Sensor Sizes

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MichaelG.
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Sensor Sizes

#1 Post by MichaelG. » Mon Jan 24, 2022 10:14 pm

I’m not sure if this will actually help anyone, but I have slightly adapted an image from
https://newatlas.com/camera-sensor-size-guide/26684/

The two diagonal lines demonstrate that there are two ‘series’ of sensor sizes
One based on the 35mm film format, and the other based on the 1” vidicon tube.

This might help explain why the recommended power of C-Mount adapters is not immediately intuitive.
… The appropriate power relates to the ratio of the sensor’s diagonal to that of the 1” vidicon.

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See : https://newatlas.com/camera-sensor-size-guide/26684/
See : https://newatlas.com/camera-sensor-size-guide/26684/
C0381538-FB19-4138-BB6F-1BB10C75D485.jpeg (76.78 KiB) Viewed 3067 times
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MichaelG.
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Scarodactyl
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Re: Sensor Sizes

#2 Post by Scarodactyl » Mon Jan 24, 2022 11:08 pm

IMO the worst part of it all is the "1 inch" terminology, which should have been dropped long ago since it is actively confusing (and even deceptive) regardless of its historical roots.
It is definitely frustrating that "1x" adapters typically crop the field of view way down, since most modern microscopes can cover much more than the 16mm diameter of a 1" sensor at 1x.

MichaelG.
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Re: Sensor Sizes

#3 Post by MichaelG. » Mon Jan 24, 2022 11:48 pm

Here are my calculated magnifications required for the various adapters :
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901AAC59-91AF-41B1-8CE1-320FCE23EEB0.png
901AAC59-91AF-41B1-8CE1-320FCE23EEB0.png (298.25 KiB) Viewed 3053 times
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MichaelG.
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Greg Howald
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Re: Sensor Sizes

#4 Post by Greg Howald » Tue Jan 25, 2022 4:20 am

Thanks for this. I am one of those who has been confused by what appeared to be a double standard.

Hobbyst46
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Re: Sensor Sizes

#5 Post by Hobbyst46 » Tue Jan 25, 2022 8:40 am

MichaelG. wrote:
Mon Jan 24, 2022 11:48 pm
Here are my calculated magnifications required for the various adapters :
...
Thanks for this useful compilation.
In principle, would the best solution for a given microscope and a range of sensor sizes be a 0.4X-2.7X zoom ocular for afocal photography ?
And even more cheeky, an ocular that, on top of that, performs the required corrections (for the appropriate 160mm TL objectives) ?
Do such oculars exist ? are they worth it ?
I sometimes see an add for a zoom ocular, often unbranded.

Scarodactyl
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Re: Sensor Sizes

#6 Post by Scarodactyl » Tue Jan 25, 2022 4:12 pm

Leitz (and later, Leica) did make a zooming adapter. That said zooming is a convenience that comes with optical sacrifice. It's called for when you're going to be changing magnifications frequently between numerous settings, so the hit to quality (and/or extra expense to avoid a hit to quality) is counterbalanced. That's usually not the case with a camera adapter which is usually a one and done type of deal.
Of course once you're dealing with more expensive adapters like these the stated magnifications break down a bit anyway. These numbers assume a 16mm fn, which some adapters may be limited to and others may not.

apochronaut
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Re: Sensor Sizes

