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Rodenstock 35mm f/4.5 apo-sironar digital: Experience? Why discontinued?
- Thread starter epforever
- Start date
jotloob
Subscriber Member
ethan
Just to tell the truth about this lens . This lens has a backfocus problem . That was confirmed by RODENSTOCK .
I do not understand much about optics , but perhaps can somebody else can tell something about backfocus problems .
I found , that about 75% of focus is behind the set distance and about 25% before at given apertures between f5,6 and f16 .
Therefore , the hyperfocal point does not seem to be correct .
Just to tell the truth about this lens . This lens has a backfocus problem . That was confirmed by RODENSTOCK .
I do not understand much about optics , but perhaps can somebody else can tell something about backfocus problems .
I found , that about 75% of focus is behind the set distance and about 25% before at given apertures between f5,6 and f16 .
Therefore , the hyperfocal point does not seem to be correct .
Jurgen, a follow-up question: even if it backfocuses, the lens must have a plane of sharpness somewhere. If I used an HPF ring, and adjusted the position of the HPF ring to compensate for the backfocusing, wouldn't it then work just fine? Or are you saying that the lens has so much field curvature that there is no proper plane of sharpness at all?
Can you clarify this?
Do you mean focus shift, where you focus wide open, then the in-focus point moves when you stop down?
Or were the distance marks on your helicoid off?
jotloob
Subscriber Member
Yes , of course , there is a plane of sharpness , and when you investigate in depth , you will surely find a „rule“ for compensation .
jotloob
Subscriber Member
Yes , I think that is correct . This was mentioned by RODENSTOCK as well as backfocus issue .
I use a LEICA laser distometer and never focus using a matte screen and aperture wide open .
I just set the aperture and distance and found the sharpness not to be as expected according to the hyperfocal point .
Steve Hendrix
Well-known member
I can only say that I struggled to be impressed with the native sharpness of the lens whenever I tested it, regardless of whether the actual focus point had moved.
Steve Hendrix/CI
Steve Hendrix/CI