Bronica S2 and Komura lenses

First post, please be gentle!

 

I recently acquired two Komura lenses (50mm and 200mm) for my Bronica

S2. However they don't focus correctly in my standard Zenza Bronics

helicoid mount (I was warned this might happen - an alternative lens

mount was suggested as the solution to the problem, but the person

suggesting it couldn't give me any more details about what kind of

alternative mount I might need!)

 

So now I'm wondering exactly what I do need to make these lenses work

on my camera.

 

I currently have just the 75mm Nikkor and a Zenza Bronica helical

mount (can't find a serial no) that says '50', '75', '135' and '200'

on the distance scale - which is why I hoped these Komura lenses

would work OK. They certainly bayonet into the mount correctly, so

they are definitely S2 lenses. I've read up on the 'net about a

different helical mount for lenses 300mm and longer. But I haven't

been able to find anything about any other helical mounts for shorter

lenses.

 

The Bronica sites have lots of detail on using all sorts of non-S2-

fit lenses with S2's - so surely I should be able to make these

lenses work: they were made for the S2 after all! I found articles

saying these lenses existed - but I couldn't find anything to say

what else I would need to make them focus OK.

 

I would very much appreciate any suggestions from any Bronica S2

owners out there who have ever owned/used these focal length Komura

lenses.

 

Thanks in advance,

Maggie.

Maggie, I've been shooting with S, S2, S2a's, and EC's for years. I've never heard of the Komura lenses needing and kind of special mount beyond the normal helical. Now all of my lenses have been Nikkors and Zenzanon except for 1 Komura 50mm years ago. And I don't remember having any trouble with that. I wish I could offer more insight, but your welcome to my 2 cents worth.

Dear Maggie:

 

I have a 45mm Komura lens and it works fine with my S,

S2, & S2A bodies. I have the Helical Unit II which is

needed for using the 300mm, 400mm, & 500mm Komura

Lens. I certainly am not an expert, but perhaps the

viewfinder on your S2 needs to be adjusted for proper

focusing...possibly in need of shims?

 

Best wishes, Jon

Thanks for your replies so far. The focus screen is fine - works perfectly with my 75mm Nikkor, so I'm reluctant to change it for these lenses - it is fiddly and difficult to get the screen working spot on.

 

The lenses are not just a little 'off'. The 50mm doesn't focus in my S2 no matter what distance the subject. The 200mm doesn't focus at infinity, and the distance scale is way off - by several hundred percent.

 

I also noticed since posting that there is the same problem with the diaphragm on both lenses. Outside my helicoid mount the action is smooth and light, and the aperture even, on both lenses. Inside the mount the action is very stiff wide open - I can only get down to f/4, can't get to f/3.5 - and the aperture doesn't get narrower than f/11 even though I turn the ring. The aperture also distorts when moving from f/22 down to f/4. This happens exactly the same on both lenses - it is almost as if the metal nub that moves the diaphragm lever on the lens is in the wrong place for both Komura lenses. This makes me think the seller was right, and I need a different mount.

 

The lenses did bayonet into my helicoid - smoothly and easily, without forcing - so I'm still convinced they should work OK with my camera once I find out what I need to make them work... Again I'm sure I don't have a broken helicoid, as my 75mm Nikkor has no problems with setting any f/stop, nor with a distorted aperture.

 

Is there a Komura web site where I can check the lens serial numbers to see exactly what I have got? I'm starting to think the seller was right when he said I need a different helicoid...

 

Thanks for your replies!

Maggie.

Is it possible the lenses could have been ruined by some kind of botched repair job? I've seen that kind of thing happen.

Hi,

 

Do you already know this site?

 

http://medfmt.8k.com

 

Probably the best Classical Bronica Site I have found.

 

 

For the S2A it states:

 

Focusing Ring

 

When using Bellows Attachment or long focal length interchangeable lenses (105mm, 300mm and over 300mm) equipped with their own focusing systems, remove the camera's focusing ring.

 

1 - Press the focusing ring release button and twist the focusing ring to the left (counter-clockwise), then remove the focusing ring.

