larryepage Loc: North Texas area

There was recently a discussion here from a member who had found a D90, 18-70mm Nikkor lens, and some other great stuff at a thrift store. When he tried the D90, the results that he got were surprising, and a discussion ensued around what was "wrong" with the camera and whether it could be fixed. Originally, several of us thought that the problem might lie in the white balance adjustment system, but additional information eventually led us down the trail of the camera being an IR conversion of some kind.

Fast forward to today, which finds the camera in my locker, with the assurance that it is a conversion to an infrared-sensitive camera. While some work remains to determine exactly what the cutoff wavelength is, I now know that the conversion is to infrared-sensitivity only, with no remaining sensitivity to visible light wavelengths (verified by testing with an assortment of colored LEDs, known to have no IR in their output). In addition, it has been verified that the conversion process included removal of the RGB Bayer filter array, so the camera is now monochrome only. The only color component that imparts to images is that which arises from the white balance biasing system, which is still functional in the camera. Camera output is fully monochrome.

I have been working with the camera, learning its characteristics, as well as how to achieve proper exposure and focus. I'm not perfect yet, but I've learned quite a bit, and have gotten some images that at least have some level of interest, even though they really are still mostly technical exercises. Thought some of you might be interested in seeing how it's going, especially the member who is convinced that I've been tricked into buying a broken camera.

Here is a recent image captured after a local snowstorm. If you look carefully, you can see some residual snow on the ground.

(Download)

CHG_CANON Loc: the Windy City

Have you determined why the image is not in focus?

larryepage Loc: North Texas area

Achieving focus is always the number one technical challenge with IR photography. Many, if not most, of the best IR images tend not, under close inspection, to be in proper focus under close inspection. In fact, if you notice, the subjects for most IR images are chosen such that slight focus shortcomings are not a distraction. It had been my hope that Autofocus in Live View would be an effective focusing method, but so far, I have not found that to be the case.

In this case, part of the issue is the old Nikkor 18-70mm zoom that I am using right now. It's just not really a very good lens. Part of the issue is that the long wavelength light behaves differently from visible light when passing through the lens. Not only that, but different IR wavelengths behave differently from each other. Part is that the visibility of the rear display of the 12 year old D90 is problematic in daylight, even though it offers magnification of the Live View image.

One thing I have learned already is that if this develops into more than just a short-term "novelty" interest, I will be purchasing a mirrorless camera and having it converted to IR. Having a magnified image available in the viewfinder would be of tremendous value.

Manglesphoto Loc: 70 miles south of St.Louis

I had a D70 converted by Lifepixil quite a few years ago and they recalibrated the lens an 18-55 to match. I can use auto focus or manual and always get a sharp focus. Plus I have to use a custom W/B using green grass as a reference. Then post process in PSto get B&W I/R.

larryepage Loc: North Texas area

Thanks for this information. I am planning to do further research to find out who did the conversion. There are no stickers or other identifiers on the camera, My immediate goal is to work through the technique issues and make sure that I get to the point of being able to do everything that I need to do to achieve focus. When I had done some checking before, Life Pixel would calibrate to the 18-70 lens without even having the lens. I also plan to try some other lenses to see if they might work better (or at least easier).

I'm pretty far from a point of frustration right now, having really just started to learn how the process works. We'll see where it goes. By the way...which conversion did you have done?

Manglesphoto Loc: 70 miles south of St.Louis

When I had my D70 converted sometime shortly after the D7100 came out 2013/14
There was only one choice B&W!!

JimH123 Loc: Morgan Hill, CA

I had my mirrorless Sony A6300 modified to be a mono sensor, full spectrum, camera two years ago. I absolutely love it. With the focus magnifier, manual focus is a breeze. And being able to use the various color and IR filter is so much fun. And some of my AF lenses work great with the A6300. But there are some that expect phase detect focus to work that no longer works on the camera with the removal of the CFA which includes rendering the phase detect non-functional. But the lenses it still works with, it nails the focus.

A must piece of software for processing RAW mono images is an app called Monochrome2dng. This turns the image into a monochrome DNG file in which there has been no demosaicing. This allows the mono image to obtain the detail that can't be achieved when subjected to demosaicing.

With the D90, can you magnify the live view?

I have two cameras modified to IR but retaining color. One is an older Sony A55 and the other is an Olympus EM5ii. The Sony absolutely requires that I do manual focusing. AF always misses. But the Olympus, being that it is mirrorless, is wonderful at autofocus. I much prefer using the Olympus.

larryepage Loc: North Texas area

Thanks for the information. I'll be trying some other lenses soon...first up will be some prime lenses that have fewer elements.

