Some shots from the Porst 55mm f/1.2 PK lens 
Monday, November 2, 2009, 03:19 PM - Lenses

Here are a few shots from the "Porst color reflex mc auto" 55/1.2 lens, in Pentax K mount. This lens is built by Cosina, and features 6 optical elements in 6 groups (so it is different from the 55mm f/1.2 Tomioka lens in M42 mount which features 7 elements in 6 groups). Oddly, its aperture ring does not feature any stop between f/1.2 and f/2. All the shots are wide open (ie f/1.2)

In daylight, when shooting wide open this lens exhibit some kind of dreamy behavior:

At night, it does not exhibit this dreamy/fuzzy look unless there is significant light on the subject in focus:

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A few more Vivitar/Soligor 21/3.8 shots 
Wednesday, October 21, 2009, 04:13 PM - Lenses
Some more shots from my Vivitar/Soligor 21/3.8 lens (T4 mount):

(I actually own two copies of this 21mm lens: the Vivitar version and the Soligor version)

All the pictures are from my 2009 pic-a-day gallery.
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Zenitar M2s shots 
Wednesday, September 2, 2009, 12:23 PM - Lenses
The Zenitar M2s is a very surprising lens. Designed to be a cheap replacement for Helios 44-x lenses as a kit lens for Zenit DSLRs, is a 50/2 lens in a fully plastic barrel (although some internals are made of metal). This plastic housing is really a pity, as it gives it a cheap look and feeling.

However, from an optical point of view, it is really surprising. A smooth bokeh wide open, quite robust against flare and very sharp once stopped down (even if wide open sharpness is already quite good). Krasnogorsky Zavod (the manufacturer) rates it as able to resolve 65/40 l/mm, while the supposedly very sharp MC Helios 44M-7 is only rated as able to resolve 50/30 l/mm.

It is available under the "Zenitar M2" and "Zenitar M2s" labels for the m42 version, and "Zenitar K2" for the K mount version:
KMZ page about this lens

Here are a few shots with it, from my 2009 Pic-A-Day gallery:

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Jupiter 9 (M42 version) servicing 
Monday, August 24, 2009, 06:23 PM - Servicing
Here is a partial repair guide for Jupiter 9 lenses. Unfortunately I was not able to fully dismantle it, as several screws broke when trying to use them.

This lens optical schema is made of 7 elements in 3 groups. The diaphragm is located between the two triplets.

The front element can be accessed by unscrewing the front ring using a spanner:

The rear group can be unscrewed in a similar way, but it can not be directly removed from the lens barrel. However, if you set the lens to it minimum focus distance, you will be able to move the rear group inside the barrel. If you are very careful, that might be enough to allow you to clean it or the aperture blades.

Remove the rear ring by removing the side screw and unscrewing the ring:

You can now remove the focus ring:

That should be enough to allow you to access the focusing helicoid, by setting the lens to its minimal focus distance.

Now, remove the diaphragm ring:

From there, you can access the clicking mechanism of the preset aperture. If your aperture preset ring doesn't click properly, you might need to clean this small cylinder, or re-shape the metal part that sits on top of it.

You can now remove the aperture selection ring:

This allows you to remove the front part of the lens, which includes the front element and the front triplet. The front triplet can be removed by unscrewing this rear ring (using a spanner):

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