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UltravioletPhotography

Learning the Sony A7R-BB: Part Two


Andrea B.

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See also: Breaking in the Sony A7R: Part One

 

Today I wanted to make some UV test photos outdoors in sunlight with my newly converted, full spectrum Sony A7R. For me that naturally implies shooting a botanical subject. My local Stop & Shop had a slightly fading bunch of Helianthus available for cheaps which had a couple of days left in them. Sunflowers make the perfect UV test subject with their signature UV-dark central bullseye.

 

My purpose was to become comfortable setting in-camera white balance under various filters, to test the performance of my choice of shooting variables stored in the A7R's two memory banks, and to see how well some of my UV-pass filters work with the A7R and the 60/4.0 UV-Objektiv which I chose for today's experiment. All this while outdoors with the wind blowing, the sun shining and the light giving me trouble with its constant changes - in other words, under typical field conditions.

 

Equipment:

Sony A7R full spectrum conversion

Carl Zeiss Jena 60mm f/4.0 UV-Objektiv lens

Baader UV/IR-Cut, BaaderU UV-Pass, U-360/2mm + S8612/2mm UV-Pass Filter Stack, AndreaU UV-Pass

and

Vello FreeWave wireless remote

Really Right Stuff ground pod

Manfrotto pistol grip ballhead

Edmund Optics white spectralon square

Color Checker Passport

Sunflowers

 

Measuring Custom WB with a7R: Easy, mechanically.

The center circle was easy to see on the monitor through the UV-pass filters when the lens was opened wide. One button press to measure, then select one of the 3 WB storage registers and you're done.

 

Obtaining an a7R Correct WB: Errors in UV light.

With each of the 3 UV-pass filters, I got the error message "Custom WB Error". However, I could still save the measurement. Most likely the A7R can only go so far in push/pulling the red/blue axes when trying to measure WB in UV light? Further WB corrections could perhaps be needed when converting the file? At least the A7R moves UV white balance much closer to the desired look than does my Nikon D600-BB.

I will try to follow up later on this Custom WB Error problem.

 

Resetting an a7R Custom WB while using a Memory Bank: No can do.

This was disappointing. To make a new custom WB you would have to return to M or A mode, make sure all settings in M or A mode matched what you just left in the Memory Bank, measure and store the new custom WB, and then re-save it and all the other settings back to the Memory Bank.

Other settings can be changed while using a Memory Bank.

 

a7R Aperture Mode vs. Manual Mode in UV: Manual mode is probably best for UV.

When using aperture mode and center-weighted metering, I sometimes needed more than the maximum +3 EV. So it's probably best to stay in M mode and simply adjust the exposure length.

 

a7R File Quality: Really, really nice in either Visible or UV.

The a7R raw files are easy to work with, are amenable to highlight restoration and shadow lifting and provide lots of detail.

 

CZJ 60/4.0 UV-Objektiv Lens: The chromatic aberration of this lens in Visible light is unpleasant. The UV files look fine.

 

 

 

************************************

 

Visible [f/8 for 1/200" @ ISO-100 and EV+0.3 with Baader UV/IR-Cut Filter]

a7R_czj_helianthusSp_visSun_20160331wf142222pn.jpg

 

Visible [unresized crop of Color Checker Passport white patch and white-lettered ruler showing chromatic aberration]

a7R_czj_helianthusSp_visSun_20160331wf141700noEdit.jpg

 

 

 

************************************

 

Ultraviolet [f/8 for 1.6" @ ISO-400 and EV+1.0 with BaaderU UV-Pass Filter]

a7R_czj_helianthusSp_uvBaadSun_20160331wf143749pn.jpg

 

Ultraviolet [same, in black & white]

a7R_czj_helianthusSp_uvBaadSun_20160331wf143749pnBW.jpg

 

Ultraviolet [raw composite with Raw Digger]

a7R_czj_helianthusSp_uvBaadSun_20160331wf143749raw.jpg

 

Ultraviolet [unresized crop]

a7R_czj_helianthusSp_uvBaadSun_20160331wf143749pn01.jpg

 

