Leitz Milar 6,5cm loupe lens

[ulf]

The Leitz Milar 6,5cm loupe lens is an interesting old lens designed for high magnifications.

As I'm bitten by the lens-hoarding bug I could not resist this lens.

 

I got min with a step up ring for the Leitz Aristophot system, but the lens itself has a standard M25x0.75 thread.

With a few step-rings I was able to mount it on my conical tube intended for one type of Nikon microscope lenses

 

The Milar is in the same category as the famous Zeiss Luminar, even if it is not regarded as quite as good.

The design is simplistic, with few lens elements and no coating.

 

It has a quite deep UV Reach similar to a Cassar S

The blue curve show the relative transmission of the Milar.

The brown curve, added as a comparison, is from a 20mm Canon Bellows lens 20mm.

 

As the Milar is designed to work in a very limited magnification range it is reasonably sharp there.

Due to the design it has quite some transversal chromatic aberration, generating coloured fringes outside the focal plane

 

Fortunately this problem can mostly be eliminated by photo stacking and some editing.

Both images, scale 2.4 : 1, at 100%, grabbed from Zerene stacker, before final editing.

[dabateman]

Interesting lens. That depth of field is very narrow. Was that taken at its f4?

What camera did you mount it too, a Sony E-mount?

As it lets in some UVB, this should give some nice deep yellow green UV colors.

 

What is the tube length recommended for it?

 

[ulf]

The aperture indications 2, 4 ...12 are not F-stops.

Fully open the lens is F/4.5 and there are no click-detents for different stops.

I think I stopped it down to the 4-mark

 

Beside the conical adapter I had a helicoid and some M42 extension tubes, finally attaching via a short Sony E-mount to my Sony A7III.

The extension from sensor plane to the front of the lens used here was ca 235mm.

 

There is no recommended tube length as it is not a microscope lens.

The magnification is changed by varying the extension of the lens.

The original Aristophot setup might have looked like this:

https://www.alamy.co...age3178185.html

[JMC]

Nice looking lens Ulf, showing some very deep UV transmission. Out of interest, have you flocked the inside of the conical tube you have? I don't have one myself, but I've heard stories that they can reduce contrast due to reflection from the internal surface unless something is applied to give them a more matt finish.

[Stefano]

Yes, the transmission is very deep, down to about 305 nm. If UVB is defined as 280-320 nm, it definitely transmits a good amount of it. I'm not sure this will allow you to see greens in your images, since sunlight and sensor sensitivity (and usually UV-pass filters) all have a descending curve at shorter wavelengths.

[ulf]

Nice looking lens Ulf, showing some very deep UV transmission. Out of interest, have you flocked the inside of the conical tube you have? I don't have one myself, but I've heard stories that they can reduce contrast due to reflection from the internal surface unless something is applied to give them a more matt finish.

Yes I have, a long time ago.

I complained about that problem when I got my sample.

Rear view before flocking:

This design is actually mine. I made it for free to a Chinese Web merchant.

He is still selling it. Here an image with my Mitutoyu 5x lens:

https://www.ebay.com...XcAAOxy~iJQ~dYw

[JMC]

Cool. Nice one Ulf

[Guest]

That transmission curve is comparing the Canon Macrophoto 20mm f3.5?
 

Am I reading that correctly about 90 percent at 365nm.

[ulf]

This comparison graph is intentionally not set up as an absolute transmission.

They are normalised that way from the original measurement data.

The telltale is that both graphs reach 100%. That would never ever happen in the real world.

It is drawn that way to compare the relative UV reach.

 

For correct absolute transmission graphs, please look at my posts in the Lens Data section.

https://www.ultravioletphotography.com/content/index.php?/forum/645-uv-lens-technical-data/

[Guest]

I was more interested what you found for the Canon series. Thanks.