Light

[Tim Welting]

Frank, did you already made a list of all the possibilities proposed here?
Lots of variables so to see.
I also think that LED light might, in some cases,  give some non-natural appearance.
Incandescent or halogen seems to be used the most.

T

[Fred Kruijen]

Surely you can make beautiful pictures with all these kinds of light sources. More important is the amount of light, the light angle, indirect light, etc. etc.
Is use always light dimmers. Changing colors is no problem, you can change the white balance on your camera within seconds.
I think lots of pictures are ruined by an overkill of light. What's the problem if you have an exposure time of 1 second (or more) ?

Fred.

[Frank de Wit]

Fred is correct.
But in an attempt to be perfect (I have the psychological disorder that I try to do things perfect :) I rather start right instead of correcting whitebalance afterwars and/or software correcting reflections afterwards. Although setting whitebalance for every shot is no problem too if the result equals Fred's quality

To do so, I have now finished my light setup with
-four movable arms (to flexible direct angle of light in all directions)
-with 20W/230V halogen lamps giving 4.200 Kelvin light (almost daylight temperature)
-with multiple diffusors (to minimize flare/reflections and to 'dim' the light) on flexible arms
  (the diffusor plastic (cut placemats) blocks heat and does not seem to alter colorT)
-and with multiple 'mirror-aluminium' reflectors to indirectly aim light on flexible arms
(and we should not forget that light needed to photograph micro crystals on micromounts is something different then the light needed to photograph 1:1 large pieces)

:)F

@Krizu, Ich habe der Verkaufer uber der Glass-coating gefragt, aber das wusste er nicht, so das wird eine uberraschung sein

[Amir Akhavan]

I'm with Fred on that a long exposure time is a benefit for the photo and doesn't bleach your specimen.
I only need enough light to see something myself while adjusting the lamps.

But you might want to calibrate your camera (that's very difficult), and that includes taking into account the light used and then you would not vary the temperature of the light source too much.
If you are really that pedantic.

It is much easier and much more important to calibrate your monitor.
Otherwise you will just do crazy things to the color without knowing it (others will notice, though).
However meticulously you design your setup and workflow, you will feel the desire to fix the colors in some photos, some specimen apparently misbehave - actually in most cases it is the camera sensor that does not mimic the behavior of the retina perfectly.
Do you remember the pink camp fire in some cameras at the last Strahlen.org meeting? Probably just a infrared filter missing in the cheap cameras, but you get the point. White balance does not help here.
A calibrated monitor helps.

Other than that, the description of your setup sounds almost like mine, Frank.
Don't forget to put the power switches before the lamps within the reach of your hands so you can turn them on and off individually and see how much each of them contributes to the overall illumination.

Cheers
Amir

[Stefan Örtel]

I would not make white balance on the camera as you loosing informations in doing that. Save pics in RAW and let the software do it....

I discussed monitor calibration with Luxurbex some time ago, he is using http://www.datacolor.eu/de/produkte/monitor-kalibrierung/spyder3pro/index.html to do this, and his pic are outstanding.....

Cheers
Stefan

[Amir Akhavan]

True.

I would never do the white balance computation / conversion in the camera,
I do it in external software and of course save in RAW, just as you say, and convert to 16bit TIFs for image manipulations.
But it is a good idea to have a white balance setting in the camera that fits the light setup.

Cheers
Amir

[Frank de Wit]

Don't forget to put the power switches before the lamps within the reach of your hands so you can turn them on and off individually and see how much each of them contributes to the overall illumination.

Done, see email

ps: calibrate this !
http://www.designboom.com/weblog/cat/16/view/8686/152-inch-plasma-tv-by-panasonic.html
I think I will link that TV to my remote live view camera to check mineral pictures before I click...

[Frank (Krizu) Mersch]

Hi there,

if I want to photograph handpieces etc I just put a small white piece of paper close to the piece.
It is easy to cut it out. But then it is easier to check the white balance.

