Thanks for your responses! Am getting both pieces of film scanned so I can post them here.. In the meantime, I contacted the original seller and he is going to take the lens back and I am going to buy a Xenotar 135mm 3.5 and pay him the difference. Hopefully that should give more of the drop of focus I am looking for.. Anyone had any experience with this lens? How does it compare to the Xenotar 150mm 2.8 and the Zeiss Planar 135mm 3.5? Mainly in sharpness terms? Thanks again.
Best Regards Josh
Hi All, SO here is the film that I just had scanned. One is taken with a Rodenstock 150 Sironar N and the other is the 150mm Xenar 3.5. Both shot wide open, the Rodenstock at 5.6 and the Xenar at 3.5 ( or 4.5 ) This is somewhat of a rough test but you should get the general idea. Basically, I had the leaves on the bottom of the frame and the part of the tree where the branches first appear to branch out on the top part of the frame, appear basically in the same part of the groundglass ( 2 horizontal lines up and 2 horizontal lines down ) I did put focus on the bottom container of the tree but for some reason on the Rodenstock image, focus has appeared slightly before that, where the leaves are.. ANyway, as I said, not exact but you should get the point.. So, as you can see from the side by side comparison, the Xenar looks like its focal length is longer than the 150mm Rodenstock and it does seem to have a drop of focus that I thought a 3.5 lens would warrant. Obviously there is some pretty extreme fall off of focus at the front part of the image with the Xenar ( this I put down to being an old style lens ) but the drop of focus BEHIND is not so great ie if you have a close look at the back wheel of the closest blue car, it is more out of focus with the Rodenstock.... Same goes with the white car in the back! Once again, I realise that my initial focus is slightly off and therefore altering test procedures a little bit but still.... Very confusing! Would welcome all thoughts and opinions and thanks again to all who have already contributed.. Best Regards Josh
Just to follow on...
Here are two more that show the drop of focus in the background.. Thanks Josh
Ok, just to sum it all up..
1. Rodenstock 150mm @ 5.6
2.Xenar 150mm @ 3.5 ( or 4.5 )
3. C/U with Rodenstock
4. C/U with Xenar
5. C/U of background with Rodenstock
6. C/U of background with Xenar
So it seems that the Xenar is sharper ( Ok, not sharper but doesnt have as severe drop of focus ) but overall the image has a softness to it.. Look forward to hearing your thoughts..Ok, thanks again.. Josh
Ok, there positively is something wrong with one of them - the focal lengths should not differ as large as that for sure. It is hard to tell what is actually wrong, though - my gut feeling is that the Xenar is too long, as it also seems to have more curvature than it should have. Probably the cells are spaced too short, a element is reversed, or you have a wrong rear to it.
But I am not entirely satisfied with the Rodenstock either - the edge falloff seems to be exaggerated, compared to my (relabelled Rodenstock) 210mm Sinaron on 5x7. But that might be due to wrong contrast settings in the scan, and shorter focal lengths may be worse offenders in the falloff-when-fully-open domain - these Plasmat types are designed to be used at above f/8 in any case, the first stop positively is a focusing setting only.
As to your speculations on front/back focus drop - you can only seriously compare them once the lenses are flawless, so you'd better get all problems sorted out before you embark on that. One thing however is sure, a 135mm/3.5 won't help - the Tessar and Planar types that exist in that length and opening only cover quarter plate to 9x12cm, but not 4x5", and besides, their DOF is about equivalent to that of a 150mm/4.5, so no improvement for what you seem to be into.
If you really want a narrow DOF, you'll eventually have to bite the bullet and get a 150/2.8 Xenotar (or Pentac or Aero Ektar, if you are prepared to wrestle with aerial lenses that aren't really intended for mounting on regular cameras and are of very mixed production quality and condition), or settle for a somewhat longer 3.5/180 or up Tessar type.
Sevo
Hi Sevo, Thanks for your response! Have just traded that lens in for a 135mm Xenotar. From my initial tests this seems to be much better! Although, now I am having the problem of having a misaligned groundglass with my camera! I have focused on a stationery object with this lens and a Rodenstock 135mm Sironar and with both the focus point is before the focus point.. Not ideal for portraits! Hmmmm, the list goes on... Thanks so much for your response! Best regards Josh
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