The impossible lens club?! - Page 2

stevebrot · 06-25-2009, 09:50 AM

Originally Posted by Nesster

I stuck a Schneider Componon enlarger lens on, but as it's 35mm (I have it from my 1/2 frame days) about the only thing it did was extreme close ups. People have got excellent results using 105-135-180mm enlarger lenses.

Currently I'm working on a 75mm view-rokunar f/3.2, but can't get infinity - bellows is too long, and the tubes also (which is strange: 75mm - 45.46 register = 29.54mm so I thought I could get reasonably long focus... have managed maybe 2 feet so far.)

I have been tempted to try the enlarger lens with my bellows, but only have a 50mm Componon-S. I would definitely like to see the results from a longer lens!

Steve

Steinback · 06-25-2009, 02:29 PM

@stevebrot: I've posted this shot before in another thread but this is a 105mm Telesar enlarger lens on a set of bellows:

Ironically I was given an enlarger that the previous owner hacked what appears to be a modified TLR lens onto so I can't use my only real enlarger lens on it.

Douglas_of_Sweden · 07-01-2009, 07:02 PM

What's the thread on those enlarger lenses? (My enlarger is stored in boxes somewhere) Did you make an adapter yourself?

Steinback · 07-01-2009, 10:34 PM

My enlarger lens is M39 (Leica); when I bought it second hand it came with an M39 to M42 adaptor included.

The optical quality is pretty good but it can be a pain stopping the lens down manually to shoot without changing the focus point and I pretty much have to meter using test shots and the histogram. I've also never tried using the enlarger lens in difficult lighting so I have no idea how it handles things like flare.

stevebrot · 07-02-2009, 01:02 AM

Originally Posted by Douglas_of_Sweden

What's the thread on those enlarger lenses? (My enlarger is stored in boxes somewhere) Did you make an adapter yourself?

As mentioned by Steinback, most enlarger lenses have M39 (Leica) thread mounts that may be easily adapted to M42 and from there to K-mount.

Steve

richard64 · 07-02-2009, 02:01 PM

Originally Posted by georgweb

This lens is from a russian night vision device. It has an M42x1 mount (read: "Pentax screw mount"), but the rear elements are protuding waaay deep behind the mount.

Hmmm, interesting effect. What's the lens like as a macro? You could mitigate the issue of protruding rear elements with an extension tube.

Richard

georgweb · 07-03-2009, 11:53 AM

Hi Richard,
never tried as you suggested. A lens which does not get to full open infinity is quite
useless for my style of photography (big word). That's why I've become a tinkerer .-)
Here's what the entire lens looks like.

One more lens which is quite well convertible to PK, incl. inf. adjustment:
Contax Planar 1.7/50 AE on K100D

MattGunn · 07-03-2009, 02:49 PM

I got a Contax / Yashika fit Carl Zeiss S Planar 60mm f/2.8 macro a couple of weeks a go through the usuall online auction site. I had intended to get one of the Leitax conversion mounts but as I was too impatient to order one and I have a lathe I had a go at making a mount.
I got an old K mount off a badly damaged tokina and soldered / machined it to the dimensions of the original mount. This gives me focus from infinity to 1:1. Here is one of the first test shots (1/30, approx F/16, ISO 100):

I have since started converting it from M to A. I have added electrical contacts and made / fitted a new aperture lever. It can be used in all exposure modes now but needs progressively more negative exposure compensation as the lens is stopped down. Need to devise a mechanism to convert the linear diameter change of the aperture to a linear area change. In spite of this it still workes qite well.

georgweb · 07-04-2009, 07:01 AM

Matt,
great effort with the conversion ! I remember somebody tried the same (incl. aperture lever conversion) and ran into the same diameter vs.
area problem (will post when I find it). I guess the 'S'-version of that lens is smaller but still quite a lump of metal and glass.

Here's just one more Contax Planar .-), it's the 1.4/50AE full open. Long bokeh is OK for me (this lens has a very bad bokeh rap). Full open
sharpness is allright for me also (Ser. 59xxx ninja star version). Built like a tank (incl. weight :-)

Carl Zeiss C/Y Planar 1.4/50 on K100D full open contrast-fiddled but no sharpening

Best, Georg (the other)

MattGunn · 07-05-2009, 08:02 AM

The area / diameter problem is one I have encountered with every lens I have tried converting to KA except the Adaptall mount and even that only workes well with some lenses. I will continue to think about this problem but I am confident that eventually I will find a solution (I'm sure that there is room for a simple mechanism if I can only be bothered to calcuulate the correct geometry). It is likely to be a while before I get round to this though as there are a few other intersting lenses I plan to converty to K / m42 mount. A couple that I have started planning / working on include:

A mount to fit microscope objectives onto am M42 extension tube stack / bellows (mostly complete but not tested very throughly)

An adapter to mount my DSLR in place of the film back on my Ilford Monobar view camera (for those not familiar with this relatively rare camera pictures can be found here: Kennedy Instruments Monobar )

Douglas_of_Sweden · 07-23-2009, 02:17 PM

Does anybody knows a way to adapt a Canon FD lens to a Pentax K (or m42 would be OK also)?

