Highest Resolution at About 2x

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mjkzz
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Post by mjkzz »

Robert wrote:I like to wrap a small section of a flocking sheet around the front of the Min5400 to serve as a soft lens hood. It really helps. I do this with almost all lenses before I shoot.
You mean this :D

Image

Lou Jost
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Post by Lou Jost »

PS...I know what you are going to say...downsize the FF image to same size as APS-C and it will be more detailed.
Close. I was going to say "upsize the APS image to the same size as FF, and the FF will be sharper and more detailed", or equivalently, print them both as large prints, and the FF print will show more detail.

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:
PS...I know what you are going to say...downsize the FF image to same size as APS-C and it will be more detailed.
Close. I was going to say "upsize the APS image to the same size as FF, and the FF will be sharper and more detailed", or equivalently, print them both as large prints, and the FF print will show more detail.
Do you make large prints? Many folks do, and this is of course a prime reason for ensuring maximum information and detail in the image. But most everything I do to present my efforts is online, where showing large images is difficult without a site like EasyZoom, so images are almost always downsized, and/or shown with 100% crops.

I'd bet if I uploaded two images, taken at f4, 2x on APS-C and 3x on FF, then uploaded them to the EasyZoom site (or alternatively posted 100% crops), folks would say the FF image is "worse" than the APS-C image because the 100% crops are fuzzier and look less detailed. The FF image may actually have more detail, and may print better, but it won't win the contest.

Lou Jost
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Post by Lou Jost »

No matter what you will eventually do with an image, the one with more detail leaves you with more options. You can always downsize it to the point where it is sharp at 100%. You can't do the opposite, recover missing detail from the smaller image. I like to leave my options open in case I want to exhibit an image.

Some of my rainforest images from my film days were chosen to be made into permanent exhibits at the Missouri Botanical Garden, where one of them was printed at least five feet tall. Who could have predicted that? Because I always worked to get max resolution in my photos, my work was up to the task. It is good to have the option.

Beatsy
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Post by Beatsy »

RobertOToole wrote: Hi Beatsy, I like to wrap a small section of a flocking sheet around the front of the Min5400 to serve as a soft lens hood. It really helps. I do this with almost all lenses before I shoot.
Yes, I do the same. There are still ways to sneak stray light up the tube though, (e.g. reflection off the front of a diffuser with a "too small" hole in the front). It doesn't take much to introduce veiling flare that steals a lot of contrast. A small disc of black card around the hole (white on the diffuser side to reflect light back to it) keeps all the un-needed light on the subject side though, and that solves the problem. None of the issues are insurmountable - you just have to be aware of them...

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:No matter what you will eventually do with an image, the one with more detail leaves you with more options. You can always downsize it to the point where it is sharp at 100%. You can't do the opposite, recover missing detail from the smaller image. I like to leave my options open in case I want to exhibit an image.
No disagreement on keeping options open. I do have an issue with the word "detail" though, since that is a subjective term. I think "information" is a better term for what you're suggesting. A sensor with more pixels will generally record more information from the subject. How detailed an image looks depends on how you view it.

RobertOToole
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Post by RobertOToole »

mjkzz wrote:
Robert wrote:I like to wrap a small section of a flocking sheet around the front of the Min5400 to serve as a soft lens hood. It really helps. I do this with almost all lenses before I shoot.
You mean this :D

Image
Hey Peter that looks just like my lens!

:D

Robert

RobertOToole
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Post by RobertOToole »

Beatsy wrote:
RobertOToole wrote: Hi Beatsy, I like to wrap a small section of a flocking sheet around the front of the Min5400 to serve as a soft lens hood. It really helps. I do this with almost all lenses before I shoot.
Yes, I do the same. There are still ways to sneak stray light up the tube though, (e.g. reflection off the front of a diffuser with a "too small" hole in the front). It doesn't take much to introduce veiling flare that steals a lot of contrast. A small disc of black card around the hole (white on the diffuser side to reflect light back to it) keeps all the un-needed light on the subject side though, and that solves the problem. None of the issues are insurmountable - you just have to be aware of them...
100% Agreed.

When photographing wafers I cut a black mask with an approx. 24mm x 36mm cutout in the center to keep light from bouncing up to the lens. Seems to help with contrast.

Robert

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Post by rjlittlefield »

Lou Jost wrote:Rik has shown that the aerial image of even a good 10x infinite objective contains significantly more detail than ordinary sensors can capture.
It could be that my memory is losing things, but I don't recall posting anything like that, except in the case where the objective was pushed significantly below nominal magnification by use with a shorter than normal tube lens, e.g. delivering 5X on a 100 mm TL.

When a 10X NA 0.25 objective is used at nominal magnification, it's running at effective f/20 back at the sensor, and I know that's small enough to be in diffraction-limited territory with any of my usual cameras.

Can you provide a link to this thing that I don't remember?

---Rik

PS. I wonder, are you're remembering one of my demos that even an inexpensive enlarger lens at 1:1 and nominal f/4 or f/5.6 will out-resolve most sensors?

Lou Jost
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Post by Lou Jost »

Oops, if you don't remember it, I am probably mistaken. I'll look for it right now...

Lou Jost
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Post by Lou Jost »

I searched on the word "aerial" and could not find it. I'll describe it to you and maybe you will remember which post I am mis-remembering. As you say, it doesn't make sense that the post referred to the 10x, and in fact as I think more about it, I am probably remembering that you used a microscope lens only to look at the aerial image of some other lens....You set up a USAF resolution chart and photographed the aerial image of something with a microscope lens, and showed that it contained more detail than the image recorded by the sensor.

Sorry for my mis-remembering. I should have realized it didn't make sense. I'll edit the comment...

ray_parkhurst
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Post by ray_parkhurst »

Lou Jost wrote:
"But the resolution of the objective is the same in both cases... it is a case of "empty magnification", isn't it?
Edit--I misremembered the thing in brackets. Please ignore it: [Alligator, not necessarily. Rik has shown that the aerial image of even a good 10x infinite objective contains significantly more detail than ordinary sensors can capture. So increasing the number of pixels by spreading the image over a larger sensor with more pixels will improve the image.]

The Mitu 2x is known to be an under-performer though.
Lou...although the 10x objective comment may be unsupported (I thought I remembered such a test from Rik as well), the second part of your statement should still be true. Spreading the image over the larger sensor (with more pixels...) should indeed add information to the image, long as you're not beyond the Nyquist limit. But whether this "improves" the image still depends on how the image is viewed.

JohnyM
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Post by JohnyM »

10x/0.45 definately produce more details than A7RII 4,5um pixel can capture.

rjlittlefield
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Post by rjlittlefield »

JohnyM wrote:10x/0.45 definately produce more details than A7RII 4,5um pixel can capture.
Yes, good point. I've never had one of those to play with.

But 10X NA 0.45 is effective f/11.1, and long ago I posted a demonstration at http://www.photomacrography.net/forum/v ... 164#101164 that an f/11 aerial image carries a lot more detail than could be captured by 4.7 micron pixels (in a Canon T1i then)

Edited to add: https://www.microscopyu.com/tutorials/m ... resolution says that 3 micron pixels are needed for 10X NA 0.45. That agrees nicely with the calculation that at lambda=0.55 microns, f/11.1 has a cutoff frequency nu_
0 = 0.1636 cycles per micron = 6.11 microns per cycle.

--Rik

Lou Jost
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Post by Lou Jost »

Rik, that's the post (the one with the aerial image) that I mis-remembered!

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