@azkay
I'd like to answer your question from other thread rather here.
using several LED in series, with a smaller series-resistor, genarally yields better efficiency on same supply voltage.
with 70R resistors you should be safe to use 3 pcs LED specified as 1.3V@20mA in series, on a supply voltage of 5V. BTW aiui the datasheet says the LEDs can handle up to 100mA continuous forward current, I'd maybe go for 50mA.

OTOH sixwheeledbeast has quite some point with his suggestion to use LEDs in the 850nm range. For those you should get specifications and redo the math.

/jOERG

Well OK, but nobody corrected me.
You don't measure frequency in distance and you don't buy IR LED's by frequency.
Yes, you are correct that wavelength and frequency oppose each other in the scale of waves.

Also if possible try even lower wavelength like 740nm, they will be even more visible but you will get better images and spread of light at close range.
Also different LED cases make a difference as to how even the light is spread, they can be bought in a variety of "spread" angles

Absolutely awesome! I was fighting with camera module 2 weeks ago (resulting in broken autofoxus in two camera modules - it works ok only for up to ~14 cm, don't want to focus on further objects, even via manual adjust, as per fcam or camera-ui from cssu), as night-vision via N900 was idea that "struck" me more than a year ago.

To be honest, after looking @ camera module internal, I haven't balls to try removing filter. It seems, that your first attempt resulted in ruined (scratched) sensor, but You know (now) how to do it properly.

Could You share Your experiences here, as detailed as possible? Some guide for removing (replacing by regular glass?) IR filter in N900's camera module would be great
---

OTOH, how You have destroyed original module by removing it (what happened)? Also, do you think that it's possible to fix broken autofocus on such module (or problems like ones I've described, with ~14 cm max focus distance), or module looks too delicate?

/Estel

Not much reason, was just looking for something and I hadn't played with it before so I went with 940nm.

My fourth module just came int today.
First one I ordered I broke the autofocus, I started dismantling from the top up. After that I broke the original one trying to take it out, so I had IR without autofocus. The third one I got a few weeks ago I did perfectly, but the phone was giving me an "Operation failed" when I tried to use the camera. I got my fourth one today, tried it before touching it- worked fine. So, the third one was faulty- too bad I didn't test it first to get a refund.

Took it apart perfectly, took out the IR filter and put it back together and it works with autofocus, though as you said it doesn't seem to focus too well on further away things. I havn't tried replacing where the filter was with glass, might have to try it.

Basically, now it's working fine but not for landscape type photos, I still have a little noise on the sensor but it's probably dust/glass particles which I could probably clean out later if I can bother with it.

Hard to not make a mess trying to cut out glass filters with screwdrivers and knives, lol.

Here is a picture of how I took apart the faulty one- same as the working one.


I pretty much just used a small flat screwdriver on each corner and twisted it slowly to break the seal/glue stuff, then I used the edge of a flat screwdriver/sharp knife to cut the edge of the filter slowly as to not go through into the sensor, then when it cracked I used a needle to snap the glass off away from the sensor.

Also bought 720 and 950 dslr filters to cut out and modify into the case.
Not sure where I'll find .5mm piece of clear glass to replace the old filter with.

Looks very good, I think I have nice use case for my "broken" camera modules.

BTW, oddly enough, my module refused to focus on objects further away than ~14 cm after only removing it from N900's mainboard, not after disassembling it (I've disassembled it later, when I knew, that I had nothing to loose). In fact, even when adjusting manually, I can not get it to focus further away.

IDK if it's the same in Your case, maybe not. While reading through pages about modifying cameras for IR, I've found information, that replacing IR filter with non filtering glass is required to keep autofocus working - it may be related to Your problems.

Best way to check it, is to use fcam or CSSU'ish camera application - use manual focus, and see, if You can get sharp view on far away objects. It would be very useful to know.

/Estel

I tried it with fcamera an hour ago, focus set to >5m outside is still blurry. Anything within a few meters is fine, though.

Guess it's the problem with not having the glass there.

Unfortunately, no. glass helps only to regain *autofocus* - You should be still able to focus manually, though. It looks like same problem as mine - it's just that mine blocked @ 14,77 cm, and Yours at 1m or so.

What troubles me, is that this "damage" may occur even, when just removing camera module from slot, without actually disassembling it. No clue WTF - it looks very sturdy, and it's held in slot via regular, mechanical thigie' lock - can't imagine what may get destroyed, when carefully disabling this lock and removing module :/
---

As for Your question where to get 5mm square of glass - cut it out from bigger one, of course. You just need to find piece of clear glass with reasonably similar thickness, then carefully cut it, using glass cutter toll. They're very cheap, fortunately (tools, not glass).

/Estel

The autofocus on mine still works, it's just blurry at distance. I can still see it go in focus/out of focus on things.

.5mm, half 1mm thickness lol.
I think I read somewhere awhile ago that plastic works as a makeshift alternative, just won't be as good as glass. Can't hurt to try.

Also, don't forget that the focus point is different in IR photography (although if you deal with this stuff you obviously know this). Maybe the autofocus needs to be "shifted" a bit to adjust to IR?

Keep on trying, IR is awesome.

Agreed, you may get focus shift depending on the "wavelength" of the IR's; as I mentioned in more detail above.

You will find the autofocus will be setup as white light. So with higher wavelength IR and/or the further from the object you are; the more the focus shift will need correcting.