MattGunn · 07-24-2009, 12:50 PM

The flange focal distance for the canon FD mount is shorter than the pentax ( Lens mount - Wikipedia, the free encyclopedia ) and so you are highly unlikely to be able to focus to infinity no mater how you mount it. If the rear lens group is small enough it may be possible to make a special mount for it so that it is just inside the camera without fouling the mirror but unless you have a particularly special lens it is probably not worth tye hastle.

*ltdstar* · 07-25-2009, 09:22 PM

i have a Tokina 300mm in FD mount that i plan to convert to PK...i think its possible to focus to inf w/ this lens. Douglas, what lens you want to convert? the 85 1.2 (or any 1.2) would be sweet on Pentax.

Douglas_of_Sweden · 09-29-2009, 04:24 AM

I'll get back to the Canon FD mount another time (have not had the time yet), but here are the first results of another project that I've been thinking on for ever.

I have a Konica macro-Hexar 55mm f3.5 (1:2 macro) lens that I've been wanting to use on my Pentax DSLRs. Like the SMC Takumar or Pentax 50mm 1:4 macro 1:2 this is a tessar lens design and it is as sharp, but a little faster, and like some micro-Nikkor 50's, it has a built in mechanical function that in manual mode change the apperture opening while you focus towards 1:2 (and while the lens loose light) so that the effective apperture stays constant (would be very usefull on a Pentax DSLR since it would mean that you don't need to press the green button again if you have moved closer or further away, unless the light changed). It comes with a dedicated extension tube that gives 1:1 macro and maintain all mechanical functions.

With Konica Hexanon lenses, like the 85mm I posted pictures from before on this thread, the problem is that the lens-sensor/film distance is ~4mm too short on the Konica compared to the Pentax systems. Either no infinity focus (in most cases focus only to a few meters distance), or hacking lens or camera.
But for a macro lens this is not such a big problem. I've simply merged the thinnest extension tube from a Pentax tube set with the thinnest tube from a Konica set semi-permanently, resulting in a Pentax K to Konica AR adapter that also work as an extension tube about 20mm thick (adding the 4 mm in flange distance difference we get about 25mm tube and get somewhere between 1:2 and 1:1 macro. Of course I have to close down the apperture manually because my adapter does not transfer apparture setting. But if I don't hunt fast flying bugs it is not that big problem.

The following shots are made with the K20D+my home made adapter + Konica auto bellows+macro-Hexanon 55mm f3.5 and the AF540FGZ flash with diffuser:

Old flower on a Jasmin bush.

Tomato.

Tomato flower.

Didn't knew tomatoes were so hairy!

Now, 4/3rd shooters have started to buy these lenses (and hacking them rather irreversible), but besides them there is very little market for them since Konica gave up SLRs before digital age and Konica-Minolta used an entirely different mount (rumors has it that Konica were preparing a new autofocus mount before they gave up, and that is the mount Sigma use today). So the Konica Hexanon AR lenses have few users and that lowers the prices compared to the so much more wanted K mount lenses. So I suggest that if you want a ~50 macro consider this an inexpensive option compared to a K mount. It is not all that difficult to make an extension tube into a K-AR adapter. And you anyway want to work with a tube on it since most macro 50's of this age was 1:2 macros and require a tube to get to 1:1.

georgweb · 09-29-2009, 05:08 AM

Douglas,
those macro pics just look so good. I never knew why those Hexanons would disappear into oblivion.
Interesting story about their AF-mount going into Sigma's pipeline.

Here's two more from the hacker's delight,

A heavy crop from a Praktica-B-mount 80/1.8 Pancolar on K100D stopped down (fireworks, no aliens involved :-).
The same lens exists in M42, so no real reason to hack it other than compulsary hacking .-)

Y/C mount Yashica ML 1.4/50 on K100D @f/1.4- I did the bayonet hack so no hack of the lens really. Y/C mount will have infinity sometimes and sometimes not - better test it before or know if you can adjust inf. on the lens.

Best, Georg (the other)