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View Full Version : is this super angulon 121 fully open?



chris77
4-Oct-2017, 15:39
hello.
i have 2 questions regarding this lens.
is the synchro compur correctly adjusted? is this lens open lile this (pic1) at f8?
and how about the shutter blade (pic2) is this normal? its the only synchro compur i own, so i cannot compare..

thank you

chris

170526170527

EdWorkman
4-Oct-2017, 15:53
chris
Did you try a quick measurement and calc the resulting f stop?
Some folks will chime in and say not precision, but it should get a close answer- like say it should look wide open instead.
You could also do a quick and dirty to see how big the opening should be at f8 and compare
regards
Ed

Greg
4-Oct-2017, 16:19
I have and use a 5.9” f/14 No. 5 Gray Periscope lens on my 11x14. As with your lens, the aperture is half closed at the marked f/14. But the aperture can be fully opened beyond the f/14 mark for focusing purposes only (so I was told). Same thing with some other lenses that I have owned. I've made exposures with the apertures fully open and the results were poor.
just adding in my 2 cents...

Leszek Vogt
4-Oct-2017, 17:07
I've checked my 121/8 and the aperture you are showing is near F11. If you need F8, then you shouldn't even see the aperture blades. Can't compare the shutter to my Copal O. Hmmm, there might be an issue.

Les

Don Ciccone
4-Oct-2017, 18:21
Just checked my SA 121/8 and I agree with Les, wide open (f8) you cannot see aperture blades. They only become visible as you stop down. Seems like an issue with your shutter.

Don

chris77
4-Oct-2017, 19:54
thanks for verifying!
any ideas how to change that, in other words how to adjust the aperture setting on a synchro compur?

ottluuk
5-Oct-2017, 02:13
The 121mm SA was offered in a couple of different shutter mounts. Some apparently mount directly to a #0 shutter. Mine doesn't. It has a Synchro-Compur shutter in a metal shell with cutouts for levers and an oversized knurled speed ring (see attached photo). Is yours like that?

From memory, I'd say the aperture blades are just visible when wide open but I don't have the lens with me to confirm.


170537

chris77
5-Oct-2017, 14:08
The 121mm SA was offered in a couple of different shutter mounts. Some apparently mount directly to a #0 shutter. Mine doesn't. It has a Synchro-Compur shutter in a metal shell with cutouts for levers and an oversized knurled speed ring (see attached photo). Is yours like that?

From memory, I'd say the aperture blades are just visible when wide open but I don't have the lens with me to confirm.


170537

no, mine is a usual synchro compur.
i am wondering how to adjust the aperture. maybe i should do some testing, leaving everything just the way i got it..

Corran
5-Oct-2017, 19:14
A little thought experiment. If your 121 SA has a smaller opening than it is supposed to have at f/8, then the lens focal length the shutter is marked for must be slightly shorter. 90mm f/8 lenses are very common in #0 shutters. A 90mm lens at f/8 would have an aperture size (as seen through the front element) of roughly 11.25mm. Therefore, it is reasonable to assume that at that setting, the iris opening is around that size. This would correspond to roughly f/11, or one stop of correction. It would also follow that if this is true, it is likely your shutter is a #0 size as mentioned, perhaps originally for a 90mm SA. Some Synchro-Compur shutters have removable / replaceable aperture scales - finding the correct one though for your 121 SA will probably be difficult. If it is a #0 then perhaps you should look for a good shutter with a trashed lens.

If I were you, I would shoot a few sheets with a one-stop correction (if you want f/22, set it at f/16), and see how the negatives look. I did this for a while with one barrel lens I had that fit into another shutter I had on a different lens. I would swap the elements and mentally correct the aperture. In this case it was a 305mm lens into a 150mm lens shutter, and I corrected by 2 stops. Negatives were fine. If you are shooting chromes in exacting conditions, obviously the precision of these corrections would be problematic.

scm
6-Oct-2017, 08:31
It appears from the photo that one of the aperture blades has popped out of place and is preventing the aperture assembly from opening fully.

Louis Pacilla
6-Oct-2017, 08:42
It appears from the photo that one of the aperture blades has popped out of place and is preventing the aperture assembly from opening fully.

+1

I wondered when that obvious problem would be mentioned. I was going to point that out but was being lazy and did not want to peruse all the post closely to see if it had already been posted.

Corran
6-Oct-2017, 09:01
Good catch, I only looked at the first picture. There should be resistance if opening the iris then, and if pushing all the way to f/8 there is probably a serious problem if the aperture blades are not in the right position (forcing it to f/8 at that point despite the resistance and not opening). The aperture blades may already be damaged.

chris77
6-Oct-2017, 14:34
Good catch, I only looked at the first picture. There should be resistance if opening the iris then, and if pushing all the way to f/8 there is probably a serious problem if the aperture blades are not in the right position (forcing it to f/8 at that point despite the resistance and not opening). The aperture blades may already be damaged.

well, i mentioned this in my original post, seems no one reacted so far, but thanks, now its come up.
shall i try to push it back in, and if so, in which position of the aperture?
now that u mention it, the aperture lever moves well but less smooth than my other shutters. its, like i said, my only synchro compur..

thanks evrybody

Louis Pacilla
7-Oct-2017, 09:25
well, i mentioned this in my original post, seems no one reacted so far, but thanks, now its come up.
shall i try to push it back in, and if so, in which position of the aperture?
now that u mention it, the aperture lever moves well but less smooth than my other shutters. its, like i said, my only synchro compur..

thanks evrybody


hello.

and how about the shutter blade (pic2) is this normal? its the only synchro compur i own, so i cannot compare..

thank you

chris

170526170527

That is an "aperture blade" and NOT a a "Shutter blade" and no that is not normal.

To your question should you "push it bake in" and I'll tell you to simply "push" a metal aperture blade back in position may lead to bending the aperture blade then you may not be able to reassemble the aperture properly but if your going to try to slip it back under the rim just be careful not to damage the aperture blade. You can also disassemble the iris rack and put the blade back in it's proper position you should be able to fix it . Once in the proper position your aperture scale stops should be accurate.

chris77
8-Oct-2017, 03:38
That is an "aperture blade" and NOT a a "Shutter blade" and no that is not normal.

To your question should you "push it bake in" and I'll tell you to simply "push" a metal aperture blade back in position may lead to bending the aperture blade then you may not be able to reassemble the aperture properly but if your going to try to slip it back under the rim just be careful not to damage the aperture blade. You can also disassemble the iris and rack and put it back in it's proper position you should be able to fix it . Once in the proper position your aperture scale stops should be accurate.

hello louis.
the term shutter blade is also in use, easy..
it was no problem to push the blade back in position, gently, just using a screwdriver and a finger without dismantling it. this has not changed the opening of the aperture at f8, but i found a solution by dismantling and changing the aperture levers original setting. f8 is f11 now and f6 is f8, not showing the blades in this position. the whole lens opening is visible now.
problem solved.