 binos
32,20,12.5 Plossl,4mm uo abbe,42mm 2"gso superview
17mm Hyperion,8mm TMB
spc900nc,OM-1
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JBull
sage
Reged: 10/10/05
Posts: 401
Loc: Dallas, TX
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Another option for focus besides stiletto is to use another OM-1 body with a small clipping of film on the film rail (with the film door open or removed and shutter held open). Since the OM-1 bodies have become less expensive you could get two of them and use the better one for photography and the lesser one for focus. It is possible to tape a small clipping of film in place on the film rail and use the edge of the film as a "knife edge" focuser. Then once you have focus remove the camera and insert your imaging camera. It actually works but requires a willingness to tinker and experiment.
There are several web pages that explain this and here is the best one IMO:
http://www.howardedin.com/articles/knife-edge.html
Just an idea that could save you some money and also give you some flexibility both in terms of an extra camera and ability to adjust and refine your focus mechanism.
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Jeff Bullard
Dallas, TX
Check observing forecast for astronomers anywhere in the world:
http://astroforecast.org:8080
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Mopman
sage
Reged: 10/14/06
Posts: 283
Loc: Richland, WA, USA
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Hi Jeff, Have you tried this (using a 2nd camera body to build a knife edge focuser)? Is there any reason it would not work on medium format(Mamiya 645) camera? Thanks! Mopman
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JBull
sage
Reged: 10/10/05
Posts: 401
Loc: Dallas, TX
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I've used two different methods for focus: hartmann mask and a homemade knife edge. I used the method above to calibrate the knife edge focuser. Knife edge focusers work well and its actually pretty neat to see the star blink out as you hit the exact focus "sweet spot".
You could test this with your own camera. Just attach the camera to scope as normal and point it at a star. Open the camera back and tape a razor blade or other suitable sharp, flat edge to the film rails exactly in place where the film would normally be and use bulb mode to hold the shutter open.
It works best with two parallel blades w/ about 3-4 mm gap between them. You will be looking at the star through the 4 mm slit between the blades with your head about 6 to 12 inches behind the camera. Your eyeball will not be at the focal plane of the OTA so the star will appear out of focus and as a disk.
Keep looking at the star while you turn the focus knob. As you approach the focal point you will see the the star blink away and disappear. If the disk disappears slowly and from only one side, that means you are not quite at the focal point. If focus is slightly off then the disk will only partially disappear leaving a half-disk. Use the fine focus knob to adjust focus so the star's disk completely and instantly blinks away. this is the point where the blade is right at the focal point. If you have another camera then lock the focus and switch cameras.
I don't know how well it works with other specific cameras. It only depends on the ability to secure blades or some other sharp and very flat surface to the _exact_ place where the film should be _while the camera back is open_. Its fun to try anyway.
There is a pretty good description and diagram of how this works here about half way down the page
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Jeff Bullard
Dallas, TX
Check observing forecast for astronomers anywhere in the world:
http://astroforecast.org:8080
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Mopman
sage
Reged: 10/14/06
Posts: 283
Loc: Richland, WA, USA
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Thanks Jeff!  Mopman
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