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Zeiss Makro Planar 100/2.8 Owner Comments Wanted

I'm sorry Tomasz, but you've missed something in your logic. You say you are doubling focal-length F, but keeping M constant. But you said M=F/f, which means you have to double your distance. This is why you get the same DOF for the same magnification and same focal ratio. You then confuse things further with your comparison of 35mm and medium format standard lenses. The magnification is not the same for the 50mm and 80mm lenses even though the field of view is the same, because the image in the medium format camera is larger (i.e. larger magnification).
On the other hand, your thoughts about smaller digital formats are nearly right, for the same reason that things cancelled out between 35mm and medium format - you have confused magnification with field of view. The DOF you'll get with the Sony will be the same as a 35mm camera with a 200mm lens set to F/11, but the brightness of the image is the same as at f/2.8. This could be viewed as a big advantage of digital. Your calculations are right about the DOF compared with the 85mm at f/1.4 though - to get so slim a DOF with a 21mm lens is practically impossible.
I hope this helps. :)
Mark
 
Well Mark, I'm not convinced. The problem is
that hyperfocal distance depends on THE SQUARE
of the focal length, so doubling the focal length
you need to increase your distance FOUR TIMES to get the same DOF,
while to keep magnification constant you need
to increase your distance only TWICE. This suggests
that changing the focal length you cannot keep both magnification and DOF constant at the same time.

From the other hand I shot two portraits using two
lenses 2.8/50 and 2.8/135, both wide open. I framed both pics so that the head of my subject filled the whole frame (so mag was the same, I
needed of course to move back using 135 lens to
increase the distance). I really do see a huge difference in DOF in both pictures. In picture
taken with 2.8/135 distant backround is
completely blurred, while on the other picture
there is a recognizable, but soft image.
(Unfortunately I haven't got them scanned.)

Tomasz
 
466462.jpg


It is quiz time.

Could this photo be taken by Makro-Planar 100 2.8 ?

The other possibility is Apo-Makro-Planar 120mm f4, the one for Contax 645.

I will come back with the answer.

Opinions welcomed.
 
nice portrait! a too complicated question at Web-quality 800x742 pixel at 96 ppi resolution for me.
It could be a couple of other lenses als well to make the quiz even more complicated.
- like Voigtlander APO-Lanthar SL Series Macro 2.5/125 in Contax Yashica mount or a 6x6 Zeiss Planar 2/110 adapted to Contax/Yashica or ... :)
 
Let us stay within the two lenses.

Let us wait for more opinions before I come back with the answer.
 
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