MicrobeHunter.com Microscopy Forum

I have been trying to find out exactly what a lens in my ortholux is doing. It is a 1.25x lens that is in between the objectives and eye pieces. This is an old black enamel ortholux with 170 objectives. Is this the lens people refer to when talking about creating infinity correction when using non-infinity corrected objectives? I so need a light source for this scope.

mnmyco

make you eyesight bigger,20mm x 1.25 =25mm

DISCLAIMER: There are participants of this forum who can describe the technical applications of "mechanical tube length" with finesse that actually accounts for the physics involved... I'm a Leitz collector, machinist, and optical instrument - mechanical - repairman and not at all adept at describing the nuances of tube length... having said that...

These old German microscopes do not, generally, allow for mixing of infinity and non-infinity optics. If your scope has the 170mm relay lens, then you need to use 170 objectives. Even in these old black scopes, Leitz made infinity systems. Pictured is my Ortholux epi-flourescence next to one of my Ortho pols... The epi flourescence uses an infinity relay and the Ortho epi pol actually features a -1 diopter above (what I call) the "glimmer slot."

The old black Ortholux did have infinity available but, usually, just offered it on the epi flourescence and epi Metalux configurations... they're out there, if you're patient!

My last pic shows one of my epi pol Orthoplan bodies which is infinity corrected - HOWEVER - even most Orthoplan setups are still configured for 170mm tubelength. And a subject for another post... PLEZY adapters....!!!!!

I did not think it was a lens to correct for infinity, but what is it for? Just increasing image magnification?

hello mnmyco
maybe you can find some information at here
https://www.mikroskopie-forum.de/index.php?topic=7973.0

This is another GREAT resource:

http://www.microscopy-uk.org.uk/mag/art ... on%201.pdf

ebenbildmicroscopy wrote:This is another GREAT resource:

http://www.microscopy-uk.org.uk/mag/art ... on%201.pdf

Indeed it is ... and the key point is nicely summarised:

Provisions to add certain accessories force microscope makers to build microscopes with a longer finite tube length than the mechanical tube length required for correcting their optical system (e.g. longer than 170 mm). As a result, for each such accessory in a finite system, optical elements (known as a tube lens) must be added to bring the tube length precisely back to its proper value (e.g. 170 mm). ... This concave tube lens leads to an unwanted extra magnification factor that commonly plagues microscopes designed for the finite mechanical tube length.

MichaelG.