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Mineral PhotographyHigh-power, high CRI LED lightning
15th Jan 2017 17:05 UTCJyrki Autio Expert
I see an advantage of getting lot of light on budget and possibility to get the light source close to the sample.
Any experiences on LED-lightning?
15th Jan 2017 19:37 UTCTony Peterson Expert
15th Jan 2017 19:48 UTCJyrki Autio Expert
http://www.yujiintl.com/high-cri-led-lighting
15th Jan 2017 19:50 UTCReiner Mielke Expert
16th Jan 2017 16:24 UTCJyrki Autio Expert
Yuji
Cree
Nichia Ra 90
16th Jan 2017 17:24 UTCRonald J. Pellar Expert
16th Jan 2017 17:50 UTCJeff Weissman Expert
17th Jan 2017 17:17 UTCJyrki Autio Expert
17th Jan 2017 18:40 UTCRonald J. Pellar Expert
17th Jan 2017 19:14 UTCJyrki Autio Expert
17th Jan 2017 23:28 UTCRonald J. Pellar Expert
18th Jan 2017 03:58 UTCTony Peterson Expert
18th Jan 2017 12:40 UTCRonnie Van Dommelen 🌟 Manager
Diagram of the problem:
http://cdn.digital-photo-secrets.com/images/color-space-cmyk-compare.jpg
18th Jan 2017 14:15 UTCVolker Betz 🌟 Expert
I was a bit absent from internet for a few days. So my late comments. I switched from halogen lights to LED-lights a few years ago.
At present my experience is, that LED ( I use now mostly 5500 K versions) and control colour in life view with colour calibrated monitors works fine.
The colour of crystals is not as simple as that from "normal" pigments as luminescense (the alexandrite effect) can vary colour, also plechroism is present.
My experineces with LED are fine, but the secret is the post processing. Pictures from dioptase can be set to any hue you want, if not to many other colours are present. The tools color-balance, saturation an spectral sensitivity are very powerful. I mostly do that with helicon filter.
I wrote a paper about the subject in two parts. The first was was printed in Lapis 12/2016 and the second will be in Lapis 2/2017.
Sorry, it´´s in German.
And by the way: Ronnie hit the most important point: if the crystals show colours outside the colour space then only a fifth colour additional to cmyk can help (in printing).
Volker
18th Jan 2017 14:57 UTCLarry Eicher
Regards,
Larry
18th Jan 2017 15:13 UTCRonnie Van Dommelen 🌟 Manager
It's hard to know what the lighting will be like on a specimen with flashes. You want to reflect light off crystals to highlight shape, striations, transparency, etc and thus you need either many lights or a few lights and reflectors. I've seen professionals use very high end flashes that output a low level constant light that is used during lighting composition (i.e. flash and reflector placement), but without that you are in-the-dark so-to-speak.
18th Jan 2017 15:30 UTCJyrki Autio Expert
If we take above diopside as an example: It is mixed with calcite which should be white. Any odd color in calcite would be discernible. There are no clear areas of diopside and calcite because they are randomly mixed.
How difficult it is post process this?
18th Jan 2017 20:25 UTCRonald J. Pellar Expert
1) Colors outside the RGB and/or CMYK locus are referred to as "out-of-gamut" colors.
2) The out-of-gamut colors cannot be reproduced exactly in staturation and/or brightness.
3) Out-of-gamut colors can be matched exactly in hue.
4) White balance affects hue only.
5) The dioptase problem is minimized by proper hue rendition.
5) "Alexandrite" effect is related to the color temperature and spectral content of the light source as well as the spectral content of the minerals spectral reflectance characteristics.
6) Full spectrum light sources and proper white balance are two way to remove some of the color rendition problems. LEDs, with their large gap in the blue-green are a real problem for some mineral rendition. There are some new LEDs that use a UV LED and a better assortment of phosphors and should provide better CRI numbers, e.g., 95 or above, and offer more hope for the photographer. Until these are more readily available I would recommend tungsten or tungsten-halogen.
7) Selective hue adjustment in photos can be done with masking techniques to affect the mineral that needs hue adjustment without affecting the other minerals on the specimen. Very diverse specimens are a real problem (pain) to create the masks, but who said mineral photography was easy? :-D
19th Jan 2017 14:11 UTCRonnie Van Dommelen 🌟 Manager
Thanks for that clear explanation! Especially #1-4; I didn't know that. So, in other words, we can match the hue exactly, just not the saturation of the green? So a specimen in the hand will look richer (more saturated) in color than a photo of the specimen.
