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Vega-25 50mm/5.6
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PostPosted: Fri Nov 22, 2013 12:30 am    Post subject: Vega-25 50mm/5.6 Reply with quote
Hello,

I received this strange lens yesterday, from Moscow.



I have very few info about it. It's russian (written in cyrilic) but there isn't any plant symbol... which can looks a bit strange for a russian lens. Even modern russian lenses have symbols. Aperture ring is dented, so looks like it is from motorised machine (obviously an enlarger). Serial is 3001. Coating is green/turquoise. Mount is M27. Seller told that it has special optiks (ultra low dispersion, or something like that), hard to know if it's true.


Nevertheless...
I adapted it on Nex, using a lens cap and helicoïde. It looks very amateur, but it's working like a charm : I've got the infiny and closefocus.




I went to Paris in order to make some test shots (so, not artistic shots).

All shot are straight from camera, no PP, even if some deserve noise reduction (1 and 7 are ISO 1600, other - ISO 800... yes very poor light, and all shots handheld). All shots are wide open (f/5.6) exepted #2, which was a bit closed.


#1

#2

#3

#4

#5

#6

#7

#8


PostPosted: Fri Nov 22, 2013 12:42 am    Post subject: Re: Vega-25 50mm/5.6 Reply with quote
Interesting lens! Thank you very much for sharing samples. I'm also very curious about USSR enlarger lenses but I was afraid of playing russian roulette again after bad experience last times Wink
BurstMox wrote:
...seller told that it has special optiks (ultra low dispersion, or something like that), hard to know if it's true.

I bet the same glas like in Industar L leses (for example Industar 61 L/D) - it contains some Lanthanum (slightly radioactive). IQ wise these Lanthanum glas lenses are not better than other's by the same (sovjet) makers in my experience - I guess they mainly use these special glas to save correction elements inside the lens (=money)/make an easier construction, not to improve their old lens designs.

Last edited by ForenSeil on Fri Nov 22, 2013 3:44 am; edited 7 times in total


PostPosted: Fri Nov 22, 2013 12:43 am    Post subject: Re: Vega-25 50mm/5.6 Reply with quote
ForenSeil wrote:
BurstMox wrote:
...seller told that it has special optiks (ultra low dispersion, or something like that), hard to know if it's true.

I bet the same glas like in Industar L leses (for example Industar 61 L/D) - it contains some Lanthanum (slightly radioactive).


I thought Lanthanum was yellow


PostPosted: Fri Nov 22, 2013 12:57 am    Post subject: Re: Vega-25 50mm/5.6 Reply with quote
BurstMox wrote:
ForenSeil wrote:
BurstMox wrote:
...seller told that it has special optiks (ultra low dispersion, or something like that), hard to know if it's true.

I bet the same glas like in Industar L leses (for example Industar 61 L/D) - it contains some Lanthanum (slightly radioactive).


I thought Lanthanum was yellow


No, or at least not automatically. I had several Industar 61 L/D and they were all nearly colorless (except the coating reflections).
As far as I know yellow coloration comes from Thorium and can be cleaned with UV light.

Is the Vega-25 really a 50/5.6 lens or a lens with another formula (50/2.8 etc.) with fixed min. aperture of 5.6 for enlargements?

PS: Does anyone here know exactly from which chemical reaction this typical yellowish color comes from?
PPS: Color rendition and overall character reminds me a lot of Industar 61 L/D - I bet it's a very similar design.

Last edited by ForenSeil on Sun Dec 01, 2013 6:23 pm; edited 1 time in total


PostPosted: Fri Nov 22, 2013 1:15 am    Post subject: Reply with quote
Quote:
Is the Vega-25 really a 50/5.6 lens or a lens with another formula (50/2.8 etc.) with fixed min. aperture of 5.6 for enlargements?

I would be glad to know Smile
But if this lens follow the soviet logic, Vega has to be a Biometar, not a tessar like all Industars. Now, this lens obviously doesn't follow soviet logic (no logo, not usual look)...so hard to know. I don't have knowledge to disassemble it, and I don't want to train on this rare lens Smile .


PostPosted: Fri Nov 22, 2013 3:17 am    Post subject: Reply with quote
BurstMox wrote:
Quote:
Is the Vega-25 really a 50/5.6 lens or a lens with another formula (50/2.8 etc.) with fixed min. aperture of 5.6 for enlargements?

I would be glad to know Smile
But if this lens follow the soviet logic, Vega has to be a Biometar, not a tessar like all Industars. Now, this lens obviously doesn't follow soviet logic (no logo, not usual look)...so hard to know. I don't have knowledge to disassemble it, and I don't want to train on this rare lens Smile .