The other problem is the color index of the light. I posted some light source spectras some times ago.
The number RA indicated the smothness of a spectra. A RA of an LED is low, because thier are only two band (blue and yellow red).
All black bodies light sources have levels higher than 98, flourescent light is depending on the normally first numer of the index (5 band vs. 3 band)

br

Frank

[Amir Akhavan]

Which gets me to think about the spectral fidelity of the camera sensors.
I remember that some of the problems with certain minerals (dioptase) are caused by sensors that have spectral sensitivity functions similar to the spectrum of LEDs or fluorescent lights.
In plain English: there are gaps in the sensitivity of the sensor elements (red, green, blue), and overall the sensor is not very sensitive to a particular wavelength or does weird computations to guess the real value.

If I got this right, that should not be too much of a problem as long as the spectral sensitivity function of each sensor element is still smooth and if there's sufficient overlap in sensitivity between the different elements.  Then you should be able to compensate just as one does white balance.
Real gaps should pose serious problems, though.

It should be easy to detect gaps in the spectral sensitivity by taking a photo of a spectrum projected by a prism.
I don't have a prism, maybe I should try to get one and see if there's a difference between the output of my DSLR and the output of my mobile phone camera.

It seems to be even more difficult than I have thought, as discussed on
http://www.dxomark.com/index.php/eng/Technologies/Measurement-definitions/Color-measurements

(how independent they really are I don't know)

But as Frank (de Wit) wants to do it right, he will use a brand new DSLR anyway. 
So color fidelity should be a minor problem.

[Frank de Wit]

I love your postings Amir :) and... what a coincidence, I ordered a prism 3 weeks ago! They're hard to get! I will receive it end of january and I'll shoot the spectrum then with my new DSLR
:)F

[Frank de Wit]

For 5.500 Kelvin daylight lamps (tip from Matteo and my neighbour who is restaurator)
see http://www.deffner-johann.de/ -> click left on "Restauro-Lampen und Leuchten" and then "Luxo Tageslicht-Arbeitsplatzleuchte"
(the site does not work in Google Chrome)

[Marko Burkhardt]

Hello!

I try to improve my lighting technique.
At the moment I use LEDs on flexible arms for my macro/micro-fotos.
I use transparent paper (German: "Butterbrotpapier) to get diffuse light. Is there any better solution? Perhaps something like this:
http://www.falcon-lighting.de/led_beleuchtungen_streuscheiben.html
??

Does anyone have experiences with lamps like these:
http://www.mediaresort.de/shop/de/STUDIO-EQUIPMENT/Ersatz-Lampen/Dauerlichtlampen/walimex-Spiral-Tageslichtlampe-35W-entspricht-200W.html
http://www.pearl.de/a-NC1255-1123.shtml

Marko

[Philip Mostmans]

I am currently using two OSRAM Dulux S 11W fluorescent lights which have a light of about 6000K mounted in 2 Novoflex flexible arms with fixture (http://www.novoflex.com/de/produkte/magicstudio/magicstudio-zubehoer/magicstudio-light/).

On my camera I use a custom WB which is a bit lower than the 6000K indicated for the lights.

Very happy with the results so far (colourwise)

Cheers!

Philip

[Florian Wrobel]

Hello all,

i will re-open this theme - i have some problems with the light for microphotos.
I tryed a lot in the last weeks with diffusers, inderect light ect. - but i´m not satisfied.
Is the distance between light source and diffuser - diffuser and micro imported? -
It is better to make a photo with a "lot of light" and a shorter exposure time (under 1 sec.) or it is better with longer exposure time (over 1 sec.?)
If i took a picture with longer exposer time i think my photos looks more "flat" and diffused. If i use more light the refections are too much ....

Sorry for the questions - here in south germany is  a rainy saturday and so i have much time to "tinker" on my photo equipment.


Greats Florian

Photo 1: too much reflections

[Florian Wrobel]

Photo 2: reflections better (could be better ) but photo to "flat"