A comparison of three colour meters

Discussion in 'Exposure Discussion' started by Helen B, Jan 24, 2007.

  1. Helen B

    Helen B Member

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    Just in case anyone is wondering which colour meter to choose:

    When Minolta stopped production of the Color Meter IIIF I began to be asked about how the Minolta IIIF compared to the Gossen Color-Pro 3F. I had no experience of the Gossen, so decided to get one and find out. That meant that I had three colour meters: the Minolta II (MII for short) and IIIF (MIIIF for short), and the Gossen (G3F for short). I've never seen a comparison of the three, so thought that it might be worth making a few notes.

    eBay prices: about $300 or less for the MII, and about $800 for the MIIIF and G3F.

    The MII is the most basic of the three meters. It only measures continuous light in its standard form. A separate flash receptor is available. I don't have one of those, so can't comment on it. I'd be grateful if someone else added their experience of it.

    The head is removable, and can be located remotely from the body of the meter with a ribbon cable. I have one of those, but have never found any reason to use it. There's a standard 1/4" tripod thread on the head, so you could put it on a pole to get extra reach while holding and reading the meter body. The head does not rotate, unlike the other two meters. I've never found that to be important. Mine can read in slightly lower light levels than the other two. It has three preset film types; daylight 5500 K, Type A 3400 K and Type B 3200 K. There's also a variable setting.

    It takes a 9 V battery, and the blade contacts are built into the side of the battery compartment. This is a robust, quick system - I wish that all PP3 connectors were that good.

    It displays colour temperature, reciprocal megakelvin (MKˉ¹ = mired) shift and a green-magenta index. There's a table on the back to convert from mired to Wratten filter numbers, and from the G-M index to CC-G and CC-M filters. For example an index of +8 corresponds to CC20M and an index of -7 corresponds to CC20G. The index display resolution is 1, so this means that you can estimate the reading to better than the nearest 2 CC units. In practice that is a reasonable expectation for the accuracy of this meter: plenty good enough.

    I'll cover the other two meters feature by feature.

    Batteries: The MIIIF takes two AA cells. Simple. The G3F takes a 9 V battery
    but has one of those flimsy connector pads on a thin bit of wire. Gossen could do better.

    Range: The G3F comes with two flat receptors [colour meters always have flat (cosine) receptors instead of the domed (cardioid) type usually found on light meters]. One receptor has a semi-silvered mirror that decreases the sensitivity by five stops. Lose the attenuating receptor and it will cost $125 to replace. Lose the normal one and it will cost you $24 to replace. The MIIIF has a range switch.

    Flash: they both have good flash/continuous functions, and a sync socket. The G3F will give the flash output in lux-seconds, and the gate time is adjustable.

    Display: they display similar information. MKˉ¹ shift, Wratten filter, CC adjustment. The G3F gives lux as well. But here's the thing: the G3F only gives the CC adjustment in steps of five, while the MIIIF gives it in steps of one. No big deal, because who carries CC filters in steps of less than five? I carry them in steps of ten when I'm travelling light. If I get a reading of five, what do I do? In fact it doesn't lead to a significant average error, but the MIIIF has a definite advantage. Even if the absolute accuracy of the two meters is similar, the extra resolution of the MIIIF can give it an advantage.

    Size: the G3F is the smallest of the three. The MIIIF is slightly smaller than the MII.

    I hope that gives a general idea of the differences between the meters. If there is anything specific that you would like to know, just ask. In case you haven't guessed, I think that the MII is great value if you don't need the extra functions of the other two.

    Best,
    Helen
     
    Last edited by a moderator: Jan 24, 2007
  2. Lee L

    Lee L Member

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    Helen,

    Thanks for the review. One quick question comes to mind, probably in the manual, but I'll ask here for other readers of the thread. Does the G3F have a storage compartment or other place to securely attach the unused second receptor? Just thinking about how this might lessen the chance of losing it.

    Lee
     
  3. Pinholemaster

    Pinholemaster Member

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    I own the flash attachment for the MII. Works just as well with flash as the standard head does with ambient.

