Exposure settings with medium format film

[barry_r]

<p>I recently purchased a medium format film camera that has manual exposure settings (no AE). I do have a light meter but there are some circumstances where the meter can't be used so I could use a second camera's reflective meter to get exposure settings. I have purchased both color negative and slide film.</p>

<p>I did a test recently using two cameras: a Nikon D700 (digital) set to ISO 100 with a 50mm focal length lens at f/5.6, matrix metering, and a Pentax K1000 (film) set to ASA 100 with a same focal length and f/stop, both focused on the same subject on an overcast day. Sometimes the results differed by a stop or so. For instance, D700 said 1/50 sec. and K1000 said 1/125 sec. Results didn't change much by using spot metering on the D700 as expected due to the weather conditions.</p>

<p>I read that the Pentax uses some kind of center weighted metering, which is not exactly what the Nikon is using, but the magnitude of the difference surprised me.</p>

<p>So my question is which camera's meter should I use for the medium format film camera? On the one hand, the Nikon is more modern so possibly more accurate, but on the other hand the Pentax is a film camera so is its meter maybe more appropriate for film?</p>

<p> </p>

[PapaTango]

<p>An old adage called "Segal's Law" states, "A man with a watch always knows what time it is. A man with two watches is never sure..."</p>

<p>Light meters typically run one of three ways--spot, center weighted, and evaluative (aka matrix). The spot grabs a small area about 1-5% of the center of the frame and returns a value. One can meter the main focus (such as a face) or several parts of the scene (highlights and shadows) and average a value.</p>

<p>Center weighted camera meters take a larger section--as much as 60% or more of the scene--but concentrate the sensitivity the closer to center frame. Matrix of course looks at a number of parts of the frame and averages the result through electronic magic. Here is a nice little article on the use of each:</p>

<p>http://www.digital-photo-secrets.com/tip/2879/which-is-best-spot-center-weight-or-matrix-metering/</p>

<p>For a fully manual camera, I would select a good handheld light meter for the job--and forego the cameras as light metering devices. There are a number of advantages to this, including the ability to measure direct and indirect light--and with an electronic meter--adjust your flash as well. Others will likely make a number of suggestions on reasonably priced handheld meters. </p>

<p> </p>

[John Seaman]

<p>It's not unusual to find one stop or more difference between different cameras and/or exposure meters. There are so many variables at work - the chances are that the D700 reading is more reliable, as the K1000 will be probably thirty years old by now, and has a fairly primitive system.</p>

<p>Actually correct exposure is somewhat subjective anyway. In general digital and film, whether 35mm or medium format, should not need different exposures although there are many opinions about exposing for highlights and shadows with film, and exposing to the right with digital.</p>

<p>You say you have an exposure meter but sometimes can't use it and use a camera instead - what kind of meter is it, and how does the meter reading agree with the two cameras? You can easily drive yourself crazy trying to make sense of all these different exposure readings. One thing I've never regretted was investing in a modern accurate digital meter - much as I enjoy using vintage equipment, there is no point wasting time, film and processing costs on badly exposed pictures. Far better to stick to one instrument and get to know how the readings work for you.</p>

[AlanKlein]

<p><br />You'll never get the right reading with two camera meters. You'll drive yourself crazy. Pick one and use it exclusively. Check what readings match you film shots through bracketing and adjust your exposure settings from then on. It will be more convenient using a hand held meter that has both reflective and incident reading capabilities so you don't have to carry an extra camera. </p>

<p>As an aside I always had difficulty with consistency with camera matrix metering and use camera center-weighted when shooting with my digital camera. When I'm using my Mamiya RB67 MF film camera, I use a Minolta Autometer IIIa hand-held meter. It also can be used for strobe measurement and balancing. But there are many fine, used hand meters that have both reflective and incident readings that you should be able to buy fairly inexpensively. Good luck.</p>

[barry_r]

<p>My response didn't seem to go through - pardon if this is a duplicate...</p>

<p>My light meter is a Sekonic L-358. I forgot that it had a "Lumigrid" for reflective light measurement. I'll compare that to the two cameras.</p>

 

[BrianS1664879711]

I believe the K1000 meter is an averaging meter,

not a spot meter. You likely compared apples to

oranges in terms of what luminance a were

compared.

