Rollei/Tessar lens question

[v._b.]

Hello,

 

I have recently purchased used Rolleiflex automat, 1951-1954 model

with Tessar 75mm lens. I shot two rolls of color negative film. When

I took my prints from the lab and examined, noticed that some

pictures (especially those that were shot on infinity) are much

sharper in the center and looks kind of blur in the corners. Is this

the lens spherical aberration or anything else?

 

Thanks,

Valdas

[pete_andrews10]

Hi Valdas.

 

Spherical aberration affects the whole of the image, not just the edges. What you're describing sounds like curvature of field, but Tessar lenses aren't usually prone to that fault. The lens might have suffered some damage, or been carelessly reassembled after an attempted "repair".

 

It depends how critical you're being, I suppose, since all lenses are at their sharpest in the centre, and less so at the corners and edges of the field. Especially if used at, or near to, their maximum aperture.

[v._b.]

Pete,

 

thanks for reply. In fact I shot at f stop of 8, so the aperture should not be a problem. Maybe I'm too critical, but it's a my first MF camera, so I expected something like "WOW" from my first roll. It's not an obvious blur though, just less sharp than in the center. I have read somewhere that older Tessars are not that equal center vs edges compared to later versions of Planars. It does not look like a badly treated lens, although I bought it on ebay. Everything works perfectly, all speeds are correct, even flash synch works, cosmetically very nice, I simply don't believe lens was disassembled at all.

I should probably have to print a few b&w prints myself in the darkroom to judge...

[mike_earussi1]

No matter how far you stop down a tessar the corners will never truly be sharp. That's just the limitation of the tessar design and why rollie later came out with both planar and xenotar 5 element designs, which are much sharper in the corners. The best compromise between center defraction limitation and edge sharpness is f11; past this and the center resolution drops off more than the edge sharpness increases. Nonetheless, the tessar and xenar are razor sharp and produce beautiful pictures over most of the picture. Enjoy.

[patric_dahl_n]

I think something must have happened with the lens. Maybe it needs to be recollimated. I have older Tessars than that, that are razor sharp from corner to corner stopped down a little.

[jorge_jimenez1]

Mike said "No matter how far you stop down a tessar the corners will never truly be sharp". What world are you living in? At F8 a tessar is razor sharp everywhere. I may agree at 5.6. His camera may be out of focus or something else is wrong.

[v._b.]

Thanks to adding even more confusion :)

 

I have also read in this forum that film flatness could be an issue with MF cameras. Maybe this is what I see (but then it should not be only corners)? The one thing I'm sure of - I see no signs that this camera has been damaged in any way -(unless it was disassembled but this is impossible to tell). Maybe I'm just too demanding? I will try to scan and post it for your judgment.

 

Thanks,

Valdas