Sony NEX-5N monochrom conversion results

[Alex H]

Andrea, two NEX models I have do not have UniWB in the menue. I can set the color temperature and A-B and G-M vaues manually but nothing more.

[Shane]

UniWB is unfortunately no longer possible with newer Nikons. They do not want to read a file which has been uni white balanced in an editor for using as a wb choice in-camera.

 

Either I misunderstand you or you have forgotten the original way of building a UniWB reference image.

 

You tweek the PC monitor target and use that to CAPTURE your WB reference image. The camera should treat it like any other subject when obtaining an in-camera custom WB. There is no uploading requirement of a tweeked WB reference file. Once the custom WB ref image is established in the camera and set as WB, take a picture of anything (in jpg) using the custom WB. Export the image and save it as your UniWB reference image. It should be possible to upload this image back to the camera (or any other camera of the same model) and now save it as a real UniWB reference image rather than the "virtual" custom WB image the camera was storing in a firmware "black hole".

 

Alex, I used to use Rawnalyze for evaluating "true" exposure values but this software development stopped in its tracks when the author died. I now have Rawdigger which performs the same analysis and more. Dcraw is also still useful at times when "poking" around the RAW data.

 

I had intended to provide the RAW histograms of the two images you sent me using Rawdigger but now that is redundant as you have already provided them (no problem). If you ever find the 830nm filter I would still be interested in looking at images from the cameras.

 

Andrea, I tried uploading a completely man-made CS image to Nikon but could never get the configuration correct for it to work. Unfortunately it is beyond my current program/hacking talents.

 

If anyone ever figures out how to do this I would be very interested to hear. It opens up some interesting possibilities with regards to reverse engineering some of Nikons processes.

[Shane]

I'll probably wait until http://www.sonyalpha...-sensor-camera/ mostly because it'll probably have micro lenses and be a bit cleaner and less risky, assuming it materializes.

Or you could get the Leica Monochrom and just remove the internal cut filter.

[Andrea B.]

Last time I tried to perform the iterative routine for creating uniWB by using a magenta-ish monitor screen, the process wouldn't converge to give the 1,1,1,1 multipliers. I think I tried it with the D3S. We had a tutorial about it long on NG.

And then I tried Lujik's (spell?) "grey point" method and couldn't get the cam to wb on the monitor chart.

But that was a long time ago. Now with better exposure range in newer cams, I feel like I don't really need to use uniWB.

 

But it isn't uniWB I want to load into the D600-broadband, rather it is the blue/yellow/darkGreen standardized UV look that seems to occur "naturally" when white-clicking UV photos made under a Bayer array. The Pentax K5 will wb through a Baader-U after a few tries and almost matches it.

 

(Shane, I clarified my preceding post #24 by adding 'via NX2'.)

[Alex H]

Sounds good!

I'll probably wait until http://www.sonyalpha...-sensor-camera/ mostly because it'll probably have micro lenses and be a bit cleaner and less risky, assuming it materializes.

 

With the claimed ISO sensitivity up to 409600 ;)

 

But I do not understand your statement about micro-lenses. Most of the current cameras have those, right?

[Alex H]

Shane, I will take pictures with B+W 093 filter for you, no problems. But it will probably be in the end of the month. On Wednesday I am flying to Ukraine to see my relatives over the Easter holidays. I just have no time to look for the filter right now. Besides, by that time, there will be some IR-reflecting vegetation around here...

[nickspiker]

With the claimed ISO sensitivity up to 409600 ;)

 

But I do not understand your statement about micro-lenses. Most of the current cameras have those, right?

Yup, most of them do, and I would assume the Leica M has them as well, but I would have to change lenses and drop 8k USD on one.

As far as the microlens comment, when you remove the CFA to make it monochrome, you have to remove the microlenses first, so a stock monochrome camera would have a better response due to the microlenses being installed.

[Alex H]

How do we know if microlenses do not block any UV?