    Yes the MII is bigger, especially with the added flash head, but never saw the need to upgrade since I so rarely use them.

    One thing I do is always remove the 9v battery when not in use.
     
  4. Jim Rice

    Jim Rice Member

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    A clarification please (?) : the MII does read ambient as well as flash, right?
     
  5. Pinholemaster

    Pinholemaster Member

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    The MII reads ambient, and with the additional flash head will read strobe.
     
  6. Helen B

    Helen B Member

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    Hi Lee,

    The soft nylon case has a little pouch for the unused receptor disk.

    Best,
    Helen
     
  7. Kirk Keyes

    Kirk Keyes Member

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    Helen - so if you didn't have a color meter yet, which one you you buy?

    BTW, I picked up a Minolta Colormeter II last year for under $100. It does all I need, except flash would be nice. So someday I'll try to get the other head.

    Kirk
     
  8. Kirk Keyes

    Kirk Keyes Member

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    Also - do you get the same readings with all 3 meters in various lighting situations? Does one seem more accurate that the others?

    Kirk
     
  9. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Hmmm...Thanks for the review. Since I don't typically rent strobe equipment and have tested my own strobes with film, I suspect I could get by with a color meter that only read ambient, or do you find that strobe color varies with output? Do you find a lot of variation between brands of studio strobes?
     
  10. Helen B

    Helen B Member

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    Kirk,

    I'd buy a Minolta - either the II or the IIIF, depending on how important the extra flash functions were. Personally, I'd be happy with the II. If you know from experience how your flash equipment compares with daylight, you only need a continuous meter to balance flash and continuous - only the continuous is unknown. I know what I'm trying to say, but I'm not saying it very well.

    Accuracy etc: The short answer is that the three meters are remarkably close. I'll go into more detail in a minute.

    David,

    I've never felt the need to use a colour meter to balance strobe to strobe, but I don't have enough experience with different brands of strobes. My only use of a colour meter with strobe is to balance to ambient, in which case you can usually manage without measuring the strobe itself. I think that my situation is very similar to yours. Perhaps someone with more experience with colour meters and strobes could answer that one.

    Back to accuracy.

    I think that colour meters are fairly consistent, especially between 5500 K and 3000 K. My MII drifts a bit below 3000 K, but it is old. The maximum difference between any of them is about 12 mireds in the 2300 K to 2600 K region. That's not a big difference in practice. The green-magenta index is comparable as well, although the fact that the Gossen reads in steps of five does lead to differences. My MII consistently reads -2 for blackbody sources, but if I take that into account it compares well with the MIIIF.

    When you think about how the readings from a colour meter will be used, the differences between the meter readings look unimportant. If you are balancing sources to each other then absolute accuracy isn't necessary, of course. All the meters show good precision, equalling the resolution of their displays.

    For balancing a source to a film type accuracy is more important, but I haven't noticed enough discrepancy for it to be a problem.

    Here's a summary of the nominal shift values of the least dense standard filters.

    Lighting gels
    Eighth CTO, CTS: +20 mireds
    Eighth CTB: -12 mireds
    Eighth plusgreen: CC 3.5 G (CC035G)
    Eighth minusgreen: CC 3.5 M (CC035M)

    Camera filters
    Wratten 81: +9 mireds
    Wratten 82: -10 mireds
    KR 1.5: +15 mireds
    KB 1.5: -15 mireds
    CC green: CC 2.5 G (CC025G)
    CC magenta: CC 2.5 M (CC025M)
    (I don't have the need to use camera CC filters in 2.5 unit steps)

    Those values should give some perspective on the degree of accuracy (or lack of it) required from the meter. I think that all the meters I've used have been sufficiently accurate.

    Best,
    Helen
     
  11. Helen B

    Helen B Member

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    Just in case anyone needs convincing what an inexact business colour balancing is, here's a graph showing the relative power across the spectrum for theoretical 5500 K and 3200 K sources, and the combination of a 5500 K source and an 85B filter, which is supposed to convert 5500 K to 3200 K. The three lines have been adjusted to meet at a relative power of 1 at 550 nm.