Yes..Live View on the D90 does allow magnifying the image. But it's an older technology display with limited resolution, so it can still be something of a chore to focus in sunlight.

I'm learning. Still fun so far.

Chan Garrett

This looks like a sensor filter conversion to c. 830nm. I have that conversion because I am more interested in good B&W images than the very colorful possibilities of the full spectrum conversions. This 830nm conversion usually needs a tripod and slower shutter speeds. I use Live View to guide me in all of my camera settings and manual focus. Your histogram is still based on visible light and will not be a good guide for IR.

larryepage Loc: North Texas area

Thanks. I am doing everything in Live View now. I have found that Matrix Metering generally does a good job with an EC of +1 stop. A big current emphasis is to find a lens that doesn't have such a tight focus scale at longer distances. Compressed focus movements contribute to difficulty in getting good focus outside.

As stated, I have proven no response to visible light, and no color component in images except that created by WB adjustments. I am previewing and saving images in B&W for now. I may eventually add raw files, but camera dynamic range is only 9 stops @ ISO 200, so I see little benefit over Fine/Large JPEGs at this time and state of competency.

Your assessment of the 830nm conversion seems very reasonable. The only thing that might be a little confusing there is that I experimented with the on-camera flash and got pretty impressive results. I was a little surprised that there was that much IR in the flash. Skin tones are also rendered reasonably naturally.

This is as much fun as I've had with a camera in quite a while, in spite of the camera's shortcomings against today's models. We'll see where it eventually takes me.

JBRIII

How did you confirm the bayer is gone. Replacement of the hit mirror with a 830 would block everything below 830.
If actually converted first to monchrome, the resolution would be higher of course. Cinverting a camera to both would around around $12-1300 $, bayer removal is expensive.

If no bayer and you decide to sell, I might be interested?
Jim

larryepage Loc: North Texas area

Of course, it is possible that the filter is still there...no way to visually verify with the IR filter in place. It is certainly possible that the deep IR cutoff just renders it totally ineffective. In any case, there is no color content evident in anything coming from the sensor. Color histograms follow each other in all cases unless shifted by WB adjustments. (I may have extrapolated and over-inferred.)

JimH123 Loc: Morgan Hill, CA

The main benefit of shooting RAW and then using an app such as Monochrome2dng is that there will be no demosaicing of the image. This is a big deal. The way that a sensor is arranged with the RGB colored filters means that to solve the solution so R + G + B values are found for every pixel means that averaging is performed. And when shooting mono JPEG, the camera still does that demosaicing. Without demosaicing, every pixel is used as is with no averaging at all. Theoretically, detail could approach 4x, but in reality, it's not quite that high, but it is very noticeable.

Monochrome2dng is sold by the same people that produce RawDigger and FastRawViewer
https://www.fastrawviewer.com/Monochrome2DNG

Once it produces a mono DNG file, that file can be opened in Lightroom, Photoshop or whatever editor you use. But the Topaz AI tools cannot directly open a mono DNG file. But they will open a file that Lightroom hands off to it since Lightroom converts it to sRGB. Probably a good idea to switch it back to Grayscale when done editing.

Attaching a red rose that was one of the first images I took with my modified Sony A6300. Red Rose + Red Filter = White Rose in picture. I shot RAW and then used Monochrome2dng. Then loaded it in Lightroom for processing, including a crop. And then converted it back to mono.

(Download)

Chan Garrett

The way professional conversion is done is to totally remove the original filter designed to block all (or most) IR light. It also blocks UV light. The new filter installed (there are now various options) that blocks all light below 830nm is designed so that none of the visible light spectrum will be recorded on the sensor. Thus, B&W. There are other filters that will let in more visible light. Thus, recorded color data can be used to provide the altered color of some popular IR images. The cost of the conversion is usually in the $200.-$300. price range.

elee950021 Loc: New York, NY

If you have an older lens for a film camera, there was very often an "Infrared" focus mark which was slightly offset from the infinity focus mark. You had to adjust the focus using it. "Modern" lenses no longer have it. On IR conversion websites, it is mentioned that some lenses do not work well unless they have been calibrated to match the body. Some lenses are not recommended at all as they create a dark spot in the center of the image.

Is the converted camera body possibly full-spectrum? I bought a converted Olympus DSLR that was so converted as well and I shoot at different wavelengths by using the appropriate filter.

If you are interested in a conversion, I would look at eBay or inquire at reliable outlets for deals as very often a converted camera is available at a much lower price than the cost of a camera body and its conversion. I surmise, people get tired of the camera as it is a one-trick pony!

Be well! Ed