Strange Hoya U-340 effect at UV index 11

[lukaszgryglicki]

I did a 11 mile walk today in Paradise Valley, Arizona - extreme UV index 11 (I'm on business conference for 1 week).

Gear Nikon D600 FS (non debayered) - shooting RAWs with Nikkor 50/1.8 AF-D - all handheld:

- No filter.

- Hoya 720 nm filter.

- Hoya UV/IR cut filter

- AndreaU

- SEU

- Hoya U-340.

 

All looked as expected - except the last Hoya U-340 - it has IR leaks which is known to me, so I just assumed I'll shoot for a try - see what happens - I have no S8612 filter with 52mm (and I wanted light setup so I took all my 52mm filters and single Nikkor 50/1.8 AF-D from Poland to USA).

 

Usually that Hoya U-340 was not usable without S8612 - IR leaks - but today ? due to high UV index ? seems like UV and IR recorded just about the same amount of light, so effects were KILLING. When I switched to manual focus I saw that I can focus almost everything twice - once for UV (IR creates blur then) and once for IR (UV creates blur then).

This is the photo that was recorded (I need to retry this tomorrow because it wasn't obvious when shhoting - I see this when postprocessing files now):

When I shoot photos as JPEG (so camera records anything) I default to monochrome - otherwise everything is all pink - so I include JPG (mono) and JPG from RAW that is just auto-white-balanced via: *dcraw -v -H 1 -a -T -q 3 "$1"* and then processed by my own *jpeg* toool:

 

 

 

[colinbm]

Interesting effects.

[lukaszgryglicki]

Like double focus - is my (guessed) explaination correct in your opinion? I'll research this tomorrow - but unfortunatelly very time-limited (especially around noon) - The Linux Foundation confernece.

[Nate]

I noticed this too in one of my experimental stacks last year, I think it was the kolari v1 hotmirror and a zwb1. I searched my drive for the photo, but couldn't locate. I figured the same was happening as you described. It was kinda cool, but I thought of it as a fail stack as I was so new and just looking for UV only.

 

[Andy Perrin]

The blur situation is observable even with visible and IR. A few years ago I posted a picture to the forum taken at night with multiple light sources. The objects in the photo in visible light were sharp, but the objects illuminated with mainly infrared were extremely blurry! That’s what focal shift looks like when you have very widely separated spectrums in the same picture. 

[Andrea B.]

I did a 11 mile walk today in Paradise Valley, Arizona.

 

Wow!! Good for you!

But be careful out there in the that arid, hot place. Always carry water when hiking. Wear a hat!! 

 

I hope you are enjoying your time in Arizona. I used to live in Tucson, Az.

 

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I agree with Andy that this kind of mixed light can cause the aberration. The Nikon 50/1.8 can't focus both the long IR and the short UV passed by the dual bandpass U-340. You might try playing around with the chromatic aberration tools to see if that improves the blurred edges.

 

There's more UV in sunlight at higher altitudes. Although Paradise Valley is not particularly high at about 1300 ft (395 meters), it might be higher than normal for your usual UV photos? Also the UV is increasing at this time of year as we get closer to the summer solstice.