[UV, VIS, NIR] Show the camera sensitivity for UV and IR easily

A have often been asked how one could esily see how deep a converted camera body reaches into UV and/or IR. Using a UV sensitive camera and a special transmission grating, this can indeed be done using two different lightsources, a tungsten lamp and a continuous Xenon lamp.

[click on image to see a larger one]

TUNGSTEN lamp:


top: unfiltered
middle: Baader UV/IR Cut filter
bottom: 695LP long pass filter

XENON lamp:


top: unfiltered
middle1: Baader UV/IR Cut filter
middle2: Baader U2 filter
bottom: 695LP long pass filter

I had previously made a similar test and used some astronomers software (RSpec) to calibrate the results, so here for reference the Xenon spectra (1 Angstrom = 10 nm):


So, that transmission grating I used was not very well suited as it stops working around 360-370nm already, as it is on a normal glass substrate. Maybe I get a better one and repeat the tests sometime...

Be aware that the result does not reflect the absolute sensitivity of the camera sensor, but if using a Xenon source whose spectra is very close to bright noon sunlight (UV and VIs, less so in IR), gives an indication of what to expect when shooting outdoors.

It also reveals, why from 800-850nm onwards only monochrome results in IR can be expected, as all sensor dyes making up the RGB Bayer pattern get transparent.

Another remark: be aware that these spectra are always taken in a way to get them properly exposed, not too high and not too low, so the brightest parts of the spectra determine what is recorded. If only IR or UV is intended, it would be better to shoot through that UV or IR filter and expose these shots accordingly, as in the UV-IR spectra those parts will easily getting lost as they are several stops beyond the visible usually - in case of UV sometimes 8-10 stops!


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

[UV] Valentine's Day Flower Bouquet

A Valentine's Day flower bouquet - so here it is as it looks like in reflected ultraviolet light. It was shot using my UV sensitive camera and a special, high UV transmitting lens. Filter used for the UV shot was the 2" Baader-U filter and a modified high power Xenon flash was the light source used.

[click on image to see a larger one]

These UV image here also uses my standardized false UV color normal + high intensity palette:






I found it quite interesting how detailed the flower structures are rendered using that lens that reaches down to about 300nm, quite rare actually. That same lens was also used for the primrose shots I have published about earlier

So I wish everyone a belated Happy Valentine's Day!

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

[UV] BBC How to Grow a Planet - The Hidden World of UV (III)

I had previously announced here my contribution to the BBC2 new three episode series "How to Grow a Planet" (renamed from "Green Planet") which will be presented by Professor Iain Stewart.

So Episode 2 "The Power of Flowers" will be broadcast at 9pm GMT on BBC2 (and BBC HD) on Tuesdays 14 February 2012 in the UK (and the following Friday in Scotland at the same time) and a bit later will also be visible through BBC's iPlayer.



Beware: It is only permissible to play this clip, if you are located in England, Scotland or Ireland

Stay tuned, more will follow on that fascinating subject...


More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

[UV] White Primrose (Primula) in deep ultraviolet light

When I passed by my friends' flower shop and saw he had some primroses (primulas), I wanted to see, if there would be some UV structure visible if shot in reflected ultraviolet light. This one is a bread form, all white and filled.

[click on image to see a larger one]

These UV images here also uses my standardized false UV color normal + high intensity palette:



Well and indeed there gets something visible...

VIS:

UV:


Now I was wondering about the contribution of the shorter wave, deeper UV sub-bands (as I call them). Here the results of using the plain Baader U2 filter (left) versus that same filter stacked with a filter that cuts all below 360nm, but passes all above (right)



It gets pretty obvious, that these shorter UV wavelengths are able to differentiate and make more structures visible. Here the red and especially green channel response play an important role.


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

[UV] BBC Green Planet Series - The Science of Plants - How to Grow a Planet (II)

I had previously announced here my contribution to the BBC2 new three episode series "How to Grow a Planet" (renamed from "Green Planet") which will be presented by Professor Iain Stewart.

It has now been published that the series will be broadcast at 9pm GMT on BBC2 (and BBC HD) on Tuesdays 7, 14 and 21 February 2012 in the UK (and the following Friday in Scotland at the same time) and a bit later will also be visible through BBC's iPlayer.

The official BBC episode list is here with previews and my part will be shown in episode 2 on Feb 14, 9pm GMT.

This is the official broadcast card:


Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos

[UV, VIS, IR] Lyman Alpha deep UV lenses

Well, an old collectors rule is "everything comes to him who can wait" - that it would be 16 years from when I first learned about that lens and personally had contact with its inventor Richard Nye, I had not really expected.

Now a few days ago I was able to acquire three prototypes of those lenses, made 1992, which came from the estate of the inventor, Richard Nye, who has passed in 2007, then 77 years old. His company, Nye Optical, La Mesa CA, unfortunately does not exist anymore.

So, the scientific lenses he invented and custom made were for deep UV recording (capable to work beyond 200nm, especially made to record the 121nm Lyman alpha lines, hence the name - only in vacuum or nitrogen atmosphere of course), but having no chromatic aberration also in VIS and IR. It is a catoptric (reflex) Cassegrain design, which came in f2.8/200mm and f1.1/90mm versions for full format cameras (43mm image circle), but also for intensifier tubes and video cameras (25mm image circle), with focusing from 250mm to infinity and some adjustable 50mm resp. 18mm back focal length.

[click on image to see a larger one]



Inside the aluminum housing resides an about 25mm (1") thick quartz (ZERODUR most likely) mirror block, front aluminized plus a secondary mirror (most likely made of the same material) held by an adjustable metal "spider" in front of that first one. Quite built like a small 90mm diameter Cassegrain astronomical telescope.

DOF at one (1) meter (3ft) is as thin as a razor blade when using the Lyman Alpha f1.1/90mm lens and that doughnut shaped bokeh etc. makes it fun to use. So here a first visible light shot:



Additionally a short test video I shot using that lens:


which shows its dreamlike/surreal/ethereal rendering of images.

Stay tuned, more will follow on that fascinating subject...

More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos