Colour Temperature Meters + Digital Photography

Discussion in 'Lighting Equipment' started by chris_hardiker, Sep 6, 2006.

  1. Hi all, This is my first post on these message boards, though I have found it most useful in answering many questions. One question that has been asked before, but has not quite garnered the responses I need (or that I can see at least, this is a very vast archive...) is the use of Colour Temperature Meters in digital photography. So here are my questions: Firstly; several articles/snippets that I have been able to locate online in regeards to this topic have said not only does a colour temperature meter work, but is also suggested as a means of getting true data for digital photography. I have read that one must use the meter to measure the degrees Kelvin of a light source and then dial that number in on their DSLR. How is this done though? Do you not have to firstly enter the type of /film/ used (Tungsten/Daylight etc.) for a point of reference to which the meter will base it's results upon? Or does this only apply to the filter compensation aspect, and infact (for example the Minolta colour meter II) measures purely and seperatly the colour temperature without the need to enter any film type? With that said; does the data from the meter differ under the same light source when each respective film type is chosen? If one does have to enter a film type to garner the correct responce in degress Kelvin; what film type should be chosen for digital and how is that choice made? What I am basically asking for, in a "newbie" kind-of-way, is a simple step by step guide to using a colour meter with a DSLR. Also, I am mainly interested in the Minolta Colour Meter II. Can anyone shed some light in regeards to the Flash receptor unit and how that compares to the Minolta IIIF's flash capabilities? I have read opposing thoughts. It would be nice if it were as simple as metering, reading the data displayed in degrees Kelvin, and entering that manually into the camera for ambient/flash and both. Things are never that simple sadly. Thanks for your time, and I look forward to any responses! Chris P.S. - Sorry if this is in the wrong forum/catagory. If it is I would appreciate it if a moderator could move it as they see fit. Thanks!
     
  2. Colour meters are expensive. The way most photographers evaluate colour temperature when shooting RAW (you don't mention if you shoot RAW) is to take a picture of something neutral (a whibal card for example) that is in the same lighting as your subject then take a photo of the subject. Leave your WB on Auto when you do all this. Then when you get home open the picture of the neutral card and use the WB function of the RAW converter by clicking on the Neutral area. This will then make the image of the neutral card exactly neutral (with me so far!) then just copy the WB settings to your other image. I always carry a whibal with me and take a photo of it every couple of hours to keep in step with the changing daylight temperature. If it is partly cloudy I take one in cloud shadow and one in sunlight. I know I haven't exactly answered your question but when you can accurately get a WB temperature for a few quid instead of hundreds of pounds then it might be relevant. With normally Digital photography (landscapes, sport, portraits etc. a colour meter is more or less defunct. The only use is probably when you are in one lighting situation but you are taking photographs in another lighting situation (your in the dark at the back of a stadium and your subject is floodlit with sulphur lamps). But in this scenario you can always take the photograph and then when you are home WB a bit of white hording or an advertisement that has white or neutral grey in it, this will not be totally accurate but will normally good enough for most purposes.
     
  3. Chris, I'm one of the moderators here. Your question isn't strictly about lighting but my guess is that this is the best forum for it. Welcome to PN. I've used a Minolta colour meter for years, with transparency film, I'm not sure how it should be used with digital because I've never found it necessary - I too use a grey card as a reference point. The colour temperature meter gives a reading in mireds which is then used to select filters. A clumsy process IMO.
     
  4. Color meters are useful for people who worth with controlled or mixed lighting (like cinematographers). Digital SLRs can compensate for the color temperature after the fact, so you need not worry about taking measurements in general use.
     
  5. Thanks for your replies; they are grately appreciated. I'll get straight to the point. Steve: Grey cards are fine, but not always what I'm after. I'd rather have the data infront of me, then base my WB decisions when entering the degrees Kelvin. I want to spend very little time in post production as possible. I have a light meter to deal with exposure, which I find to be a very useful tool. I also find grey cards a little cumbersome and time consuming (though as a quick, cost-effecting point of reference for many shots/situations they can be superb). Your answer was certainly helpful, though thanks! If a colour meter isn't going to meet my needs (and it might not) then a WhiBal will have to do the trick. I've been through such discussions with many regearding grey cards, Expodiscs etc. Garry: Thanks for the welcome. Does your minolta give an unbias reading of degrees kelvin? Or is it dependant on what film-type you select the meter to measure at? Emre: Again, I'd rather have the true data at the time of capture as opposed to post production. Every situation is different of course, but on the whole I like to get things as accurate as possible in the camera. For general use, other processes might indeed be easier, I don't know. Never used a color meter (maybe the best thing to do would be to rent one and compare it to other methods....see what's right for me). However I shoot in Jpeg mainly, and while I shoot a wide variety of things (photography is a "hobby") I have the color meter in mind for shooting my main hobby, collecting prototypes of toys in which an alternating mix of flash, ambient/both will be used with the freedom to be creative. I'll certainly keep my options open though, it's just nice to know how it all works. With that in mind, does anyone use a colour meter in digital photography? Thanks again! Chris I'll certainly keep my optio
     
  6. lwg

    lwg

    My Minolta color meter II gives the color temperature in Kelvins. This works fine for choosing the white balance on the digital in theory. In practice you will get faster results just using the camera's custom white balance feature. On the Nikon I have (D100) you can set a custom white balance as quikly as I can get out the meter and then look up the right value to input into the camera. Maybe some newer cameras allow you to directly enter color temperature, then I bet this is faster. Either way will reduce post processing - getting it right in the field is always a good idea if you have time.
     
  7. Thanks for the info L G. I have a DSLR on which you can directly enter the colour temperature in degrees Kelvin. The camera then automatically compensates for the colour temperature entered to give balanced colour. Sorry to be specific on this, but I wasn't quite clear on your comment about your meter giving a readout in K. Is the reading dependant on the film-type that you set the meter to read for? Or does it just read the actual colour temperature regeardless. If you have to enter a film-type first; which should one enter for Digital photography? Thanks again! Chris
     
  8. i've owned both the Minolta II and the IIIF. the IIIF is the better of the two meters, in fact it is the best color temp meter made. It gives you a number of read out options: color temp in kelvin + CC filter factor (i.e 4300K + cc10R ) ,or myrid value, or the ct filter + cc filter recommendation. The flash function i n the IIIF is far superior to the flash meter attachment for the I because it reads the color temp information at all shutter speeds where as the flash module for the II only let you read color temp only at 1/60th and 1/250th if my memory serves me well. Stephen Johnson uses a Minolta IIF meter for his digital photography created with a 4x5 BetterLight scanning back and his Canon and Kodak DSLRs. "It would be nice if it were as simple as metering, reading the data displayed in degrees Kelvin, and entering that manually into the camera for ambient/flash and both. Things are never that simple sadly." you can of course do since color temperature is basically a red/ blue relationship it leaves out the green/magenta bias. but a better option is to use spectrally neutral Gretagmacbeth gray card (spectrally neutral means it reflects back equal amounts of Red, Green and Blue light in all lighting conditions. The overwhelming majority of gray cards are not spectrally neutral including the Kodak are not spectrally neutral. If you are working to get this kind of precision you are likely shooting "RAW" and in that case the settings on the camera really won't affect the image data. Once a gain we go to gretagmacbeth for a colorchecker card, or a colorchecker SG and use that in conjunction with your raw processor to precisely nail the values for a particular set up. There is the free Fors script for use with ACR 3.4 ( http://fors.net/chromoholics/download/ ) t calibrate or camera and lighting set up or you can profile your camera + lighting set up using the Gretagmacbeth EyeOne Photo or the Gretagmacbeth EyeOne Design profiling toolset to accurately profile your set up.
     
