[lmd91343]

I'm getting very frustrated with Spencer's. I've emailed several times about dirt that came back on the sensor after a full spectrum conversion and a weird cyan cast with no response. Finally got someone to answer the phone last week and he said he'd look into the issue (I sent photos with the artifacts clearly visible) and get back with me and send a shipping label to send it back to have it looked at. Nothing so far. I ended up driving an hour to a camera shop and paid to have the sensor cleaned but still having problems with the color cast. I've tried different lenses and filters (590-850nm) and still get the colors. White balance is good.

They gave you bad service. That is unacceptable. I don't think I'll go there for my next conversion,. Even though I am happy with what they did to my K3 II. But I have an old issue with Kolari too.

A cyan cast sounds like they installed a 665nm or a 590nm filter instead of a 720nm filter by mistake. Check out this:

IR Filter Options :: Spencers Camera

I got a 720nm in both my K3 II and K10D. However when I went to Europe I bought a converted P&S Panasonic DMC zs50 from Kolari for my pocket. I thought it was a 720nm filter, but anything blue shows up like a sore thumb!
Here is Grosvenor Square just outside the US embassy in London. The other buildings housed US army HQ in WWII. The FDR statue is from the people of the UK. Notice the blue jeans the guy is wearing at the base of the statue and the guy on the bench. 720nm filters should not allow blue yet this one does. I bought the camera with it from Kolari.

https://www.pentaxforums.com/forums/attachments/6-pentax-dslr-discussion/544361d1627430392-ir-conversions-6910460c-c754-4fde-926a-45f21b3c0aa2.jpg

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[stevebrot]

A cyan cast sounds like they installed a 665nm or a 590nm filter instead of a 720nm filter by mistake. Check out this:

Full spectrum conversion. The cast could have come from anywhere depending on the quality and types of filters used on-lens.

There is a separate thread on the subject...

https://www.pentaxforums.com/forums/6-pentax-dslr-discussion/428681-infrared...nce-issue.html


Steve

[lmd91343]

Full spectrum conversion. The cast could have come from anywhere depending on the quality and types of filters used on-lens.

There is a separate thread on the subject...

Infrared white balance issue - PentaxForums.com


Steve

True true. Any of those three are likely. The image would need to be examined.

Whatever the the problem is, I'd bet, dollars to donuts that the wrong filter is installed.

[cdd29]

They put the correct filter on it, that I can confirm. One of my images is posted somewhere but I cant find it so here's a repost. White balance is good but there is a cyan cast in the lower corner. I've replicated this on a few different shots. If I shoot at a white wall, the color is even across the frame. Here's the test image. I need to go out and shoot alot of different things to check it. Might be environmental as well.

OK, for some reason I can't post a photo here. I've uploaded it, confirm it did but it doesn't display. That's new. So I have nothing to show the problem with.

[Ishpuini]

Notice the blue jeans the guy is wearing at the base of the statue and the guy on the bench. 720nm filters should not allow blue yet this one does. I bought the camera with it from Kolari.

No, getting blue in your final image is very possible with a 720nm filter. I have the same on my full spectrum K-3II. It all depends what the in-camera white balance is set to. Anything cooler than what is considered neutral by that white balance will show blue, anything warmer will be orange.

The infrared wavelengths above 720nm result in a different reaction of the RGB cells on the sensor as the wavelengths increase. Without application of the in-camera white balance the shorter wavelengths would yield a very warm saturated orange response (a lot response in the red, some in the green and a tiny bit in the blue), gradually desaturating (cooling) as wavelengths increase and RGB values get closer to one another, until somewhere above 800nm or so all three channels yield the same response and the result is basically neutral grey.

Applying a cooler whitebalance on a colour in the middle of this range (e.g. translating slightly desaturated orange into grey), will turn the greys into blues and partially desaturate the saturated oranges in the RAW. I.e. the effect you observe.

---------- Post added 28-07-21 at 12:03 ----------

They put the correct filter on it, that I can confirm. One of my images is posted somewhere but I cant find it so here's a repost. White balance is good but there is a cyan cast in the lower corner. I've replicated this on a few different shots. If I shoot at a white wall, the color is even across the frame. Here's the test image. I need to go out and shoot alot of different things to check it. Might be environmental as well.

OK, for some reason I can't post a photo here. I've uploaded it, confirm it did but it doesn't display. That's new. So I have nothing to show the problem with.

Have you tested different lenses?

BTW, even a white wall that is illuminated from the side might look evenly lighted to our eyes, but it might not be necessarily so in infrared. You should shoot the same section of wall with the camera rotated to different 90 degree angles. If the cyan cast rotates in the resulting images as well, the infrared light in your scene is not even and your camera is fine. If all shots have the cast in the same location, the cause is likely in your imaging system, i.e. the camera-lens-filter combo, all three of which can be culprits.

[lmd91343]

I’ll check the P&S WB. I’ve never done that. My K10D has always been fine.
Thanks.