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504 distagon CFi lens not tac sharp


New Member
I have a 50/4 CFi lens (which has since broken), but the pictures I took with it were not in focus anywhere. I only noticed this when I blew the pictures up to 16x20". The focus was so close everyewhere but not quite sharp where the focus should have been let alone anywhere. The pictures always "appeared" focused everywhere. I focused the grain perfectly when printing. This was a repeated problem. I constantly use apertures of f8/11 all the way down to f32. I have an 80/2.8 which is tac sharp.
Does anyone know what could have been the problem? I have a 501 CM body...I'm at a loss unless there wasa problem specific to my lens.

Also, what is the orange button next to the "F" (and what does the "F" on the shutter speed ring stand for)?

Lastly, I have to preview my shots wide open (via the depth of field preview button) even in bright sunlight. SometimesI forget to return to depth of field preview. Does the aperture snap back down if I leave the depth of field preview wide open when I take my shot? I can't imagine the shuttercould stop back down in a fraction of a second...

Lots of questions, I know.

Hi Annie,

I've got the CF 50mm FLE with the floating elements and I have to remember to set the floating elements to the correct range for shooting or I get a soft neg. Also you can leave the depth preview off (wide open) and the lens will automatically stop down when you take a picture, I rarly use it and usually leave it wide open. The F position on the lens is for using the lens on a F series body(these bodies have a shutter built into the body and do not use shutter in the lens). In the F position the shutter is disabled and the camera body shutter is used. Hope this helps.

I don't know whether that will be the cause, but stopping down a lens as far as possible will reduce sharpness.

There is a balance between the good and bad things stopping down does. It always (!) limits maximum attainable resolution (important part of "sharpness"), by increasing difraction. And it does that rather quickly.
The other thing it does is, depending on the lens design, reduce image quality compromising lens faults.
At first, reduction of aberrations will improve quality more than increasing diffraction will reduce the same. After a stop or two (depending on lens), there is nothng left to be gained by further stopping down. But diffraction will continue to increase, and further limit image quality.

So unless you need DOF (increasing DOF = lowering the difference in 'sharpness' between the in - and out of focus areas. You can do that by increasing sharpness of the out of focus bits, but also by reducing sharpness of the in focus bits...) don't stop down a lens.

Interesting about the DOF. I usually try to stay in the middle apertures to get the most possible focus for landscapes.


Are teh floating elements controlled by the outermost ring? I consider that ring to control closer shots, so I try to leave it on infinity when shooting landscapes.

I have some scratches on my lens. Is repair more than the cost of a new lens? Does anyone know about how much I should expect to fairly spend for this kind of repair? The scratches are on both the front and the back of the lens. Must have been a confusing day for me.
Hi Annie,

Yes this is the floating element setting. it needs to be set to match the focus distance, if you focus at 10m then set the FLE control ring to the right range. if your using hyper focal distances to improve your depth of field than you need to make sure the ring is set to the focus distance. Ex&le shooting at f16, you set the infinity mark to the f16 mark on the right and the f16 mark on the left shows about 1.7m. this would give you a depth of field from 1.7m to infinity. now looking at the focus mark it shows the focus point at about 3m, you'll need to set the FLE ring to the 1.2 to 4 range if not you will get a soft out of focus picture. As for the scratches, this could be a costly repair. I would clean the front and rear elements with a good lens cloth and a drop of lens solution (applied to the cloth only) and do some more tests. a few light scratches won't make that much difference in the sharpness. Zeiss designed the FLE lenses because the older designs were not as sharp as they wanted. I had the older 50mm T* and it was not as sharp as I needed, it was OK for 8x10 or so but I needed a lens to do large group portraits in smaller spaces with the ability to make 16x20 inch or larger prints and the FLE design fits the bill.

Thanks so much, Franc.
The info is a HUGe help. I appreciate it. Wish me luck and scratches be gone with a cleaning, though I think they may be a little more than minor. I'll do some tests.