Detail depending on the depth of field and the selected step

[Igor]

And another question arose. This seller here: https://aliexpress.ru/item/100500229674 ... 9967754666 has a 20X lens with the same 0.3 aperture and depth of field as the 10X lens . Somewhere here on the forum I met an explanation that an increase of 20X in reality gives an increase in detail of only about 30%. Sorry, I can't find this post. It turns out that it makes little sense then to take a lens with a large increase, if the detail does not increase proportionally?

[Scarodactyl]

The ratio of resolution to magnification generally gets worse after 10x, and much worse if you want a longer working distance. It's the optical price you pay to resolve smaller details. The 20x/0.3 is a specialty objective which is not meant for high image quality, just for routine inspection.

[Adalbert]

Hi Igor,

Detail depending on the depth of field and the selected step

I always use the same step size, namely DOF/3 and am very happy with it.
Best, ADi

[Igor]

The ratio of resolution to magnification generally gets worse after 10x, and much worse if you want a longer working distance. It's the optical price you pay to resolve smaller details. The 20x/0.3 is a specialty objective which is not meant for high image quality, just for routine inspection.

Scarodactyl, thank you!

I always use the same step size, namely DOF/3 and am very happy with it.

I understand. One of these days, the NISI 200 macro guide rails will come and I will start trying.

[Igor]

Just a side note to your plans on using the zoom: That 130mm, which you mention, is pretty much the same as using the full 200mm on FF camera. That likely means that extreme corners become dark due to vignetting in the tube lens. Going smaller than that will just increase the dark area in the corners. That was the case with EF 70-200mm f/2.8 III and RF 70-200mm f/2.8. I haven't tried others. The lower limit without vignetting would likely be around 150 mm or so.

The lens "Canon ef 70-200 mm" came today. Tested it on camera "Fujifilm X-H2" (crop factor 1.5) + adapter "Fringer EF-FX II Pro" + microscope lens 10X (https://aliexpress.ru/item/100500444023 ... ?spm=a2g2w .orderdetail.0.0.4fd44aa6V4r4J7&sku_id=12000029188252250 ). There is no vignetting from 200mm to 135mm. Immediately after 135 mm or less, vignetting begins.

NISI 200 macrorails also came. But the seller sent not what he ordered, some kind of hybrid ones (the platform itself is new, but the positioning knob is old, that is, there is no way to make an accurate step of 10 microns). Opened a dispute, but I think it will not lead to anything, wasted money (((

[Adalbert]

Hello Igor,
I use the Raynox DCR-150 as a tube lens with my rail.
For internal focus bracketing I use Canon EF 70-200L and EF 100L Macro.
So if you want to use a rail, the Raynox is good enough :-)
LG, ADi

[Igor]

I use the Raynox DCR-150 as a tube lens with my rail.
For internal focus bracketing I use Canon EF 70-200L and EF 100L Macro.
So if you want to use a rail, the Raynox is good enough :-)
LG, ADi

Hello Adalbert!
I read your comments from 2020 or 2019 where you talked about this. I was thinking about getting a "Raynox DCR-150" but decided the Canon would be more versatile, including for general photography. So I opted for it.

[rjlittlefield]

Does vignetting affect which microscope objective is used? I now have a cheap lens, I bought it on Aliexpress for testing, in order to understand whether macro photography will captivate or not. Captivated I bought this 10X with a working distance of 15.8 mm (I checked it, it’s true): https://aliexpress.ru/item/100500444023 ... 9188252250 . With it, there is no vignetting on the tube tube (fixed lens "Jupiter 37A" 135 mm). Now I want to buy this lens: https://aliexpress.ru/item/100500229674 ... 9967754666 . Is it possible that with him vignetting will be on the same tube tube?

I do not expect much difference in vignetting. The reason is that (1) vignetting is caused by a conflict between the limiting apertures inside the microscope objective and and inside the tube lens, and (2) all the microscope objectives I know have their limiting aperture in almost the same place, very near the mounting threads.

Лу Йост thank you for the clarification!

And thank you for a glimpse into the difficulties of translation! Lou's last name is Jost. I have not asked Lou, but I expect that the sound of the first letter is like "j" in "jar". "Й" is one of the traditional ways of translating "J", but "Йост"then gives a pronunciation that sounds more like "Yost". A better spelling would be "Джост".

(The above paragraph survives translation to Russian and back to English, using Google Translate and Bing Translate. I do not remember much Russian from college 50 years ago, so this is the best check I can do.)

--Rik

[Igor]

I do not expect much difference in vignetting. The reason is that (1) vignetting is caused by a conflict between the limiting apertures inside the microscope objective and and inside the tube lens, and (2) all the microscope objectives I know have their limiting aperture in almost the same place, very near the mounting threads.

Rik, thank you!