  9. The Minolta color meter does measure color trmperature in degrees Kelvin and it also will suggest a filter pack to correct for the proper color when using tungsten or daylight film. These are two seperate fuctions. The meter doesn't care whether you are using a daylight or tungsten film or digital setting to read color temperature. Aim the meter at the light source, push the button and the meter will display the color temperature. To find a filter pack to correct ambient color you do need to tell the meter whether you are using daylight or a tungsten balance film/capture. The meter will then suggest a filter pack in cc's to balance the light. You can apply those recommended filters on the camera lens or the light source. Just because you know the color temperature in degrees Kelvin, doesn't mean that you can use that information to accurately control the color in a scene. The color temperature only tells you how warm (yellow) or how cool (blue) the light is. The Kelvin scale doesn't measure any other color, such as green. And you'll find a lot of green light in any indoor setting with fluorescent lighting. Or you could have an excess of magenta light or cyan, or red light etc. Kelven temperature only refers to the amount yellow versus blue light. And if you have a mixed lighting such as you suggest with a combination of strobe (daylight)and ambient (tungsten, fluorescent ?) you can only balance to one or the other or find a compromise where neither light source is correctly rendered. It's much better to include a Macbeth color checker or grey/white card in a sertup shot and balance to that. And of course, it's better to shoot raw than j-peg for many reasons, only one of which is to have more control of the color in a scene.
     
  10. Ellis is a much faster typist than I am......
     
  11. Chris, Have you thought about getting an expodisc instead. Cheaper, easier to use and great results. http://www.expoimaging.net/products/product_detail.php?prodid=2&productname=ExpoDisc_Digital_White_Balance_Filter_-_Neutral Regards.
     
  12. Thanks for the responses all, this was exactly the information and opinion needed. Now to take stock of what was said and see what the best solution is for me. Once again, thanks for the info. This site is a fantastic resource for every aspect of photography - keep up the good work! Chris
     
  13. You have been given some excellent answers to your questions as posed. I would like to add a couple of related points. Firstly, the colour balance in an image is often a matter of artistic choice rather than scientific accuracy (although if you are e.g. photographing botanical specimens as a matter of record then accuracy may count very highly). A sunset would look odd if corrected to a daylight colour balance, and cold subjects will give a colder impression if presented as bluer. If you are interested in minimizing post processing workflow, then it can make sense to use something like a Warmcard which provides an automatic offset to a strict white balance to give you a desired end result: http://www.studio1productions.com/warmcards.htm There may be other methods of achieving the same kind of result, depending on the features of your camera - e.g. you could input a slightly higher than metered Kelvin colour temperature to produce a slightly warmer result. Note that if you are using white or warm cards, it's important that they should be at the same distance from any flash as the principal subject will be so that they get the same mix of ambient and flash illumination, unless you gel the flash to match the ambient light. Secondly, some colours are difficult to capture accurately - they are "out of gamut" or suffer from metamerism. Sometimes these problems can be dealt with by skewing the recorded colours using a colour filter over the lens e.g. to reduce the intensity of a particular colour channel that is blowing out - and then correcting for the filtration in post processing. Sometimes you will have to make intelligent compromises in how particular colours are rendered. One very useful introduction to the issues and how to deal with them can be found in this series of tutorials: http://www.cambridgeincolour.com/tutorials.htm
     
  14. Thanks for the input! That's funny actually Mark, I was reading those tutorials right before I chekced the status of this thread. They are indeed very useful, some great reading material there! I agree with you completely, it's nice to have the freedom of artistic choice. A prime example of this is the "Sunsets" etc. rule whereby grey cards, Expodisc et al will, obviously, neutralise the color and exposure level. I'm more interested in having the information infront of me so that I can make a decision based on what the effective colour temperature is; and the desired effect for the photo. Another reason why I'm leaning towards a cheap/used colour meter. While a colour meter will seemingly take care of most of my needs, I'll still probably get a sturdy grey card or WhiBal at some point down the line, as both can be effective depending on the situation. As it stands though I can see myself using a colour meter more frequently for desired effects. The same can be said for warm/cool cards. They are a convenient idea if the situation calls for them, however it's more pieces of equipment as opposed to altering the colour temperature directly onto the camera with one instrument. That minus green card sounds great though....more to research. Thanks for the link! Once again, thanks for all the advice! Chris
     
  15. When TV moved away from film to video, the colour temperature meter became redundant. We simply point the camera at a white target in the ambient light illuminating the subject and press a button. It takes 10 seconds at most. The more sophisticated cameras will tell you what the colour temperature is if you need to assess different light sources, but mostly it is a confidence booster. Occasionally we fool the white balance deliberately ( using a slightly blue card etc.) but these things are more subjective and best left to post production, time and budget permitting.
     

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