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UltravioletPhotography

Focusing distance and the Steinheil munchen EDIXA 50mm f2.8


dabateman

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The Steinheil Munchen EDIXA 50mm f2.8 lens is good known UV performer in M42 mount.

However it's mostly plastic on the inside. When I fully depressed the aperture pin, I heard a crack and the aperture was no longer adjustable.

But it is easy to take apart. Mostly with just insung screws that recess into the plastic parts. The part I snapped was not a spring, as I thought, but a plastic guide that slides the aperture rail. So simple crazy glue fix. However, in the disassembly, I didn't mark the helicoid focus possition.

The stock lens is set to focus from 80cm (2.5 feet) to infinity. You can actually set the lens to also focus from about 1 foot to 20 feet focus range or 4.5 feet to well past infinity. Infinity becomes the 2m mark.

So this made me wonder if it could be adjusted for a Nikon. The short answer is no.

With my M42 to Nikon adapter (no glass), set at past infinity. I get 2 feet to 40 feet focus range on my DF.

 

This was all tested in the visible spectrum.

 

With my Sigma 30mm f2.8. I noticed that using minimum focus distance. I get closest to the subject using IR (720nm filter) and with the Baader venus, I am furthest away to hit the minimum focus.

I am not sure if that is true for all lenses. But I will adjust the 50mm to have infinity in UV, as that the spectrum I use the lens in.

Thought I would post these recent observations. In case others are interested in shifting the focus range or wondering if a lens can be modified for a Nikon camera.

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SteveCampbell

Ah yes, I prefer the Cassar due to the all-metal construction. Unfortunate about that annoying Nikon flange distance. One day I'll buy a full-spectrum mirrorless full frame, and life will be so much easier.

 

With the minimum focusing distance in IR vs UV, I think you're seeing a result of the wavelength-dependency of refractive index - UV will tend to refract more strongly towards the normal than IR. This means that, even more annoyingly still for Nikon users, you'll need the lens even closer to the sensor to reach infinity in UV than in visible. The minimum focusing distance suffers the same effect - using the visible minimum focusing distance in UV, the image will be focused on a plane in front of the sensor due to the higher diffractive index, forcing you to move the lens closer to the sensor to compensate. Infrared is the flip side of all this, making adapting vintage lenses a little easier.

 

Chromatic-Longitudinal-v01.jpg

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I am still contemplating converting either my Olympus Em1 or Nikon DF to full spectrum. I think though the Olympus has won and will most likely be converted in September.

Soon Nikon will release their mirrorless system and kill off the old F mount. I know they say now that they won't. But we all know they will. This should drive down the cost of older Nikon lenses.

I think I will wait to get a good autofocus macro.

Thought I would post this in case anyone thought possible to modify a M42 lens to Nikon. It may be possible for some though after taking a part a couple. I haven't found one yet though. A lot of times though a T mount is hidden under the M42 mount, which leads to easily adaptation. This is true for my 8mm Peleng fisheye.

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Years ago I removed the mounting flange on a Nikon, ground down an M42 flange, and inserted the M42 flange into the hole of the Nikon. Naturally I had 1.04mm of depth to gain ( M42 has a 45.46mm register vs Nikon F with a 46.5mm register) so I had to do some work with a Dremel on the camera body. It did permit me to use M42 lenses to infinity. I also glued M39-M42 rings on my Exakta lenses and used those as M42s.
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David, I would convert the Oly EM-1 simply because it would make life so much easier when using lenses that require a flange focal distance less than Nikon's very long 46.50 mm. It is so easy these days to find good Oly (or any other) adapters to ensure a proper non-leaking adaptation. That Nikon Df is such a good a camera for "regular" (i.e., non-UV) photography that I'd recommend keeping it for that. And the Df is the only Nikon which will take the really old pre-AI lenses should you ever want to try one.

 

Reed, that was a lot of work to adapt the Nikon. I always though it shouldn't be too hard to get to 45.46 from 46.50. But I would never have the nerve nor the steadiness of hand to dremel the Nikon body.

You were a brave soul for sure !! :lol: B)

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