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UltravioletPhotography

Canon 20mm f3.5 Macrophoto in UV


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I recently got a Canon 20mm f3.5 Macrophoto lens for a non UV project, and got to wondering how it would perform in the UV. I started with a transmission test. Without having a working integrating sphere setup, I just used a pair of collimators on my light source and spectrometer, and then normalised transmission to be between 0 and 1 between 300nm and 420nm. I also ran 2 other Canon macro lenses, 50m f2.5 macro and 65mm MPE macro lens. This is what the 3 lenses looked like;

post-148-0-72292100-1535630717.jpg

 

The 20mm Macrophoto keeps transmitting down to below 340nm unlike the other 2, so it looked like it may be ok for UV work.

 

A very basic test to have a look while the rain has stopped. Mounted the lens on my Eos 7D which has been converted for UV by ACS (with their proprietary filter), and took pictures of a sunflower. Hazy sunlight, ISO640, f11 and 30s exposure. Flower and camera balanced on the wooden decking in the garden. Taken as RAW files and white balanced using a PTFE tile in Darktable. These show the whole image, but reduced in resolution for here, and have had their contrast increased slightly. No colour change though.

 

Firstly the edge of 2 petals.

post-148-0-18477600-1535631011.jpg

 

Secondly, close up on part of the centre. I guess those bright dots are pollen grains.

post-148-0-63871000-1535631014.jpg

 

And yes, I am aware there is some motion blur on there. As the camera was not on a tripod and I was outside using sunlight, that is not a surprise. Working distance about 25mm and I'm guessing between 1-2x magnification.

 

Finally, here's what it looks like on a camera.

post-148-0-21436800-1535631170.jpg

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This lens does even better when the magnification is increased. I use it at 10X or thereabout.

 

Here is a section of a "petal" of Lysimachia punctata, showing the fine surface pattern in UV. Light source 2*Broncolor strobes with uncoated Xenon tubes.

 

T14082161998.jpg

 

The camera was a full-spectrum Nikon D600 and the Baader U was rear-mounted (see below)

 

U1408252936.jpg

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Wow, very nice Birna. It certainly does help having a good flash when using a lens like this, especially at higher magnifications. One of these days I must add some decent lighting to my kit.
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oh very cool stuff ! That lens looks so tiny on the camera. "-)

 

I have a Nikon macro which I need to try out. Nikon macros are called "micros" for some reason.

 

I suppose it is OK to add just a touch of sharpening of fine local contrast to bring out those details?? :D

 

What does that sunflower look like if you put some BG glass over the lens?

The UV-dark area on the sunflower doesn't look dark enough.

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The reason for Nikon -- correctly -- calling these lenses 'Micro' not 'Macro' simply is because they end at 1:1 life-size. Hence they do NOT magnify the details. So 'Micro' is correct, notwithstanding that almost everyone else uses the wrong term.

 

For the '70s Nikon Multiphot system there was a range of Macro-Nikkors ranging from 19/2.8 to 120/6.3. Together they covered the range 0.5X - 40X or thereabouts, each lens optimised for a quite narrow range of magnifications. Very sharp lenses for their time, but one probably could do equally well or better with today's infinity-corrected Mitutoyo or similar. I sometimes include one of these Macro-Nikkors in specialised setups. They won't perform well in UV, though.

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No problem Ulf, and thanks for linking yours in. As you say the method looks to be suitable for cutoff, even if it can't be used for absolute transmission.

 

Andrea. Further testing on the lens on hold for now while I find a better way of supporting it and the subject (and until the sun comes back).

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A Stranger In The Wind

That's cool and great to know. I have all three of them and also 35 Macrophoto lens. Just have to think on the various options for mounting. Could go RMS M42 - M42-EF route for my Canon 5D MKII or use the official Canon FD-EF macro adapter with the FD adapter for the macro photo.

 

Where did you get the RMS-M42 adapter from?

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Where did you get the RMS-M42 adapter from?

 

I just got mine from eBay - just search for M42 to RMS adapter. If you are feeling a little flush, RAF cameras (as well as the usual selection of Chinese vendors) do a nice one which tapers to a cone at the RMS end. I then just used an EOS to M42 adapter.I went down the M42 route, rather than the FD one as I already had some M42 bellows.

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If you are feeling a little flush, RAF cameras (as well as the usual selection of Chinese vendors) do a nice one which tapers to a cone at the RMS end.

 

This brings back memories to me. :)

 

This is a cone adapter with a different thread, that I suggested and designed for the vendor 2009:

https://www.ebay.com...er/362159373349

The Mitutouyo-lens on the photo is mine.

 

I do not remember if I made production drawings for the RMS version too, or just inspired them to make a RMS version:

https://www.ebay.com...ne/142516574491

The internal surface inside the cone is a bit too shiny and can be improved by adding some adhesive velvet.

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