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Rodenstock 35mm f/4.5 apo-sironar digital: Experience? Why discontinued?

epforever

Member
I'm considering picking up one of these for my Alpa. Can anyone contribute their experience with it? Or address why Alpa discontinued it? I'd be using it on a Credo 60 back (54x40).

thanks
ethan
 

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 .
 

epforever

Member
Jurgen -- Well, that would explain why it was discontinued. Too bad. Image circle of 105mm would be amazing. Thank you.

Still interested to hear any additional input others have.
 

epforever

Member
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?
 

Alan

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 .
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
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?
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
Can you clarify this?
Do you mean focus shift, where you focus wide open, then the in-focus point moves when you stop down?
. . . . . . . .
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

Active 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
 
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