Perfect distance between Sigma LSA and microscope lenses=?

Adalbert · Post by **Adalbert** » Mon Jan 01, 2018 12:01 pm

Hello everyone,
Does anybody know the perfect distance between the Sigma Life-Size Attachment and the microscope lens?

Is it constant for all microscope lenses e.g. NIKON BE Plan 4x (RMS) and NIKON LU PLAN 5x (25mm) ?
BR, ADi

Lou Jost · Post by **Lou Jost** » Mon Jan 01, 2018 5:07 pm

I don't have experience with the Life Size Adapter, but I have played a bit with varying the distance between objective (or reversed prime) and tube lens, and I think there is no single right answer, and that it varies from lens to lens. What I have seen is that some kinds of aberrations are minimized by short separation distances, and others are minimized by long separation distances.
So I think we need to test it ourselves for our particular combinations of lenses.

Adalbert · Post by **Adalbert** » Wed Jan 03, 2018 5:07 am

Hello Lou,
I am a little bit confused because NIKON recommends 100mm till 200mm but in many setups the distance is smaller.
BR, ADi

Pau · Post by **Pau** » Wed Jan 03, 2018 5:49 am

That distance is not critical: this is one the advantages of infinite systems over finite, because the rays are parallel the infinite system allows for more flexibility and to put flat optic elements at the infinite space without altering the properties of the system.
The best point for an specific objective and non official tube lens can only be established by careful tests.
In principle this distance would be the same for the same kind of objectives like in the microscope when you change them

I got the Sigma but still waiting the adapters to test it, don't expect much, I'm not a good tester like other members

Lou Jost · Post by **Lou Jost** » Wed Jan 03, 2018 5:50 am

Same with Mitutoyo's recommendations. Like I said, I think there is no single right answer. It also doesn't make a huge difference. Edit, I see Pau answered while I was writing. I agree.

Adalbert · Post by **Adalbert** » Wed Jan 03, 2018 7:00 am

Hello Pau, hello Lou,

Many thanks for your hints!

Robert uses the Sigma LSA too but he hasn’t tested any LU PLAN up to now :-)
http://www.photomacrography.net/forum/v ... hp?t=36071

So, I have already tried with 50mm for the LU Plan 5x / 0.15 and with 100mm for the BE Plan 4x /0.10

BR, ADi

Lou Jost · Post by **Lou Jost** » Wed Jan 03, 2018 7:51 am

Why don't you do a test, comparing 50mm and 100mm with the same lens? The differences will probably be subtle so you will need to post 100% crops.

RobertOToole · Post by **RobertOToole** » Wed Jan 03, 2018 1:35 pm

Hi Adi,

With the Sigma LSA, I just happen to have one set up right now, I use a 50mm (2 in) M52 tube between most lenses and can get great corner to corner sharpness and very tiny amounts of CAs so 50mm should be a pretty good distance to start with. Your results may vary.

Hope this helps.

Robert

Adalbert · Post by **Adalbert** » Wed Jan 03, 2018 2:18 pm

Hi Robert,
OK, 50mm :-)
Many thanks!
BR, ADi

RobertOToole · Post by **RobertOToole** » Wed Jan 03, 2018 4:01 pm

Adalbert wrote:Hi Robert,
OK, 50mm :-)
Many thanks!
BR, ADi

You are welcome, anytime, always very glad to help.

Robert

lonepal · Post by **lonepal** » Mon Jan 15, 2018 9:52 pm

Did anyone make a test about it?

I use both Sigma LSA and Raynox tube lenses but this matter confuses me.

Because the lenses are infinite, does the distance matter between the tube lens and the microscope lens

Ichthyophthirius · Post by **Ichthyophthirius** » Tue Jan 16, 2018 5:26 am

Hi,

The distance does matter.

It can obviously be too long, leading to vignetting.

It can also be off (too short or too long) because of the complex interplay between objective and tube lens. Both are usually complex lens systems. So it would be better to say "distance doesn't matter within a specified range."

For example, for Nikon CFI60, the distance is 100-200 mm https://www.edmundoptics.com/images/catalog/7257.gif

Olympus UIS it's 50-170 mm www.olympusamerica.com/seg_industrial/f ... _guide.pdf

and Zeiss ICS has different tube lenses (different lens diameters!) for different setups.

Lou Jost · Post by **Lou Jost** » Tue Jan 16, 2018 5:56 am

Yes, as I said above, you can see the differences, though they are slight.

Adalbert · Post by **Adalbert** » Tue Jan 16, 2018 6:30 am

Hi,
I have taken some photographs with the distance of 50mm between the microscope-lens and the tube-lens:
http://www.photomacrography.net/forum/v ... highlight=

BTW, the distance between the sensor and the tube-lens can be a little bit different then 200mm but the tube-lens should be focused to the infinity.
BR, ADi

Lou Jost · Post by **Lou Jost** » Tue Jan 16, 2018 7:21 am

Adalbert, why not do some comparisons of different distances?