Strange Band in Test Image with R72 Filter

**Aging Violinist** · 11-20-2023, 01:51 PM

Hello fellow Pentaxians -- On a whim, I thought I might try experimenting with a Hoya R72 filter plus my (unmodified) K1ii. I like the results from the couple of test images I have, but I'm curious what might have happened on this image:

You'll notice the dark band across the top. It was shot WITH the lens hood on and about 45-degrees left of the sun, if that matters (probably not ideal angle for getting a good IR effect). Any ideas on what might cause this?

Here's another test image that worked out much better, and was about 100-degrees left of the sun. The bright green leaves on the palm tree and bird of paradise plant responded quite nicely and I don't see any dark bands. I did not have the lens hood on for this image.

Both images were shot on the DFA*50mm lens at 30sec f/8. I put both images straight from raw into nik silver efex and made a slight contrast adjustment to darken the shadow areas a bit more.

**AstroDave** · 11-20-2023, 02:35 PM - **3 Likes**

Your first image also has some artifacts in that top darker band. Look sorta like a light leak (perhaps with some internal reflections as well to give it the curved arcs).

For this long exposure (30 seconds), did you have the viewfinder cover in place? If not, I wouldn't be surprised if some light got in via that route, which would NOT be attenuated by your IR filter.

**Aging Violinist** · 11-20-2023, 02:52 PM

Originally posted by AstroDave

Your first image also has some artifacts in that top darker band. Look sorta like a light leak (perhaps with some internal reflections as well to give it the curved arcs).

For this long exposure (30 seconds), did you have the viewfinder cover in place? If not, I wouldn't be surprised if some light got in via that route, which would NOT be attenuated by your IR filter.

Ahhh, I bet that might be it. I'll do some more experimenting with a covered viewfinder. I didn't even think of that. Thanks!

As for the curved arcs in the band, I wondered if maybe it was a stray reflection from the lens hood or maybe even the filter ring.

**pentaxus** · 11-20-2023, 07:36 PM - **1 Like**

If you don't have an eyepiece cover handy, cupping your hand and holding it close to the viewfinder without touching the camera works almost as well.

35mmfilmfan · 11-21-2023, 02:00 AM - **2 Likes**

Or the traditional standby - gaffer tape ! I always have a couple of strips wound round an old Kodak 35mm film can (currently re-purposed to carry Trebor Extra-Strong mints !).

(So I don't end up with a 'Minty' camera ! [Sorry !])

11-20-2023, 01:51 PM	#1
Aging Violinist Site Supporter Join Date: Jul 2023 Location: San Francisco Bay Area Photos: Albums Posts: 149	Strange Band in Test Image with R72 Filter Hello fellow Pentaxians -- On a whim, I thought I might try experimenting with a Hoya R72 filter plus my (unmodified) K1ii. I like the results from the couple of test images I have, but I'm curious what might have happened on this image: You'll notice the dark band across the top. It was shot WITH the lens hood on and about 45-degrees left of the sun, if that matters (probably not ideal angle for getting a good IR effect). Any ideas on what might cause this? Here's another test image that worked out much better, and was about 100-degrees left of the sun. The bright green leaves on the palm tree and bird of paradise plant responded quite nicely and I don't see any dark bands. I did not have the lens hood on for this image. Both images were shot on the DFA*50mm lens at 30sec f/8. I put both images straight from raw into nik silver efex and made a slight contrast adjustment to darken the shadow areas a bit more.

11-21-2023, 02:00 AM - 2 Likes	#5
35mmfilmfan Pentaxian Join Date: Oct 2016 Location: Norfolk, UK Posts: 3,943	Or the traditional standby - gaffer tape ! I always have a couple of strips wound round an old Kodak 35mm film can (currently re-purposed to carry Trebor Extra-Strong mints !). (So I don't end up with a 'Minty' camera ! [Sorry !]) Last edited by 35mmfilmfan; 11-21-2023 at 07:58 AM. Reason: pathetic joke added

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11-20-2023, 02:35 PM - 3 Likes	#2
AstroDave Loyal Site Supporter Join Date: May 2007 Location: Flagstaff, Arizona Posts: 1,543	Your first image also has some artifacts in that top darker band. Look sorta like a light leak (perhaps with some internal reflections as well to give it the curved arcs). For this long exposure (30 seconds), did you have the viewfinder cover in place? If not, I wouldn't be surprised if some light got in via that route, which would NOT be attenuated by your IR filter.

11-20-2023, 02:52 PM	#3
Aging Violinist Site Supporter Join Date: Jul 2023 Location: San Francisco Bay Area Photos: Albums Posts: 149 Original Poster	Originally posted by AstroDave Your first image also has some artifacts in that top darker band. Look sorta like a light leak (perhaps with some internal reflections as well to give it the curved arcs). For this long exposure (30 seconds), did you have the viewfinder cover in place? If not, I wouldn't be surprised if some light got in via that route, which would NOT be attenuated by your IR filter. Ahhh, I bet that might be it. I'll do some more experimenting with a covered viewfinder. I didn't even think of that. Thanks! As for the curved arcs in the band, I wondered if maybe it was a stray reflection from the lens hood or maybe even the filter ring.

11-20-2023, 07:36 PM - 1 Like	#4
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,286	If you don't have an eyepiece cover handy, cupping your hand and holding it close to the viewfinder without touching the camera works almost as well.

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