#7 Post by apochronaut » Wed Jan 26, 2022 3:55 pm

Prior to the advent of digital photography, AO and B & L both produced adapters which are of the zoom type, having a moving lens adjustable to use with 35mm, 2 1/4 and 4X5, the most common film formats used at the time. The camera adapters came with several extensions, with a progressively longer tube for the larger formats. Stand alone photographic stands also existed using a fixed photo eyepiece in a photo tube mounted in the trinocular port and a bellows with which to adjust the film plane for the different film formats mounted over it. While those camera adapters used a built in lens of variable magnification matched to several fixed locations of film planes; AO's adjusts from 2.8X to 5X for instance which correlates well with your chart for a full frame sensor; there were no low magnification photo eyepieces manufactured by either AO or B&L for use in the photo tube. Each used a standard well corrected 10X visual eyepiece in the photo tube, and in the day, a camera back, either 35mm, 2 1/4 or 4X5 was mounted on a separate bellows equipped photo stand, which was centered over the photo tube and adjusted vertically to precisely locate the film plane.
Obviously , the distance the photo optic is positioned from the camera affects the projected image overlap of the film plane/sensor and each photo eyepiece is designed to be used at an optimum projection distance. Olympus marked that distance on the eyepieces at one time.
However, in the case of a 10X visual eyepieces, is there some reason that a well corrected 10X eyepiece positioned at an appropriate distance below the sensor to create a condition of ideal image field-sensor overlap would not produce an equivalent quality of image with for instance an APS-C sensor as a lower magnification eyepiece, since the image circle of a modern 10X W.F. eyepiece is almost 1:1 with an APS- C sensor?

MichaelG.
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Re: Sensor Sizes

#8 Post by MichaelG. » Wed Jan 26, 2022 4:09 pm

apochronaut wrote:
Wed Jan 26, 2022 3:55 pm
... However, in the case of a 10X visual eyepieces, is there some reason that a well corrected 10X eyepiece positioned at an appropriate distance below the sensor to create a condition of ideal image field-sensor overlap would not produce an equivalent quality of image with for instance an APS-C sensor as a lower magnification eyepiece, since the image circle of a modern 10X W.F. eyepiece is almost 1:1 with an APS- C sensor?
If the eyepiece is sufficiently well corrected, I think it would be a worthwhile experiment.

MichaelG.
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apochronaut
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Re: Sensor Sizes

#9 Post by apochronaut » Wed Jan 26, 2022 4:37 pm

I have tried it and that is the system I use on all of the AO and AO/Reichert microscopes I have taken images through. In those systems though, I use one of those older clamp on photo adapters, such as an Asahi mounted with a mirrorless body instead of a separate photo stand.
The system can actually be set up as parfocal in any case I have tried with APS-C, so I know it works in terms of parfocality and the fullness of field capture but my question is:
Is there any technical reason that a 10X eyepiece under those conditions, i.e. full field capture to APS-C, would yield poorer image quality than a 2.8X photo lens projected to fill an APS-C sensor?

Scarodactyl
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Re: Sensor Sizes

#10 Post by Scarodactyl » Wed Jan 26, 2022 4:58 pm

Just on a theoretical level a viewing eyepiece does want to project its image to infinity, and making it do otherwise is pushing it out of spec. But beyo d that I don't k ow any systematic reason. I'll admit I have only tried it a couple of times and it didn't give me very good results, but I may have picked bad eyepieces or systems to try it on. In particular I had a try with the chinese 10x/22 eyepieces on my optiphot when I had it, but the results showed pretty strong chromatic aberrations. Maybe I lifted it too much though, it wasn't a very systematic test.

MichaelG.
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Re: Sensor Sizes

#11 Post by MichaelG. » Wed Jan 26, 2022 5:31 pm

apochronaut wrote:
Wed Jan 26, 2022 4:37 pm

[…] but my question is:
Is there any technical reason that a 10X eyepiece under those conditions, i.e. full field capture to APS-C, would yield poorer image quality than a 2.8X photo lens projected to fill an APS-C sensor?
I don’t have the knowledge or experience to answer that authoritatively … but surely it will depend upon at least these two variables:

1. The optical design of the eyepiece
2. The design of the pixel ‘wells’ in the sensor

If these two are in harmony then the results should be good.

I know, for example that the Russian K7x for the Lomo Biolam, etc. gives good photographic results on film if it is lifted by about 5mm … but I have never tried it with a digital sensor of any size or type.

MichaelG.
Too many 'projects'

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