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03-28-2017, 08:08 AM   #16
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QuoteOriginally posted by fwcetus Quote
There are some lenses that are known to show "hot spots" when used for IR
I was just curious after seeing your post this morning and mounted DA 15 on my IR converted NEX6. I forgot I left an PL filter on it and noticed a bad hot spot . It disappeared after the filter was removed.

I used FA 20 before I sold it. Here is one I took at my backyard in the morning before I pack the lens for mailing, so the last shot with this lovely lens. Rain's coming. Not a best time for IR since IR is not very strong, so the leaves are not bright and shinny. But it is not overly contrasty and I like the details in the sky.

If anyone want to convert a camera into IR one, I highly recommend using a mirrorless camera. DSLR's metering and focusing system are not on the same path and things are a lot more complex.


03-28-2017, 08:21 AM   #17
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Intriguing results. Mirrorless cameras make a lot of sense for IR work because they focus with their sensors, thus insuring sharp results. So for those who can handle lack of EVF (I can't), K-01 is an excellent candidate for IR conversion.
03-28-2017, 08:44 AM   #18
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QuoteOriginally posted by redrockcoulee Quote
I should did out some of my images with the 15DA to add to this thread.

Please do.
03-28-2017, 11:47 AM   #19
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I thought I would spend a few minutes and a few bytes explaining about the post-processing methods I used. [Disclaimer -- Since I have never attempted taking (or processing) IR images before recently (which is why the gallery I've mentioned here is titled as " 'InfraFred' Experiments March 2017"), the following list of methods may be simplistic and/or even a bit incorrect.]

Since an IR image does not look "normal" to the eye, an IR image can be (and usually is) modified in some way so that it has either "no colors" at all (i.e., so that it is a monochrome "black and white" image), or so that the colors can appear (~somewhat~) more "normal" (which usually involves transposing colors to make the "coppery" sky appear at least somewhat blue). So, in my experiments gallery, there are four versions of each image, as follows:

1. The first image in each grouping is the original IR image, with the only processing being a reduction is size (for quicker downloading online). You may notice that a blue sky will generally end up sort of a dark "coppery" color -- the sky is fairly dark because IR light is quite a bit by the atmosphere. You may also notice that any vegetation will generally end up almost white, since green leaves absorb very little IR light and reflect most of the IR light back at the camera. The filename for each (sort of) "unprocessed" image in each case has a "YYYYMMDD_HHMMSS.jpg" format.

2. The second image in each grouping is the same image, but converted from the IR "false color" to black and white. This is the simplest manipulation to make, involving only converting the color image using some sort of a monochrome function, as found in most image processing software programs. So, the sky will usually end up looking medium to dark gray, while vegetation will end up looking very light gray or white. The filename in each case has a "YYYYMMDD_HHMMSS_bw.jpg" format (with the "_bw" standing for "Black and White").

3. The third image in each grouping is the result of using processing software to perform a "color channel swap", switching the red and blue color channels -- the filename in each case has a "YYYYMMDD_HHMMSS_cs.jpg" format (with the "_cs" standing for "Channel Swap"). In my experiments, generally the sky will end up looking blue or perhaps slightly greenish blue, while the vegetation will end up having a pale pinkish hue.

4. The fourth image in each grouping is the result of using processing software to perform a "hue shift" of 180 degrees, essentially switching the red and blue colors -- the filename in each case has a "YYYYMMDD_HHMMSS_hs.jpg" format (with the "_hs" standing for "Hue Shift"). In my experiments, generally the sky will end up looking blue or perhaps slightly purplish blue, while the vegetation will end up as white or as having a very pale greenish hue.

Please note that, for simplicity, I made the color swaps all 0% to 100% or 100% to 0%, and I made all the hue shifts all exactly 180 degrees, ignoring the effects of adjusting the "sliders" a bit, but it is easily possible to play with the "sliders" to tweak the color manipulation a little or a lot.

Please note. too, that I generally also increased the color saturation of the channel-swapped and hue-shifted images, to make the colors somewhat more intense (hey. nobody ever accused me of subtlety, amirite? - LOL).

[I will mention the freeware and shareware software that I used in another post here, just in case anybody is interested (well, actually, I will shortly mention it even if nobody is interested).]

If any IR veteran wishes to correct any of the above, or to add to any of it, please feel free to do so.


