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Shutter speed question...

 
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troublemaker



Joined: 24 Nov 2003
Posts: 715
Location: So Cal

PostPosted: Wed Aug 25, 2004 12:25 am    Post subject: Reply with quote

I have a simple question about my press shutter speeds and thier proper or intended settings. Should I be using my shutters set at the designated settings, like 1/25 or 1/100 etc..., or will they function properly when set inbetween so as to obtain a 1/30 or 1/125 and so on, thus make the difference up by adjusting the aperture accordingly.
The shutters in question would be the basic press Kodak, Wollensak/Graphex, and Century Graphex shutters.
It seems like a silly question, but I am wondering about the springs and how the mechanisms are meant to function properly.
Regards,
Stephen
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Dan Fromm



Joined: 14 May 2001
Posts: 2144
Location: New Jersey

PostPosted: Wed Aug 25, 2004 1:15 am    Post subject: Reply with quote

Quote:

On 2004-08-24 17:25, troublemaker wrote:
I have a simple question about my press shutter speeds and thier proper or intended settings. Should I be using my shutters set at the designated settings, like 1/25 or 1/100 etc..., or will they function properly when set inbetween so as to obtain a 1/30 or 1/125 and so on, thus make the difference up by adjusting the aperture accordingly.
The shutters in question would be the basic press Kodak, Wollensak/Graphex, and Century Graphex shutters.
It seems like a silly question, but I am wondering about the springs and how the mechanisms are meant to function properly.
Regards,
Stephen
Stephen, I think you're misusing the words "press shutter." When most of us say "press shutter," we mean a self-cocking shutter. With them, pressing the shutter trip lever cocks the shutter and then fires it. One press on the cable release does it all. Examples include the Copal and Prontor Press shutters used on many Polaroid close-up cameras, e.g., MP-3, MP-4, CU-5, Ilex Universal shutters, Alphax, and Betax. The Century shutter (not Century Graphex) is another. All of the press shutters I've used don't like being set to speeds between the marked ones.

The shutters you've asked about, Kodak (= Supermatic, I think), Graphex/Rapax (they are the same), and others you didn't ask about such as Ilex Acme, Compur Rapid, Synchro Compur, Seikosha, ... are sometimes called cock and shoot shutters. They have one lever to cock, another to fire the shutter. Old Compurs can be set between the marked speeds to get intermediate speeds, as far as I know the others can't. When in doubt, stick to the marked and click-stopped (sometimes) speeds and tune the aperture to get the right exposure.

FWIW, there's not much difference between 1/25 (40 milliseconds) and 1/30 (33 ms) so there's no reason to be anal about matching exactly what the lightmeter says.

Cheers,

Dan
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glennfromwy



Joined: 29 Nov 2001
Posts: 903
Location: S.W. Wyoming

PostPosted: Wed Aug 25, 2004 2:14 am    Post subject: Reply with quote

These shutters are rarely accurate enough to make a difference, anyway.
Trying to get intermediate speeds by setting them between the marked speeds can result in wildly fluctuating and wholly unpredictable results. I've tested it with my shutter speed tester.

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Glenn

"Wyoming - Where everybody is somebody else's weirdo"
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jsiladi



Joined: 20 Aug 2004
Posts: 34
Location: midwest

PostPosted: Wed Aug 25, 2004 4:22 am    Post subject: Reply with quote

Correct... Partly.. Shutters that haven't been serviced are rarely acurate at any speed. The lower speeds however can be brought into line with a clean and adjust as they rely on a timing mechanism. Rarely though will the upper speeds (without replacing parts), which rely less on the timing mechanism and more on the main spring, 1/200, 1/400, etc be acurate.. Some suggest that they never were accurate. The thing to remember is that the shutter spring always runs at about the same speed. What you are doing by changing shutter speeds is placing resistance to that speed into the equation..

A good way to proceed is to get used to taking photos with your particular camera and then stick to it.. As long as your shutter isn't sticking, it will probably operate consitantly. That is, if you decide that your results always appear a stop to dark, open up a stop when you shoot.. It's all a matter of practice and having fun (that is what photography is, isn't it?? )
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troublemaker



Joined: 24 Nov 2003
Posts: 715
Location: So Cal

PostPosted: Thu Aug 26, 2004 7:01 am    Post subject: Reply with quote

Yes...fun. That is how this all got started if I recall...
I took the 4x5 out about town today and shot a dozen exposures at the marked settings and it worked well. The light meter settings was a habit I got into when the fun began...
Now that I rarely use the meter anymore I have been more inclined to pick the speed and then the aperture unless precise and supported focussing is necesarry. Thus I began to wonder about the shutter speed dials, and thought I remembered someone mentioning proper function here once.
Thanks for the instructional discourse concerning "press shutters". I do have two Century press shutters, and they seemed bomb proof until one went down on the slow speeds this last trip (not to mention a tripod destroyed in granite talus, and a bent focussing hood. nothing a bit of electrical tape and J.B. Weld didn't take care of.)
As far as exposure tollerances, everything I have been doing, except for mistakes and lack of experience, has been printable, some excellent, some salvageable, the bulk lying somewhere in between.
Yes, it has been a fun learning experience, and I am becoming comfortable with my equipment.
Regards,
Stephen
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Les



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

PostPosted: Thu Aug 26, 2004 1:31 pm    Post subject: Reply with quote

While the question has been answered, I will add a bit more.

Inside the shutter there's a pin that rides in an ever widening slot...the slower speeds get the widest end.

However this slot is not tappered, it's stepped, so that the width is constant until you get to the next speed, then widens further. At best, setting the shutter at intermediate setting will get you the same speed, at worst, you'll be "on the step" and get variable speeds.

But as was posted above, the variance between actual vs theoretical speeds is greater than anything you could get trying to find the inbetween speed.
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troublemaker



Joined: 24 Nov 2003
Posts: 715
Location: So Cal

PostPosted: Thu Aug 26, 2004 5:31 pm    Post subject: Reply with quote

Thanks Les,
I believe that is about what I had read here that left me wondering.
Stephen
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