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View Full Version : Why do lf lenses have inbuilt shutters?



jm51
6-Jan-2012, 21:06
I know that there must be a good reason or people wouldn't spend on getting barrel lenses adapted.

I can understand the advantage with MF lenses but with LF it would seem more logical to me to have a shutter at the camera front then add a barrel lens.

What am I missing?

Leigh
6-Jan-2012, 21:11
It has nothing to do with the shutter.

The aperture diaphragm must be at a specific location relative to the optical design of the lens (roughly in the middle).
It makes sense to put the shutter and everything else at the same location in a single package.

An exception to the single-package approach is the Sinar DB series of lenses and shutters.
The aperture diaphragm is inside the lens at the required position, but the shutter is a separate assembly that sits behind the lens.

- Leigh

Daniel Stone
6-Jan-2012, 21:18
Leigh said it right. The APERTURE(diaphragm) most be positioned correctly, but the shutter doesn't have to be in the middle, or at the same point as the aperture blades.

The Sinar shutter system(DB mounted lenses) have the shutter unit mounted behind the lens. Nice in some ways, since all your shutter speeds for each separate lens are the same, where as in separate shutters(individually mounted shutters in each separate lens), you can have varying levels of accuracy in timing.

-Dan

jm51
6-Jan-2012, 21:31
Thanks for the speedy replies.
Thanks for the speedy replies.

Kuzano
6-Jan-2012, 22:24
It beats holding a hat over the front of the lens....

I never could do 1/250th or faster with the hat.:p

Brian C. Miller
6-Jan-2012, 23:15
Graflex made some of their cameras with seperate shutters. These shutters were made from cloth with variously sized slits for the exposure speeds, but I think that the Super Speed Graphic used a leaf shutter. Anyways, the shutter mechanism introduced a certain amount of vibration in the camera, while a built-in leaf shutter has much less vibration. Also, leaf shutters are typically still operational after all these decades.

There are various external shutters, such as the Packard, and there's another slit-cloth type which was made in the late 1800's, 1900's, but I can't remember the name right off. Some of the members have restored them to working order. Packard shutters are still made, and you can buy them new.

BrianShaw
6-Jan-2012, 23:26
Thornton Pickard is what you are tring to recall. Unlike Graflex the T-P shutters only had 1 slit and used spring tensioons for varying the speed.

BrianShaw
6-Jan-2012, 23:27
Thornton Pickard is what you are tryng to recall. Unlike Graflex the T-P shutters only had 1 slit and used spring tensioons for varying the speed.

Jim Galli
6-Jan-2012, 23:34
History has much to do with it. Plus the pure physicality of the sizes. Things started out in barrels with slow films. Primitive shutters appeared in the sizes we still use long before cameras got smaller. Then as lenses got better and sharper, and movie cameras with smaller film areas, small cameras became popular. Evolution (I hate that word) happened along parallel paths with the big film sizes getting more and more sophisticated built in shutters, and 35mm cameras that evolved to tiny titanium shutters that could cycle 100's of thousands of times. So here we are. A 4" titanium shutter would be ungainly. As would a tiny in lens shutter on an 8mm digi camera lens.

As the others mentioned, there are exceptions for those of us who want to use ancient barrel lenses.

JBAphoto
7-Jan-2012, 02:22
Film speed did it, with slow speeds a lens cap was sufficient

Lenses with shutters came in after a few other ideas, like the Thornton Pickard shutter, commonly referred to as a "mouse trap" shutter, already mentioned (I have an LPL copy behind a 36cm Heliar, it works well but can not be used as it is 142m long and is used to mount the lens with the shutter running horizontally on a Sinar panel, which is only 140mm square - The TP shutter has to run vertically - Yes, I could make a spacer, but. . .

