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Carl Zeiss Jena MC BIOMETAR 2,8/120mm on APS-C
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PostPosted: Fri Apr 29, 2022 7:05 am    Post subject: Carl Zeiss Jena MC BIOMETAR 2,8/120mm on APS-C Reply with quote



On my APS-C SONY A6000 and A6500, I like to adapt this 6x6 medium format lens, having an compact 180mm telephoto lens. It should be used always with an proper lens hood! Since the sweet spot of this lens will be used, the lens has an excellent performance!





PostPosted: Sat Jun 04, 2022 3:55 am    Post subject: Re: Carl Zeiss Jena MC BIOMETAR 2,8/120mm on APS-C Reply with quote

OPAL wrote:
. . .
Since the sweet spot of this lens will be used, the lens has an excellent performance!


You're putting that lens to good use!

Like 1


PostPosted: Mon Jun 06, 2022 3:01 pm    Post subject: Reply with quote

The Biometar 80 and 120 were go-to lenses for me on medium format: easily adaptable and reliably excellent. Truly cut-price 'Blads.


PostPosted: Tue Jun 07, 2022 9:02 am    Post subject: Reply with quote

. . . and they've never, ever been expensive.


PostPosted: Fri Jun 10, 2022 5:46 pm    Post subject: Reply with quote

I also have a CZJ Biometar 120mm F2.8 lens, which I consider a good lens. The Bimeter 120mm was a portrait lens for the Pentacon Six system. It isn't especially sharp wide open, which is actually desirable for portraiture, but if you close 2 or 3 stops, the lens becomes fantastically sharp.

A detail that few people pay attention to is that the Biometar 120mm is not a telephoto lens, it is a 5-element Double-Gauss lens. As a result, the Biometar 120mm is a relatively long lens, and when adapted for FF, it is considerably longer than a typical 135mm lens. On the other hand, the Biometar 120mm has some unique advantages over a 135mm lens:

1) As it is a quasi-symmetrical lens, performance remains good even when focusing at short distances, unlike most telephoto lenses, whose performance drops rapidly at focus distances less than 10x the focal length.

2) Precisely because of the quasi-symmetrical optical structure, lateral chromatic aberration is virtually non-existent.

The figure below shows 100% crops from corners of test images (24 MP FF camera) for a Pentacon 135mm F2.8 and a Biometar 120mm F2.8:

.


The Pentacon 135mm is an optically good 5-element lens, with a thick doublet, whose design was certainly derived from the famous Zeiss Sonnar 135 F4. However, despite the Biometar 120mm being an MF lens, so having a coverture much larger than the 35mm format, the Pentacon 135m's performance at corner is no match for the Biometar, especially in terms of lateral CA.


PostPosted: Fri Jun 10, 2022 5:49 pm    Post subject: Reply with quote

That is an interesting point you raise- good to think about. Haven't seen it before and think many people comparing 135mm 35mm SLR lenses would benefit from hearing it.

I was going to say it looks alot bigger, but it doesn't:



However.

The prices of this Biometar make it abit pointless... hundreds of pounds.


PostPosted: Sun Jun 12, 2022 4:53 am    Post subject: Reply with quote

Were the CZJ 80mm and 120mm Biometars made in M42 mount as well?

While in Central Europe, I saw these occasionally in both in camera shops and online.The ones I saw in shops were all for Pentacon 6x6 cameras. As I was doubtful how to adapt them to K-mount cameras, I did not buy any.


PostPosted: Sun Jun 12, 2022 6:34 am    Post subject: Reply with quote

All the CZJ P6 lenses I've seen had an interchangeable mount that screwed on and you could fit various mounts to them such as P6, M42 and Exakta.


PostPosted: Sun Jun 12, 2022 12:17 pm    Post subject: Reply with quote

iangreenhalgh1 wrote:
All the CZJ P6 lenses I've seen had an interchangeable mount that screwed on and you could fit various mounts to them such as P6, M42 and Exakta.


Wrong information. Surely he confused it with the Pentacon 300mm and 500mm lenses that actually have "an interchangeable mount that screwed on". Embarassed

Carl Zeiss Jena lenses for Pentacon Six have a fixed bayonet mount. I own approximately 12 P6 CZJ lenses, at focal lengths of 50, 65, 80, 120 and 180mm and they all have the same fixed bayonet mount.


