?: Canon 7 (rangefinder) to M42 theories requested.

[thePiRaTE!!]

Hi all, before I get too far I'll just preface the question by stating we know the registration distance makes a direct usage impossible. However, for a very special lens (the 'dream lens' 50/0.95, in my case), I was hoping to tap the collective here for a few hints how one might use a teleconverter to 'amplify' the output to fit a SLR.

The negatives with this direction are fairly straight forward: loss of speed and IQ. The positives are being able to use the bokeh of this lens as I wish with my current body and ironically, probably not having to buy a large ND filter in order to shoot said bokeh in the full light of day.

I must first thank Arkku who on Dyxum suggested the TC would be the place to start, but wonder where to go from here? Could anyone share an insight on how I might go about the task?

Thanks,


Kelly.

[kds315*]

Read a good book about optics - how about that start?

[Attila, can we please have an Emoticon where someone pulls out his
last remaining hair on his skalp and face showing extreme pain...?]

[thePiRaTE!!]

Sorry to annoy you. I was hoping that someone had tried this before. I guess the fact is, I've learned quite a bit dabbling inside lenses to be comfortable to do basic things (CLA), but I have no theory background, as you point out. My interest is in photography, I just happen to have a passion for the appearance of light through old glass...

K.

[kds315*]

Oh, we certainly share that very same passion Kelly! What I meant was, that altering the register
length of a lens is a complicated optical issue which needs profound optical understanding
so that the results are useful and worth the effort.

[thePiRaTE!!]

Ok, I see what you mean, thanks for the clarification. I was worried I'd angered a MF lenses god with my ignorance

On the other hand, I am disheartened to hear this wouldn't be something it sounds like I could handle myself with a few pointers.

Because I am stubborn, I will probably attempt this blindly at some point in the future - at the very least I'm sure I will revisit this topic then with something more specific to ask. In the meantime, hopefully somebody has a magic adapter up their sleeve

K.

[tkbslc]

by adding a TC, you would be losing enough light that it would not be worth it. you can find ~100mm f2 lenses that adapt without extreme conversion

[cooltouch]

The problem with adapting a lens with a narrower registration distance to an SLR with a longer one is, if you want infinity focus, you'll have to use an adapter with an element, which I guess is what you've already figured out. Those of us who shoot EOS and wish to use Canon FD lenses on our EOS DSLRs are familiar with this -- we can buy adapters with elements which allow infinity focus to be maintained. But they have severe drawbacks when used with fast lenses. The faster the lens, the worse the flare.

You would need an adapter with an element designed for your specific registration distances, but even so whatever you end up with will probably have the same problem. Unless you have a team of optical engineers available to put together an adapter that will rival the quality of the one Canon offered briefly for FD to EOS.

And even then, such an adapter amounts to about a 1.2x teleconverter, which will take your 0.95 to about a 1.2. And there is a pretty big variety of 1.2s out there, at least some of which could be adapted to fit M42 with less difficulty, I'll bet. Plus -- and this is a big plus -- no flare.

[luisalegria]

You could always aquire a Micro 4/3 body specifically for this lens.

Thats not such an odd idea. Its a rare and unique sort of lens, with unique capabilities, and it may well deserve its own camera. The lens itself is probably worth more than a micro 4/3 body. Olympus ones are running @$600 these days.

It would also be cheaper and less troublesome than any physical/optical conversion or adaptation I can think of.

[thePiRaTE!!]