[MJKoski]

Infrared certainly makes shooting in bright daylight worthy. Today I tested BP642 again with Samyang 24mm T/S:



F/11 if I remember correctly. Channel swap done in Photoshop. There is some greenish color cast on the lower left corner. Dunno where it comes from as Samyang has been behaving nicely with front mounted filters before.

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Last edited by MJKoski; 05-14-2020 at 12:19 AM.

[JensE]

Now that's nice to know. I too have the very same Samyang fisheye. IR could be fun with a fisheye.

Oh, I'm sorry, but I'm using the Astronomik CLS - blocking Sodium orange from (oldish) city lights. Revisiting the pictures, there may be some uneven color. But the light falloff is very gradual, as usual, and seems to properly be compensated by applying the lens profile. On the DFA 15-30mm at 15mm, it looks even more uniform.

The CLS filter seems to be an interefence based filter, so the angular dependency and thus some color shift towards the corners is to be expected, see the attached shot. The lights in the foreground lighting the houses are high pressure sodium lights, from which we see the little there is outside orange, whereas the greenish tint comes from city lights behind the Battle of the Nations Monument in the center - modern LED lights.

[MJKoski]

Oh yes there is a color shift with this BP642 as well. It is clear to me now. So, practically this experiment did not help me getting better IQ with separate filters. Yes, it will allow IR work with non-threaded lenses but quality is not that much different compared to mounted filters. Have to admit a defeat here.

To be honest, the only lens+filter combo which currently gives me better results compared to my €200 720nm Fuji X-A3 is FS K-1 & Zeiss 50MP with front mounted filter. 'Tis driving me nuts.

My current thoughts:

[MJKoski]

I'm putting this BP642 on the shelf for now. It is not working very well - every lens which works with front mounted IR filters gives fair amount of color cast in the corners with BP642.

There is other issue as well, while I did not notice any camera malfunction during the period I left the filter in place, I had to constantly reseat the filter. Every time I moved with the camera and camera bag bumped to something, the filter got dislocated inside the camera. Not totally off place but enough to notice loss of contrast and uneven sharpness.

The best part of the filter is that it completely fixed all infinity focus issues I had while it was in place.

[MJKoski]

I received a set of KolariVision AR-Coated Gen 2 filters and they seem to be the real deal.



That is Pentax 40mm f/2.8 pancake against super bright background and very dark foreground subject. The lens itself has minor hotspot issue with super color filter, but there is very low or non-present flare in such high DR situation. Also, no color shifts in the corners. I have never been able to do something like that with my 720nm Fuji or other filters I have used including 780nm coated Heliopan filter.

[MJKoski]

Here is another clip filter which seems to do things in different way:
Clip Filter Series (for PENTAX APS-C / Full-Frame) | STC eShop?OPTICAL CO. LTD.

This does NOT block the mirror and seems to fit very tightly between the lens and the body when the lens is attached. No messing with live view needed. Gonna try this out.

[Oakland Rob]

Ever try gels? I've mounted them in adapters I use with M43 converted cameras for fisheyes, etc, and works semi-OK. The big wides don't have the sharpness of some of my other lenses, so a decent compromise. Some tape the gel on the back of the lens, but my lens has a bit of a bulge back there. I use a K-01 too. Having a flapping mirror would of course complicate matters.

[MJKoski]

It could work but I'm currently thinking about shutting this project down. I just cannot get the same clarity out of the setup as I can get with a simple 720nm converted cheap Fuji X-A3 and their 23/2 WR. I have only one nice lens (Zeiss 50MP) and Kolari's 67mm filter kit for it. The lenses which do not have bad hotspots (Samyang 35mm and Samyang 24mm T/S) suffer from low contrast and weird flares.

Just...do NOT convert FF sensor DSLR camera to fullspectrum. It seems brain dead idea unless the selected brand has suitable selection of IR capable high IQ lenses. Full Spectrum short register distance MILC can at least use the best pieces of all brand offerings.

[Oakland Rob]

Can't say I disagree. I have converted mirrorless and they're great. Even some lens that have hot spots on other bodies don't on mine. I do have a converted K-01, but it has trouble with some lenses. Mirrorless also doesn't have the same hassles with VF, focusing, etc.