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Cosina Stereo K - Stereo SLR with Pentax mount
Rolleicord Stereo - my TriLR
Classic Rolleiflex with modern meter
Mamiya 6,3/50 adapted to Graflex Century Graphic
Wistamiya DIY Hybrid
Rollei 35 feeling on the Sony A7
More weird lens adaptations to the Sony A7R(II)
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Rolleiflex SL 2000 with digital back „SWVS“
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Rollei 35 feeling on the Sony A7  (2015)

Similar to 'perceived temperature' there is something like the perceived “best lens”, even if the lines per millimeter test chart says otherwise. One of these lenses is the Rollei 35 S Sonnar 2,8/40. The Rollei 35 gave me some of the nicest picture I ever made and I always found the Sonnar performance faultless, sharp, contrasty, simply the best. Also if compared to lenses of other prime compact cameras like the Olympus XA or the Minox 35, the Sonnar was always ranked #1.

Now, times have passed over the Rollei 35 and its siblings, even though I still use it every now and then. Whenever I do however, it is for the joy of using a classic camera, and not for its compactness.  And to tell the truth, it also is not for the quality of the Sonnar, because what even a good 24x36 slide can deliver, is easily surpassed by a multitude of even smaller digital compacts of today, Sonnar or not.  

With regard to compactness, the digital competitors have made exceptional progress anyways, to an extent I had thought impossible, even way after the beginning of the digital era. Especially the Sony cameras with their large 24x36mm sensor are so small today – who (apart from Sony) would have imagined these cameras five years ago?

One factor that is spoiling the party a little is the size of the lenses. I don’t want to bash Sony, but the perceived size of their lenses is big, compared to the cameras (even if they are very compact, if compared to similar lenses). Adapting compact lenses of other mount standards (like the Pentax M 2,8/40 or 2,8/28) is very easy and yields very usable combinations, thanks to the phantastic focusing aids of the Sony, yet not especially compact ones. For combinations as compact as the smallest current Sony lens, the Sonnar FE 2,8/35 (37mm long, 120g), you need to look for Leica M mount lenses.

If you want something even smaller, the only option of buying one off the shelf is the new Voigtlaender (Cosina) VM 2,8/40 Heliar, 32,2mm long including the adapter (22,4mm if collapsed), yet 250g heavy.

So what would you get with a Rollei Sonnar 2,8/40 adapted to the Sony A7?

Unsurpassed compactness plus Sonnar quality and some Rollei 35 feeling on the A7?

Let’s see.

My old 35 S, defect meanwhile and wearing dents on almost every corner was the donor camera, which I dismantled to almost the very last screw. Rollei lists about 24mm as register to the film plane, which leaves 6mm for the adapter – enough space. Transplanting the aperture actuation and the lens barrel lock mechanism was more difficult.

Here is what was left after taking the camera apart:

Since I still have neither lathe nor milling equipment (only my bare hands…) the adapter thickness is only as accurate as can be achieved with file, sand paper and caliper, but I am still happy with the result. The optical performance does not differ between the corners, so I believe I did a good job with the file. And correct infinity setting can easily be achieved, since the stop is adjustable  – as if it was made for me.

The complete external shutter mechanism was removed, and the internal shutter actuation mechanism blocked in open position with a drop of glue.  

The body sided rails that guide the lens when pushed into the body were impossible to mount inside the adapter, so pulling out or collapsing the lens needs to be a gentle movement. This is a tight fit anyways - the lens can be pulled out and collapsed when mounted on the camera, but can only be removed from the camera in operating position. 

I have given an extra thought to whether or not I could add a true aperture ring from another lens and connect it to the tiny aperture lever of the Sonnar, but I found the original Rollei wheel more attractive, even if it affects the ergonomics of the camera, in that it partially covers the grip.

This in turn sparked the idea to keep some other design elements of the 35 S, like the lens lock button and the section of the shutter speed wheel.

It would have been possible to keep (almost) the complete front side of the Rollei and mount one camera in front of the other, so to speak, but this I found somewhat silly, with only aperture wheel and lens lock having any function.

Then again, I did want to keep the classic “Rollei 35” lettering.

So now, the design is neither fish nor fowl, and I don’t really like it either. Design is a difficult subject…

This is how the lens looked during the build:

And attached to the camera:

My scales show 130g of weight and a length of 31,1mm (19,6mm if collapsed!), so my adaptation is almost as light as the Sony Sonnar and flatter even as the Voigtlaender Heliar!

As for the feeling, well… The distance ring is not as easy to turn as I would like it to be, and one of my fingers inevitably blocks the lens while turning, but I can manage. Aperture selection is a joy and even if I will not always have this lens on the camera, there is no reason to not have it with me, as light and as small as it is.

And as small as it is, the optical performance is not too bad either. The utmost corners are not good at full aperture, they are surprisingly bad, actually. Can it be that Rollei accepted this weakness, knowing that the corners would almost never be visible on a projected slide or printed picture, in analogue times?

All other parts of the image are acceptable.

For comparison, here is the Sony/Zeiss Sonnar FE 1,8/55, one of the sharpest lenses on the planet and the old SMC-Pentax M 2,8/28, at f=8 in the center, with the 40mm Sonnar being an equal partner.

Not so in the corners and borders of the frames, and also not at f=2,8, but I am not going to show this ;-)

Rollei Sonnar 2,8/40 at f=8, center of the frame:

Sony/Zeiss Sonnar FE 1,8/55 at f=8, center of the frame:

SMC-Pentax M 2,8/28 at f=8, center of the frame:

So the golden rule continues to be to use f=8 and enjoy other people looking at your camera with interest.

More of such adaptations (and on a much higher level of skill) are done by Mr. Miyazaki in Japan  – even smaller lenses can be found there.

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