Thornton Pickard also made a focal plane shutter for half plate cameras in England, but the one I had went to a collector as it needed serious work to make it function

The best practical answer is a Sinar Shutter with or without the DB mounted lenses, as it has very stable speeds and will work with shuttered lenses if they are set on B - I have very carefully removed the auto aperture scale from the side of mine so I can fit it behind the front standard of my brand new 10x8" Tackyhara as part of the modifications to make the Tacky' a practical camera - Currently it is more suited to being a prop' in a BBC period drama

Below is a pic of the Sinar shutter plus Heliar and LPL rat trap, but minus flower pot lens hood

http://www.jbaphoto.com.au/images/jbaphoto100818d3035med.jpg

The LPL/TP "rat trap" shutter be available after I have bought a new flange for the Heliar so I can mount it just clear of the Sinar Shutter - Any offers of flanges welcome also any ideas on who has the great lens flange hoard - Someone must know

Lightbender
9-Jan-2012, 23:38
What you are missing is the size of the shutter. If you think of the light rays in a pinhole camera, the narrowest point is right at the pinhole where they intersect.

So if you put the shutter in the same location as the aperture, you get the smallest size shutter.

So the next questions is why are small shutters better?
1. Minimal vibrations. If you have ever seen or heard a graflex rear shutter curtain go off, you know they create vibration as the torque is released. The behind-the-lens shutters are smaller than the graflex, but still larger than integral shutters and so by definition have more vibration.
2. faster than behind-the-lens leaf shutters.
3. Leaf shutters sync with electronic flash at all speeds, wheras roller-blind shutters like the graflex will only sync at their slowest speed.

Len Middleton
10-Jan-2012, 09:38
To comment further on Lightbender's post, size also has an impact on lens size and fastest shutter speed.

A larger shutter will reduce the risk of vigneting and maximizes the lens speed / aperature opening. you sometimes see the situation where a the same lens in a barrel is faster than one in a shutter. That is a limitation with the Sinar copal shutter as well.

With greater size comes greater mass, and more inertia to start and stop the mass from moving. Hence the difference in fastest speeds on a Copal 0 (1/500s), 1 (1/400s), and 3 (1/125s) related to the increase in size.

For those using electronic flash, a leaf shutter will sync with electronic flash at all speeds, unlike a moving slit shutter.

Hopefully that will provide some additional insights,

Len

Greg Lockrey
10-Jan-2012, 10:03
It beats holding a hat over the front of the lens....

I never could do 1/250th or faster with the hat.:p

you could if you put a slit in it... :p :p :p

jm51
11-Jan-2012, 06:18
I was reading threads in this sub forum and lots of talk about spending cash getting shutters fitted, now I know why.

Lightbender
13-Jan-2012, 12:32
"A larger shutter will reduce the risk of vigneting and maximizes the lens speed / aperature opening. you sometimes see the situation where a the same lens in a barrel is faster than one in a shutter. That is a limitation with the Sinar copal shutter as well."

just to be a nit-picker:
vignetting (darkening of the edges) is only an issue with a shutter behind or in front of the lens. A between-the lens shutter (that is smaller than the lens aperture) will darken the image evenly across the field. Also, a larger shutter is not always needed for some lenses. You will see older super-angulon lenses in small size 00 shutters. This is because the lens is hour-glass shaped, or very narrow in the middle. later models used the size 0 shutter either because the 00 shutter was no longer made, or because it was less reliable.

Sevo
13-Jan-2012, 12:46
You will see older super-angulon lenses in small size 00 shutters. This is because the lens is hour-glass shaped, or very narrow in the middle. later models used the size 0 shutter either because the 00 shutter was no longer made, or because it was less reliable.

... or rather, because the 00 shutter was designed for fixed-lens compacts and had neither a preview lever nor T setting, which was somewhat annoying in LF use.

IanG
13-Jan-2012, 13:15
Thornton Pickard is what you are tryng to recall. Unlike Graflex the T-P shutters only had 1 slit and used spring tensioons for varying the speed.

Actually some of the TP focal plane shutters had two curtains and some have variable slit widths, both quite different to the multi slit Graflex shutter curtains. I've yet to find one with all it's parts to restore, the smaller ones are reasonably plentiful. I have about a dozen most fully restored & operational, two will fit on the front of quite large lenses.

Ian