19th Jan 2017 15:58 UTCJyrki Autio Expert
In my pictures there has always been something wrong with color of almandine-pyrope garnets (red-violet). That color seems not to be that far out of gamut so the explanation might be something else than with color of dioptase.
19th Jan 2017 17:48 UTCRonald J. Pellar Expert
Jyrki, the two biggest contributors to color problems are, in order, white balance and spectral quality of the light source. They can impact a mineral specimens in different ways, but hue errors seems to be the cause of most complaints. Fortunately hue can be corrected to match a given specimen, but you must be very careful to match "apples" with "apple", i.e., make sure that the color temperature of the light source used to look at the specimen is the same as the color temperature of the monitor image that you are trying to match and that extraneous light sources are not present to affect your eye's adaptation. The biggest problem in hue matching is keeping the other parts of the specimen from changing hue in a bad way while getting the main mineral correct.
19th Jan 2017 18:51 UTCJyrki Autio Expert
Here is one example:
When I found this garnet on a sunny spring afternoon I thought this must be the bluest garnet I have ever seen. It is from a metamorphic garnet and cordierite rich rock and most probably Mg-rich almandine.
However when photographed it turns out dull reddish purple, not vivid blueish purple seen in low sunlight. This is second or third take of this mineral I uploaded in Mindat but not a good one still.
So this difference in real life and picture is about both the spectral quality of light and eye adaptation to ambient light?
19th Jan 2017 19:06 UTCVolker Betz 🌟 Expert
as I use ( only LED) I find the benefits of new light architecture are supreior against some hue trouble with some problematic species like dioptase.. I may be a bit old fashioned but thre are two different goals. The one is the sceen picture in the rgb colour space and the other the CMYK + extra colour for printed pictures.
At present LED perfome well for mineral photography if all the "tricks" are used.
I used halogen light for alsmost 40 years and I also never made better pictures as now with LED.
Despite some arguments with lacks in spectral continuity.
So my hint: ist not the instrument, ist the skill and experience of the photorgrapher.
Volker
20th Jan 2017 13:07 UTCLarry Eicher
I thought that was part of learning to be a photographer. I suppose it is like the old film days when you had to intuit the exposure. I have been finding that I need reflectors. I want to highlight the crystal faces but not over expose them. I find that I need to lean toward underexposure and improve exposure in post processing. I have been trying a scrim between the subject and the flash which seems to help.
I am thinking of looking into LEDs on goose necks. WUSIWUG. I have a long way to go.
Regards,
Larry
20th Jan 2017 15:20 UTCJyrki Autio Expert
20th Jan 2017 16:45 UTCScott Rider
. So, I have looked into ordering some high CRI LED lighting, as I don't want to mess with tungsten (heat issues with my setup). I bought some LED bulbs with a CRI of >95. They weren't too expensive, but not too cheap either...
If I can remember, I'll post to this site whether those LEDs I ordered will be any good in the blue-green spectrum. I currently was using cheap fluorescent lighting (I am a newby in terms of photography and the box said daylight so I was suckered into that...) and was satisified with most my images of my specimens, less all the blue and green ones. They always come out more yellow on my current lighting setup...
I think I'll try to do both the prehnite, and Cavansite, another mineral I cannot reproduce on camera.... Cavansite is one of my favorite minerals and I cannot reproduce the colors unless I am outside, and it gets close there... But not with my controlled lighting setup... Its quite frustrating... But thanks to you all, I think these new bulbs will be great. I should get them hopefully by the end of this week.
THe CRI is supposidly 95 on the bulbs I bought... Looking into the research, those should cover the blue spectrum...
20th Jan 2017 18:30 UTCVolker Betz 🌟 Expert
I experimented with your almandine photo. I could get it more blue but only limited. Due to the white luster on the almandine crystal the possibilities to alter the hue are limited. I would recommend to use non reflecting spots from the side or a back light with 5500 K.
Then you see more the transmitted light than reflected light and the bluish hue is better visidible and can better adjusted.
Volker
20th Jan 2017 19:38 UTCJyrki Autio Expert
I'm glad you took time to think about my question. I will try again as suggested and compare it against natural lighting conditions after couple of months, when we have good light here up north. ;-)
Jyrki
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: March 28, 2024 20:49:00