Metallurgical Objectives

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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Dave S
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Metallurgical Objectives

#1 Post by Dave S » Tue Sep 10, 2019 8:55 pm

Am I correct in thinking that Metallurgical objectives have a greater working distance than standard objectives. :?:

If I attach an objective lens to a dslr via T2 to RMS adapter, does it matter if it is infinity corrected, or standard 160mm :?:
Brunel SP100 (with 4x, 10x, 40x,60x, and 100x (oil) plan objectives), and Canon EOS 4000d Camera (microscopy use only)

PeteM
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Re: Metallurgical Objectives

#2 Post by PeteM » Wed Sep 11, 2019 12:43 am

A metallurgical objective may or may not have a longer working distance - you really need to check. The main difference is that "M" objectives aren't meant for a cover slip, but are focused directly on a specimen (such as a metal, silicon wafer, etc.). They may also be designed for epi illumination and have coatings and baffles to reduce the possibility of reflections and loss of contrast from a light source going through and back.

Biological objectives meant to be used with a cover slip have different corrections for that extra bit of glass. At low magnifications, say 4x, you can often use either one in either situation with OK results.

Some biological objectives have long working distances and will usually be marked as such (e.g. "LWD"). Point being, you really need to investigate the specific objectives you're using rather than assume a greater working distance.

Scarodactyl
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Re: Metallurgical Objectives

#3 Post by Scarodactyl » Wed Sep 11, 2019 4:51 am

An infinity-corrected objective needs a tube lens to converge the rays onto your sensor, typically a 200mm fl (varies with manufacturer).
You should spend soms time on the photomacrography forums as well--this sort of thing is more the central focus over there.

Hobbyst46
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Re: Metallurgical Objectives

#4 Post by Hobbyst46 » Wed Sep 11, 2019 6:09 am

Also, please note that the thread on a metallurgical objective is often not RMS.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

Dave S
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Location: Suffolk, UK
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Re: Metallurgical Objectives

#5 Post by Dave S » Wed Sep 11, 2019 8:59 am

Thanks guys, informative input, as always.

Much appreciated.

When the adapter arrives, I can take the 4x 160 plan objective off of the microscope, and experiment with the principle.
Brunel SP100 (with 4x, 10x, 40x,60x, and 100x (oil) plan objectives), and Canon EOS 4000d Camera (microscopy use only)

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