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DMR light meter accuracy


albertknappmd

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I have just started to use my R9-DMR and find that in the usual straightforward exposure circumstances, the MATRIX meter functions perfectly jsut like my analog R8s. The problem arises in indoor-low light shooting and I noted that the DMR overexposes by one or two stops... Any idea as to why. In spot, the overexposure persists but is much less.

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Guest guy_mancuso

Albert because meters always tend to see things as grey not black or white, so your meter wants to add exposure to get grey. Plus with matrix you are taking in a much larger area than spot so it boost the whole scene more. Off course this depends on the scene and the more black they more it will want to overexpose

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I don't own a DMR combo, but shot 60-70 shots a couple of weekends ago at a Leica demo shoot. Indoors and out.

 

Definitely I needed to dial in some underexposure on the exposure compensation - 1 to 1.5 stops - for both jpeg and RAW shots. Although oddly, MORE compensation outdoors and less indoors. I think I was using centered-weighted pattern.

 

The Leica rep running the shoot confirmed this as 'normal' practice with the DMR - although obviously 'correct' exposure depends on what the photographer is looking for in the final picture.

 

And Like Guy "the Man" said, abnormally large areas of light or dark can trick even the matrix metering.

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I fully agree and I am guilty of posing a vague and poorly worded question.... Mea culpa!

I meant to ask the following:

<p>I NOTED THAT IF YOU TAKE A CERTAIN PICTURE (EXAMPLE INDOOR SHOT WITH BRIGHT AND DARK AREAS) AND YOU SHOOT THE SAME PICTURE WITH FILM AND THEN WITH DMR, THE FILM SHOT IS PERFECTLY EXPOSED WHERAS THE DMR IS OVEREXPOSED BY 1-2EV... SEEMS TO ME THAT THIS IS NOT A METER PROBLEM THEN BUT A DMR PROBLEM...WHY AND CAN YOU ALL TEST THIS OUT AND CONFIRM MY FINDINGS... THANKS.

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Albert, no need to shout ;-)

 

Two things come to mind. First, what film are you comparing the DMR to? If it's colour negative film could the film's exposure latitude be masking metering errors?

 

Second, digital sensors don't always match the ISO that they're set to. So set to ISO 100 the sensor's _real_ sensitivity could be 125 for example.

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Exposing with digital seems closest to working with transparencies. I have to be careful not to blow out the highlights. My R9 meter generally does well, but if there are highlights where I want to preserve detail, the exposure is likely to require considerably less light than with negative film. Under most circumstances the histogram is my guide.

 

I've been using a hand held meter but haven't yet figured out relationship between digital exposure and incident readings.

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Albert - Are you using Selective, Multipattern or center-weight average metering? I don't have this problem to be honest but I use selective metering pretty much exclusively. I still had to learn that selective metering no longer represented 7% of the viewfinder image. It's more like 30% with the DMR crop. I learned to compensate for that when selecting an area to meter.

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I have been using selective as well as multiple pattern. As to the latter, I realize now that by using an automatic EV change of -0.5 or -1, that my histogram is normalized. If selective now represetns 30% of the picutre surface, I suspect that it is prone to the same errors as matrix or centerweight and will benefit from the above EV change as well. If the selective were truely 7%, then finding the exact neutral gray area and holding the shutter release down ever so slightly should accomplish the same sans EV corrrection. I will try!

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Hello Albert,

 

I'm now working 1/2 year with the DMR...there is a different between Film metering and DMR...with the DMR you need about -1 stops exposure compensation..... and for flash 1,5-2 stops......but look, see it positiv!..you have better use..you can put the camera for 100 ASA and you get the "time" for about 200-400 ASA..this is realy great!...and you can always check the display with the diagram...:) .

 

regards,

Jan

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Albert,

 

I've used a R9 +DMR for 9 months now (two, because the first one died after 3 weeks) - and several months ago this issue was raised when people began to acquire DMRs. Overexposure seems normal - with the consequence of blown highlights. The R9 metering was dead-on with film (both positive and negative)

 

I need between 1 and 2 stops underexposure on all meter settings (spot, matrix, centre weighted). I haven't been able to pin down when to use only -1ev or -1.5, or -2ev. I use the histogram to check, and push it as far to the right without clipping highlights. Different scenes, inddors, outdoors and time of day all affect it so it is a matter of trial and error. It certainly isn't a problem that needs factory readjustment because then your film metering will be out.

 

As others have said it gives extra iso which can be really useful in low-light conditions. (Incidentally, shots in low light show amazing rendition of tones - much better than the blocked out shadows on slide film).

 

Hope this helps

 

Best wsihes, Graeme

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Thanks Graham!

I now realize that everything you and the others have said is correct. I made teh EV adjustment and all is well. I supect teh reason for the exposure discrepancy with multi-pattern, centerweight and spot lies in the fact that the actual metered part is smaller than the screen (eg multipattern & centerweight) or larger than what the analog meter is programmed for (eg spot where the analog spot is 7% but the enlarged spot on digital is about 30%.) It is now making more sense.

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.....you can put the camera for 100 ASA and you get the "time" for about 200-400 ASA..this is realy great!...

 

...there is a big discussion about the "noise problem" of the camera...but in my opinion it is "only" a problem of the software.....

... 100 ASA is like 200-400 ASA and 400 ASA is like 1600 ASA !!! this is bad for the image (of Leica) but NOT bad for the user!....

.if I take a shot with the DMR with 400 ASA, I have to shot it with a Canon,Nikon with 1600 ASA......;)

 

regards,

Jan

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I've just happened on this thread but I tend to put between half a stop underexposure using my R9 / DMR with 180mm 2.8 and as much as one and a half under with some older lenses (for example 400mm f 6.8), my meter is set to spot though, so in my case the overall lighting of a given scene might be having an influence.

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