Limnochares aquatica, Sessilida

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rjlittlefield
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Re: Limnochares aquatica, Sessilida

Post by rjlittlefield »

Fero wrote:
Sat Jul 10, 2021 4:17 pm
I think I understand this basic concept, but reality is often different.
Hhmm...

When my reality is different from my understanding, I've learned to bet that the problem is with my understanding. I would be interested to hear what differences you perceive.
That is a good article, but some time and possibly other experience is required to understand everything that's in it.

With microscope objectives, many configurations will automatically scale the effective F-number to match the size of sensor. In particular, this happens whenever you tweak the relay optics (such as tube lens focal length) so as to maintain constant FOV by changing the magnification. In addition, with microscope objectives the sensor is often good enough to capture all detail that's in the optical image, so diffraction is the limiting factor. In these cases, DOF depends entirely on the objective, not at all on the sensor size.
I wonder why f/8 on Canon relates to f/16 on Nikon?
To explain...

With modern Nikon systems, the setting on the camera is expressed as effective f-number, already corrected for magnification. With Canon systems, the setting on the camera is expressed as nominal f-number, which must be corrected for magnification. The usual correction is to multiply by a factor of (m+1), although this may not be exactly correct with some lenses. So, "f/8" at 1:1 on Canon is likely to be around f/16 effective, while on Nikon "f/16" already means f/16 effective. I suspect that this difference is responsible for many discussions about why some lenses give so much DOF. Especially in Nikon communities, the Canon MP-E 65 is famous for giving lots more DOF than people would expect based on their own equipment. The difference is more easily understood by realizing that f-numbers on the MP-E 65 are expressed using the industry standard of "at infinity focus", while actual magnifications are limited to the range of 1X to 5X. As a result, in practice a setting of "f/11" on the MP-E actually means an effective f-number from f/22 to f/66, depending on magnification.
I was thinking to buy full frame to get better DOF
In general the advantage of full frame is more flexibility. By stopping down farther and cranking up the ISO to compensate, you can take the same image with a full frame camera that you can with a crop sensor. The reverse may not be true -- for example while you can buy an f/1.4 lens for full frame, you cannot buy the corresponding f/0.875 lens for 1.6 crop. So, if you want seriously blurred backgrounds for portraits, full frame is a better bet. Similarly if you want to work in low light with moving subjects, and you do not care about DOF, then full frame is better because the larger hole in the longer FL lens allows to collect more light in the same time.

For most macro/micro applications, there is little difference in image quality between full frame and crop sensor, unless you're in a position to obsess over pixel noise, and then full frame will win if you can provide enough light to fill up the sensor.

--Rik

pawelfoto
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Re: Limnochares aquatica, Sessilida

Post by pawelfoto »

For me it was always confusing. Here is quite clear explanation of this matter (if you prefere video and have enough patience) 3 parts: https://www.youtube.com/watch?v=tqbUinSaLls https://www.youtube.com/watch?v=o6odajLSGw0 https://www.youtube.com/watch?v=Z41Leaskr9g

==best, Pawel

Fero
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Re: Limnochares aquatica, Sessilida

Post by Fero »

@rjlittlefield thanks for explanation, did not know about Nikon recalculating effective f-number. Good to know. Also I like your first sentence regarding understanding/non-understanding, you are totally right. The problem is that there is so many variables, which are not taken into account when you read theories, like siffused/vs. direct light, angle of light, extension tubes, ...
As for picture quality full-frame vs. APS-C I am still not convinced, even after seeing videos recommended by @pawelfoto especially as I was thinking about R6 vs, EOS80D I have now, both cca same pixel count, hence different pixel size, so in case to get same magnification without cropping I would have to moce closer with R6 and since it has bigger pixels I could stop down more. For sure full frame is better regarding dynamic range, ISO sensitivity, R6 is mirrorless which I love, you see exactly how your photo will look, amazing low light autofocus ( I shoot often at night with flash), etc. I guess I need to buiy and see for myself.
I am really looking forward to test my Mitutoyo 2x and 5x lenses, I polan to use them especially on mossses and lichens. I just need to buy a lens in between the objective and camera.

pawelfoto
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Re: Limnochares aquatica, Sessilida

Post by pawelfoto »

I use Canon M6 MarkII and Canon 5d Mark IV alternately. The number of pixels is similar, but the FF sensor image quality is much better even if I do a crop. My M6 APS produces more noise. I'm in love with the electronic shutter. In the 5d, every shutter noise breaks my heart, and with long stacks it will have to be replaced soon. If you are serious about upgrading, it may be worth waiting for the Canon R3 ?. It will be possible to use a flash with the electronic shutter.
==best, Pawel

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