PostPosted: Sun Jun 12, 2022 12:28 pm    Post subject: Reply with quote

Fuck off Gerald, your troll act is getting beyond the pale now.

Pentacon made an adapter that has a P6 mount on one end and either an Exakta or M42 mount on the other, it is extremely common to see P6 lenses with this adapter fitted.

I mixed this up with the Pentacon lenses that do have interchageable screw on mounts.

To err is human, and I am definitely human.



PostPosted: Sun Jun 12, 2022 12:59 pm    Post subject: Reply with quote

chhayanat wrote:
Were the CZJ 80mm and 120mm Biometars made in M42 mount as well?

While in Central Europe, I saw these occasionally in both in camera shops and online.The ones I saw in shops were all for Pentacon 6x6 cameras. As I was doubtful how to adapt them to K-mount cameras, I did not buy any.



The Biometar 120mm F2.8 (and all other CZJ lenses for Pentacon Six) uses a fixed bayonet mount for direct use on Praktisix and Pentacon Six cameras.



The pin is the diaphragm actuator, which opens the diaphragm when pushed by the Pentacon Six mechanism. The operation of the actuator pin is exactly the opposite of the actuator pins of native M42 lenses, which close the diaphragm when pushed.

For use with Praktica cameras, Carl Zeiss Jena provided P6-M42 adapters. This is the "zebra" model:


The small serrated lever is used to cock the semi-automatic diaphragm mechanism.

This is the last original model that even had an internal variable resistor to electrically transmit the selected diagram value to the photometer circuit of Praktica PLC and VLC cameras:



There are many third-party P6-M42 adapters on the market today, but as far as I know, none have the semi-automatic diaphragm mechanism.


PostPosted: Mon Jun 20, 2022 6:45 am    Post subject: Reply with quote






PostPosted: Tue Jun 21, 2022 8:29 am    Post subject: Reply with quote

iangreenhalgh1 wrote:
All the CZJ P6 lenses I've seen had an interchangeable mount that screwed on and you could fit various mounts to them such as P6, M42 and Exakta.

just bought nikon-version. if using M42-version(no on Ni obviously otherwise no infinity- and the right one with A/M lever. one can quickly open aperture for focussing. pity not for Nikon.
I would rather compare 80 biometar with C/Y 85/1.4 on APS-C or FF. its like day and night reg. resolution/sharpness. further tests will be made with tripod. also have the arsat VOLNA 3 80mm and CY 85/2.8.


PostPosted: Tue Jun 21, 2022 9:07 am    Post subject: Reply with quote

Gerald wrote:
chhayanat wrote:
Were the CZJ 80mm and 120mm Biometars made in M42 mount as well?

While in Central Europe, I saw these occasionally in both in camera shops and online.The ones I saw in shops were all for Pentacon 6x6 cameras. As I was doubtful how to adapt them to K-mount cameras, I did not buy any.



The Biometar 120mm F2.8 (and all other CZJ lenses for Pentacon Six) uses a fixed bayonet mount for direct use on Praktisix and Pentacon Six cameras.



The pin is the diaphragm actuator, which opens the diaphragm when pushed by the Pentacon Six mechanism. The operation of the actuator pin is exactly the opposite of the actuator pins of native M42 lenses, which close the diaphragm when pushed.

For use with Praktica cameras, Carl Zeiss Jena provided P6-M42 adapters. This is the "zebra" model:


The small serrated lever is used to cock the semi-automatic diaphragm mechanism.

This is the last original model that even had an internal variable resistor to electrically transmit the selected diagram value to the photometer circuit of Praktica PLC and VLC cameras:



There are many third-party P6-M42 adapters on the market today, but as far as I know, none have the semi-automatic diaphragm mechanism.

if you have problems attaching the adapter to P6-bellows( I have two and for using on one i had to shave the adapter) shave the front ring(take it apart) to have 1.6mm.
there is another important trick but only P6-mount-cams related so i will not mention this here. removing lenses/bellows etc. when sticky can be a big pain til impossible. I have the solution.


PostPosted: Tue Jun 21, 2022 9:10 am    Post subject: Reply with quote

I need to know the seller of these p6-body-caps to use whatever lens on it. here i drilled a hole for pinhole-plate.