Infared IR Conversion Considerations and Options

[Craig Gerard]

I've secured a Nikon D50 which has been converted to colour IR. It seemed like an interesting avenue to explore.

It's only a 6.1mp DSLR (10,585 actuations) and I only have one MF Nikon lens that would be compatible, the Micro Nikkor 55/3.5. I also have a small number of M42 lenses that may be suitable via an adapter.

I've had no experience with IR and I'm not sure what to expect....any information would be appreciated.

Is colour IR conversion a good option (there appear to be many variations of IR conversions)?

*I've been looking over the information on the following site :
http://www.lifepixel.com/tutorials/infr ... hop-videos


Sample image taken by the previous owner (linked from my DropBox):




Craig

*edit: changed title of the thread to reflect the expanded discussion

[enricosavazzi]

Hi Craig,

as far as I understand, what LifePixel calls color IR is a filter that passes part of the visible range together with near-IR. Whether this is good for your purposes remains to be seen. If you are interested in the same type of color images of the sample, then the answer is probably yes. If you are interested in "pure" IR images, then you need to mount an additional IR-pass, visible-cut filter on the lens and frame and focus in live view. Either way, you will almost certainly need to use manual exposure, since the (unfiltered) exposure sensor has a very different response spectrum than the (filtered) sensor.

M42 lenses have a shorter registration distance than Nikon F lenses, so you will be able to focus at infinity only with an adapter equipped with divergent optical elements, which may or may not add focus shift and other aberrations in the IR. Some lenses also display a tendency to produce a central flare spot in the IR, so you will have to test them.

[magus424]

passing all visible + IR is actually referred to as "Full spectrum" on lifepixel

the "enhanced IR" and "super color IR" use 665nm and 590nm filters, respectively, so it will probably be close to that

other posts online (example) I've seen referring to "color IR" look a lot like the 665nm version, so if that's the case, it'll work perfectly for the type of image in your post

I've been considering converting my 60D to full spectrum now that my 5D Mark 3 is about to arrive; especially now that I've found this site which has 590nm and 665nm filters for sale that would go with my 720 and higher filters

[Craig Gerard]

Thanks for the responses.

I've also received some additional information from another member via PM.

The item listing does not state which company did the conversion. I am attempting to obtain that information from the seller, but am uncertain if it will be forthcoming.

The camera you purchased looks like it has an IR-665 longpass conversion which will produce a reddish image as it bleeds red from 665nm on up to IR.. to get the blue sky like this example of mine:

http://dl.dropbox.com/u/48523277/example.jpg
Nikon D200, Nikkor 16mm f/3.5 Ai Fisheye, 1/640s, f/5.6 @ 16.0mm, ISO 160

[*Note: I temporarily redirected the image link to my DropBox in case the member wishes to remain anonymous ]

You have to swap the red and blue channels in Photoshop or some simlar program.. otherwise you will have a reddish image.. of course, you have to adjust the white balance accordingly..

True IR only conversion are 830nm and up.. and is black/white.. and if your camera is IR-665, you can always purchase a longpass IR-830 to restrict the spectral to above 830nm.. a B+W 093 lens is a Schott RG830 and will do the trick.

The Micro Nikkor 55/3.5 may not be appropriate (can't see it listed as such) and may exhibit the "hotspot" issues Enrico mentioned in his initial response. A Micro Nikkor 105/4 would be a contender [but not the 105/2.8] and among the wider angle lenses the Nikkor 20mm f/3.5 Ai and Ai Nikkor 28mm f/3.5 (K-series lens Ai'd).

Basic Photoshop channel swapping video:
http://www.youtube.com/watch?v=h_rNR5f0qVU

Colin thanks for the additional link in your response. I've been thinking about having a Canon 50D converted, but I'll play with the Nikon D50 initially.


Craig

[Harold Gough]

This may be of interest:

http://www.pbase.com/andersonrm/d100_hot_filter_removal

Harold

[ChrisLilley]

If you are interested in "pure" IR images, then you need to mount an additional IR-pass, visible-cut filter on the lens and frame and focus in live view.

Although, the D50 does not have live view.
http://www.dpreview.com/reviews/nikond50

So for pure IR images you need to focus with visible light, make the IR focus correction, flip down a vis-cut filter, take a trial shot, examine the histogram (D50 just has one, no RGB histograms), adjust exposure, and take the shot.

[ChrisLilley]

I've secured a Nikon D50 which has been converted to colour IR. It seemed like an interesting avenue to explore.

It's only a 6.1mp DSLR (10,585 actuations) and I only have one MF Nikon lens that would be compatible, the Micro Nikkor 55/3.5.

