Bronica S2a focusing upgrade tip

Well, I originally posted the questions about hacking a Acute

Matte screen to fit a Bronica S2a.

 

...I decided to try an inexpensive solution first before plunging

into ruining an Acute Matte screen.

 

Another alternative to hacking an expensive Acute Matte screen

is a Kiev 88 screen. Yes, I am serious! I know Kiev 88's can be

great sources of headaches, but their screens are actually

impressive. They some of the brightest standard screens

around, IMO. Next time you are at a camera swap meet and

there is a Kiev 88, look through it, you'll be pleasantly surprised

at it's split image grid screen's brightness and contrast. It's

better than the rest of the camera!

 

I hacked the Kiev 88 screen and replaced the finder foam in one

of S2a bodies and it works like a charm. It's not as bright as the

Acute Matte screen, but much brighter than Bronica S2a screen.

There Kiev screen is virtually free of grain.

 

I would suggest upgrading and modernizing your screens too if

there are any older Bronica body shooters reading this. It makes

a world of a difference in focusing both in low light and bright

light. Having spent a week shooting with my "new" and improved

Bronica S2a, I have actually forgotten that I was shooting with an

older classic camera.

 

I was able to get the screen from Kiev Camera. Mike Fourman,

who runs Kiev Camera, is a trustworthy source for Kiev stuff.

Best part is, it was only $25. So for $25 and $10 in replacement

foam, I now have a modern bright viewfinder image.

 

I now understand why photographers who upgrade there older

500cm Hasselblads to the Acute Matte have such impressive

reactions to their new screens. It makes a huge difference!

Have you checked the infinity focus to see if it is still spot on? It is common when swapping different screens from other cameras to run into a problem where they have slightly different thickness, and this can throw the focus will be off at all distances.

On the S2A, the fresnel is separate from the focusing screen, and the groundglass surface rests on rails that put it at the right distance, and it is held down from the top with a frame with a foam seal. The fresnel is inset below these rails. The thickness of the glass is not critical, as long as the foam is good and as long as the new screen is not a one-piece fresnel/groundglass unit with the fresnel on the bottom (unless the fresnel is smaller than the groundglass so that the matte groundglass surface can rest directly on the registration rails).

Yes I have checked infintity focus and all is fine.

 

These Bronica's are strange beast I must admit.

I've had two bodies where even after foam replacement, infinity

focus was off. The original ground glass was seated properly on

the rail and the fresnel below was properly positioned.

 

There are ideas on why focus is still off with a properly adjusted

screen and foam. The mirror over time has shifted. I'm the NOT

inventor of this reason, so please don't flame me. But' it's

something that I read on the Bronica mega site ran by Bob

Monaghan.

 

http://www.smu.edu/~rmonagha/bronica.html

 

the section that mentions the mirror alignment issue is:

 

http://www.smu.edu/~rmonagha/broncrisp.html#tuning

 

I don't rule this out, as I had to lower the height on one of my

Bronica bodies to achieve infinity focus on the focussing screen.

I shot some test rolls and made a makeshift ground glass from

an old TLR and all checked out fine with my new adjustment.

 

This is an issue with older Bronicas and I would suggest any

potential buyers to read the link above.

 

My S2a that had the focus problem was a mint in original box set

up that look prestine and not a day over it's original factory

delivery condition. Yet it had this focusing problem. I solved it by

lowering the ground glass height. But's still a mystery as to why

or how this happened.

Many SLR cameras have the mirror attached with a firm but resilient foam pad --- my theory is that when the mirror snaps up the resilient foam will endure this violent action better over time than a less flexible bond like glue or clips or screws.<p>

If your Bronica fails to focus on infinity, perhaps this foam has shrunk over time due to age, thus changing the position of the mirror...this is a problem with older Hasselblads. Service entails replacing the foam beneath the mirror and resetting infinity focus.

so how did you do it?

 

this post is old... but i can buy a kiev 88 screen for $40 (new) and i want to know what "hack" means... did you break it out of its case? did you have to cut the glass to fit it in the S2A?

 

i'm very tempted to do this...

I too had focusing problems with the Bronica S2 - I spent ages replacing the foam and the focusing screen was sitting in its correct place, but it still wasn't focusing on infinity (really obvious with the 50mm Nikkor O 2.8 lens). Eventually, after trying everything I removed the 2 shims that are where the screen rests. These are silver and have two screws in each. Once I had them out, making sure not to drop the screws into the mirror/shutter assembley, I could see that each "shim" was made up of three strips of varying thickness silver metal, perhaps some way of adjusting the height of the viewing screen to calibrate the viewfinder. Once I had removed these and replaced the fresenl lens and viewing lens (both shiny side up) - I could see, for the first time in the 8 years of owning this camera that the focus on infinity was truly sharp - I tool a Polaroid, using the polaroid back, with the S2 and it came out as sharp as polaroids ever do. I have a roll of Ilford HP5 drying in the bathroom at the moment and checking with a torch in the dark to see the silver the negs look spot on.

That's true, when you remove the 2 shims that are where the screen rests, the focus is fine (tested at 2 meters). Measure 2 meters from a target and read the focus on the helical mount. In the "original" mount, with replaced foam = approx. 60 cm error !! I don't know what is this reason but the error is real (controlled with a screen et the film place).

Note : my bronica S2A is one of the latest (serial # 17xxxx) whith Nikkor HC 75 (6 elements)

I am also interested in replacing my S2a focusing screen. I found the Kiev88 screen available at arax photo for $24. However I would like to understand something: what is this talk about replacing the foam? Is this somehow necessary? As far as I know I have no problems with focusing with my original screen, apart from the fact that it's very dark of course. Can I just get the Kiev screen, swap it with the original one with relative ease and relatively little risk of breaking anything and be happy?