    Best,
    Helen
     

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  12. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Helen was kind enough to loan me her two Minolta meters, so I've started doing some tests just to see how consistent flash output is.

    Just figuring out how to use them, I discovered that, yes, one should really wear a black shirt when taking color readings to avoid influencing the meter.

    First observation testing a small Metz 30BCT4 and a Norman LH-2 portable head with a 200C pack--well my 200C wasn't charged, so I only got a few flashes off at low power before the battery failed.

    Quick observations--both were fairly close to daylight on the cool side--less than the amount of correction provided by an 81 filter, which is even weaker than the common 81A. The Metz drifted more from flash to flash, while the Norman stayed within a tighter tolerance. The lesson there is that you would have to be very sure of the tolerance and consistency of your strobe heads, film stock, processing, and viewing source, before it would be worth making adjustments of .025 CC, and I have have filters in that strength.

    I'll test more rigorously with the Norman portable at different power levels when the battery is charged, and I'll also test my Norman studio heads when I have some time to set them up.
     
  13. Ray Heath

    Ray Heath Member

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    g'day helen

    an interesting thread, but do colour meters actually get much use nowadays? why? how? where?

    thnx
    Ray
     
  14. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I'm shooting some 8x10" Polaroids under window light, so I had another chance to test the meters, and I threw my simple Gossen Sixticolor into the mix, which only reads red/blue, so it can't handle fluorescents, and it doesn't work terribly well in low light, so it's not that great for tungsten.

    Well the first shot revealed that I needed a warming filter, so it seemed like a good situation to compare the three meters, though of course I could have made the correction from looking at the Polaroid itself.

    First off, the Minolta IIIF is more sensitive than the others. I could get a reasonable reading from the subject position, maybe 8 feet from the window. The Minolta II and Sixticolor required that I go up to the window, and it could be that the light is bluer 8 feet away than it is right there, due to reflections in the room.

    All three gave me about the same reading calling for something in the range of 81, 81A, or 81B, and it could be different depending on how precisely I directed the sensor. The conclusion might be that there is no meter that can tell you precisely whether you need an 81, 81A, or 81B, because there are just too many variables involved in the process, but it does seem informative to have some readings to base a judgment on.

    As to the question of why one might want to use a color meter, I think they get the most use in mixed lighting where you have the possibility of gelling all the lights to the same color balance, or making multiple exposures with different filtration on the lens for each light source, as is often done for architectural interior photography.
     
  15. pgomena

    pgomena Member

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    David --

    Stobes can vary widely in color depending on the age of the flash tube. Also, any time you modify the lighting with a softbox, umbrella, bounce panel, etc., it will change the color of the light. The older the softbox, the warmer the light.

    In the studio where I worked, we used to use strips of Rosco gels (close to, not touching) over the flashtubes to correct the color to within +- 50 degrees Kelvin on the meter. There usually was quite a bit of difference between modified and unmodified light sources.

    Peter Gomena
     
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  16. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I just had time to try another test just using the Norman LH2 heads that I keep on my copy stand most of the time.

    Adjusting the strobe power from 50 to 100 to 200 W-s, there was no significant difference in color temperature from one setting to the next--at most 10 degrees K, which is within the range of variation from flash to flash on a single setting. This is as it should be, since in theory the flash output is regulated by changing only the duration.

    On the copy stand I use the heads with 5" reflectors that have an opal glass diffuser and a very uncalibrated white handkerchief over each head, and the color temperature is 5480-90K--almost exactly what it should be. If I remove the reflectors, the temperature of the flashtube is a little on the blue side 5950K--enough for the IIIF to recommend an 81A.
     
  17. kapro

    kapro Member

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    I'll maybe bring an old thread alive.
    Does anybody have experience with Kenko KCM-3100 and Sekonic Prodigi Color C-500. My Gossen 3F died during the trip to Iceland and I don't want to buy same. It has very poor construction for heavy outside use. My lost contact with display and after dismantling I'm not sure I'd like to go back to Iceland with the same color meter construction.