Advice on objectives

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arnsteins
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Advice on objectives

Post by arnsteins »

I friend of mine who has been working in the microscopy industry business offer me some objectives. I want to know which one to go for to get the sharpest picture of e.g a little ants head. These Are the ones he has for sale:
1    Luminar  16mm/2.5 Zeiss/Winkel
1   Luminar  25mm/3.5 C.Zeiss
2    Luminar  63mm/4.5 C.Zeiss  
 
2  Summar  25mm/2.8  Leitz 
1  Summar  42mm        Leitz 
1   Summar   12cm/4.5   Leitz  M39
1  Photar     25mm/2.5   Leitz 
2  SP-Reflex   1/3x 

Thanks!
-ArnsteinS[/code]

dmillard
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Joined: Tue Oct 24, 2006 7:37 pm
Location: Austin, Texas

Post by dmillard »

If the lenses offered are all in good quality, from my experience I would recommend the 25mm f/2.5 Leitz Photar for this range of magnification, and/or possibly the 16mm f2.5 Zeiss Luminar.

Best regards,
David

Pau
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Location: Valencia, Spain

Post by Pau »

I have a Summar 24mm (not 25) and the Luminar 25mm and the later is better, but as noted, the Leitz Photar may be the best choice.
The mark Zeiss Winkel is tipical of the oldest series of Luminars. The lenses whith longer focal lengh are suitable for less magnification.
Hope this can help.
Pau

pierre
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Joined: Mon Jan 04, 2010 12:37 pm
Location: France, Var, Toulon

Post by pierre »

Depending the magnifition you need.

But I guess those are a good choice:

1 Luminar 16mm/2.5 Zeiss/Winkel
1 Luminar 25mm/3.5 C.Zeiss


Cheers,
Pierre

rjlittlefield
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Post by rjlittlefield »

If you are short on funds, see also HERE, where it is shown that a 10X microscope objective gives significantly higher resolution than a Luminar 16mm/2.5.

I seldom use my Luminar 16mm/2.5, generally using either a Nikon CF N Plan Achromat 10X NA 0.30 microscope objective for higher resolution, or an Olympus 38mm/2.8 bellows lens for longer working distance.

--Rik

enricosavazzi
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Re: Advice on objectives

Post by enricosavazzi »

arnsteins wrote: ...
These Are the ones he has for sale:
1    Luminar  16mm/2.5 Zeiss/Winkel
1   Luminar  25mm/3.5 C.Zeiss
2    Luminar  63mm/4.5 C.Zeiss  
 
2  Summar  25mm/2.8  Leitz 
1  Summar  42mm        Leitz 
1   Summar   12cm/4.5   Leitz  M39
1  Photar     25mm/2.5   Leitz 
2  SP-Reflex   1/3x 
Basically, the three Luminars and the Photar are later designs of proven good performance. The three Summars are quite older designs with simpler antireflection coatings (or perhaps, none), and the comparable models I tested (mainly Leitz Milar) were not as good as the Luminars (more chromatic aberration, in particular). I don't know the SP-Reflex ones. The Zeiss/Winkel is the oldest among the Luminars, and it might have not-so-efficient coatings. The two other Luminars are newer, but there are at least four successive versions:

http://goto.glocalnet.net/savazzi.net/p ... rsions.htm

This is not to say that the older Zeiss Luminars are worse: the differences are minute, and probably not visible in practice:

http://goto.glocalnet.net/savazzi.net/p ... enses6.htm

The Photar 25 mm f/2.5 is not the latest either - I have no experience with this model, but I get good results with the newer 25 mm f/2. The extra 1.5 stops with respect to the Luminar 25 mm do make it easier to frame and focus. The Luminar, on the other hand, is a proven good performer.

In conclusions, I would pass up on the Summars (a bit too old) and the Luminar 16 mm (difficult to use), get either 25 mm for the subjects you describe, and perhaps also the Luminar 63 mm for lower magnification (I find it fine up to at least 5x, but a bit too dark to focus with an optical viewfinder above this magnification)
--ES

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