 

2 - To return the focusing ring, insert into body mount, lining up the red dots on the focusing ring and body mount. Twist the focusing ring to right (clockwise) until the focusing ring release button snaps closed.

 

Nothing about changing the helicoid mount for a 50 or 200 mm lens. Probably the difficulty is in the two lenses itself ...

 

Regards

Leeuwtje

Thanks for all your replies. I'm starting to think the lenses must have been "repaired" to death :-(

 

The medfmt.8k.com site was the first place I looked, but thanks for suggesting it - it's a fantastic resource for information on ancient Bronicas isn't it :-) That's why I suspect there are only two helicoids - and I've been sold a couple of pups.

 

Anyone know a good lens repair specialist in the UK?

 

Thanks again,

Maggie.

 

Maggie.

My reply is a bit 'after the event' but it relates to some observations just recently made with my own S2A system.

My lenses focus correctly at the infinity stop but 'sharpest focus' does not coincide with helicoid distance scales at closer settings.

My S2A came originally with the 80mm Zenzanon f2.4 and helicoid distance scales for(I think) 75mm and 80mm lenses. After buying a 50mm Nikkor, I bought a helicoid marked for 50, 75, 135 & 200mm lenses but decided to swap the distance scales only because the eBay acquired helicoid had some other mechanical issues. Now I notice the considerable lack of agreement with sharpest focus and distance marking on the 135 and 200mm lenses I've just bought.

I wonder, do Bronica helicoids differ in the pitch of their threads? I can't think of any other explanation since this is s problem of 'scaling' and not 'offset'. The latter being explained by the position of the ground glass focusing screen.

This posting just links to my new email address.

Getting back to y'all on my Komura lenses...

 

A little light cleaning and more careful mounting of the 200mm lens, and it works fine. Infinity is a little soft, but I like my pictures like that!

 

I sent the 50mm lens to be repaired. It apparently had been taken apart and reassembled incorrectly. My repairer did a fine job (found him at a camera fair) for a reasonable price. Again pretty soft at infinity, I'm sure it would bother other people but not me :-)

 

Since then I've bought a 2x converter and a set of extension tubes. All work fine with all the lenses, and make my little kit pretty versatile so long as I use a sturdy tripod :-)

 

Thanks all for your help and suggestions!

 

Maggie.

Your focus problem could possible be deteriorated foam under your focus screen. Seems to be a common problem with the S2, S2A. Not really a big job to repair. I have replaced several myself. If you shoot with a large DOF you may not notice the focus as being much of a problem. When you shoot wide open and say speed of 500 then the focus becomes more apparent.

Old thread, I know, but as the S2 system seems to suddenly be popular for discussion again this specific question could use a definitive answer.

 

The standard focusing helicoid that comes with the S2-C-EC-EC/TL camera bodies and 75mm lens is also used by ANY lens focal length (of 200mm or shorter) that fits its internal bayonet mount, regardless of brand (Nikkor, Zenzanon, Komura). The system was designed so multiple lenses could share the single body-mounted focus ring, which made the lenses more affordable since they are optic units only. The drawback of this approach is you often can't rely on the "universal" focus ring markings to accurately check focus distance or depth-of-field (aside from the hard infinity stop).

 

Most of these cameras came with a focus ring marked for the 75mm lens only, which is fairly accurate with that lens but useless with others. Later cameras changed the scale so it indicates distance for the four primary Nikkors: 50mm f/3.5, 75mm f/2.8, 135mm f/3.5 and 200mm f/4. That multi-lens scale offers a rough distance approximation, but isn't very precise. Its best to think of the focal plane shutter Bronica system as a strictly SLR, focused-via-viewfinder concept: the shared focus ring can't possibly provide an accurate scale for all the dozen or so lenses that use it.

 

Larger longer Bronica teles work more like traditional lenses for other systems: you remove the camera "universal" focus ring completely, and the larger lenses then fit the wider-diameter secondary bayonet that is revealed when the helicoid is removed (the optional macro bellows also attaches this way). The larger longer teles come with their own independent focus ring/helicoid that is accurately scaled.