At what aperture lens has the most resolving power?

[DREW WILEY]

Ian - I always shot Ekfe 25 at 25, and pyro developed. But it was a tight squeeze film if you needed its full 12-stop potential. It also had a fragile emulsion, and one had to be careful to use a weak stop bath too. In 120 version, the anti-halation layer was so-so; you had to load it well shaded. I last used the roll version on an especially long hike to one of my bucket list places before I got too old. There were four high passes each direction toward and back, two of them way off trail and dicey in terms of a narrow ledge un-negotiable if wet. And every afternoon there were giant rain and lightning storms. No trails whatsoever into a remote basin, or even any signs of a trail or prior human presence, though climbers are known to get in there. We didn't see anyone else an entire week of the two weeks involved. A companion decided to shoot Ekfe 25 too, in his Contax MF system, while I carried 6X9 roll film backs for my 4X5 Ebony folder. Long story with my friend slipping in a creek and dunking his gear plus breaking legs to his new Gitzo tripod, and me duct taping on whittled pine prosthetic legs.

Finally we got back to his van at the trailhead slightly after dark, two weeks later, exhausted of course. He had placed a Hide-A-Key inside his bumper, but some critter, probably a chipmunk, had found it and carried it off. On go headlamps, and we eventually found it a distance off in the brush. In the meantime, he decided to rearrange all his exposed roll-film edge-on in a metal box via headlamp illumination. Upon development, fully half the rolls were fogged. So let's add it all up ... A $2000 Zeiss lens needing repair, a broken $500 tripod, a sprained ankle needing therapy (also duct taped the return half of the trip), and most of the memories on fogged Efke film. ... I did better, being paranoid about the anti-halation layer to begin with, with just a bit of edge fog in a few cases outside the image area itself. Got one real classic from that trip, which would have been darn difficult to bag in terms of sheer detail and extreme luminous tonality using any other 120 film.

 

[jerrybro]

In the 80s I was doing technical training for electronics field service engineers. I put together a slide presentation of all the circuit boards they would encounter and how to recognize them. I took all the photos with a Nikon F3 using a 55mm f2.8 Micro lens, hot lights and Ektachrome tungsten film. All photos were taken on a set I built so the boards were as close to full frame as possible. Camera was mounted to a Bogen 3036 tripod. I used 1 roll to test for the optimum ISO setting. All photos were then taken at f5.6 or f8 (I’m not sure at the moment) to compensate for any DoF issues, I do not remember the shutter speed.

Projection was by a new at the time Kodak professional projector with a pro grade flat field lens. Projection was made on a classroom wall painted for projection. The results were amazing. You could read the writing on the ICs. You could read the silk screening on the boards. The color code on the resistors was clearly visible.

With todays higher resolution film, and higher resolving lenses, I’m sure that even more detail could be resolved. But to what end? When do you go from chasing grain/pixels to producing photographs? There are many links in the chain from what you see to the final image you can produce of that scene. In engineering there are two I try to always keep in mind. The performance specs the final product needs to achieve and better is the enemy of good enough.

 

[wiltw]

Published lens tests by photozone.de show that many lenses adhere to the rule of thumb that a lens generally is 'the best' about -2EV from wide open. But then there are proofs that the rule of thumb is not rigid. The Canon 100mm f/2.8 macro test charts clearly prove the best performance comes at f/4 for this lens, one f/stop down

...yet note that it is only in the Center that that lens performs 'the best' at f/4...the MTF values at Border and Extremes are best -2EV down or -3EV down, respectively, from wide open! So even armed with objective values, for this lens what would you say about where it performes 'the best'... -1EV or -2EV or -3EV ?! It seems that status would depend upon where in the frame the subject is located.

 

[Bikerider]

Asking questions like this about resolution of lenses is a bit like asking how long is a piece of string? The answer is infinitely variable with no set standard. The resolution one day with a particular lens may be best at F5.6 but the next it can be different of there are outside influences such as being very warm or very cold. Differences of temperatures can alter the physical properties of optical instrument's. There is no way of saying categorically what is the best or the worst except in laboratory conditions with measurements taken over a period of time.

Graphs are fine but they represent one set of figures on one particular day and in fact, as an answer to the question they are virtually meaningless. The next day they could and almost certainly differ.

As it happens the finest lens for resolution that I ever used was a Nikkor F2 50mm with a screw thread fitted on a Leica 111f body used on a tripod. From F4 to F11 there was no difference, but at F2 it was passable!

But to be realistic any lens worth using. will outperform the user most of the time, asking which is best is another way of filling up space in a forum pages.

 

[Nodda Duma]

To be fair, in a radially symmetrical optical assembly like what’s used for photography, changes in temperature affect focus which is corrected by refocusing. The cause is changes in indices and thermal expansion of the glass and barrel materials.