Infrared photos around Sydney taken with an IR modified E-PL1

Started Mar 15, 2012 | Discussions thread
technic Veteran Member • Posts: 8,932
Re: internal filters?

leafinsectman wrote:

Sorry for the non-technical replies. I'm afraid I'm not too well versed on the technical side of things. But here goes...

technic wrote:

interesting solution, did you make a special construction to keep the filter fixed in place there? doesn't it give problems with certain lenses?

It hasn't given me any problems with any of my native Micro Four Thirds lenses. It looks like the lenses might hit it but surprisingly enough, the lenses don't go that far back. I think it gets very close though. No problems with my legacy lenses and C-mount lenses too except for the CS-mount lens that I modified to fit on the C-mount to M4/3 converter.

The red filter I'm using was a circular filter and I just filed it down on one side to make it flat until it fit in that small area. When I use the internal UV/IR cutoff filter (for taking regular photos) it's a little less secure but the rear of the lens keeps it in place.

OK, I had not seen this solution before, but it looks quite clever

If you use an interference type UV/IR cutoff filter (like B+W 486, has purple glow when seen from an angle), does this work fine with WA lenses? I like full spectrum conversions, but one of the problems is that external interference-type IR cutoff filters don't work well with WA (hue shift in the corners, needs PP for best quality visual light images). And the absorption cutoff filters are not very effective IMHO (causing less saturated colors and sometimes artifacts).

I have an external UV/IR cutoff filter from B+W (forgot what number it has on the ring) and the colours aren't that great. I have to spend time playing with the white balance later on and it just takes the fun out of it. Plus it's 46mm so I can only use it with my 14mm and 20mm pancakes. I've only taken a handful of pics with it on and I didn't inspect corner performance. I just use the E-PL1's UV/IR cutoff filter internally so I can use whatever lens I want with it.

judging from the description, the external one is probably the B+W 489. This is a bit cheaper than the 486 and is an absorption filter. Those have a cyan-greenish glass color, and no 'purple glow' when viewed from an angle.

The 489 will not correct the standard whitelance settings and give less than satisfactory color saturation. You can get decent color shots (in my area, maybe less in the strong sun down under), but it requires a lot of PP to get it right. With the 486 you will have great colors but strong hue shift in the corners with WA lenses (very similar to the problem NEX users have with legacy WA glass).

I'm surprised that you can still use the internal IR cutoff filter, as it is now further from the sensor I assume. I guess it works because of the telecentricity of m43 lenses. Again a clever solution, because it gives the best of both worlds; when it is mounted behind the lens the hue shift will be minimal.

I'm still looking for a good IR WA solution in a relatively compact system, something better and smaller than the full spectrum dsc-f717 with WA converter that I use now. m43 has nice bodies and lenses, but there is still very little info about how well those m43 (S)WA lenses work in IR.

I'll try taking some pics using my 7-14mm. I took some pics with it once using floppy disk film attached to the back of the lens and thought it was okay but I've yet to do it with a red filter.

that would be great! This is one of the lenses on my list if I buy m43 (either for normal work or for IR). My major concern is IR hotspots, with some lenses they are very obvious.

I wondered why the IR look is a bit muted in your images, probably that is because of the red filter: you have relatively more visual light (more color for processing) and relatively less IR (a bit less 'glow' from trees, foliage etc.).

Yeah I think that's why. I've been meaning to get an IR filter as opposed to just a red filter. I'll post back here when I get around to it.

your current setup has better colors than my 717 with a real IR filter like Hoya 720; so despite the simple filter the results are pretty good. You will probably have even better color PP options when using a deep red filter like B+W 091 or something else in the 600-700nm range. For the really dramatic (BW) IR shots you will need a real IR filter, something in the 800-900nm range.

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