Be careful if your Micro-Nikkor is pre-AI. The D50 has a minimum-aperture sensor switch that is slide-round (rather than a push-in type like on D40). See mount photo at
http://www.dpreview.com/reviews/nikond50/5
the black switch at 8-oclock.
The flange on most pre-AI lenses will jam on this switch and eventually break it.

To check, look at the back of the lens for aperture indexing (AI) ridges (these were sometimes added to pre-AI lenses, either with an aftermarket kit or by filing the flange).

Or check the serial number to see if it is an AI or AIS version.
http://www.photosynthesis.co.nz/nikon/s ... ml#55micro
http://www.photosynthesis.co.nz/nikon/s ... ml#55micro

[Craig Gerard]

Chris,

Thanks for the information. The Micro Nikkor 55/3.5 which I currently own is Ai made somewhere between 1977 and 1979 1104568. I have used it with my D100 (no longer in my possession) and assumed it would be approriate for use with the D50; but the more I read about which lenses are good for IR and which are not appropriate (for various reasons) the more reluctant I have become to pursue this area of photography via the Nikon path due to the cost and availability of suitable glass; so I've begun making enquiries regarding the conversion of a Canon 50D (more megapixels and Live View), plus I have a good selection of Canon glass.

The most perplexing question is which conversion to apply (in camera)


Craig

[Oskar O]

The 55/3.5 should be a fine lens for this. My older version was very good in IR. Passing both visible and IR allows for experimenting with various filtrations, provided that you buy various filters to use. The drawback is that visible-blocking filters make the viewfinder useless when in place.

Pretty basic manual focus glass will be sufficient to explore Ir with this camera. I've used a D70 for years for IR, but switched to a Sony NEX last year and I'm going to sell the D70 now. The mirror doesn't add anything for IR shooting.

[magus424]

The most perplexing question is which conversion to apply (in camera)

I'm going with full spectrum because then with purchase of the right filters, I can do any look I want - deep B&W, enhanced color, light color, or even use a uv/ir blocker to go back to visible light.

[DQE]

Is there any reason(s) that LiveView would not work for IR photography?

[Craig Gerard]

Phil,

Live View will work with IR. Many of the external IR filters will darken the viewfinder rendering it unsuable for observation, but Live View will attempt to compensate for this if the appropriate Live View options are selected in the DSLR menu.

Oskar,

Thanks for sharing your experiences. I've reconsidered the purchase of the D50 and decided not to go ahead with the transaction. I'm currently looking at other options.


Colin,

Going 'full spectrum', won't most of the external filters add considerably to exposure times, etc? What benefits does this approach present as opposed to just using a visible light camera and external filters?

.....................................

Regarding lens 'IR hot spot' issues. Here is one list (there are many such lists): Search criteria 'IR LENS HOT SPOT'
http://dpanswers.com/content/irphoto_lenses.php



Craig

[magus424]

Going 'full spectrum', won't most of the external filters add considerably to exposure times, etc? What benefits does this approach present as opposed to just using a visible light camera and external filters?

No, full spectrum removes the IR/UV block just like IR conversion, but instead of adding a UV/Visible block, it adds glass that lets everything through.

So then putting a 720nm or 665nm in front is just as if you had the glass replaced with that, and you'd see no difference, as far as I'm aware.

[soldevilla]

CCD or CMOS sensors are highly sensitive to infrared. So much so that to achieve accurate color reproduction camera makers put a IR cut filter in front of the chip.
Like many celestial objects emit far infrared radiation, many amateur astronomers are modifying their SLR by removing the cut filter and get so much more sensitive camera. Here in Spain there are several people offering that service. It's pretty easy to see these cameras modified in the areas of equipment change the astronomy forums
So if you get a pure IR image must be installed only on the lens or at the mouth of the camera body a filter that only let pass the infrared. If the aim is to get a photo "normal" then either make a proper white balance or placed a filter that cuts off the IR.

[typestar]

Craig,

I had a Nikon D70 - converted for infrared (converted in Germany) - as far as I know, this 6 MP camera was best suited for this, now I have a D200 converted, but I have to try again, I played around with black-and-white, this including channel-shifting - which brings for me - for my taste and asthaetical reasons - the nicest results.
for higher resolution, the Nikon D200 (10 MP) is nice -- (Bjørn Rørslett also works/worked with IR-converted D200 cams) -- this has been the lastest model, which makes "sense" for IR-conversion, as far as the basic IR-sensitivity of the camera is concerned.

Best regards: christian