Hello!

[mha42]

I'm Mikael

 

I live in Sweden and am a full time IT security consultant. On my spare time I have an interest for photography.

 

Since a couple of years back I've been interested in IR photography and have explored it and different filters / modifications. I even successfully converted a Nikon D60 to a 590nm IR camera.

 

In last year I won a Nikon CoolPix A (16Mp APS-C sensor, same as the D7000, fixed 17.5mm f/2.8mm lens). I sent it in to LifePixel for a full spectrum conversion and have collected the arsenal of filters, and now since just a few days back an UV pass filter from uvirphotography.

 

As I didn't know what lens properties I could expect on the fixed lens as for UV transmission rates it has been a bit of touch and go. And I have yet to start investigating it's potential.

 

I realize some of you use the UV-Nikkor 105mm which is the stuff to use, and I can probably not expect this setup to perform as well on the budget. It's a stellar IR performer, however UV seems to be a different ball game. :-)

 

So, as for a summary I thought I'd share the first UV photo taken with the setup. It's of a dandelion in direct sunlight.

 

17.5mm f/2.8 ISO 6400;

 

 

Cheers!

 

/Mikael

[nfoto]

Welcome to you and your dandelion-capable camera (!).

[colinbm]

Welcome aboard Mikael

Yes UV is a whole different ball game to IR, that is for sure.

What filters did you get from uvirphotography (where are they) & which did you use for this photo please ?

Cheers

Col

[Andrea B.]

Hello Mikael and welcome to UVP.

 

It is cool to see your converted Coolpix A !! I have that camera for a walkaround and have thoroughly enjoyed its capabilities. How nice to see that it is convertible and useable as an UV/IR cam.

 

You have indeed captured the dandelion bullseye. However, it does not appear to be as quite as dark as would be with a filter like the Baader-U. So I would like to know which UV-Pass filter you were using as that may explain the appearance?? Also, at ISO 6400, what was the shutter speed on that shot?

 

I think that a converted Coolpix A would be a great UV/IR "street" cam. So I hope to see some non-floral photographs in our UV Open Informal area.

[mha42]

Hey guys! What a warm welcome :-)

 

So first off an apology, that shot was at ISO1100 @ 1/15s 18.5mm. Just had the photo and none of the EXIF data available at work! Ohwell. :-) Had a couple of others taken at ISO 6400 at the same time, hence the confusion.

 

Filter

 

The filter purchased was the LUV U-2 H (available @ http://cgi.ebay.com/...em=291016379234). The LUV U-2 version was supposedly UG11 + S8612. I received a U-340 + S8612 (unverified) as separate 46mm filters. According to the seller it should have a combined frequency response of 315-395nm with a peak transmission at 359nm.

 

It seemed like a more economical alternative to the Baader-U ($359 vs $219). But it has lower transmission rates giving a longer shutter time. Foremost I did not even know what the transmission level for my built in lens would be like for UV.

 

 

Performance

 

I do find that over all transmission rates seem poor. As you guys say, UV is a different game. On a clear sunny day the camera will want to go up to ISO 1000 - 2400 at 1/15s. At 1/50s+ it will almost certainly default at ISO 6400 for a direct sun lit subject. This might be normal for UV photography? It however to me seems unusable for a good carry around/street camera for UV.

 

As for the coloring; as I understand it the shorter the wavelengths passed to the sensor, the more obvious the variations in coloring of flowers? Might it be that the dark portions not being as visible is due to lens transmission specs rather than the UV-pass filter? Does it sound likely?

 

 

Input

 

I would like to get your input on to how to "on the cheap" measure transmission rates?

 

I've tried to light up scenes in the best way I could think of, which was one of those CFL bulbs producing UV light. However, this light source did not seem to spread a whole lot and it seemed quite narrow frequency. I can use natural light, but would like to have some concrete test scenarios.

 

I've tried putting a 340BP10 filter on top of the UV filter. But it only shows up as a black spot during daylight. No color response. Then again I might not do it right or have incorrect exposures / conditions. Realizing the filter having a top transmission rate at 359nm 340 might have been a bit too optimistic?

 

 

Samples

 

Another sample taken at the date. ISO 6400, f/2.8, 1/25s:

 

 

The UV CFL light. ISO 100, f/2.8, 1/25s:

 

 

[nfoto]

Here is what a typical Wood Anemone (Anemone nemorosa) tends to look like in UV (D40X, UV-Nikkor 105, Baader U2 ("Venus") filter, Broncolor studio flash with uncoated xenon tube).

 

 

Based on this, I think it's likely your image has significant IR contamination. You need to raise the UV:IR ratio of the illumination.

[mha42]

Here is what a typical Wood Anemone (Anemone nemorosa) tends to look like in UV (D40X, UV-Nikkor 105, Baader U2 ("Venus") filter, Broncolor studio flash with uncoated xenon tube).

 

Based on this, I think it's likely your image has significant IR contamination. You need to raise the UV:IR ratio of the illumination.

 

That actually looks like an exquisite sample photo of one

 

Unfortunately the S8612 is the best suppressant I have. But I'll try some other stuff.

