Stuart Richardson
Active member
Thanks for the information Thierry. This clears things up nicely. Now people can make an informed decision about whether they want to embrace the new lenses or make do with the old.
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- AFD lenses take in count the focus difference (longer path) due to the IR filter on top of the sensor. The glasses, though not newly designed, have been adapted for this.
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Thanks Thierry. As always, excellent information.
Can you tell us how this particular difference affects the actual image quality? Does it affect resolution, contrast or CA (or all three?) of the image at the sensor? It would be interesting to know why this had to be done in the optics, as opposed to compensation via the focusing electronics.
Thanks again,
David
I am guessing that manual focus will be unchanged, given that this camera has been setup with a normal viewfinder and that there are several manual focus lenses still sold with the camera. I doubt this compensation will make much of a difference for film. Digital sensors are perfectly flat and make extremely high demands on the plane of focus being absolutely spot on. Film has a natural curvature and depth to the emulsion that makes these focal issues not quite as critical. I would assume that Sinar, Rolleiflex and Leaf are wise enough not to ship a camera that can shoot film, but does not correctly focus with it. I think this is one of the cases where it is angels dancing on the head of a pin...that 1mm or less difference in focal plane will not likely make a difference unless you are looking at 100% pixels on a 33mp or above back.
I'm afraid I'm still a little lost.
Given that one can focus at any distance within the range of a manual lens, it seems very unfortunate if only AFD lenses can focus with complete accuracy with a digital back because of some auto compensating mechanism. If we are just talking about the depth of the IR filter, there should be a way to compensate for that. It sounds as if with non-AFD lenses, you can focus with greater accuracy with film than with digital, just the opposite from what I would choose.
I think for the price of the camera, manual lenses with focus compensation should focus as well as AFD.
I know this is all speculation, and suspect I'm not understanding, but I'd like an explanation.
Best,
Mitchell
Michell,Thanks Thierry,
You are probably right. It's just that based on what's been said ( a little knowledge is a dangerous thing), it's reasonable to suspect that non-AFD lenses will be out of focus by the depth of the IR Filter when using the digital back but right on when using film.
David, glad to hear you are seeing no problems.
Best,
Mitchell
Hi Mitchell,
this is definitively only speculations. I would not worry as you do. First we have already a bunch of photographers shooting with the Hy6 on film, and they didn't complain about focus issues, secondly I believe that one simply has to take as a fact that AFD lenses are built for digital and that they are optimized for it. Why should this not be the case? In the contrary, it is good to know that one can do this.
This being said, I believe and have trust in our technicians and R&D people to built a camera that is able to focus under each circumstance, being it with film or with a digital back.
To re-assure you even more: most of my lenses for the Hy6 are either non-AF or AF lenses from my 6008. Up to now I did not have any problem.
Best regards,
Thierry