Nikon Z6/Z7 as a UV/IR Conversion: the Bad News

[nfoto]

Actually I'm stuck between a rock and a hard place here. The cost of restoring the Z6 to factory condition will be massive as the local repair tech decided it had to go back to Nikon Europe. I might as well dump the camera and purchase a new one. So for now I'll just let it sit there fulfilling its mission, which obviously is to annoy me.

[Andrea B.]

Well, that is not such good news. When I restored my bad-conversion-D700 the cost was really not high.

 

Perhaps you could make some wall art from that Z7 Z6? I think I recall something about a painted yellow Nikon DSLR as wall art. Was that you or one of your friends? I know I've seen one somewhere.

[nfoto]

It's a Z6 Andrea, and yes, I have friends who make painted obsolete cameras.

 

 

Hm. Have to look in the shed for suitable paint?

[Stefano]

So your camera will end up painted?

[Andrea B.]

Suggest a multi-hued approach. Don't think I've seen one like that.

[otoien]

Short of a multi-hued paint approach , or a permanent filter replacement, what about installing a clip-in regular UV-IR block filter and use it for the visible spectrum:

https://www.astronomik.com/en/clip-filter/xl-clip-filter-nikon-z.html

(It seems that these just became available.)

It would change effective register distance, but perhaps not a problem if used with adapted unit focusing lenses?

[nfoto]

I might just give the camera away to a deserving person -- so he can experiment with its sensor without financial risk. Perhaps it ends up being a monochrome UV/IR camera?

[nfoto]

The Norwegian playwright Henrik Ibsen in his national heroic play 'Peer Gynt' produced a wealth of memorable quotations, a number of which have entered our language as idiomatic expressions. One of them is "kom senerehen til andre resultater", directly translated as "came later to other results".

 

I suddenly remembered this expression when I made a remarkable discovery in a last attempt to make the wretched Z6 being useful to me, before I decided whom should receive it as a gift. The Japanese program SilkyPix Developer Studio has been on my computers for a long while. I only have used it to process RAF files from my Fuji S3/S5Pro UV/IR cameras. Silkypix handles these easily, but the program itself has a steep learning curve, not the least due to some strange translations of commands into English. Thus it is often far from obvious what something actually does, one has to try everything out.

 

I did run SilkyPix on the infamous Z6 NEFs with the bad striping, ventured into a section of SilkyPix which I previously had left unexplored, and had an epiphany. Photo Ninja, my trustworthy go-to solution for UV RAW files, fails badly on the Z6 files. Even Nikon's own Capture NX-D does show the striping pattern although perhaps a little less pronounced. Still more than enough reason for me to colour my hair red lest it should end up snow white in despair.

 

Here are the full frame and 100% crops. All of a sudden, SilkyPix now handles the Z6 NEFs with aplomb.

 

The test sequence is with the modified Z6, UV-Nikkor at f/8, Baader U, exposure 1/15sec, ISO 100 under hazy sun. The flower is the endearing Tussilago farfara, our harbinger of better times to come ahead.

 

Full frame overview (SilkyPix Developer Studio Pro 8):

 

100% crop (Photo Ninja):

 

100% crop (SilkyPix Developer Studio Pro 8):

 

 

Need I say more? I've suddenly own another UV camera!! This after two - 2 - years of agony.

 

As v.8 does not recognise Z5 files, I decided to upgrade to the latest v.10 for a modest outlay.

[colinbm]

That is light years ahead, excellent.

How high does the K degrees WB go, please ?

[nfoto]

The various W/B presets go up to 10000K. However, I just used the standard "click-white" approach like in Photo Ninja.

 

SilkyPix has a whole section of settings relating to underwater photography. Just discovered them .... Much of the UI bear a similarity to Capture NX-D, by the way, however the actual wording of the command functions can be difficult to disentangle.

[Andy Perrin]

Hm. If the problem vanishes with proper processing of the RAW, does that imply it was misdiagnosed in the first place?

[nfoto]

Well, that is a tricky question. All conversion programs used so far showed the problem. Even Nikon's own offering, I'd like to add.

[Andy Perrin]

Well, that is a tricky question. All conversion programs used so far showed the problem. Even Nikon's own offering, I'd like to add.

You mean all of them except SilkyPix, I take it. Andrea's first post in this thread says,

The PDAF banding in the Z6/Z7 is *not* a function of the sensor. It is rather due to the camera's data processing which attempts to fix the well-known problem of PDAF striping due to reflections from the PDAF pixels' metal masks. (The older Sony As had this PDAF striping, for example. Along with Sony lossy compression and shutter shock, it is why I dislike my Sony A7R. But nevermind that because I learned to use it anyway.)

This would tend to throw doubt on that, since instead it seems to be a function of the RAW processing on the computer side, not the camera side.

[nfoto]

No. All reports on mirrorless cameras have told about "banding" or "striping", usually related to shadow regions. The unexpected outcome from the modified Z6 was simjply that the obvious striping became bad immediately when the camera was used for UV, whether or not the exposure was noisy in itself. In fact, you can see the striping directly in the EVF. If visible light is introduced, striping is almost completely mitigated, to return in a subdued form for IR.

 

Silkypix adds some ingenious filtering so as to remove the issue, which as I said, is lurking there from the very onset. Nikon has failed to clarify for me why the problem suddenly is so severe under UV illumination. The modified Z5 is much better, but does show some striping in UV too. Even this model can on occasiona make the striping visible in the EVF, but not with the same prominence as with Z6.

[Andy Perrin]

Silkypix adds some ingenious filtering so as to remove the issues, which as I said, is lurking there from the very onset.

Oh, FILTERING. That's different then just converting the RAW. I mean, I can filter stripes out of my Sony images also with a Fourier transform. When you said it wasn't present in Silkypix, I understood it to mean "with no additional processing other than assembling the RGGB values into pixels."

[dabateman]

Birna did you ever try this method to clear up the banding in RawTherapee:

https://www.dpreview.com/forums/thread/4362718

[nfoto]

RawTherapee never worked well for my Z6 files. True, the more obvious striping disappeared, but so did most of the fine detail. Colour balance suffered as well. Do remember the observed striping on the UV captures done by Z6 was magnitudes worse than any issue observed with the stock camera.

 

The SilkyPix approach is in another league .No comparison there.

 

For the record, I could get useful results from RawTherapee with my Fuji RAF files.

[dabateman]

So apparently at least the Z6 will work with the Megadap adapter and focus bracketing as a cheapish rail alternative.

 

[nfoto]

The appearance of the UV-Nikkor 105mm f/4.5 in UV. Just to satisfy my curiosity.

 

 

By another UV-Nikkor, Baader U, Broncolor studio flash (uncoated xenon tube), ISO 100, Z6. The NEF processed through SilkyPix 10. 100% crop shown -- do click the image to see it full size. I see no striping here?

[Stefano]

I see some striping, although very faintly. Still much better than before and probably visible only at a careful look on a uniform background.

[colinbm]

The Day of the Triffids......well read.

[nfoto]

The Day of the Triffids......well read.

 

John Wyndham wrote a number of excellent sci-fi stories. I grew up with "The Day of the Triffids" as a chilling play on Norwegian radio so only natural later when my grasp of English sufficed to delve into his writings as well.

[dabateman]

Birna can you test the New Nikon NX studio free replacement for NX-D to see if it solves the stripping problem of the Z6?

[nfoto]

Alas, it does not. Just tried.

[dabateman]

Thank you Birna. That is disappointing that you need to use Silky pix, but at least there is an option.