Full spectrum mod - gone bad?

[Guest]

I just got my Nikon D750 back from being converted to full spectrum (by Lifepixel). I haven't contacted them yet, because I don't think they would be open this early, but I will be calling them today.

 

Here's the issue: The camera I had converted now has some kind of hot spot - and its not just a little thing! I took a series of images, from short to long exposure, because it seems to be pronounced at longer exposure times (which I'd be shooting all the time!). All the images were taken with the lens capped, so these are essentially blacked out images.

 

Has anyone else seen this, pointedly in a Nikon D750? Does anyone know if there is anything that can be done to fix this? I'm not even sure at the moment if this is due in some way to a fault of the conversion service, or if this is an IR shutter monitor thing (though I thought the D750 does not use an IR shutter monitor...)?

 

Any advice or suggestions would be very much appreciated.

[enricosavazzi]

I am just guessing, but is there any significantly strong light entering the viewfinder? Can you repeat the test with the viewfinder closed? Some DSLRs have a built-in curtain to manually close the eyepiece, others (e.g. some of my past Nikons) came with an external black plastic cover that can be slipped onto the eyepiece. I don't know which is the case with the D750. A converted camera could have an enhanced problem with stray light entering the eyepiece, especially in the NIR.

[Guest]

I will try that test later on when I get home (covering the viewfinder), but - I did take these photos in an almost darkened room, with only one small light on the far side of the room behind me. And, it is an LED light, so it doesn't give off much of any IR or UV anyway (re: NIR leaking in via the viewfinder). Whatever it works out to be, I just hope there is a fix for it! I don't want to be stuck with a brand new (expensive (for me)) camera that has a permanent junk spot on every image I try to capture.

[JCDowdy]

Does the D750 have an infrared self-diagnostic shutter monitor?

 

I do not have a converted Nikon but the Sticky :: UV Photography Intro, Cams, Mods, Lights, Links posts the following warning:

 

Warning about Some Unconvertible Cameras: Nikon D700, D3, D3S, D3X, D4, D4S

Do not convert these Nikon DSLRs because they have an IR-LED self-diagnostic shutter monitor which can produce IR contamination of photos. The excess IR light from the shutter monitor will show up as a lighter area of flare, smear and discolouration in a photo. An exposure with low ISO and short speed might mitigate the IR contamination, but many shooting scenarios do not allow this. Note that newer Nikon DSLRs having a shutter monitor - D7000/D7100, D600, D800/E -

are

convertible. Apparently their shutter monitor is of such a design that it causes no IR contamination. You can see the IR shutter monitor for the D3S on this

Nikon Flagship Reliability

page. Scroll down to Shutter Unit section.

 

Added later:

I would note that member DaveO has a converted D750 which produces fine images. Perhaps this is not your problem.

[Andrea B.]

Mark, it is a light leak as Enrico suggested. Don't panic just yet. :)

 

We first go through the various checks to determine where the light is entering.

 

A few things to look for - all of which can cause light leaks.

• Check that all port doors are tightly closed.
  
• Make sure the lens mount on both lens and body are not warped so that no light leaks in around the connection.
  
• Make sure a lens aperture widow is not the culprit by covering it with a thick towel.
  
• Ensure any filter fits tightly onto the lens whether front or rear mounted.
  And make sure the filter is properly fitted into its mounting ring.
  
• Always cover the viewfinder in a full spectrum DSLR camera. Temporarily use your thumb if you can't find the viewfinder cover.
  

I have had light leaks from all those listed factors.

 

If you are sure that none of those factors is causing the light leak, then we go to Plan B.

 

Please report back after you check the above!! B)

 

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

 

ADDED: Checking for the Shutter Monitor Problem

To check for the shutter monitor problem, put the lens cap on or remove the lens and put the body cap on. Cover the viewfinder tightly. Then cover the whole camera with a towel or jacket or something. Turn out all the lights. Make some exposures at various long lengths (1 sec, 2 sec, etc) and ISOs. If there is a shutter monitor problem, you will see it this way.