Last edited by fwcetus; 03-28-2017 at 12:13 PM.
03-28-2017, 02:33 PM   #20
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QuoteOriginally posted by grahame Quote
I was just curious after seeing your post this morning and mounted DA 15 on my IR converted NEX6. I forgot I left an PL filter on it and noticed a bad hot spot . It disappeared after the filter was removed.

I think the most useful lists of Pentax hotspot-immune and hotspot-prone lenses I've seen are at Lens Hotspot Database - Kolari Vision (scroll about half-way down to "Pentax Lens IR Hotspot Performance"). [There are several online pages out there that list good and bad lenses but don't even bother listing any Pentax lenses at all.] The DA 15/4 Ltd is a "good performer", for example.

EDIT: I should point out that, to my (limited) understanding, IR hotspots are not the same as flare spots -- that is to say that IR hotspots tend to be in the center of the image and tend to be diffuse in appearance, unlike the more commonly seen hexagon-shaped and octagon-shaped (etc.) flare spots. [I am not suggesting that grahame does not know this -- this note is just intended for anyone who might conflate the two aberrations.]

Last edited by fwcetus; 03-28-2017 at 03:02 PM.
03-28-2017, 06:39 PM   #21
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QuoteOriginally posted by fwcetus Quote
Thanks for the comments, everybody.




1. Since I hadn't numbered them, I had to count each image to see just which two you meant, so that prompted me to edit the post with each pic now being numbered.

2. Since I had so much fun with these experiments, I'd have trouble whittling them down to just two -- I guess my own personal favorites (at this moment) are #4, #6, #10, and #15. [However, I would have to say that my favorites are affected by the ~context~ of the "what", the "when", and the "how" for each image , say, and ~not~ just by the final images themselves.] But if you were to ask me tomorrow, I'd probably pick four different ones. [And, as I suggested in my first post, I might also choose to pick different post-processing favorite methods for each Image as well.]




Basically, an IR conversion involves removing the visible light filter (that favors visible light while discouraging both UV and IR at the opposite ends of the spectrum) that was already installed on top of the cam sensor by the factory, and replacing it with a filter that favors just IR light (while discouraging both visible and UV light). The cut-off point for the filter can greatly affect the nature of the images -- I chose to go with the (I believe) most common cut-off wavelength of 720 nm, although there are filters available for other wavelengths also. There are other considerations to think about as well (and checking the various conversion service web sites will provide some useful education). I chose the K-01 as being an ideal cam for the conversion, and I think I made a good choice.

Being somewhat of a hardware klutz (capable of designing occasionally decent construction projects and sometimes capable of making clever mechanical repairs, but also "well known in these parts" for many foolish, horrible blunders as well), I decided to ~not~ take the DIY route, and so I used Isaac Szabo to handle the conversion. There are several individuals and/or companies that will convert cameras to IR, but Isaac seemed as if he would do a good job, and so I decided to go with him. Not only did he offer the best price that I saw online for a K-01 conversion, he also was selling his conversions on eBay with a "Best Offer" option that I was able to take advantage of. However, most importantly, the quality of his conversion - totally separate from the cost - turned out to be superb, and I can recommend his conversion service most highly. [Disclaimer -- I have no connection with Isaac other than as being a very satisfied customer.]
Thanks. I've converted a Nikon D70 to full spectrum. I was just curious about the actual process within the K-01. K-01 glass wasn't available from Life-Pixel when I did the conversion, so I found a cheap D70 instead. Since you've got a converted K-01, it is obviously available now. Thank you for the contact information.
03-28-2017, 09:44 PM   #22
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While the colour swap shots are interesting, the b&W are more normal (less frivolous). I like them for their drama.
03-31-2017, 01:14 PM   #23
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QuoteOriginally posted by arnold Quote
While the colour swap shots are interesting, the b&W are more normal (less frivolous). I like them for their drama.

And I've heard (read) that before in other discussions of IR image processing. However, while I personally do like b&w images for some IR subjects and scenes (and that's the output I chose for certain of the images above), I also find some of the "original IR color" images and some of the false-color images to be interesting (and dramatic) as well. [And the comparison of the various outputs was actually an intentional part of my "experiments". ]


Last edited by fwcetus; 04-02-2017 at 08:23 AM.
04-04-2017, 10:26 AM   #24
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Have the RGB matrix shaved off for real fun. Offered for some sensors - bascially leep a spare K-01 in case the process fails.
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