at last infinity

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

Moderators: Pau, rjlittlefield, ChrisR, Chris S.

Adalbert
Posts: 1184
Joined: Mon Nov 30, 2015 1:09 pm

at last infinity

Post by Adalbert »

Hello everyone,
Yesterday I received the adapter 67mm to 25mm from Russia.
Image

So, I have just taken some photos with Nikon CFI plan 10x an Lomo plan 25x and Canon EF 70-200L.
Does anybody know why there is no difference between the magnification of the 10x and 25x ?
BTW, enclosed you will find the link to the test:
https://mikroskopie-forum.at/index.php/ ... unendlich/

Thank you in advance.
BR, Adi

Pau
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Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

:shock:
In fact your images taken with the 25X Lomo have lower magnification than the Nikon 10X ones, so something must be wrong

Is your Lomo infinite corrected?. If yes, maybe the Lomo microscope tube lens is much longer than Nikon (200mm) but this is very unlikely
If finite, what is its tube lenght? (160mm or...)
Pau

Adalbert
Posts: 1184
Joined: Mon Nov 30, 2015 1:09 pm

Post by Adalbert »

Hello Pau,
This lens looks as follows:

Image

What does F=25 mean? Maybe it is a focal length ?!

BR, Adi

Pau
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Joined: Wed Jan 20, 2010 8:57 am
Location: Valencia, Spain

Post by Pau »

0.25NA is typical of achromat or planachromat 10X objectives, so this could explain all. F 25 could refer to FL but I'm not sure, are there any other numbers at the opposite side?
If it's finite corrected the remaining small magnification difference will also fit.
Pau

Adalbert
Posts: 1184
Joined: Mon Nov 30, 2015 1:09 pm

Post by Adalbert »

Hello Pau,
At the opposite side you only can see the following number: 87209
But the finite LOMO lenses have usually the length of the tube ( like 160 or 170 or 210 etc.)
BR, Adi

rjlittlefield
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Post by rjlittlefield »

I'm betting the Lomo's "F=25" is focal length.

The Nikon 10X is 20 mm.

Compared to that, a 25mm focal length lens would give 8X (=200/25), consistent with the images shown at the link.

--Rik

Adalbert
Posts: 1184
Joined: Mon Nov 30, 2015 1:09 pm

Post by Adalbert »

Hello Rik,
Yes, you are right, and this fact has been verified by my test.
BR, Adi

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