Big Glass: Another look at Medium Format


Anyone who has read any of my posts probably has the idea that I like cameras. Well, I suppose I do. I collect cameras, and like trying different types of cameras. I also like to compare different cameras so I can know what their strengths were/are and what kinds of photography each camera was best for.

Recently I’ve been trying various medium format cameras. I published a couple posts on cameras with 6×6 format – but now I’m taking a look at the 6×7 format. I’ve acquired a Mamiya RB67 Pro SD with a couple lenses. This format (6×7) is just a little larger then 6×6, and the RB-67 is a larger camera. But the thing that surprised me most was the size of the lenses. They are quite a bit larger than the lenses for my Bronica 6×6 cameras. These lenses are a handful, literally.

I’m also an amateur astronomer, and these lenses remind me of what it’s like to go from 1 1/4 inch eyepieces to 2 inch. 2 inch eyepieces are literally a handful – the 1 1/4 inch eyepieces can be held between 2 fingers, the 2 inch ones you grab with your whole hand, and they feel substantial – and they cost significantly more too!

Now, part of the reason the RB67 lenses are larger is because they have a shutter in each lens. The RB67 doesn’t have a shutter in the body like the Bronica S2 and EC bodies. So that adds some size to the lens, but the glass itself is bigger, and that makes these lenses bigger, heavier, and more expensive than some medium format lenses.

The RB67 is from the same era as the Bronica EC/EC II camera. The newest RB67 Professional SD is a bit newer, but the first model (RB67 Professional) was released in 1970. The Professional S came out in 1974 and sold for the longest period. The Professional SD came out in 1990. I have a Professional SD, mainly because I wanted one that was a bit newer than an S – although the S was very well built and very well accepted by professional photographers. There’s probably more Professional S bodies out there just because they sold it for so long.

The RB67 is a bit more complicated than my Bronicas are. First off, you have 2 steps to advance the film and cock the shutter instead of all that happening together in one step. This is mainly because the shutter is inside the lens, and not in the body. In an all mechanical body, like this is, it’s very difficult to accomplish some kind of connection between the body and lens. In electronically controlled cameras (like the RZ67 and the Bronica ETRSi), electronic connections between the body and lens facilitate a more streamlined operation.

The image below compares the sizes of the RB67 (top right) with the Bronica EC (bottom) and a Nikon F2 (top left). I put my hand in the photo holding the Bronica so you’d have some frame of reference. The RB67 is quite large, and the lenses it uses are quite large. But sometimes, larger is good.

Here’s an image from the RB67 of my cactus (one of my favorite subjects). This is shot on Tri-X at ISO 400. Notice the smooth grain. On 35mm, this would be quite a bit grainier.

Cactus shot on Tri-X – maybe a bit underexposed, but it was a dark day

I’m interested in seeing how a finer grained film might look on a 6×7 negative. Here’s the same cactus, shot with FP4+ at ISO 125. Grain is less, but I’m honestly pretty impressed with how fine the grain is with Tri-X on this size negative.

Cactus shot on FP4+
Chairs Shot with Film Back in the Vertical Position – FP4+
Torch on Tri-X

The grain in these photos is very similar – very fine. I’m wondering what some other types of photos would look like with FP4+ on 6×7. Also, I should mention here, I’ve seen mixed reviews about the RB67 and it’s lenses. Some reviews paint the lenses in a fairly negative light. I’ve also read that some of the Mamiya lenses of the time were manufactured with poor quality control, and some produced nice, sharp images. Others seem to produce soft, unsharp images. I’m not sure I believe every report out there – so I’m going to try things for myself.

Now, Regarding some technical details of the Sekor lenses. I own both K/L lenses and C lenses. The C lenses are the second generation of the RB lenses. The first, original lenses have single coatings, so, even if they are optically equivalent (which I’m not sure all are) they will suffer more from flare than later C and K/L lenses. For better, more advanced, multi-coated lenses, go with C or K/L. The K/L lenses are supposed to have better, more modern coatings as well as being multi-coated.

Another thing about the lenses. The mount of the RB67 Professional SD had a slightly larger opening, which accommodated the L series lenses which had a larger base, and maybe a slightly modified mount. The L series lenses (of which there were only 2) could not mount on the Professional and Professional S bodies, only on the modified mount of the Professional SD. Now, due to the slightly larger opening, older lenses could mount on the SD body as long as there was a small spacer ring placed around the base of the lens. I have identified the spacer ring in the photo below. The ring is supposed to come with K/L lenses. Without the spacer ring (it can be removed as I show in the second photo) K/L lenses will fit on the Professional S body, and maybe the original Professional body – I think the ring is the only difference – except for the quality of the lens and more advanced multi-coatings the K/L lenses have.

Sekor K/L Lens with spacer ring in place.
K/L Lens with Spacer Ring Removed. Without the spacer, this lens would fit on the Pro S body.

Now there is a bit of confusion about the K/L lenses. According the Mamiya documentation I have read, the spacer came installed on K/L lenses when they were sold. It could be removed if you wanted to use the lens on an older body (preserving backward compatibility – and gaining sales of new lenses by those who didn’t want to buy a new body). You could buy a spacer and use it on older lenses if you wanted to use those lenses on your new Pro SD body (so people could upgrade to the new body without buying all new lenses – all you needed was a spacer to put on your lens to make it fit perfectly). Technically, the old lenses would/should mount on the new Pro SD body, but there would be (or so Mamiya engineers thought) too much space between the lens barrel and the mount on the body. I guess the fear was that the extra space could cause a light leak… I’m not sure how much of a problem that really is/was, but I have spacers on my lenses – I look for lenses to buy with the spacer on. You can tell if a lens has the spacer in a photo. As long as the photo is of the actual lens for sale, you should be good. If you need a spacer, you should be able to find one online for not too much $. I have a feeling the reason many K/L lenses I see online don’t have spacers is that sellers, looking to make an extra sale, removed the spacers and sold them separately. That’s just a hunch though. And, by the way, the spacer I have is all metal. Not a rubber gasket or something as some rumors I read imply.

Overall, I like the quality I’ve been able to achieve with the RB67 and my Sekor K/L 127mm f/3.5 lens. I’m waiting for a 50mm Sekor C lens to arrive before I do some landscapes with the RB67, at which time I’ll post some landscape photos – maybe even some color! But, don’t hold your breath.