 

ADDED:

Think of a good explanation for what you are doing there shooting in the dark with a towel wrapped camera in case anyone should happen by and question your sanity. :lol:

[Guest]

Thanks for all the ideas! I'll try not to panic.

 

Just a note regarding the sefl-diagnostic shutter monitor suggestion: according to the info on Lifepixels' website, the D750 does not incorporate such a shutter monitor (though the D700, and others do).

 

I'll try checking with all of the suggestions above tonight when I get home from work. I'll report back with whatever I find.

[rfcurry (1950-2024)]

The flare looks like your left ear. Check and see if your left ear is stuck in the lens mount. :)

[Andy Perrin]

Turn widdershins three times...

 

I seem to have a light leak through the flash shoe?! I did not realize light could enter the camera through there, but covering it seems to help. Another place to consider.

[Guest]

So, I just got home, and did a test right away. I took the lens off the camera and put the body cap on - then double wrapped it in black plastic and stuffed it under a blanket to keep out any possible stray light. Here's what I got:

 

The light flare is still there. So, its coming from inside the camera.

 

I spoke with a rep from Lifepixel, who said if the problem persists he would send me a UPS label to return the camera for further diagnosis/fixing. I guess I'll just have to wait a little longer before I can start shooting with this thing.

[colinbm]

Hi Mark

Just for the record, most black plastic bags are transparent to NIR light...... :P

But the blankets would have covered that.

[Andrea B.]

Yes, send the D750 back to Life Pixel immediately.

 

We know there are working D750 conversions in use. And I haven't seen any reports of problems with D750 conversions. So I am somewhat baffled as to what this could be. Is this a brand new D750? Could there be some sensor board problem? Did you make any shots with the camera before sending it in for conversion?

 

I hope that because you immediately reported the D750 problem to LifePixel ((and also here on UVP !!), it will be promptly analyzed and fixed. So, please update this thread as the case progresses. We may be a small forum, but we are somewhat known in the UV world. So I do like to report on and follow conversion problems and how the various conversion shops handle them when they occur.

[renaud]

Could this be a heat/radiation source causing noise rather than a light leak? Electronic components next to the sensor can cause asymmetric noise patterns in long exposures, see for example: http://www.nies.ch/doc/nikon-d200/noise/index.en.php. Maybe a radiation/heat shield was damaged during the conversion, exposing the sensor to this very peculiar "ear shaped" noise source.

[Guest]

Interesting, but I don't think its heat from the electronics - because I'm seeing the problem in shots I take at even less than one second; compared to the 1 to 30 minutes of on-time shown at the link you shared. Though I would guess you are right that something must have gotten damaged during the conversion, because this was not a problem before I had the camera converted.

[OlDoinyo]

The other website referred to shows examples of "amplifier glow", which the present case does not seem to resemble. Either there is an internal light source causing this or some sensor damage is causing the sensor to report a non-existent signal. The fact that it was not apparent with the hot mirror on suggests an infrared source to me. I do not really know how plausible the other scenario is. The best hope might be some firmware hack to disable the internal light, if that is possible. Iff, on the other hand, t is damage, you will need a new sensor.

[Andrea B.]

http://www.nikonusa....Nikon-D750.html

 

Mark, please go to Nikon USA at the link above and enter your D750 serial number to see if your D750 is one of the bodies afflicted with a "flare" problem.

 

Because you said that you did not notice any problems with your D750 prior to conversion, it does not seem like the factory flaw is the root cause. But it is best to check anyway.

[Guest]

Thank you for that link Andrea. I checked my serial number there, and it turns out my camera is not one of the affected units.

 

I also got a shipping label from Lifepixel today, and the camera is already on its way back to them. Hoping its a quick turnaround - and I'll update as soon as I get info on what the problem is.

[JCDowdy]

You have good evidence for an internal light leak. Question is what is the source?

Both the AF-Illuminator and the control panel backlight are near that corner of the sensor.

