IR/UV related questions

Saved this old compact (Sony DSC-W15, 5.1 MP) from the bin and got it donated to do with as I please and since it still functioned I'd thought to make it into a little diy experiment so I disassembled it, removed the pinkish/bluish IR filter and re-assembled it. Have to say on assembly I left out a part that fell out during disassembly and that I couldnt get to fit anymore but inspite of that the camera functions as well as it did before I took it apart so I guess its now IR (and possibly UV as well?) sensitive.

It was just a little fun experiment but I've gotten very curious as to what I'm able to do with it now as I dont know anything about IR/UV related photography. I'm kinda hoping I can just take pictures with it which then can be (IR/UV)appropriately adjusted to only show the IR (or the UV) spectrum but that just seems a bit to easy as I'll probably need something like an "IR-pass" (uv-pass?) filter?

I'm going to do some related searches anyway but any hints/tips are highly appreciated.

Regards

Update

I have just taken some pictures which are pinkish under normal lighting conditions while I also took a picture in total darkness (bathroom) and exposed for the camera with a simple IR remote control (single led) so I guess its now able to photograph with in total darkness 

petrochemist wrote:

The hot mirror that you removed blocks both UV & IR so you will indeed have made the camera more sensitive to those wavelengths. If you've not replaced the hot mirror with anything the focus distances are going to be affected, but hopefully not so much that you can't take some interesting shots with it.

When you're not shooting in visual darkness you'll probably want to use filters to limit the wavelengths being imaged at any one time. I do this a lot with my full spectrum modified cameras, as well as standard long pass IR filters strongly coloured photographic filters can be used (nearly all of these transmit IR as well as the visual colour).

Imaging UV will probably prove difficult, even without the hot mirror sensors are not as responsive to UV as they are to visual light. then lenses will often block considerable UV as well. The small lenses on compact cameras should be better than big SLR lenses in this respect. All the affordable UV pass filters (like Schott U330) also transmit significant IR - this wasn't an issue with film which isn't sensitive to IR but makes the IR portion significant with digital imaging. UV is generally less interesting for imaging, but skin & flowers can make great subjects looking very different in UV. the combination of UV & IR generally works much better for landscapes than UV alone does.

If you don't want to wait for filters to arrive there are a couple of DIY options that will give IR while drastically reducing visible light and you might just have around.
Magnetic media from old floppy disks works but reduces the IR significantly too.
Unexposed but developed film negatives work reasonable well if you have some around from the end of a roll.
Variable ND filters are quite effective when set to their darkest.

Shooting 'full spectrum' (as your conversion without additional filters) can sometimes give interesting results but typically just looks like the colours are wrong. portraits tend to be among the better subjects for this. Clothes can change colour significantly (especially blacks) & skin will tend to have a little of the infra red glow...

You might also want to get yourself a IR flashlight with IR LEDs these can be quite reasonably priced & they'll be much brighter than the TV remote.

The pinkish hue you got is very common for 720nm IR shots, simply desaturating should give nice monochrome IR results, otherwise customised white balance is usually required.

Have fun !!

Thanks for replying with so much great information, totally appreciated!

For now I'll follow your tips about using film, of which I have some around here in the form of the unexposed ending of a developed roll. I also have some old floppy disks but it definately is a lot more darker and with this old compact probably wont work as well as the film anyway due to the aged sensor.

I'll also order a flashlight as you mention, will be very interesting, perhaps even give some nice results.

Thanks again!

Regards

Thanks for replying ProfHankD, appreciated!

I havent made any (floppy/film)filter yet but I did capture some images today which I processed in LR. I really like the surreal feel of it but there isnt much definition in these pictures as 5.1MP (jpeg only) from an old compact sensor doesnt give much to work with and the camera probably offers less controll than almost any of todays smartphones.

Still I enjoyed what it offered but it is thus different from regular photography, its like 'shooting some alien cam' if you know what I mean.

ProfHankD wrote:

Damovich wrote:

Those colors are off less than I expected... until I looked-up the DSC-W15, which uses a Super HAD CCD.

Not all, but many CCD sensors have somewhat less sensitivity to NIR than newer CMOS sensors. Obviously, you're still getting some sensitivity, you just might find NIR-only exposures require a bit longer than for some newer sensors without NIR-blocking filters. The good news is, I don't see an NIR "hot spot" in the middle, so your lens is probably ok for NIR.

BTW, these are NOT good, but here is a quick attempt to isolate RGB vs. NIR. The correct way to do this involves a calibration procedure, so this is using some guessed parameters instead:

RGB

NIR

Lots of noise and JPEG artifacting in the NIR extraction... which probably wouldn't get a lot better even if it was calibrated.

In sum, yeah, you need to buy filters.

Thanks for looking into it, I will buy me some filters then I guess 

petrochemist wrote:

I definitely know what you mean about the Alien Cam. I think it's one of the reasons I'm hooked on shooting beyond the human norm.

With a full spectrum conversion like yours there's endless chances to experiment. I've tried all sorts of transparent coloured plastic & glass, such as pencil cases, sweet wrappers etc. as well as the more normal lighting gels & filters. Nearly all transmit IR - Yes, as Hank pointed out it's actually NIR we're concerned with - silicon as used in the sensors becomes transparent to IR above about 1150nm, so there's little response above about 1100nm.

I'm afraid my image processing skills are a VERY long way behind Hank's - I usually shoot JPEG (despite ALL the advise) as the camera does a much better job of processing the RAW data than I can, & I prefer to play with optics than computers (so that probably won't change).

I'm a bit of of both I guess, I'd like to process RAW data but I'm also into optical experimentation using non-conventional material(s) and/or vintage optics. Unfortunately this little cam doesnt have any RAW options, so its jpeg only anyway, but I'm enjoying it nevertheless, just the fact that it is even usable for this type of photography, after having removed the IR-filter, is rewarding by itself in such a sense.