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Zeiss Luminar's light problems

Posted by Matteo Chinellato  
Re: Zeiss Luminar's light problems
February 02, 2011 07:51AM
    
Pavel Skacha Wrote:
-------------------------------------------------------
, on the photos is
> good visible grey tarnish (place with lower
> contrast) roughly in the middle of the view.

This sounds very much like an internal flare problem. In addition, the very flat light angle that is necessary with such a short working distance might further enhance the problem by producing some kind of veiling flare, but that is usually not showing up as a central spot. I experienced something similar with a Leitz Photar 12,5mm. I have long ago stopped using it. Nowadays, when I do not use a microscope, I only use the 25mm Photar and a reverse-mounted EL-Nikkor 75mm, both on bellows.

It would be good to know how you have attached the Luminar. Some adapters/tubes are prone to produce internal flare.

Volker Betz Wrote:
-------------------------------------------------------

> 2. Only photograph objects which are suitable for
> photography ! dont wast time !
> 3. See 2 and don´t photghraph objects which are
> unsuitable
> 4. Newer show bad pictures to anyone, just descard
> it.


That depends on. Not every image has to necessarily be a candidate for winning a photography award. In many cases the documentary purpose outweighs the need for top notch quality. Not everybody has access to high quality equipment, although expensive equipment is no guarantee for high quality pictures ;).

Anyway, one should always try to set minimum quality standards for himself that even documentary photographs should meet, at least within the available technical possibilities.

Cheers

Harry
Re: Zeiss Luminar's light problems
February 04, 2011 11:09PM
Hello Matteo!

I would like to know which objective do you use for this photo:
© Chinellato Matteo

Was this a Luminar 16mm, a Photar 12,5mm or a Macro Nikkor 19mm?

Marko



Edited 2 time(s). Last edit at 02/04/2011 11:10PM by Marko Burkhardt.
avatar Re: Zeiss Luminar's light problems
February 05, 2011 05:39AM
    
if I remember is 16 mm

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Re: Zeiss Luminar's light problems
February 09, 2011 06:51AM
Dear Volker and Harald,

thanks for your messages.
Yes, maybe it is the problem in the adapter, bcs I have relatively long variant (about 5 cm, bought on ebay) and its inner side is not free of reflexions. I will try to fill the inner side by a velvet and test it again.

Thanks for your advices
Have a nice day
Re: Zeiss Luminar's light problems
February 09, 2011 07:06AM
    
> (about 5 cm, bought on ebay)

Is that the cone shaped Beljan adaptor? If yes, then this is probably the culprit. Coating the inner side usually helps.

Cheers

Harry
avatar Re: Zeiss Luminar's light problems
February 09, 2011 01:44PM
    
I have tested my luminar lenses at all apertures on my nikon D1x camera. here's what I found :

63mm : best results stopped down to 4
40 mm : best results stopped down to 2 & half
25mm : best results stopped down to 2
16mm : best results at full aperture.

What I do is using each lens at it's optimal aperture. I adjust the step between 2 photos according to the magnification and the resulting depth of field.
16mm luminar seems to be hard to use with digital cameras. I also have sharpening problems with this lens, and friends of mine, using this lens too, noticed the same thing.
I've got a (lucky) friend who owns both 16mm luminar & 19mm macro-nikkor. the results with the luminar can't stand no comparaison with the pics obtained with the macro-nikkor, really much sharper.

One suggested me that the problem could come from diffraction combined with digital CCD building, wich is not plane but made of photosites in the bottom of a honeycomb structure, after a lowpass filter. this structure really doesn't match fully stopped down lenses, producing more diffraction.

The notice of the Nikon D1x suggest not to stop down more than f/11 (with regular lenses) for best results. diffraction problems might happend really sooner with high magnification lenses.

Pascal
Re: Zeiss Luminar's light problems
February 09, 2011 01:58PM
    
> The notice of the Nikon D1x suggest not to stop
> down more than f/11 (with regular lenses) for best
> results. diffraction problems might happend really
> sooner with high magnification lenses.
>
> Pascal

Do you use the Luminars on a bellows or other tube-like extension? You have to consider that each increase in tube/bellows extension results in a smaller effective aperture, meaning that even with fully open or weakly stopped down aperture you might get well beyond the diffraction limit when the extension exceeds a certain length.

Cheers

Harry
avatar Re: Zeiss Luminar's light problems
February 09, 2011 01:59PM
    
I use Nikkor 19 and Zeiss 16 but not full aperture, with full aperture the photo is not all in focus

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Re: Zeiss Luminar's light problems
February 10, 2011 11:32AM
Yes Harry, you are right. I will do it today and hope it helps.

Thanks
Re: Zeiss Luminar's light problems
February 10, 2011 05:43PM
    
Volker Betz Wrote:
-------------------------------------------------------



>
> Recent experiments showed me that any kind of
> shutter is not good for small fields of view. I am
> just making experiments with a Panasonic D2. It
> has no mirror and a different shutter: But even
> with that camera there is some loss of sharpness
> at short exposure time. But long exposure time
> helps. I could document that there is a
> significant difference between a 1/125 sec. and a
> 2 sec. exposure. 2 sec. a much sharper. I could
> measure a 1.5 micron resolution using a 15 mm
> Mikrotar of N/A 0.2.
>

Hallo Volker, just a curiosity... How do you measure the resolution?

Dario

----------------------------------------------------------------------------------------

Dario Cericola
My Mindat page --> [www.mindat.org]
Periodic Table of Minerals --> [www.mindat.org]
avatar Re: Zeiss Luminar's light problems
February 10, 2011 07:45PM
Recent experiments showed me that any kind of
> shutter is not good for small fields of view. I am
> just making experiments with a Panasonic D2. It
> has no mirror and a different shutter: But even
> with that camera there is some loss of sharpness
> at short exposure time. But long exposure time
> helps. I could document that there is a
> significant difference between a 1/125 sec. and a
> 2 sec. exposure. 2 sec. a much sharper. I could
> measure a 1.5 micron resolution using a 15 mm
> Mikrotar of N/A 0.2.
>

Hallo Volker, just a curiosity... How do you measure the resolution?

Hello Dario, measuring ? ist a more a rule of thumb estimation, by photographing a object micrometer with marks in 10 µm distance and about 2 µm wide. I am looking for a better micro object. 2 µm is about near the calculated resolution for a aperture 0,2.

I am still working on the subject. My object micrometer is for transmitted light, photographed in relefected light and has a cover. This causes some effects.

In some time I well have a better answer.

Volker
Re: Zeiss Luminar's light problems
February 10, 2011 09:55PM
    
I see... I while ago I made some attempts in that direction, with a pretty similar approach. but it was quite a failure...

Dario

----------------------------------------------------------------------------------------

Dario Cericola
My Mindat page --> [www.mindat.org]
Periodic Table of Minerals --> [www.mindat.org]
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