DSLR as lightmeter??

[Matus Kalisky]

One indeed needs to be careful with the different dynamic range of digital camera and different films. Still - one may use the spot metering of the camera to estimate the contrast range of the scene and then decide on the exposure.

Of course as mentioned by Greg - you need to check how does ISO 100 of your DSLR compares to ISO 100 of your film (or light meter you are used to - if you want to compare those).

I have and older DSLR which less dynamic range than the modern ones so I am closer to slide film response

[pdmoylan]

In the not too distant past I found my Nikon SLR's, when properly calibrated, served very well as backup to my Pentax Spotmeter. An N90s had to repaired as it was slightly less than .5 stops underexposed, while my 8008s was spot on. In a pinch, when the Pentax was not at hand, or I was taking both 35mm and 4x5 exposures of the same scene, I used the exposure readings from 35mm with consistently satisfactory results. However, after careful testing, I find that my DSLR exposure readings are so dramatically different from my SLR at the same ISO, I cannot employ it as a substitute for the Pentax. Of course, one could calculate this differential and factor it in with bellows extension, filter and reciprocity failure calculations, to obtain correct exposure. For me, however, less complication is a hallmark of my advancing years.

[Jack Dahlgren]

Film/silver works with light at the molecular level, not the atomic level. Silver filaments (the molecule clumps which make up individual film grains) are decidedly NOT binary: they are variably transmissive throughout, and even the densest filaments still transmit light.

There is an excellent discussion about the true nature of film at the molecular level, here: http://photo-utopia.blogspot.com/200...nd-clumps.html

Furthermore, even if for the sake of argument we agree that grain is effectively "super" binary, that is, it is values of "mostly transmit" or "mostly block" split up billions of times per square centimeter, light would still not necessarily pass through it in a binary fashion. Remember, light is neither binary nor analogue: it is quantum.

That same article says:

"During development these structures are converted into metallic silver which is black, the bromide atoms are absorbed into the developer, fixing removes the silver atoms that weren't struck by any photons, leaving that part of the grain clear."

Sounds pretty black and white to me. The author was making the point that there is a filament-like molecular structure so film "grain" is not binary.

But my intention was to point out that arguing about this stuff is nearly pointless. So I'm going to quit before I use the word quantum.

[Greg Miller]

In the not too distant past I found my Nikon SLR's, when properly calibrated, served very well as backup to my Pentax Spotmeter. An N90s had to repaired as it was slightly less than .5 stops underexposed, while my 8008s was spot on. In a pinch, when the Pentax was not at hand, or I was taking both 35mm and 4x5 exposures of the same scene, I used the exposure readings from 35mm with consistently satisfactory results. However, after careful testing, I find that my DSLR exposure readings are so dramatically different from my SLR at the same ISO, I cannot employ it as a substitute for the Pentax. Of course, one could calculate this differential and factor it in with bellows extension, filter and reciprocity failure calculations, to obtain correct exposure. For me, however, less complication is a hallmark of my advancing years.

The metering in recent Nikon dSLRs tends to yield a bright image. They are using an "expose to the right" philosophy where you expose to the right side of the histogram (but not to the point of clipping). The brighest stop is capable of holding the most tonal gradations (the darkest stop the least amount) while at the same time avoiding noise.

Once you understand how much the Nikon dSLR will try to overexpose (i.e. 1/3 stop, 1/2 stop,...), you can adjust for that for each film exposure (just like you would when using a traditional meter).

[john wood]

The metering in recent Nikon dSLRs tends to yield a bright image. They are using an "expose to the right" philosophy where you expose to the right side of the histogram (but not to the point of clipping). The brighest stop is capable of holding the most tonal gradations (the darkest stop the least amount) while at the same time avoiding noise.

Once you understand how much the Nikon dSLR will try to overexpose (i.e. 1/3 stop, 1/2 stop,...), you can adjust for that for each film exposure (just like you would when using a traditional meter).

Greg - thanks for this; my meter was forgotten on a bench a few weeks ago, so I've since tried a Nikon dslr with quite poor results. Tried again with my F100, and the results were great...but no ability to check the image. I thought it might just be some of the dslr limitations mentioned above...but your note gives me optimism to try again, with adjustments.

[Brian Ellis]

I've never used a DSLR as a substitute for a light meter. But I recently sold a Pentax digital spot meter for a friend to someone on this forum and he asked me to test it so I took four readings of different colored subjects with it and with my Canon 5D Mark II camera using its spot setting. Two of the readings were identical, the other two were a tiny bit off, less than a third of a stop IIRC.

[Bob Kerner]

Greg - thanks for this; my meter was forgotten on a bench a few weeks ago, so I've since tried a Nikon dslr with quite poor results.

Which DSLR, may I ask? I use a D200 and I have a Canon 7D that I primarily use for video and the two give Very different histograms and exposures. The Nikon is almost always a stop or so under compared with the Canon. It may be because it's an older DSLR.

I've switched to the Canon for LF evaluative and spot metering, and a small Sekonic for incident metering.

[john wood]

Which DSLR, may I ask? I use a D200 and I have a Canon 7D that I primarily use for video and the two give Very different histograms and exposures. The Nikon is almost always a stop or so under compared with the Canon. It may be because it's an older DSLR.

I've switched to the Canon for LF evaluative and spot metering, and a small Sekonic for incident metering.

Bob - the older (in digi years) D80...it's known to have faulty matrix metering, but I was using center-weighted and spot.