 

If I would like to pursue a custom light source (i.e. flash) on a budget, what would I be looking at? I see that the flash equipment mentioned above is pricey. :-) I know that pricing seem to be something hard to compromise on when it comes to UV photography. I'd also be open to other types of custom / cast lighting. Still keeping in mind that the Coolpix A lens may not even allow for a better UV transmission all in all.

[Alex H]

To see how much infrared contamination you get with your system, take two identical pictures:

1 - with LUV U-2 filter

2 - with LUV U-2 filter and one of the inftated filters you have (stacked)

Than compare the exposures of both shots.

[mha42]

Took some sample photos today.

 

Full spectrum (no filter). ISO 100, 1/2000s, f/7.1

 

http://mha42.smugmug.com/photos/i-QxTBwrT/1/X3/i-QxTBwrT-X3.jpg

 

http://mha42.smugmug.com/photos/i-3LkZVTJ/0/XL/i-3LkZVTJ-XL.jpg

 

 

 

Hoya U-340 Only (UV+IR). ISO 100, 1/160s, f/7.1

 

http://mha42.smugmug.com/photos/i-DcD4md3/1/X3/i-DcD4md3-X3.jpg

 

http://mha42.smugmug.com/photos/i-BnDs7c9/0/X2/i-BnDs7c9-X2.jpg

 

 

U-340 + S8612 (UV only). ISO 100, 6s, f/7.1:

 

http://mha42.smugmug.com/photos/i-fMd6nrH/1/X3/i-fMd6nrH-X3.jpg

 

http://mha42.smugmug.com/photos/i-8R2TDMZ/0/X2/i-8R2TDMZ-X2.jpg

 

 

 

U-340 + S8612 + Heliopan IR695nm (IR leakage test). ISO 100, 6s, f/7.1:

 

http://mha42.smugmug.com/photos/i-mNPwD3s/0/X3/i-mNPwD3s-X3.jpg

 

 

Same as above but 30s:

 

http://mha42.smugmug.com/photos/i-hBkpNmL/0/X3/i-hBkpNmL-X3.jpg

[nfoto]

You should repeat with a Baader U2(Venus) filter. That'll should block more IR.

 

There is no doubt you have to combat a massive IR contamination, thus getting "scientific" UV photography may be a move to far with your modified camera. However, and happily for all of us, there are many worlds outside the domain of documentary scientific photography.

[colinbm]

This camera appears to be giving an unusually pleasant response to what I am used to seeing with UV photography.

The 'full spectrum' photos are NOT showing classic IR responses......the green vegetation is still green ?

The 'full spectrum' photos are showing some UV response, but non of the classic IR, taking over.......why ?

I am rather liking the UV output & not seeing the strong IR pollution that is a bother.

It will be very interesting to see what the Baader U2 can output on this camera

[nfoto]

Another alternative is using the B+W 403 filter (on any broad-band camera). While this filter mainly will show IR, some UV does mix in as well. Plus you get the desirable blue skies without any later channel swapping

[mha42]

You should repeat with a Baader U2(Venus) filter. That'll should block more IR.

 

There is no doubt you have to combat a massive IR contamination, thus getting "scientific" UV photography may be a move to far with your modified camera. However, and happily for all of us, there are many worlds outside the domain of documentary scientific photography.

 

I wish I had access to a Baader-U2 filter. This would have eased my decision for even getting an UV-pass filter to begin with. The main thing I did not know was the sensitivity of my camera. Ultimately I took the chance and would just see what gives.

 

I do however believe that the degree of IR contamination (see the 6s shots) is not the cause but rather that the lens of my camera (which is not interchangeable) simply does not transmit the shorter wavelengths desired. I'm though open to input to prove / disprove this. :-) If I can improve quality with existing equipment I'd be all for it.

 

 

Another alternative is using the B+W 403 filter (on any broad-band camera). While this filter mainly will show IR, some UV does mix in as well. Plus you get the desirable blue skies without any later channel swapping

 

Yep! I've got a Tiffen 47B filter for dual bandpass IR today. It'd be interesting to compare them to the B+W 403 aswell.

 

Some sample shots with these filters below.

 

Full spectrum (ISO 100, f/7.1, 1/100s):

 

#1

 

http://mha42.smugmug.com/photos/i-BnFxxNc/1/L/i-BnFxxNc-L.jpg

 

 

http://mha42.smugmug.com/photos/i-VRZggXJ/1/L/i-VRZggXJ-L.jpg

 

 

#2

 

http://mha42.smugmug.com/photos/i-TGVgNN3/0/L/i-TGVgNN3-L.jpg

 

http://mha42.smugmug.com/photos/i-zvggZg8/0/L/i-zvggZg8-L.jpg

 

 

 

U-340 (UV + IR). ISO 100, f/7.1, 1/15s:

 

#1

 

http://mha42.smugmug.com/photos/i-6cPtktM/0/L/i-6cPtktM-L.jpg

 

http://mha42.smugmug.com/photos/i-3vdZjvV/0/XL/i-3vdZjvV-XL.jpg

 

#2

 

http://mha42.smugmug.com/photos/i-tXmH3GH/0/L/i-tXmH3GH-L.jpg

 

http://mha42.smugmug.com/photos/i-xt4vrmX/0/L/i-xt4vrmX-L.jpg

 