[rossb]

<p>I went through that exercise back in the day. I think the answer was a Tylenol.</p>

[barry_r]

<p>Okay, here are the results of my definitive, highly scientific (not) experiment. All measurements with the same f/5.6 and ISO 200 settings. For the Sekonic, I used the Lumigrid reflective attachment. It's still very overcast so there's little dependence on the exact aiming spot.</p>

<p>Shutter speeds are for Sekonic, Nikon D700 and Pentax K1000, respectively:<br>

First scene, pointing at trees: 1/20, 1/10, 1/30<br>

Second scene, pointing at top of trees: 1/160, 1/125, 1/250</p>

<p>Again, the Pentax is indicating significantly faster shutter speeds than the Nikon, but the Sekonic and Nikon are in better agreement. So I'll just plan to use the Sekonic for incident and, if necessary, reflective measurements.</p>

<p>I'm glad I posted as I had forgotten about the Lumigrid, and didn't relish carrying around a DSLR just for light metering.</p>

<p> </p>

[BrianS1664879711]

Is there any sky in the scene being metered? Try

again using a wall or fence without sky.

[barry_r]

<p>Too late now - it's dark.</p>

<p>There was sky in the background as the trees are bare now. What is the reason for your asking?</p>

 

[barry_r]

<p>I guess I could use an inside wall, but I put everything away for now. Maybe tomorrow.</p>

[c_watson1]

<p>With respect, just park the 35mm film camera and D700 and use your Sekonic 358 as an incident meter as God intended. Granted, you can't always put the meter where you're shooting but, short of getting a 1 degree spot meter(Look for a Sekonic 558 or 508 if you're interested), incident readings from your 358 will seldom disappoint.</p>

[fred_haeseker]

<p>Sort of crude, but it works for me: If there is a large area of sky in the composition I want, I take a reading from a handheld reflective meter (I use a Gossen LunaSix) aimed at something that's close to 18% gray. Make sure the area you meter is in the same light as the overall light of the composition you want.<br>

For instance I've found grass is a good equivalent to 18% gray. So is a worn roadway. If you want to be meticulous, use the 18% gray card that should still be available from photo dealers.<br>

Another possibility is using an incident light meter. Most good reflective meters come with an opaque white-colored sliding feature for incident readings. Lots of info on the web about how to measure incident light.<br>

As others have posted, comparing several meters will drive you crazy. Your results will soon tell you if a particular meter does a good job.</p>

 

[BrianS1664879711]

Cwatson is right !!

 

The reason I ask about sky is because the meters

you are comparing are weighting the scene

differently. A better test would be a large equally lit

scene like a wall, etc. That would negate the

impact of different meter weightings.

[BrianS1664879711]

That's why your measures "pointed at treetops" is

varying so much.

[bethe_fisher]

<p>I rely mainly on incident readings. Even when I can get the meter to the subject to measure the light falling right on it, I don't. I find a spot close to me where the light is the same and I measure that. Granted, I'm usually shooting B&W film and can make up for a stop or two in the darkroom. But when I've compared the internal meter on my P645N to the incident meter (they rarely agree), the incident meter helps me get a better negative.</p>

[BrianS1664879711]

Me too. Often incident reading is as good, or better,

than spot readings!

[dhbebb]

<p>To compare exposure meters you MUST ensure that they are all metering the same thing, which means an 18% grey card covering the entire reading angle of a separate meter (46 degrees unless otherwise stated) or the entire field of view of the lens in the case of meters built into cameras. If you do not do this, differences in metering pattern (integrating, centre-weighted, matrix, spot) will cause hopeless confusion. It is also very likely that the meter of your old Pentax has drifted. Calibrate this against your Sekonic and you can then use a camera meter for cases where the separate meter is not ideal (I presume this means spot metering of remote subjects).</p>

[glen_h]

<p>As far as I know, digital cameras meter the same way, but ISO film speeds only apply to film. <br>

I am not sure how digital ISO values are determined. The way film responds to light is very different from digital sensors. </p>

<p>Within one stop, and considering the variation in meter spot/average/matrix, either should be fine for negative film. For slide film, you will want to understand the metering better. </p>

