Jack Hogan

Right, if we want the near and far distances we need all of the variables below. But then the through focus is (almost) useless :-(

Funny :-)  I wonder if you were picking up IR or one of its harmonics. Jack

The retina is not sensitive to NIR.  Do you think this will be relevant to photography?

Hi Erik, A while back there were similar questions relating to the resolution capabilities of smaller formats, FF vs APS-C vs uFT. Early on APS-C/FT tended to be stuck with recycled FF lens designs ...

Not so subtle Bill, you are right. I am still wondering whether there is a better way to display the through-focus: choosing the central slice of the PSF, vs the central projection, vs... What do ...

If that were true you could have an arbitrarily small f-number by choosing an arbitrarily large EPD - but that is not the case, the f-number (N) in air can never be less than 0.5 no matter the ...

The Generalized Model treats the lens as a black box with an entrance pupil and an exit pupil - and assumes that whatever happens between those two can be completely described by specifying only ...

The x-axis is defocus (dz) from the gaussian focal plane, in microns. It is positive in the direction of propagation. The y-axis is the sensing plane, also in microns, so one can read the diameter ...

Right, read off the vertical axis the CoC diameter on the sensor. Easy enough to then convert to object space. Two observations. 1) Diffracted only differs from the geometric model for the first ...

Nice Bill! I've been playing with this diffracted version (50mm, circular aperture, f/1.4): Green Channel: 0.53 lambda, no aberrations Same as above, X-Z profile Jack

Existing thread

Errr... no, to pretty well everything above.  Perhaps a little more reading would be in order :-) Goodbye Greenmachine33. Jack

We do know their methodology: process K-14.  I would venture a guess that the spec sheet presumes that everything is otherwise just about perfect every step of the way. Nothing really, I think the ...

Is K25 at 100 lp/mm usable? Kodak does not think so, so they stop the spec sheet well short of that. Have you read my attempt at explaining why limiting resolutions are not a good criterion for ...

Yes they have, though that appears to be more than needed when comparing to K25 film under a microscope, which however does not normally include an 8K TV :-) As for different formats, I don't have ...

It is 'contrast' in the Kodak spec sheet and what I call MTF in slanted-edge Spatial Frequency Response measurements.  They are relative in the sense that they come from different sources and ...

I believe he tried a number of them and got best results with T-max, but you can read his report in the earlier link. Jack

Hi John, aliasing for the D850 is north of 115 lp/mm.  I don't know about film. Jack

Yeah, kudos to them considering they were writing 7 years ago. They also show unscanned microscope images. Unfortunately that article is not very useful for this discussion and in fact it is ...

You always sound knowledgeable John, though I often have problems understanding what you are saying (mostly my limitations). When I pixel peep at 100% I am usually less than 50cm from my 24" ...