You can't argue with their names indeed. Most Jupiters are Sonnars but the Jupiter-12 is a Biogon and so on Wink So the Vega could be also a Tessar / Industar.

hmm...
Quote:



is it wide open in that picture? For me that hole inside it looks like a build-in artificial min-aperture.
Insides it looks similar to my Noritsu 50.7/9.5 (which a an enlarging lens from an processing machine aswell but with fixed aperture), which also looks more like an 50/2.X lens based on front lens diameter and given focal length.

BTW: Many of these enlarger lenses are optically optimized for fixed magnification ratios (like ~1:5 for example, to enlarge a 35mm neg on usual print sizes like 9x13cm or 15x20cm). Some do very well far outside their original specifications but others become more or less an cruelty, especially at their widest apertures.
IQ looks best in sample #7 for my eyes which is a close-up. Mabye it's not an coincident. (But maybe it's simply a normal Industar L ~50/2.8 Tessar taking lens in an optimized build Wink)


PostPosted: Fri Nov 22, 2013 1:07 pm    Post subject: Reply with quote
Quote:
is it wide open in that picture? For me that hole inside it looks like a build-in artificial min-aperture.


You're right, this is wide open.


PostPosted: Fri Nov 22, 2013 6:40 pm    Post subject: Re: Andrew Devlin Reply with quote
bevlin761 wrote:
Is the Vega-25 really a 50/5.6 lens or a lens with another formula (50/2.8 etc.) with fixed min. aperture of 5.6 for enlargements?

Read posts above! Lens looks like it has an build in fixed aperture. According to front element diameter my bet goes to 50/2.8 Tessar-like, due "special glas" and character how it renders (colors) I would bet it's Industar 61 50/2.8 or a close derivate.

Last edited by ForenSeil on Sat Apr 05, 2014 5:00 pm; edited 1 time in total


PostPosted: Fri Apr 04, 2014 8:01 pm    Post subject: Reply with quote
I gave a new try with this lens, on A7 this time. I can see very slight vignetting wide open, so I don't think it will cover more than 24x36.

I also physicaly compared it to Industar-61. Front element is bigger than on I-61, whereas rear element is more little. I don't know if it can be related to formula. I made a comparaison with intern element reflexion :

https://www.youtube.com/watch?v=lVhxGaZj2gc&feature=youtu.be

And here are some basic shoots with this Vega-25 on A7 :


#1


#2


#3


#4


#5 crop 100%


#6


And here is the lens in his classical shape :









PostPosted: Fri Apr 04, 2014 8:56 pm    Post subject: Reply with quote
It doesn't render like a tessar so I bet it's a biometar/unilite type like the other Vegas.

BTW Lanthanum glass does make a difference, the I-61 L/D has more contrast and colour saturation than the earlier non-Lanthanum Industars like the 22 and 50.

You can also see this in the Voigtlander Color-Skopar 2.8/50 which has better contrast and saturation than contemporary tessars like the CZJ 2.8/50, the Color-Skopar makes use of Lanthanum.


PostPosted: Fri Apr 04, 2014 9:14 pm    Post subject: Reply with quote
I will compare it with my Vega-3 50mm/2.8 tomorow. Maybe it will render more similar to this Vega-25 then.
I used it on my Nex-3 some months ago : http://forum.mflenses.com/vega-3-50mm-2-8-t62766,highlight,%2Bvega+%2B3.html


PostPosted: Fri Apr 04, 2014 10:18 pm    Post subject: Re: Vega-25 50mm/5.6 Reply with quote
BurstMox wrote:
ForenSeil wrote:
BurstMox wrote:
...seller told that it has special optiks (ultra low dispersion, or something like that), hard to know if it's true.

I bet the same glas like in Industar L leses (for example Industar 61 L/D) - it contains some Lanthanum (slightly radioactive).


I thought Lanthanum was yellow


Lanthanum (Ln) itself is a silvery white metal. The Ln3+ ("3+" should be a superscipt) cation, as found in glasses, is colourless.


PostPosted: Fri Apr 04, 2014 10:42 pm    Post subject: Re: Vega-25 50mm/5.6 Reply with quote
ForenSeil wrote:
BurstMox wrote:
ForenSeil wrote:
BurstMox wrote:
...seller told that it has special optiks (ultra low dispersion, or something like that), hard to know if it's true.

I bet the same glas like in Industar L leses (for example Industar 61 L/D) - it contains some Lanthanum (slightly radioactive).


I thought Lanthanum was yellow


.....

As far as I know yellow coloration comes from Thorium .....


Thorium (Th) exists as Th4+ ("4+" should be a superscript) in glasses and is colourless.

Quote:
Does anyone here know exactly from which chemical reaction this typical yellowish color comes from?


