Been wanting to narrow down my converted-by-lifepixel E-M1 (590nm Infrared, equivalent to putting a B+W 090 "goldie" in front of a full spectrum camera for strong faux color effect) to something that cut out all visible light so that I was dealing only with infrared, something stronger than my Hoya R72, but I didn't want to break the bank either.
Was looking at a few like B+W 093 (Since I already have the 090 , 091 , and 092 ), or the Hoya R90, or one of the Schott, Heliopan, etc filters in the 850~1,000 range, but course they were all quite expensive to me for a 52mm.
Alternatively there was the Tiffen 87 which was maybe half the price of everything listed so far but I couldn't find a transmittance curve, fortunately Tiffen linked me to their PDF brochure which showed this chart (which I marked up with blue lines at each 10% increase, and horizontal at 85% and 88%).
Figured I'd mention
, according to the LifePixel FAQ, most digital camera sensors cannot see past 1,200nm (even though the filter they may place in front of the sensor can pass well beyond 2,000nm). So we're looking at a max transmittance of around 83% as far as the camera can see with this filter in front.
B&H runs them around $50-ish for a 52mm size, but I managed to find a new-old-stock one from probably the 1980s from the packaging and paperwork inside for about $38 shipped.
Received it a little after 1pm ( May the 4th be with you...
), but course it was mostly cloudy all day, occasionally some sun shined thru.
First test subject? ... the dog of course. With the Pentax-M 50mm f/1.4 in front ( aperture between f/2 and f/4, ISO 200, 1/200th for the first one )
Luminosity seemed to be roughly a stop to a stop and a half more than without using the filter and just shooting 590nm+ outside when there was bright and direct sunlight there seemed to be little to no difference in exposure from normal shooting conditions. Sunday upcoming is supposed to be bright and sunny with next to no clouds, I'll be able to do a good test between 590, 695, and 830 on both the E-M1 converted, and the unmodified E-M5 to show exposure difference (and result difference, which will be the most obvious below a 720nm filter since the visible light will be way brighter than infrared on the E-M5).
Once at campus, knowing that there's very little infrared light inside the building, and our windows actually block a good deal of infrared from getting into the rooms, I figured I would try it with the Tiffen. As expected exposure was drastically reduced compared to unfiltered 590nm (which still works, but what I'm seeing with 590nm is mostly just the red visible light).
The halogens in the display cases emit a decent amount of IR, and you can see the slight color difference of what little IR makes it in from the outside windows. Which is kind of funky considering that even with a custom white balance and no B&W conversion, 830nm+ tends to be pretty much black and white all on it's own.
First one is with the Pentax-M 50mm f/1.4 , shot at f/1.4, 1/60th of a second at ISO 6,400, the second one with the Panasonic 20mm f/1.7, shot at f/2, 1/125th of a second at ISO 3,200.
Then heading outside, towards the fountain street church (1/125th, f/5.6, ISO 200), then back inside to actually work (wanted to shoot all afternoon, but gotta work....).
It gets to about 8:15PM, finally finished for the day and rushing to slap my bag together so I can get what little sunlight there is before the sunset at 8:46, managed to get to the river area around 8:30PM.
Also added on my Marumi DHG Super Circular Polarizer for glare/reflection (or to deepen the tones on some surfaces).
1/15th, f/4.0, ISO 400
1/30th, f/5.6, ISO 200
1/60th, f/5.6, ISO 200
1/30th, f/5.6, ISO 200
1/8th, f/5.6, ISO 200, 3 minutes away from sunset.
I set the camera to record for 20 minutes from sunset onward, keeping it manual exposure (no change over duration), then sped up the video about a thousand times so that it would produce a 60 frame per second timelapse into a final 1 minute video.
If I remember correctly, 1/25th, f/2.8, ISO 200 for the video setting.
Now the sun was down, now to try a couple nighttime shots. Exposure times course were fair bit longer, and as expected longer than if I were to shoot with just the 590nm modification, or with visual light since all visible light was cut and I was relying on whatever street lighting still used inefficient bulbs (LEDs won't show). course, I still had the circular polarizer on the front until the very last image
, so compared to unfiltered, actual exposure difference remains around 1 to 2 stops darker, but with the CPL it was about 4 stops darker.
13 seconds, f/4, ISO 200
15 seconds, f/5.6, ISO 200
8 seconds, f/5.6, ISO 200
And now I was feeling like I was going to freeze to death (only had a denim jacket, didn't pack my gloves/hat since last week it was staying around 50-60F at night), so I called it quits and headed home.
Seems like the Tiffen 87 will be one of the filters I carry with the IR camera along with the B+W 092 (695nm). While there is little difference numerically throwing a 091 (630nm) in front of a 590nm converted camera, there is a difference to be seen between the equivilent of a 090 vs 091 (check out this blog for some comments on that : https://infraredatelier.wordpress.co...11/bw-091-090/
), I prefer the increased subtly of the 092 when I don't want quite as much visible light as 590, but I don't want to go fully muted either. I got the 090 originally for my film body and because I was expecting to receive a full spectrum camera originally, only to end up with one that already had a 590nm conversion [saves me a filter at least]).