 

 

************************************

 

Ultraviolet [f/8 for 1" @ ISO-400 with U-360/2mm + S8612/2mm UV-Pass Filter]

a7R_czj_helianthusSp_u360-2+s8612-2Sun_20160331wf144321pn01.jpg

 

Ultraviolet [same, in black & white]

a7R_czj_helianthusSp_u360-2+s8612-2Sun_20160331wf144321pnBW.jpg

 

Ultraviolet [raw composite with Raw Digger]

a7R_czj_helianthusSp_u360-2+s8612-2Sun_20160331wf144321raw.jpg

 

Ultraviolet [unresized crop]

a7R_czj_helianthusSp_u360-2+s8612-2Sun_20160331wf144321pn.jpg

 

 

 

************************************

 

Ultraviolet [f/8 for 1/2" @ ISO-400 and EV+1.3 with AndreaU UV-Pass Filter]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743pn01.jpg

 

Ultraviolet [same, in black & white]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743pnBW.jpg

 

Ultraviolet [raw composite with Raw Digger]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743raw.jpg

 

Ultraviolet [unresized crop]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743pn.jpg

 

 

 

************************************

 

Here are three alternate conversions for the AndreaU filter, which passes a very small amount of violet/blue. The false colour, mustard yellows which emerge from a typical white balance application (above) can be altered for a prettier look. Contrast was also increased by +10 in Photo Ninja.

 

Ultraviolet [green desaturated in Photo Ninja]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743pnGdesat.jpg

 

Ultraviolet [green pushed towards blue in Photo Ninja]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743pnG60.jpg

 

Ultraviolet [in Photo Ninja, white balance made on yellow petal to bring out blue]

a7R_czj_helianthusSp_andreaUSun_20160331wf144743pnBlue.jpg

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This series documents beyond any doubt the converted Sony can do a good job for the UV enthusiast. That in itself is very useful information.

 

The pictures might also indicate that the CZ 60/4 might not be entirely up to the task in terms of resolution for the 36 MPix sensor of the Sony. Or, an alternative explanation is that you didn't manage to get perfect focus. I had expected much better rendition of the disk flowers and the styles.

 

I would wish to see these captures done with either the Coast Optics 60/4 APO or the UV-Nikkor to give better insights into these issues.

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I was on tripod, so there should not have been any focus problems, per se. I do not yet have an adapter for Nikon F-mount to Sony E-mount, but I do have planned photos to be made on the Sony E with other lenses.

 

When my funds are replenished, I'll order the adapter. :D

 

So in due course we shall see how detail & sharpness plays out on the Sony E with a variety of lenses.

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The experience with my Sony A7 (an earlier model) is that it is much easier to misplace the focus than I originally thought with an EVF system. Using a focusing light for UV might add a further source of error as it is all to easy to disturb the setup. Or miss the perfect focus.

 

The CZ 60/4 obviously has chromatic issues in visible light and given it is an old design by now and made for film use, perhaps not entirely unexpected it should struggle in UV against the Sony's massively resolving sensor.

 

When your F>E adapter arrives, try the Coastal Optics 60 mm f/4 APO instead. I would be surprised if that combination didn't improve the outcome.

 

(FYI: I made a makeshift lens hood for your CO 60, you'll get it later in Scotland)

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I was not using the EVF. I was using the a7R monitor with the handy Magnifier (which function I placed under the AF/MF center button for easy access).

 

The CZJ most definitely does have chromatic issues, I agree. It is likely to be one of those lenses which is best used with narrowband UV-pass filters. Someday when I have spare money, I will purchase some narrowband UV-pass filters. The CZJ is very sweetly made though.

 

Most "industrial" UV-lenses are not given any chromatic tuning. The old Asahi Quartz Takumar is another one like that. (Now that is a fascinating old lens.)

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The moon is near new phase now--you could crank up the sensor gain and see if you could get any starlit night shots (assuming that your local night sky conditions will permit this.)
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Being 18 miles from Manhattan as the crow flies, UV night sky shots are problematic. When I am in Maine this summer, I will give it a try.
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