[JCDowdy]

Excellent topic Alex!

 

How do we know if microlenses do not block any UV?

 

Exactly what I was wondering. What are they made of?

[Shane]

What are they made of?

 

They used to be photoresist, although there may be a variety of polymer materials available for that application now. Whether they absorb UV or not will of course depend on the polymer used.

 

Andrea, the last UniWB I constructed was for the D700 and due to the method used it should be no problem for any of the sensors because the scalars (having a value of 1) all fall within the WB scalar tolerances, which by their nature must all include a value of 1.

 

Custom WB becomes an issue when using a target produces scalar values that fall outside the "normal" WB scalar range. I think this is why some sensors will not custom WB when converted to extended red/IR because large scalar values may be required to correct an over abundance of red and severely diminished blue. The firmware must see these large scalar values as a "mistake" and therefore not allow them. However, it is interesting that only some models are effected.

[Andrea B.]

I should try again to set a uniWB with the D600-bb. Just to see if I can.

 

I find that the Nikon's in-camera ADL settings are very useful for getting a good UV exposure. Somehow camera software masks and lightens the darker areas very well. Better than using an editor, imho. So you can expose for the brighter areas (if any in the UV scene) and change the ADL settings for the darker ones when shooting.

[Shane]

It seems to me that ADL is underexposing at the time of capture to protect the highlights and subsequently applies a tone curve modification to bring up the shadows. Since you are deliberately underexposing, I would have thought this is counter-productive to obtaining more shadow data. Of course newer models are getting better at dealing with noise.

[Alex H]

A short update on the subject, about IR sensitivity of the NEX-5N monochrom conversion comparing to the regular full-spectrum converted NEX-6. This time I used the Zeiss Sonderobjektiv SO-3.1 35/2.8 lens specifically designed for the near-infrared photography with rear-mounted B+W 093 filter. NEX-5N monochrom was set to A-mode. Than the same exposure was repeated with full-spectrum modified NEX-6.

 

NEX-5N monochrom

 

http://www.holovachov.com/img/s12/v187/p673943235.jpg

http://www.holovachov.com/img/s7/v167/p743141503.jpg

 

NEX-6 full spectrum

http://www.holovachov.com/img/s7/v161/p855762380.jpg

http://www.holovachov.com/img/s7/v156/p719733302.jpg

 

It seems like there is barely 0.5 EV difference in exposure between the two cameras, with full-spectrum modified NEX-6 being just a little more sensitive.

[Alex H]

And something else, less relevant to this particular discussion, but I thought I should try to do this test anyway.

 

Resolution comparison between NEX-6, NEX-6 (full spectrum) and NEX-5N (monochrom).

Top row - files processed with Sony IDC Raw converter (interpolated).

Bottom row - file processed with RawDigger (non-interpolated).

 

Lens - Focotar-II 50mm F/4.5 lens stopped down to F/5.6.

Illumination - flash fitted with blue filter.

 

One important note - please ignore differences in contrast between different images!

 

100% magnification

http://www.holovachov.com/img/s5/v125/p606709058.jpg

 

400% magnification

http://www.holovachov.com/img/s6/v139/p585605273.jpg

[Alex H]

Few examples with the monochrom converted NEX-5N.

All taken with handheld using Focotar-II 50mm lens stopped down to 5.6, ISO 800.

ARW files converted to Tiff using RawDigger and further edited in Photoshop and Gimp.

 

EDIT: Baader U2

 

http://www.holovachov.com/img/s6/v140/p81647671.jpg

 

http://www.holovachov.com/img/s6/v137/p235142122.jpg

 

http://www.holovachov.com/img/s6/v143/p193632512.jpg

 

http://www.holovachov.com/img/s10/v102/p486175188.jpg

[Andrea B.]

These are lovely UV photographs, Alex.

And, after all, that is my favorite part of our efforts - the photographs, not the testing of gear. :D