<p>I usually point whatever in-camera meter I have at parts of the image, ignore ones that should be too high or low (sky or unimportant shadows) and pick something in between. </p>

 

[barry_r]

<p>Okay, one last experiment. I couldn't find a uniformly illuminated wall, but it was again highly overcast so I simply pointed the light meter and cameras directly up toward the sky.</p>

<p>Light meter set at ISO 200, f/5.6: 1/800 sec, independent of pointing direction.<br>

Nikon D700 and 50mm lens set at ISO 200, f/5.6: small variation with pointing direction, average of 1/720 sec<br>

The Pentax K1000 was set at ISO 200 but it was a bit problematical as it only has discrete shutter speeds at 1/500 and 1/1000. So I stopped it down to get a reading with the pointer in the center and then calculated the required shutter speed for f/5.6, also independent of pointing direction: 1/740 sec</p>

<p>So all in all there was fairly good agreement and as I speculated in my original post and others have also pointed out, each device uses a different weighting so results with non-uniform subjects could differ. I think with my first outing using the medium format camera i will use the light meter and see what happens.</p>

 

[Bill C]

Hi, I'd personally prefer to work with the bonafide light meter, but I get the point that you might sometimes want to work with the camera

meter.

 

I'm familiar with the older ANSI standard for light meters, both reflected and incident, and I'd guess that the K1000 probably conforms. On

the other hand, the Nikon matrix is probably using internal "black magic" that maybe infers a better exposure, but might be biased to

prevent "blowout" on the digital image. If I had to choose a camera for metering with film, I'd probably go with the Nikon, but get it out of the

matrix mode; probably either center-weighted or spot. I'd guess that the Nikon would perform better when the color of the light gets farther

away from the ANSI aim. For example, under tungsten light or the bluish color of skylight. But this is strictly guessing; if it were critical

work, I'd start out with some controlled testing unit you know for sure what works best.

 

It's not clear to me how much film experience you have, so it may be worth mentioning that color neg film has a great deal of tolerance for

overexposure (make your errors in that direction), whereas color slides have to be right on the nose, and ideally filtered to match the light

source. Best of luck with it.

[AlanKlein]

Bracket and keep notes so you can review and

compare results with the meter. Half stops with slide

film and full stops with negative film. Good luck.

[glen_h]

<p>Yes you should be right on, maybe within half a stop, for slide film, but that doesn't mean that there aren't big variations between different metering methods.</p>

<p>Even if the Nikon matrix metering does try to prevent blowouts, it is probably better, overall, than spot or average. Well, unless you spot meter on exactly the right place. </p>

[Bill C]

[Glen] "Even if the Nikon matrix metering does try to prevent blowouts, it is probably better, overall, than spot or average. Well, unless you

spot meter on exactly the right place."

 

Well maybe, maybe not. But most likely, as a non-uniform scene fluctuates (perhaps highlights around the perimeter change), the matrix

meter will make exposure adjustments. Even if the main part of the scene does not change (this means that you should NOT change

exposure). To me, this means that the matrix metering is somewhat variable compared to a fixed reflective meter.

 

If I want reliable fixed exposures, I'll avoid matrix metering and stick with the conventional ANSI/ISO meter response. A disclaimer- I've

never used the Nikon matrix system; I'm just going on the principle of the thing.

[glen_h]

<p>A spot meter pointed to the right spot is best, but you have to know the right spot. The wrong spot will lead to wrong exposure.</p>

<p>The general (I don't know specifically about any one) idea of matrix metering is that you have many spots. If one is shadow, and another highlight, you have what you need to know, the full range of the subject.</p>

<p>If you follow the rule "expose for the shadows", and one of the matrix points is shadow, you can use that.</p>

<p>Note that averaging meters are easily fooled. They work as well as they do because many subjects have an appropriately average brightness. Much better would be a geometric mean over the subject, but that isn't easy with one sensor. The geometric mean is much less susceptible to being fooled by highlights than an average (arithmetic mean).</p>

<p>A center spot meter can easily be wrong if the center isn't an appropriate spot. As with autofocus on the center, a spot meter can be pointing to the background when you want to meter the foreground.</p>