PDA

View Full Version : 150mm lens which is sharpest aperture


robc
4-Dec-2006, 08:14
if you have a 150mm lens, which aperture do you consider to be its absolute sharpest ignoring dof.
Ole Tjugen
4-Dec-2006, 08:21
F:3.5 or 4.5, depending on which lens. Or f:9, on the one that doesn't have larger apertures. Ot f:7.2 on the old Aplanat, but only in the absolute center. Or f:6.8 on another one. Yet another one can't be considered "sharp" until it's stopped down to f:32 - but that might have something to do with the large chip in the front element.

Really - the maximum sharpness in the center is a function of the aperture, and decreases with increasing f-stop. But in most cases stopping down improves the sharpness in the rest of the image area, and reduces various aberrations towards the edges. So it all depends on where you measure, and how you measure.
Ted Harris
4-Dec-2006, 08:25
I'm not sure that the survey makes much sense. The answer is likely going to be different from one lens to another and from one design to another. That is the answer will not necessarily be the same for a Rodenstock Sironar W 150 and a Sironar N 150, at least it might not as the designs are different, and the same for either of those and a G Claron, etc. Moreover, there can also easily be differences from one example of a lens to another (e.g. one Symmar 150 to another Symmar 150). Take a look at the lenses tests that Chris Prez and Kerry Thalmann did several years ago.

OTOH, if you are simply looking for the subjective opinion of users that is another story.
Ron Marshall
4-Dec-2006, 08:27
Have a look at the lens test results:

http://www.hevanet.com/cperez/testing.html#100mm_thru_163mm
robc
4-Dec-2006, 08:28
thats fine if they all over the place. it will disprove my theory and I'll shut up about it. But it will still be interesting to see what people think is their sharpest aperture for each lens.
Walter Calahan
4-Dec-2006, 08:57
What does it matter? Sharpness is only a tool for translating one's vision to paper.

Can you tell I really don't like these questions. Not that I'd tell anyone not to post this question if they think it is important. Grin.
Dan Fromm
4-Dec-2006, 09:16
thats fine if they all over the place. it will disprove my theory and I'll shut up about it. But it will still be interesting to see what people think is their sharpest aperture for each lens.Rob, stop theorizing and start experimenting. You might learn something useful.