Did you recall if you happened to have either on during your testing?

[Andrea B.]

Mark, great!! It is good that that particular problem is not a source of the light contamination.

 

Was this a new or used camera?

If used, it is possible that one of the chamber light baffles is bent or not working correctly.

 

Mark, I'm sorry you had to have this problem, but it will be a very good learning experience for us all to see how it is handled and resolved. We will ideally learn what to do if it ever happens to us. And it is important for LifePixel to handle this issue in a helpful and timely way. So I'm watching how they deal with this.

 

**********

 

John, good point about the AF-illuminator and control panel backlight.

 

I am wondering if the usual focus adjustment done on converted cameras is somehow slightly "off" and that somehow causes a problem from the backlight (or other component) during exposure. Focus adjustment involves aligning the sensor plane.

[JCDowdy]

Yes, so sorry you are having this issue Mark. Lifepixel provided me excellent customer service and I expect they will take care of you.

 

Since our converted cameras are partially disassembled any misaligned internal baffling in the area or perhaps misalignment of the internal source itself is the likely culprit. Obviously an easy test prior to disassembling the camera again would be to simply turn off the AF-illuminator and/or panel backlight as surely that is possible.

 

The camera's AF sensors must be able to see the AF-illuminator but I would guess that the imaging sensor should be blind to it due to the filter. If so, could it have possibly been leaking internally prior to conversion and only revealed by the removal of the IR-blocking filter covering the sensor?

[JCDowdy]

Any update on your D750 conversion?

[Andrea B.]

MARK, what happened with this D750 conversion????????

[Guest]

Sorry for the lack of updates - this is still in progress (i.e., being fixed). I'll post a summary of my experience as soon as I get the camera back (hopefully within a week or so).

[Guest]

Time for an update on my Nikon D750 conversion.

 

After finding a light flare problem in the converted camera I sent the camera back to LifePixel to be put back to stock condition. It was then sent to Nikon to be 'repaired' under a recall notice, even though the camera's serial number indicated it was not affected by the recall problem (LifePixel had advised to send it anyway). When I got the camera back from Nikon the light flare problem was fixed, so I sent it again out to LifePixel to have it converted again. Unfortunately, once again the same light flare problem is back.

 

* Note, while I didn't save any images from the camera when I first got it, new, it did not have the flare problem (I did take a number of long exposures as I did initial tests to evaluate its 'stock' UV performance).

 

I bought this camera back in June, and as it stands it is going to be some time still until I get it fixed - in some way or another. This isn't turning out to be a great experience so far.

 

Anyone else have this kind of problem converting a camera? Any advice?

[nfoto]

Sorry to learn about this issue. Clearly the problem is with the interaction between camera and modification. Thus the D750 might be put on the same list of doubtful conversion candidates as the D3 and its relatives.

 

I have no other experiences with D750 conversions, but the events conclusively point to the camera being unsuitable for this kind of modification. It is unlikely Lifepixel is to blame except for not warning potential customers. They really ought to put this model on the 'no-no' shortlist.

[Guest]

I don't know that I blame Lifepixel for not knowing this beforehand, but I do think they should have at least tested the camera before they sent it back to me after converting it the second time. Now I'm at a loss as to whether I should continue to try to get this camera modified or simply have it converted back to stock so I can at least sell it 'used' and get some fraction of my investment back. As it stands, I've already paid for the camera, paid multiple insured shipping fees, and have lost months of quality summer shooting time (pointedly, high UV index days!). And if I can't use this camera I have to face investing in a new camera, and paying for another conversion, etc and so on. I'm not sure what to do here. I am a bit interested in the fact that Kolari Vision offers a pre-modified D750. I would expect that if they offer this, they must have tested it to know that is a saleable item. Now, if they can do it then it must not be the camera. Maybe I'll message them to see what data they have on the D750. I have no experience with Kolari. I do very much like Lifepixel, they're service, customer care, etc. But I also want a functional camera...