It's hard to find a completely definitive explanation. However it is known that (i) gamma-ray irradiation of a variety of colourless crystalline solids and glasses can cause colouration, and (ii) the decay series of Thorium produces gamma rays. The colouration is attributed to so called Colour-centres of F-centres (F = Farbe, German, colour). The nature of these centres presumably depends upon the chemical constitution of the particular glass. So, for example, it been proposed that in silicate glasses irradiation damage pushes a negative oxygen atom away from a positively charged silicon atom. There results a positively charged "hole", a negative electron sits in the hole and colouration is due to light absorption by this tightly bound electron-hole pair.

Try searching "colo(u)r centre" "F-centre" "gamma irradiation, colouration, crystal" etc.


PostPosted: Sat Apr 05, 2014 3:57 am    Post subject: Reply with quote
This is a very good lens, great quality.


PostPosted: Sat Apr 05, 2014 2:53 pm    Post subject: Reply with quote
Yahvel wrote:
This is a very good lens, great quality.

Do you really think so? For me it looks quite bad to be honest, especially considering that's 50mm and F5.6
Slightly dull and cold colors, strong blueish glow/CAs (look at "Zola Colors" sign in one of the pics) in high contrast scenes, rather low contrast, undersaturrated blacks....
Almost every 50mm taking lens I know is better @F5.6

Last edited by ForenSeil on Sat Apr 05, 2014 5:01 pm; edited 1 time in total


PostPosted: Sat Apr 05, 2014 3:04 pm    Post subject: Reply with quote
ForenSeil wrote:
Yahvel wrote:
This is a very good lens, great quality.

Do you really think so? For me it looks quite bad to be honest, especially considering that's 50mm and F5.6
Very dull and cold colors, strong blueish glow/CAs (look at "Zola Colors" sign in one of the pics) in high contrast scenes, rather low contrast, undersaturrated blacks....
Almost every 50mm taking lens I know is better @F5.6


Sorry, but I completely disagree

The resolution looks very nice, the contrast is fine, you can't expect perfect contrast in the not so good light conditions, there is a nice gradation of tones despite the poor light. Same for the colours, they are more than fine considering the light conditions. There isn't any visible CA on most of the shots and it is wrong to criticise it based on that Zola Colours sign which is a neon tube and of course has a diffuse blue glow.

I've seen a lot of worse lenses, this one looks much better than average.


PostPosted: Sun Apr 06, 2014 7:58 pm    Post subject: Reply with quote
Other, also enlarger vega's have same 2nd aperture inside. will try to remove and post results.


PostPosted: Sun Apr 06, 2014 8:54 pm    Post subject: Reply with quote
Which Vega? I'm curious Smile waiting for your results


PostPosted: Mon Apr 07, 2014 5:51 am    Post subject: Reply with quote
Vega 5U



PostPosted: Mon Apr 07, 2014 7:17 am    Post subject: Reply with quote
I've just measured - front glass diameter in Vega 5U is 42mm (diameter of part exposed to light), so according to calculations, with that additional aperture removed, this lens should become 105/2.5, which is quite interesting. But my particular lens is not sharp enough even at F4, so at F2.5 it would be much worse.

Here's it @F4:

http://fotkidepo.ru/photo/19595/45772Fj34BRUMri/OtBBRiD4xu/964208.jpg


PostPosted: Mon Apr 07, 2014 11:51 am    Post subject: Reply with quote
Ah yes, I have this lens too. I never thought about this "second" apperture. Since the lens is pretty cheap and easy to find, I may try to remove this thing.

On Vega-25, it's a bit different. There isn't any "second" aperture. It's just that the apperture wide open has little diameter regarding to the glasses.


PostPosted: Mon Apr 07, 2014 12:01 pm    Post subject: Reply with quote
I look forward to seeing samples from the Vega-5y as a 4/105 Biometar type would be interesting to use on 6x9.


PostPosted: Mon Apr 07, 2014 12:07 pm    Post subject: Reply with quote
I just disasembled optics. This "thing" can't be removed, that's simply the shape of the second bloc. If you want to remove it, you'll have to remove the second bloc. Not very good Razz .

Ian, I may have time to do some shots today. But don't espect great result, it's an enlarger lens. Also, mine is not in perfect condition, but you may have an idea. Resolution (according to photohistory) is 56/24.


PostPosted: Mon Apr 07, 2014 12:42 pm    Post subject: Reply with quote
Merci Pierre, I look forward to seeing them. Anything above 25lp/mm gives okay results on 6x9, but really, 40lp/mm and above is preferable.


PostPosted: Mon Apr 07, 2014 2:02 pm    Post subject: Reply with quote
Yes, I also taken it apart, the "2nd aperture" is flattened and black painted surface of 2nd lens Very Happy
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