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Multispectral banana

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#1 Hornblende

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Posted 09 January 2018 - 23:32

Greetings all,
Here is a multispectral banana, hope you enjoy :)

Canon 6D full spectrum + EL-Nikkor 80mm f/5.6

Visible 1/2"– 400 ISO – Baader UV/IR cut filter – Led light
Attached Image: IMG_0471s.jpg

UV – 4" – 100 ISO – Baader-U – Convoy S2+ 365nm
Attached Image: IMG_0474s.jpg

UVIVF – 2.5" – 1600 ISO – Baader UV/IR cut filter – Convoy S2+ 365nm with Baader-U
Attached Image: IMG_0476.jpg

UVIIRF – 30" – 1600 ISO – Lifepixel 830nm IR filter – Convoy S2+ 365nm with Baader-U
Attached Image: IMG_0482s.jpg

#2 Cadmium

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Posted 10 January 2018 - 01:08

I really like the UVIIRF shot! Kind of reminds me of an X-ray photo.

#3 Andy Perrin

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Posted 10 January 2018 - 01:25

The visible looks somewhat different than I'm used to (or the banana was overripe...). I admit, I'm not a regular banana eater, but I thought the middle was not as dark as shown here. Different variety than US bananas perhaps?

#4 Hornblende

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Posted 10 January 2018 - 01:27

Yes, UVIIRF images have a "watery" of "ghostly" apparence! The IR fluorescence here was veeery weak, I had to push the exposure to the max. I know Mark is using a different IR filter (720nm I think) for its UVIIRF pictures, the exposure is much faster and there is colors too!

Andy: I think all large banana fruits are the same variety. My banana was not overripe, maybe you are not used to look at a banana sliced that way? Plus there may be some surface oxidation!

Edited by Hornblende, 10 January 2018 - 13:46.


#5 Cadmium

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Posted 10 January 2018 - 01:51

Yes, faster, but keep in mind that when using 720nm filters the colors are borderline visual. You can easily see some red through a 720nm filter with your eyes.
In other words, it is a mix of visual and IR fluorescence. Looks nice, of course.
Going up to 850nm not only blocks any visible range mix, but also evens out the Bayer channels.
What you show is pure IR fluorescence, and no visual range mixed in.

Edited by Cadmium, 10 January 2018 - 03:05.


#6 Andrea B.

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Posted 10 January 2018 - 16:46

Nice work, Martin.
I love the blue banana fluorescence. I wonder what pigment or chemical in the banana is fluorescing?

I am a bit concerned in the last UVI-Infrared Fluor foto that you have picked up a bit of light leak? There are brighter areas on the right in the background than should perhaps be there?? Was there any ambient light in the room which might have affected the 30-second long exposure? Or any camera feature prone to light leak? For example, my Nikon D610 mod begins to leak a bit of light thru the upper LCD if the exposure is long enough. (Easily cured with some duct tape.)
Andrea G. Blum
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#7 Hornblende

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Posted 10 January 2018 - 18:37

Thanks Andrea.
You are right for the light leak in the UVIIRF. I don't have a perfecty dark room and even with a black fabric over my setup I could still see some street light leaking through my curtains. Thus it is not "true" UVIIRF (maybe 90%). I need to find a way to be in complet darkness for my next shots.

Edited by Hornblende, 10 January 2018 - 18:37.


#8 Andrea B.

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Posted 10 January 2018 - 18:47

Yeah, I've had this happen also! I think there is no ambient light and then my foto proves that wrong. I had a phone light corrupt some shots. Didn't realize the tiny light could do that.

If you have an old cardboard box of sufficient size, it can make a decent enough light box (or should I say light-blocking box) when turned on its side. Drape the cloth or a thick towel over the open end of the box and the camera and you probably will achieve a sufficient block of the street light. A couple of test shots into the box (with no subject) will tell the tale.

A sheet of foam paper from the craft store can be used inside the box as a backdrop. Usually a light or medium grey is best. The white foam paper sometimes is a bit fluorescy.
Andrea G. Blum
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#9 Mark

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Posted 12 January 2018 - 16:21

I really like the UV image. And, I can't believe I haven't thought to slice a banana this way (for photographing...)! (I might still try it ;))

#10 Andrea B.

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Posted 12 January 2018 - 21:41

The banana is a very famous inner and outer fluorescence subject. Shows up in the literature here and there.
Quite an unearthly glow, isn't it?

Mark, here is something to be on the lookout for - a dragon fruit (pitaya). It is way weird. I'm kicking myself for not buying the one I saw, but we had our hands full with holiday events and I didn't think I could get to it. I saw it in an Italian market, but it might be also found in a Thai market or Thai grocery store (in the Northeast, anyway).
https://en.wikipedia.org/wiki/Pitaya
Andrea G. Blum
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#11 Mark

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Posted 15 January 2018 - 00:54

Andrea - I have seen these, and I tried one once. I didn't find it all that tasty - maybe with such a name I was expecting something more dramatic. Its been some time since I've seen them in the local markets, but then, I haven't been to a Thai market for quite a while. I forgot how they tend to have unusual offerings. I'll have to make it a point to do some 'unusual' food shopping soon. Thanks for the reminder (and the idea).

#12 Andy Perrin

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Posted 15 January 2018 - 02:59

Mark, while you're doing that, I was searching the site and I don't think anyone has done cauliflower! We are missing a few standard veggies too, never mind the unusuals.