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09-26-2009, 11:29 PM - 1 Like   #1
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Contax 85mm f/1.4 on Pentax

Last month I was in search for a long, wide-aperture lens. 77LTD was too slow, FA*85 too expensive, etc, etc. Then I found a Contax Planar MMJ on fleabay for cheap, and I also bought a Leitax conversion mount. The conversion was pretty painless: unscrewing the old mount and replacing a small lever within the lens. I also cut out a slot for the body's locking pin and made insulators so that the body would recognize it as a f/1.4 - f/16 lens. Furthermore I also unscrewed the lens mount on my K20D and stuck a piece of aluminum foil over the 'A' pin to allow matrix metering.


















The bokeh is pretty smooth at close distances, but can get a little rough around the edges at f/1.4 and 50ft. out. You have to stop-down meter, but since the camera thinks it's at f/1.4 all the time, you can stop down to whatever you want and the exposure will be accurate. Things start to sharpen up really nicely at around f/2.8. I think I'm getting the hang of this LBA thing

09-27-2009, 03:57 AM   #2
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Good find, nice job and fantastic results.
I converted a CZ Planar 60mm macro from Contax to K mount but I didn't use the laitax mount, instead I slavaged and modified one from a dead Tokina K mount zoom. I also fitted insulators and an sprung A pin and I made and fitted an aperture actuating lever. Unfortunately the aperture mechanism in the lens was totally unsuitable (linear aperture area / diameter displacement thing) and the exposures were awfull so I took the A pin out again. I now use it as an M lens with stop down metering and it workes great like this. Unfortunaetly it has a bit of element separation which spoils the contrast and saturation somewhat but it is still a good and very sharp lens. I got a quote to have it fixed but it was going to be about $300 and since the lens cost me less than 20% of this it doesn't seem worth it at the moment.
09-27-2009, 06:52 AM   #3
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the FA77 isn't slow, at f/1.8 it's only slightly slower than f/1.4.. but at any rate the images look great, Bokeh looks superb.
09-27-2009, 07:00 AM   #4
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Hi,

Is there a good guide for converting old non-A lens and getting the aperture to show? Thanks.

09-27-2009, 07:01 AM   #5
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The photo of the owl is stunning!

How much was this lense?
09-27-2009, 07:47 AM   #6
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QuoteOriginally posted by systemA Quote
Hi,

Is there a good guide for converting old non-A lens and getting the aperture to show? Thanks.
I have not found a comprehensive guide on converting to A but all the info you need as far as the electrical connections are concerned can be found here:
Pentax Lens Modifications for Matrix Metering - Mark Roberts Photography and here:
Features and Operation of the Ka Mount
Getting the aperture to show does not really help that much as the it won't necessarily allow the camera to control the aperture and achieve correct exposure.
09-27-2009, 11:39 AM   #7
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QuoteOriginally posted by kkado Quote

I can't stop looking at that eye...

btw how much was "cheap" for this lens?
09-27-2009, 12:05 PM   #8
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QuoteOriginally posted by Digitalis Quote
the FA77 isn't slow, at f/1.8 it's only slightly slower than f/1.4.. but at any rate the images look great, Bokeh looks superb.
Okay, only 2/3 stop, but at any rate f/1.4 just makes me salivate

QuoteOriginally posted by systemA Quote
Hi,

Is there a good guide for converting old non-A lens and getting the aperture to show? Thanks.
MattGunn just about hits it on the nose here. If you have a "M" lens, it's just a simple matter of adding insulators on the lens flange to match your aperture range. You also need something to short the "A" pin and the data pin as well too. If you start off with an M42 lens, you'll probably want to drill a hole in the lens flange so you can mount/demount using the locking pin.

It was about $665 on ebay with the 12% cashback, plus about $100 for the leitax C/Y - M42 kit. Maybe not cheap per se, but cheaper than the other 85mm alternatives


Last edited by kkado; 05-17-2011 at 04:09 AM.
09-27-2009, 12:32 PM   #9
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QuoteOriginally posted by ovim Quote
I can't stop looking at that eye...

btw how much was "cheap" for this lens?
QuoteOriginally posted by kkado Quote

Agreed, sharpness + great bokeh. Really great shot.
09-27-2009, 10:01 PM   #10
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smart way of getting zeiss glass on the pentax on the cheap
nice pictures but the results seem a tad soft, is that resizing, lack of sharpening in post, or the lens itself?
09-28-2009, 12:59 AM   #11
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QuoteOriginally posted by k100d Quote
smart way of getting zeiss glass on the pentax on the cheap
nice pictures but the results seem a tad soft, is that resizing, lack of sharpening in post, or the lens itself?
Admittedly it's not as sharp as my Nokton 58/1.4, but it holds its own quite well even at the wider apertures. I didn't sharpen in post very much, mostly just color balance. I think it hits its max sharpness at around 5.6, but you don't buy an 85/1.4 to do that. . .



A crop at f/1.4:


Bokeh goes from nice and soft


To otherworldly and a little obtrusive.


It definitely beats my old Helios 40 in sharpness, but not extravagance of bokeh, that's for sure.
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