Topic: Swapping shutters on 4x5" lenses (Read 6712 times)

GerardK · « **on:** July 02, 2006, 04:04:34 pm »

Michael and others experienced in 4x5,

"I can swap shutters between lenses in the field in about 3 minutes", you wrote in another thread. I've a question related to this - I recently bought a 5.6/58 mm Super Angulon XL, a 5.6/75 mm Super Angulon and a 5.6/150 mm Symmar S, all Schneider-Kreuznach for my Toyo Field 45CF. The 58 mm is mounted on a contemporary Copal 0, the others on somewhat older Compur shutters (early 70's and early 80's). I would like to use the 58 mm on a recessed lensboard, but the aperture setting and shutter cocking controls on the newer Copal 0 shutter are rather inconveniently placed, the controls on the other shutters are smaller and would handle better in a recessed lens board.

What would happen to the aperture setting if I were to swap the shutters from the one lens to the other?

Also, I noticed on the 58 that at its widest setting (5.6) the actual aperture of the blades is rather a lot larger than the smallest diameter of the lens. When you stop down, it doesn't start to produce a physically smaller opening until f11 or so. Is this normal? Any input is appreciated, thanks,

Gerard Kingma
www.kingma.nu

Mike Boden · « **Reply #1 on:** July 05, 2006, 09:07:15 pm »

Quote

Michael and others experienced in 4x5,

"I can swap shutters between lenses in the field in about 3 minutes", you wrote in another thread. I've a question related to this - I recently bought a 5.6/58 mm Super Angulon XL, a 5.6/75 mm Super Angulon and a 5.6/150 mm Symmar S, all Schneider-Kreuznach for my Toyo Field 45CF. The 58 mm is mounted on a contemporary Copal 0, the others on somewhat older Compur shutters (early 70's and early 80's). I would like to use the 58 mm on a recessed lensboard, but the aperture setting and shutter cocking controls on the newer Copal 0 shutter are rather inconveniently placed, the controls on the other shutters are smaller and would handle better in a recessed lens board.

What would happen to the aperture setting if I were to swap the shutters from the one lens to the other?

Also, I noticed on the 58 that at its widest setting (5.6) the actual aperture of the blades is rather a lot larger than the smallest diameter of the lens. When you stop down, it doesn't start to produce a physically smaller opening until f11 or so. Is this normal? Any input is appreciated, thanks,
Gerard Kingma
www.kingma.nu
[{POST_SNAPBACK}][/a]

I can't answer all of your questions specifically, but I don't think that there will be a problem swaping shutters. If the thread sizes are the same, then it can't hurt to try it.

However, if you want more specific answers to your questions, I suggest you seek info at one of the two following places. The first is a website/forum specifically for large format photography and the latter is a company that specialized in repairing old shutter as well as fabricating various camera parts. Go check them out!

[a href=\"http://www.largeformatphotography.info/forum/index.php]http://www.largeformatphotography.info/forum/index.php[/url]
http://www.skgrimes.com/

Good luck. Perhaps I'll see you over at the other message board.

Mike

GerardK · « **Reply #2 on:** July 06, 2006, 08:37:40 am »

Mike,
Thanks for your input. I was beginning to suspect I might be posting in the wrong forum - is nobody doing 4x5 around here? Anyway, I did contact Grimes, they more or less gave the same suggestion you did - it could work if they're the same size but the aperture scale may be off. And I browsed the largeformatphotography forum but didn't post there.

Anyway, I found some more technical data on the 58 mm Schneider and it turns out the shutter on the copy that I bought secondhand isn't original, so that answers most of my questions. I works out all right if I add 1,5 stops to the intended setting, i.e. if I want f22 I set it between f32 and f45. Thanks,

Gerard Kingma
www.kingma.nu

BernardLanguillier · « **Reply #3 on:** July 06, 2006, 08:55:46 am »

Quote

Also, I noticed on the 58 that at its widest setting (5.6) the actual aperture of the blades is rather a lot larger than the smallest diameter of the lens. When you stop down, it doesn't start to produce a physically smaller opening until f11 or so. Is this normal? Any input is appreciated, thanks,
Gerard Kingma
www.kingma.nu
[a href=\"index.php?act=findpost&pid=69652\"][{POST_SNAPBACK}][/a]

I have just checked mine, and the behaviour I see is different.

The diameter of the opening becomes visibly smaller as soon as I start to close down from 5.6. It is clearly smaller at f8, and more so at f11.

Your unit might have a problem.

Regards,
Bernard

Sheldon N · « **Reply #4 on:** July 06, 2006, 10:37:35 am »

The other thing you might run into as a problem when swapping shutters is making sure that the spacing of the elements is correct. Some lenses use metal shims when mounted into the shutter to ensure that the front and rear elements are positioned the correct distance apart.

GerardK · « **Reply #5 on:** July 06, 2006, 03:48:41 pm »

Thanks again, Bernard, I'm now pretty sure the previous owner replaced the shutter, because this one goes all the way to f64 while according to the specs the smallest opening of this lens is f32, how's that with yours?

Thanks Sheldon, I'll check with a precision caliper according to the technical data sheet on the Schneider website,

By the way, with my first succesful images I'm now starting to realise the potential of 4x5. I should have done this years ago. It's awesome!

Gerard Kingma
www.kingma.nu

Wayland · « **Reply #6 on:** July 06, 2006, 05:11:36 pm »

If I remember my lens theory well enough the F stop size relates directly to the lens focal length, so if you change shutters from one lens to a different focal length the f stop figures could be incorrect.

