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UltravioletPhotography

Test: AUTOCRAT 1: 3.5 F=75mm No. 179906


Andy Perrin

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Tested versus the EL-Nikkor 80mm/5.6.

 

-White balance was in-camera, off the overcast cloudy sky using the Autocrat and then left unchanged for the remainder of the tests, including lens switch.

-I used a "lens hood" consisting of a 4" toilet paper cardboard insert on both lenses since there is no way to attach a standard lens hood to the Autocrat.

-Tripod

-filter was Omega 330WB80 backmount with putty

-Focus with helicoid (refocus between lens changes, but unchanged between exposures with each separate lens)

-ISO200 for all tests

 

All crops are 1:1 with no editing, aside from using the camera's white balance.

 

F5.6 tests.

Columns: 1/8", 1/4", 1/2"

Autocrat is the top row, EL-Nikkor is the bottom row

post-94-0-56789200-1488310803.jpg

 

F16 tests.

Columns: 2", 4", 8" [i should probably have tried to make the EV equivalent to the 5.6 but I forgot.]

Autocrat is the top row, EL-Nikkor is the bottom row

post-94-0-37320100-1488311386.jpg

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Nice test Andy!

The EL-Nikkor is clearly the winner with better contrast and better sharpness.

By the way, I have made a sharpness test at different apetures with my EL-Nikkor 80mm: f/11 and f/16 are the best for visible light. I did not do the test in UV light, but I guess it would still be good at f/22.

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Better contrast can make things appear to be sharper, but it's not really clear to me that one is sharper than another? Need more examples.
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Andy Perrin
I don't think it's sharper necessarily. Both of them were tested on the same helicoid, but I have a heck of a time focussing with that helicoid! Which is another way of saying I would have to do another test, maybe with a different helicoid. (Also, am I the only one who has trouble judging the focus in live-view even zoomed all the way in? Something about the noise screws me up.)
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At f/5.6 there is a significant depth of field, it is not very convenient for precisely focusing on something.
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Andy Perrin
Sure, but this was at infinity, and I had just as much trouble at F/16. The problem was not depth of field, it was that I could not tell if the image was in focus or not from the live-view, and also my helicoid had too much travel, so it was hard to adjust.
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Also, am I the only one who has trouble judging the focus in live-view even zoomed all the way in? Something about the noise screws me up.

 

Yeah, I hear you! Some Live Views are better than others, but none of them are perfect. Usually zooming all the way in magnifies detail too much and gives soft edges. Thus thwarting the purpose of the zoom-in.

 

In some situations I do a lot of racheting back & forth to settle on the correct focus. Tiring! Eventually you get a feel for your particular Live View and (usually) know when it is focused.

 

In Nikon LV for complex scenes, I sometimes focus with the lens wide-open just to find the correct plane of focus. Then I stop down to my desired aperture and, if needed, adjust/re-focus.

 

I do not focus well in LV on my A7R. Perhaps just a quirk of that particular model, but it does seem like a very busy/noisy LV. It is much easier on the Nikons. The Pentax K1 LV is somewhere in-between.

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good test. It seems at this wavelength the Nikkor performs better, but my findings were that at 360nm the Autocrat is almost identical to the Nikkor 80mm and outperforms the Nikkor 75mm. At 360nm I find it performing as well as my Phago 50mm, which is the same as JML/DO Industries, which is good down to 350nm according to our stickies, while the Nikkor 80mm is good down to 320nm, which explains why it performed better at 330nm. Can you test them at 340 and 360nm?

 

Andrea to me focusing on the NEX-6, which has the same EVF as the A7 series, turning off the live view settings effect works well in UV, well it comes with the "sideeffect" that the image will be red, but it will be much less noisy. Give it a try.

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Andy Perrin

I have a DO Industries 50mm one also, although I cannot get that lens to focus to infinity with any of the adapters I have around here! It needs to be realllly close to the camera body, apparently.

 

Yes, I'll see if I can get some bandpass filters and test them with the Autocrat and EL-Nikkor 80mm lenses.

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Andy the 50mm enlarger lenses I have (Nikon f2.8/f4, Jessops f3.5/f2.8, Autocrat f3.5, Phago f3.5, Meopta f4) are all focusing to infinity on my Sony-E at around 20mm from the E-Mount, so that's about 38mm from the sensor. I use a NEX-M39 helicoid adapter which is 17-31mm long and with it I can focus beyond infinity with these lenses. I have a 35mm Soligor enlarging lens (so far the best wide angle I've found for UV photography) and that has roughly the same flange distance, but the lens itself goes way beyond it's mount. Now that the sun starts to appear on the UK skies I might go out and do a shoot with it and post a review here. :)
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