Bronica S2 Focussing issue

duncananalog · Mar 9, 2020

I have recently bought a bronica S2, i was having issues with the focussing so replaced the foam under the ground glass and the mirror. I have to say i didn't find it as easy as many say online ( moslty the mirror section). However since i have done this the focussing seems to have got even worse. When i focus on the horizon on infinity it is super blurry still. Any one have any thoughts? I'm considering just buying a new body at this stage

David A. Goldfarb · Mar 9, 2020

Is the groundglass facing the right way with the fresnel on the correct side, both facing the right way? It’s been years since I had an S2A (same as S2 in this respect), so better I don’t advise you without the camera in front of me operating correctly, but maybe someone else can do so. This is very likely your problem.

The other likely issue would be mirror alignment, but I never tried to adjust that.

duncananalog · Mar 9, 2020

Yea they are both facing the right way. I have a feeling its the mirror alignment bit. If taken off the shims under the ground glass to get it as low as possible and it helps but still not quite getting there for full infintiy focus. Everything closer is focussing fine, although i'm yet to recheck with actual photos.

itsdoable · Mar 9, 2020

Mirror foam can be a tricky job, but compared to other 2 1/4 SLRs, you can do it without special tools or dismantling the camera.

Is it close focused or far focused at infinity? Is it focused at the film plane? As David asked, focus screen orientation, fresnel inserted? Were the shims for the screen there, or are they missing? (Some people removed them trying to correct focus error when the issue was with the mirror pads). Since focusing issues can be anything from the lens, helical, etc.. to the screen, move information is necessary to narrow down the problem.

duncananalog · Mar 9, 2020

So i have already replaced the mirror foam when i replaced the ground glass foam. I used 3mm. open cell foam so i was a little worried that i'd used foam that was too thick. I went to reopen that this morning and have managed to shear one of the screw heads partially off, so currently am just thinking of leaving it as it is. The shims were in, i have just taken them out to try and compensate for whatever was going wrong post foam replacement. I'll try have a look to see if its focussed at the film plane, but not sure i can lock the shutter up with the back off

duncananalog · Mar 9, 2020

I couldn't get anything to focus at the film plane with the back off. I had to be about 6 inches back before anything came into focus regardless of focus distance

itsdoable · Mar 9, 2020

duncananalog said:
I couldn't get anything to focus at the film plane with the back off. I had to be about 6 inches back before anything came into focus regardless of focus distance

Back needs to be on if you want to check focus at the film rails, just remove the insert. You can put a spare focus screen there, or use film and take a shot at infinity. This will tell you if the lens/helical is working properly. If so, then the problem is between the mirror and focus screen.

choiliefan · Mar 10, 2020

What lens(es) are you using?
Can you attain sharp focus at any distance at all?
6" back from the focal plane is waaay out of spec.

GRHazelton · Mar 10, 2020

Have a look at this flickr entry: https://www.flickr.com/groups/bronicas/discuss/72157696885706224/ I have the same problem with my S2a; so far I haven't attempted the fix. My manual dexterity isn't what it used to be, alas!

David A. Goldfarb · Mar 10, 2020

6” off is way far out and not a matter of fine adjustment of the mirror of the focusing screen. You should be checking focus at the film plane with the back on as recommended in post #7, but this sounds like you’re using a long telephoto lens with the normal (non-tele) helical (if that’s even possible, because the telephoto helicals often have a different lens mount) or maybe the lens is missing a cell.

duncananalog · Mar 10, 2020

Ok my apologies. I think I was being an idiot. Having not checked focus at the film plane of a camera before and due to both my film backs currently having film in them i just took the back off and tried to place my eye at the level that the film would be. I guess this isn't taking into account the refraction of by eye as well. Looked better when i held some tracing paper up to the back instead. Today i fired off a shutter for the first time since i changed the mirror foam and it feels like its better. I'm wondering if my mirror was slightly stuck off position post change and the shutter fire has brought it back. I have been trialling with the 75mm and the 135mm lenses. I think i now need to fire off a few frames and see what they are looking like. If they're still off then at least i've got empty backs that i can compare the focus at the film plane and what i'm seeing through the view finder.

abruzzi · Mar 10, 2020

a common trick for testing focus is the translucent scotch tape. If you can place it where the film path would be and lock the shutter open with a cable release and bulb mode. (this works best with a tripod, a darkened room, and a brightly lit subject set at a known distance with continuous light.)

Bronica S2 Focussing issue

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