(It's been a while since I did this at college so I suggest you check the accuracy of this statement. I just think it may be something you need to watch out for.)

Mike Boden · « **Reply #7 on:** July 06, 2006, 07:34:19 pm »

Hey Gerard,

Just remember that if you do end up swaping shutters, then you can always have S.K. Grimes make you a new aperature scale. They're kind of expensive, but if it means that much to you, then go for it.

GerardK · « **Reply #8 on:** July 07, 2006, 03:43:11 am »

Wayland,
Back to school! ;-) Focal length divided by actual lens diameter gives you the f-stop. For instance: 58 mm divided by 10,4 mm = 5,6. Therefore, if the focal length of the lens is given (which it is of course) and you want to know the actual f-stop, you only have to measure the actual aperture diameter and do the math.

That's how I found out the indicator scale on the shutter I have is 1,5 stops off. Indeed Mike, I could ask Grimes to make a new aperture scale, but it's cheaper to just put an adhesive label somewhere on the lens that says "Now this time please try not to forget to stop down +1.5, there's a good chap".

By the way Bernard, if you're still following this thread, congrats on your article on the Horseman. I've done quite a bit of spherical stitching with a digicam and PTAssembler, but there are still many shots that don't lend themselves well to stitching. Right now I'm really excited about real 4x5, and shooting with Fuji Quickload makes the whole process about as easy as shooting with my Pentax 67ii. I wish more people would try it. Quickload isn't even available in The Netherlands where I live, it's a shame.

Gerard Kingma
www.kingma.nu

Doug Kerr · « **Reply #9 on:** July 07, 2006, 02:25:46 pm »

Hi, Gerard,

Quote

Wayland,
Back to school! ;-) Focal length divided by actual lens diameter gives you the f-stop. For instance: 58 mm divided by 10,4 mm = 5,6. Therefore, if the focal length of the lens is given (which it is of course) and you want to know the actual f-stop, you only have to measure the actual aperture diameter and do the math.
[a href=\"index.php?act=findpost&pid=70003\"][{POST_SNAPBACK}][/a]

Do note however that the diameter of interest in this calculation is not the physical diameter of the iris opening itself but rather the diameter of the entrance pupil, which is how the iris opening appears when seen from the front of the lens.

Thus, for the same the same physical diameter of the iris opening (at a certain marked "f/number" setting), the diameter of the entrance pupil (as well as the focal length) will likely change when a different lens is mounted on the shutter.

Wayland · « **Reply #10 on:** July 07, 2006, 02:30:27 pm »

Quote

Wayland,
Back to school! ;-) Focal length divided by actual lens diameter gives you the f-stop. For instance: 58 mm divided by 10,4 mm = 5,6. Therefore, if the focal length of the lens is given (which it is of course) and you want to know the actual f-stop, you only have to measure the actual aperture diameter and do the math.

That's how I found out the indicator scale on the shutter I have is 1,5 stops off. Indeed Mike, I could ask Grimes to make a new aperture scale, but it's cheaper to just put an adhesive label somewhere on the lens that says "Now this time please try not to forget to stop down +1.5, there's a good chap".

Yes I thought it was something like that but I couldn't remember the exact details and couldn't find my notes either.

(BTW I think that should read iris diameter rather than lens diameter.)

I haven't had to change any of my shutters around for about twenty years so I'm a bit rusty I suppose but I just thought I'd raise the matter just in case anyone had forgotten.

GerardK · « **Reply #11 on:** July 07, 2006, 05:08:36 pm »

Doug,
Thanks, I was aware of that from a post in the largeformatphotography forum. Apparently the trick is to not remove the front cell but measure the apparent iris diameter (correct of course, 'lens diameter' is a rather inaccurate, sorry) with a caliper onto the front of the cell while holding the lens at arms length or so. A bit tricky but enough to give an indication of where the problem lies. For an accurate measurement I've read that you can somehow project the diameter with a laser and measure that, but I don't have access to that kind of gear right now. It's amazing how much new stuff I've learned in the course of a few weeks. What fun.

Bear with me, I've attached my first successful 4x5. You should see the detail printed 24" x 28" on my HP designjet 130. It's awesome. Thousands of tiny dew droplets on the grass in the shadows that you can't see on this small jpg.

Gerard Kingma
www.kingma.nu

GerardK · « **Reply #12 on:** July 07, 2006, 05:11:52 pm »

Doug,
Thanks, I was aware of that from a post in the largeformatphotography forum. Apparently the trick is to not remove the front cell but measure the apparent iris diameter (correct of course, 'lens diameter' is a rather inaccurate, sorry) with a caliper onto the front of the cell while holding the lens at arms length or so. A bit tricky but enough to give an indication of where the problem lies. For an accurate measurement I've read that you can somehow project the diameter with a laser and measure that, but I don't have access to that kind of gear right now. It's amazing how much new stuff I've learned in the course of a few weeks. What fun.

Bear with me, I've attached my first successful 4x5. You should see the detail printed 24" x 28" on my HP designjet 130. It's awesome. Thousands of tiny dew droplets on the grass in the shadows that you can't see on this small jpg.

Sorry about the double post. I must have doubleclicked something or other.

Gerard Kingma
www.kingma.nu

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Author Topic: Swapping shutters on 4x5" lenses (Read 6712 times)