 

 

Tiffen 47B (UV + Blue + IR). ISO 100, f/7.1, 1/100s:

 

#1

 

http://mha42.smugmug.com/photos/i-gSB7mHc/0/L/i-gSB7mHc-L.jpg

 

http://mha42.smugmug.com/photos/i-kBhs3b8/0/XL/i-kBhs3b8-XL.jpg

 

#2

 

http://mha42.smugmug.com/photos/i-K7D9wwk/0/L/i-K7D9wwk-L.jpg

 

http://mha42.smugmug.com/photos/i-ZJShNk4/0/L/i-ZJShNk4-L.jpg

 

 

 

 

This camera appears to be giving an unusually pleasant response to what I am used to seeing with UV photography.

The 'full spectrum' photos are NOT showing classic IR responses......the green vegetation is still green ?

The 'full spectrum' photos are showing some UV response, but non of the classic IR, taking over.......why ?

I am rather liking the UV output & not seeing the strong IR pollution that is a bother.

It will be very interesting to see what the Baader U2 can output on this camera

 

I'm glad to hear about the UV response :) Though it seems a bit limited to depth of frequencies :/ But it's probably to be expected.

 

I agree with you that the IR is not permitted to overwhelm this camera's frequency response in nature shots. Which is neat :)

 

I would though presume that the full spectrum does not reflect a lot of the UV frequencies. Mostly because the shutter speeds need to be so extremely increased so a shot in full spectrum representing 1/2000s is 6s (!) in UV only transmitted light with same ISO and aperture. But sure, some will probably leak through.

 

I'll look into my options for getting a Baader U2 for borrow and see what it'll output :)

 

Check out the dual bandpass & full spectrum shots above.

 

Cheers guys!

[nfoto]

"a shot in full spectrum representing 1/2000s is 6s (!) in UV only transmitted light with same ISO and aperture."

 

Approx. 13.5 EV difference indicates a substandard UV performance for the system indeed. The best UV lenses might manage 6-8 EV depending on motif and scene illumination.

[mha42]

"a shot in full spectrum representing 1/2000s is 6s (!) in UV only transmitted light with same ISO and aperture."

 

Approx. 13.5 EV difference indicates a substandard UV performance for the system indeed. The best UV lenses might manage 6-8 EV depending on motif and scene illumination.

 

Guess I'll be stuck to my tripod

[nfoto]

I can - under the best of conditions - easily do hand-held UV video with my broad-band Panasonic GH-2. Just to indicate the range of opportunities available. Hand-held shooting for UV stills are also possible say with the D3200/Baader U2.To cool expectations, I'm using either a Coastal Optics 60 mm f/4 APO or one of my UV-Nikkors for these assignments. Non-specialised lenses will cost you a couple of EVs extra so tripod is mandatory and UV video becomes difficult, although not impossible.

[mha42]

I can - under the best of conditions - easily do hand-held UV video with my broad-band Panasonic GH-2. Just to indicate the range of opportunities available. Hand-held shooting for UV stills are also possible say with the D3200/Baader U2.To cool expectations, I'm using either a Coastal Optics 60 mm f/4 APO or one of my UV-Nikkors for these assignments. Non-specialised lenses will cost you a couple of EVs extra so tripod is mandatory and UV video becomes difficult, although not impossible.

 

Yeah. The difference between your houses and mine is that the CoolPix A does not have interchangeable lenses. I'm stuck with the glass provided. :) Otherwise I would definitely look at look at some UV-optimized lens.

 

http://www.dpreview.com/reviews/nikon-coolpix-a/images/Handling.jpg

 

I won the camera on a Nikon NPS competition and decided to convert it.

 

It's otherwise a quite cool camera. APS-C sensor, same as the D7000, in an extremely compact format. The first one LifePixel had a chance to convert

[Andrea B.]

The 'full spectrum' photos are NOT showing classic IR responses......the green vegetation is still green ?

The 'full spectrum' photos are showing some UV response, but non of the classic IR, taking over.......why ?

 

I disagree entirely. There is something like a 60-40% 52-44% IR-Visible response in that filterless photograph. And that's granting you a full 4% UV which is high. It is usually less.

 

The subsequent Hoya-340 shot is almost pure IR.

 

We need to review the composition of sunlight. You really cannot shoot "full spectrum" simply by removing internal blocking filters.

[colinbm]

The best example of our current digital cameras responses to Sunlight on Earth is in this graph.

http://upload.wikime...on_Spectrum.png

 

 

Our digital cameras are sensitive to Sunlight reaching Earth at about the 0.6 level (my pink line).

If we want a wider response we need to go to a very high location or use a different technology.

Most of the absorption of Sunlight in Earth's atmosphere are the O2, O3 & H2O molecules.

Most of the harmful UV rays are absorbed by the atmosphere, otherwise there would be no life on Earth as we know it !

Col

 

I just found another graph showing the absorption molecules.

http://commons.wikim..._irradiance.jpg

 

[mha42]

Neat graphs colinbm! Makes perfect sense. :)