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Speed shutter fluctuations

 
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wolvertone



Joined: 27 Nov 2001
Posts: 31
Location: Southern USA

PostPosted: Sun Dec 23, 2001 7:25 am    Post subject: Reply with quote

After stripping the camera down to mahogany
and brass, polishing and complete assembly, I went about calibrating the focal shutter.

I have the shutter that goes from "0" to "D" and has a second dial going from 1 to 6 in half step increments.

I am using a Calumet shutter tester and have used it on other cameras, so I have experience with the ups and downs of this unit.

What I am having a problem with is getting the shutter speeds to be correct across the board. Meaning, I can get 1000 bang on, but it gets progressivly worse as you choose slower speeds. If I calibrate 125/th, 500 and 1000 are out. First I was over tensioning the spring and it was causing the lower roller to bind when going to "D" which gave false readings. I have corrected this by starting slow and working my way up in tension.

I have found that an overall compromise of shutter speeds is how I'll use it for now. 30th to 500th are close enough (at worse about 1/3 to 1/2 stop off) I'm only shooting b&w so I have some latitude. If I shoot slide, I'll use my Crown, as the leaf shutter is quite accurate.

I bought this camera after having the Crown, so I could get some inexpensive barrel lenses and use the F/P shutter.

QUESTIONS:
Does anybody have any insight as to what could be done to get this shutter more accurate? Do I need to order a new spring? Is this as good as it gets?

Sorry about the lengthy post, but I didn't want to get the obvious answers back like "you need to tension the spring".

Thanks,
Steve


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Les



Joined: 09 May 2001
Posts: 2682
Location: Detroit, MI

PostPosted: Sun Dec 23, 2001 2:16 pm    Post subject: Reply with quote

You are trying to hard to get antique equipment to peform to 21st century standards that I don't believe they could do when they were knew, and as you found, it will only lead you to frustration and male pattern baldness.

If you can get speeds from 30th to 500th to be within a 1/3 that is fantastic!

Don't expect a 50 year old war horse to perform like a 3 yearold filly.

Even with chrome I'd have a tendancy err on the slow side. Those cheap barrel lenses will be uncoated and depending on which ones you'll get you can loose up to 2/3 of a stop in internal reflection.

My testing (granted a bit crude) shows that my uncoated 24' Artar with 8 air to glass surfaces loses about 2/3 stop compared to my coated tessar which has 6.

If you had access to a stobe type tester you'll find that for any particular selected shutter speed, the true speed will vary from the top of the film to the bottom.

There was a popular reflex camera out of Europe, I believe it was an Ica model that didn't regulate the Focal plane shutter very well. It started out accurate, but interia caused it to speed up by the end.

Fortunatly, film of the time was blue sensitive and over exposed the sky creating a blank, bald, area of the print. The two mistakes canceled each other out, and the result were some very pleasing photographs!
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wolvertone



Joined: 27 Nov 2001
Posts: 31
Location: Southern USA

PostPosted: Sun Dec 23, 2001 5:47 pm    Post subject: Reply with quote

I have a drum strobe like the one on Steve Grime's website (Thanks Steve!). I used it for my Leica.

I agree with you that the curtains will perform differently at one end vs the other. Part of the romance and fun is understanding the "character" of these old gals and using it to your advantage.

It's cool that when you know a camera personally, no one else can get it to perform like you.

Just wanted some feedback and to get a reality check that I WAS being a bit anal!!


Thanks,
Steve
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