 

The links above no longer work, by the way.

I've successfully removed and re-inserted my focusing screen and it went well on the second try, focusing to infinity is still OK, so I was

confident enough to order a Kiev 88 screen. Hopefully it'll arrive soonish and then we'll see if it will turn a really good camera into a super

camera or not :)

 

The original screen looks like some kind of DIY screen made by Joe Hobbyist; it's not even cut completely straight.. the fresnel doesn't

look too bad. Looking in the viewfinder with just the fresnel gives a funny feeling and a headache.

Replaced by a Pentax 6x7 screen (not expensive on eBay) on one of my S2a : works fine (it is necessary to cut a little at each side) Not difficult because organic glass, but cut slowly and carrefully.

Funny you would replace it with a pentax 6x7 screen, as my Pentax 6x7 is next on line for getting a good focusing

screen.. along with my Minolta Autocord LMX. All of these cameras would be so much nicer with a good, bright screen :)

The screen arrived today and replacing the original Bronica one with the Kiev88 one was simple and straightorward; the

kiev one was slightly smaller and didn't have to be cut or anything.

The viewfinder is now brighter, though perhaps not greatly more so; and the split image is useful. All in all, a good and

cheap upgrade.

<p>Toni, have you checked your focus? I've also changed my screen but I think it's a bit off focus (probably due to the fact that the fresnel lens is incorporated in the screen). I'm about to shoot a test roll... if it really is off focus, I don't really know what to do.</p>

<p>I have checked the focus. Originally I thought the infinity focus was a very tiny bit off, but I took some test shots at close range and the focus seems perfectly fine.<br /> The way they were on my camera, the fresnel lens was sitting on some supports and the original focusing screen was simply stacked on top of it. I just replaced the original with the Kiev one, making sure I had it the right way upwards because that could screw focusing. Also at first I accidentally put it at an 90 degree angle so the split image was moving the wrong way, and I had to unscrew the very worn out screws and correct it :)<br>

<img src="http://www.delphine.org/~toni/photo/filmikikkailut/itsepilatut/09-ihmemies.jpg" alt="Focus test shot, focus was on the ilford (BIG)" width="1610" height="1619" /></p>

<p>I've also removed the original fresnel so now it's just the new ground glass installed (since it already has its own fresnel lens built-in and I spoke with someone with the know-how who told me I wasn't supposed to place a fresnel lens over another). I've also placed the glass with the split vertically but I suppose it's just the same (even better for portraits as I cand focus more easily on the eyes)<br>

I understand you left the original fresnel in place? Doesn't it act weird (with the clear spot on the original being smaller than the split zone on the kiev screen).<br>

I've measured the focus again with a ruler and it seems ok but I yet have to test it on film.</p>

<p>Yes it's a bit weird, but indeed I left the original fresnel in place as the Kiev screen (AS FAR AS I KNOW :) doesn't have one. Double fresnels would be bad, I am also guessing. But now that you've removed the fresnel the focus could be a bit off depending on the thickness of the fresnel in your new screen...<br>

Yes it's a bit weird, but better than what I started from.</p>

 

<p>:) Perhaps we're not using the same ground glass... I've bought mine from ebay and it seems to be what arax is selling <a href="http://araxfoto.com/accessories/screen/">here.</a> It certainly has its own fresnel, otherwise it shouldn't be able to focus anything, right?<br>

The glass has a slight semisphere bumb in the middle, right where the split image and microraster is. I though about differences in height and position as well but I don't really know how fresnels work actually...</p><div></div>

<p>My knowledge of optics is very shallow but still, I think the fresnel is not critical for focusing, it just makes the image brighter - thats what it was initially used for (in lighthouses).<br>

The Kiev88 screen I ordered (from arax-foto) almost certainly has no fresnel of it's own but you might have a different kind of screen than I do. The one I have is this: http://arax-foto.com/accessories/screen/<br>

On the Bronica, the matte side of the focusing screen should be at exactly the same distance from the mirror as it would be if it were sitting directly on top of the fresnel. I THINK. That means, if you remove the fresnel and use a screen which has its own fresnel, you are still OK as long as the "integrated" fresnel in your screen is exactly the same thickness as the original one - but I don't think there is any reason to believe it would be :)<br>

Ok, now if you ask anything more I'll have to completely make it off the top of my head, I'm way out of my league as it is :)</p>

<p> </p>

<p>I'm out of my league as well, as it seems. Indeed, the fresnel simply focuses the light towards the hotspot making the image brighter. On the other hand, although not visible in the image above, the screen has concentrical striations, like a fresnel lens...<br>

I guess I'll see the results on the first roll... It seems it's not the brightest ideea to start twinkering on cameras without the appropriate knowledge :)</p>

<p>One fun thing to try is to just put in the fresnel lens without the matte screen. Kind of wild looking and will certainly give you a headache quickly :)</p>

<p>By the way, if anyone can tell me some kind of exact type for the 4 screws that need to be unscrewed to get to the focusing screen, I would like to obtain new ones as these are completely worn out - I dare not open it anymore unless I have new screws to replace them with.</p>

 

<p>My whole viewfinder popped up once as it seems I hadn't screwed the screws tight enough. Being on a river bank I could only recover three of the four screws, but I happened to have a broken Oly Trip with me and just got one from it. It seems any old camera should have at least one compatible screw easily reachable.<br>

Otherwise you could try at any clocks repairman. They should have all kinds of tiny screws.</p>