old shutter speed settings

[Scott Kathe]

I've just had a CLA on a Schneider 90mm Angulon in a Synchro-Compur press shutter. The shutter speed scale is the old type: 1, 2, 5, 10, 25, 50, 100, 250, 500. What do I do when I want to set the shutter speed at 4, 8, 15, 30, 60, and 125? For black and white negatives the shutter speed isn't as important but for color transparencies...

Thanks,

Scott

[Calamity Jane]

What do you use for an exposure meter? Most have some kind of "circular calculator" with f-stop against speed, in which case you can read the f stop for whatever shutter speeds you have available.

[Richard Schlesinger]

The differences for B&W are too small to worry about. If they gave you a chart (if you paid for CLA you should have gotten one) of the actual shutter speeds, that's what you should use. For color, you should have the shutter tested and have a chart of the actual speeds, almost never exactly as indicated.

[Scott Kathe]

Hi Jane,

I'm using a Nikon N-80 with the f1.8 50mm Nikkor lens as a meter. I can set the N-80 on shutter priority and adjust the aperture accordingly but I'm used to doing things in manual mode. I'm doing large format on a shoestring. I built a Bender 4x5 and in hindsight I may have been better off with a Speed or Crown Graphic or saved for a Shen Hao. BUT the Bender was a blast to build and I have no qualms about modifying it!

What advantage does a light meter have over a camera with center, spot and matrix metering, other than weight?

Scott

[Kevin Crisp]

As has been said, the speeds are not going to be so precise on that shutter that you can even begin by assuming that 1/25th is exactly 1/25th. Even if the speeds were precisely correct, the differences between what is now the more modern shutter speed sequence and those marked speeds is very small, within the range of error on many modern shutters that have been in use for a year or two. (20% or less on most of them.) All that aside, there are some inexpensive hand meters which have both sets of speeds on them. The Weston V, for example, is a fine vintage meter which has the old and new sequences on its dial. You could take the dial off a non-working example (maybe $9 on E**y) and carry that with you. Or just make the adjustment on the aperture scale of the lens, since it is only 1/4 stop or less. Or take a Sharpie and put a small dot on the aperture scale which would make up for the small differential in shutter speeds between your desired speed and the marked speed. All this assumes that the shutter speeds are absolutely correct -- and consistent -- which I am pretty sure is not the case, despite the CLA. I think you'll find that 1/100th is running more like 1/75th to 1/80th, and I have yet to see one where 1/250th or 1/500th are accurate. Relatively faster, to be sure, but much more than 20% slow most of the time.

[Neal Shields]

I can tell you what you can't do. That is set your dial on the shutter between speeds. It doesn't hurt anything but you will get one or the other, not something in between.

If you take an old shutter apart you will find that the speeds are set by regulating the travel on an arm that moves when the shutter is fired. It rests on a set of steps cut into the front ring. If they weren't steps but just a continious ramp you could have continiously variable speeds, but they arn't.

I seen this on every mechanical shutter I have taken apart and always wondered why they did it that way.

Anybody know or care to guess?

Neal

[ronald lamarsh]

The actual differences in times are best calculated in milli sec. 1/60 =16ms 1/50 = 20ms and so on 1/8= 125ms and 1/5 = 200ms so there can be some major differences . the difference between 1/8 and 1/5 is 75ms which is about 60% 1/60 and 1/50 difference is only 25% . I actually calculated these all out and made appropriate marks on my sone dial. For B&W I'd say no big deal just use the next longer time. I don't do color so I can't comment but it seems that once you get under the 1/30 sec range the differences could be significant enough to warrant some compensation.

[John_4185]

The old settings were as rational as the new settings.

5, 10, 25, 50, 100
----------------------
4, 15, 30, 60, 125

In each case, the difference is about 1/4 a stop. It seems unlikely that the combined errors in the shutter, meter and operator error in metering is going to challenge the difference. Bracket 1/2 stops and be happy.

[Donald Qualls]

"I seen this on every mechanical shutter I have taken apart and always wondered why they did it that way."

Because it's impossible to calibrate the ramp. The steps are easy -- a light tap on a punch or a few strokes with a file, and the speed is just right, even if the setting isn't right in the bottom of the click stop. With the ramp, you'd never know if it was right or not, and it'd be a lot more expensive to try to get it that way in the first place (ask an old, pre-CNC machinist about cutting a spiral cam -- unless your ears are easily offended).

[Hening Bettermann]

You might build yourself a dial wheel, like this
www.largeformatphotography.info/misc/zswheel.pdf (http://www.largeformatphotography.info/misc/zswheel.pdf)