Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Using a camera's meter, set to average, with an Expodisc on it will yield similar results to using a separate hand-held incident meter.

https://jimdoty.com/learn/exp101/exp_expodisc/exp_expodisc.html

BebuLamar

Yes you can but you must have a diffusing disc (like the exposedisk) or a dome. Also it's best if you set the camera to center weighted but set the weighted area to full screen to make the meter a true average meter. Spot only measure the center part of the frame. Matrix metering algorithm would interact with the readings and thus not as accurate.

camerapapi Loc: Miami, Fl.

It seems to me that you are trying to use your camera as an incident exposure meter. I have never seen it done before and I question if it will work, most probably it will not but do your own testing and see what happens.
You have enough experience in photography to know that if you use a reflective type of hand held exposure meter and specially if it is a spot meter that the reading will be very accurate. All that is needed and, I know you also know this is that if metering from a middle tonality the exposure will be good for the shadows and highlights. If metering from a shadow area for b&w film you know what to do and the same applies if metering from a highlight which requires extra exposure.

Modern cameras have very sophisticated exposure meters but we all timers like to use center weighted and spot because we know their behaviour and we know what is needed to arrive to the correct exposure of the subject. A gentleman here suggested using the palm of the hand when metering and I try to do that when I have no middle gray to meter from. It is important to remember that the palm of the hand reflects 36% of the light falling on it so when metering off the palm of the hand it is necessary to OPEN one stop for the correct exposure. The palm of the hand and the subject have to be both in the same light for the metering to be correct.

These techniques are excellent but with digital cameras and having a histogram as a guide most people will use matrix metering and look at the histogram for the "correct" exposure.

bweber Loc: Newton, MA

I own a very good hand held light meter, an old Sekonic L-508. I used it to set studio lights. I also like its spot meter function and the incident light dome. I of course also use the meter in my camera almost always set to evaluative metering, although I sometimes use the spot meter for specific images, usually sunsets or sun rises. I also have a good light meter app on my iPhone with the creative name of "light meter". If you want an inexpensive meter and you use a smart phone I suggest you find a light meter app you like. I would not use the camera to take a reading for general use, although it should work for you while taking pictures with the camera. I would only purchase a hand held meter if you wanted a special feature such as an incident meter, very good for portraits, or a spot meter.

Kuzano

Or an expanse of a green grassy field. Same result as hand.

Many seem to be using cell phone meters, also!

burkphoto Loc: High Point, NC

Just buy an ExpoDisc. It's a milky plastic "filter" you hold over the lens. It diffuses all the light that would otherwise be falling on your subject, effectively turning the camera's reflected light meter into both an ambient incident meter and a custom/manual/preset white balance tool.

The disadvantage of this, of course, is that you have to BE at the subject's position to make an accurate reading.

GENorkus Loc: Washington Twp, Michigan

Just a note:
Capture One Pro has had a function to use an ordinary "plastic filter" as you described for years. I used to use that to color balance with using a fish eye or very wide rectilinear lens.

bweber Loc: Newton, MA

I think the ExpoDisc is primarily intended to set white balance. I have used various white balance tools and I have not found them helpful for anything except simple lighting situations. and these are well handled by the auto white balance on my cameras. I alway shoot RAW so I can set white balance that will enhance some of the unusual lighting I see in my landscapes. However those pictures are easier to handle if they are properly exposed. A good light meter will handle the exposure properly.

Vincejr Loc: Northern Kentucky

I would say that pointing the camera back to where you want to take the picture from wouldn't do so well because the camera is reading the light with a reflective light meter. It would give you a good reading for where you want to take the picture from.

rmalarz Loc: Tempe, Arizona

Personally, I prefer to use my Sekonic meter. I have curves calibrated to my usual cameras and it's easier to carry than a second camera simply to use as a light meter.

However, that said, it's certainly an idea that should work. I'd be interested in seeing how photographs you took using a camera for a light meter came out.
--Bob

GENorkus Loc: Washington Twp, Michigan

Bob, I'd like to see them also. (My very early analog shots got destroyed.)

lamiaceae Loc: San Luis Obispo County, CA

Sure, you can do that. On occasion I'll shoot film with my old Pentax Spotmatic camera. The meter used those obsolete 1.35v Mercury batteries. So I'll put one of my digital Pentax cameras on Manual and get an exposure meter reading I can then use on my film camera. I'll set my DSLR for single point Spot Metering.

pappleg

That would be attempting to use the camera's reflected light meter as an incident meter-they are two very far different animals and I would not recommend it. Incident meters are designed to read light sources and usually contain a diffusing dome. The metering algorithm is completely different. Pat

CO

Yes, I see that the Expodisc is an option. I'm not sure if the OP has one. I would just use my incident light meter.

CO

The Expodisc seems to be a good option. I don't have one. I always used my incident light meter in those situations.