naturephoto1
Offline
• • • • • •
Upload & Sell: Off
|
mdemeyer wrote:
One difference between them (there may be others). According to Roger's review of the Rokinon, it focuses by moving only the rear group. The Actar maintains a fixed relationship between the elements. So, if you are doing such a conversion, it seems you should still focus with the helicoid, not the bellows. Set focus to infinity, adjust Actus for proper infinity focus, then use the helicoid to focus.
I'm considering doing such a hack on a Zeiss 35mm PC-Distagon, which would have to be focused the same way since (I believe) it has a floating element.
Michael
Hi Michael,
Yes I know about the price of the Actar 24 listed on the Capture Integration website. I posted the link rather than the price to avoid issue with other sellers. I hope to place an order for the lens later in the year and hope that Capture Integration can maintain their listed selling price. I look forward to your samples and review of the lens.
As to the question of focusing lenses particularly those with floating elements with the Actus, you may be correct as to the method of focusing. But, if not and since the camera standards can not be moved close enough to focus using the Helicoid alone, the way that I visualize that we may need to focus with such lenses is to at best estimate the distance for our focus and to transfer the focus to the helicoid. The final focus adjustment would then need to be done using the Actus focus adjustment at the rear of the camera. I have my Leica 28mm f2.8 Super Angulon PC (made by Schneider for Leica) and it has a floating element. This will probably become even a little more interesting when we add using tilt to the equation. I suspect that once the focus is determined using the method that either you or I described above that we will need to then use the tilt to adjust for the plane of focus, such that providing we want a near far focus, that the original focus point will be at the near focus and to then to tilt the lens toward the far (distant subject). I have never used a yaw free tilt adjustment before, but my understanding is that you require much less further adjustment after the first adjustment for the near far relationship. In any case, I hope that the adjustment will be correct after the first or second time making such adjustment using the Actus. By the way I would suggest that the focus adjustements be made at the highest magnification offered by your A7 camera. After the adjustment is made for focus and the near far relationship, it should be a matter of stopping the lens down to say f8 or in the case of my Leica 28mm Super Angulon PC to about f11 to maintain the sharpest corners possible.
I have my Actus coming from Capture Inegration with the Leica R lens adapter coming shortly with the 39mm thread Actus lens boards to be shipped to me after they come in. I will try to confirm the best focusing and tilt adjustment procedures from my observations using my Actus with one of my A7r Cameras with the Leica 28mm Super Angulon PC soon after delivery of the camera.
Rich
|
