Camera Meter vs Hand held Meter

First I would like to take everyone that helped me with my Fill-Flash problem I was having.. Your input was a big help...

Ok.. new problem.. I was doing same test shots this morning and wanted to see how my camera meter and my Polaris meter would compare.. I was metering in bright sun so I was thinking f16 ... ISO 200 @ 125… that's what the Polaris read also... but my 40D meter read f11 ... which one do I trust now... I’m more concerned about when I shoot with my studio lights and can’t use the camera meter…

What would be a good way to check both to see which one is correct?

Take a picture at both and see which one you like?

In theory, a reading taken on an 18% Gray card should result in a digital median value centered at 127 (in the 8-bit RGB range 0 through 255).

In practice, many Canon camera seem to produce a spread centered at about 2/3 f-stop lower than that. The in-camera histogram only shows you a graphical result, but many image processing programs will provide you with a histogram and some statistics.

I should mention also that it might not be wise to try to compensate for what appears to be a simple metering error. Since the objective is to obtain a well exposed image, it may be more practical to use the in-camera histogram to evaluate each exposure in regard to the amount of clipping that occurs in the highlights. Furthermore, it is always better to shoot in RAW so as to give yourself as many tools as possible for correcting exposure errors.

here's a couple of pictures to compare... same time just different meter readings...

HOSTED PHOTO
please log in to view hosted photos in full size.

HOSTED PHOTO
please log in to view hosted photos in full size.

Well if it was bright daylight then "Sunny 16" would be ISO 100 f16 @ 1/125

@ ISO 200 the Sunny 16 would be 1/200

Given the fact that you were already @ f16 ISO200 1/125 and it was nearly 1 stop under exposed I'd say that it was a bit less light than the regular Sunny 16 (more like the slight overcast).

Strictly talking about the flower exposure the Polaris handheld meter shot @ f16 needed +.75 stop increase to bring it to proper exposure.

To me the 40D did a outstanding job.
The Polaris underexposed by nearly 1 stop (~.75).

For f16 to work @ ISO200 you'd need 1/80~ shutter speed.

Alexajlex wrote in post #5941569
Well if it was bright daylight then "Sunny 16" would be ISO 100 f16 @ 1/125

@ ISO 200 the Sunny 16 would be 1/200

Given the fact that you were already @ f16 ISO200 1/125 and it was nearly 1 stop under exposed I'd say that it was a bit less light than the regular Sunny 16 (more like the slight overcast).

Strictly talking about the flower exposure the Polaris handheld meter shot @ f16 needed +.75 stop increase to bring it to proper exposure.

To me the 40D did a outstanding job.
The Polaris underexposed by nearly 1 stop (.75).

For f16 to work @ ISO200 you'd need 1/80~ shutter speed.

With the "correct" exposure, the red channel is clipped a lot and, hence, not correctly exposed, i.e. the red is blown. The red in the shot metered by the handheld meter is much better exposed although it's also clipped but slightly. Pictures of red flowers in direct sunlight is very difficult to expose correctly without underexposing the rest of the photo.

PacAce wrote in post #5941606
With the "correct" exposure, the red channel is clipped a lot and, hence, not correctly exposed, i.e. the red is blown. The red in the shot metered by the handheld meter is much better exposed although it's also clipped but slightly. Pictures of red flowers in direct sunlight is very difficult to expose without underexposing the rest of the photo.

That is true and of course some variations would be needed.

Something like .64 would probably work better on paper.

In reality +.64 exposure will clip red a bit so .60 would work a bit better.

I'll use 85 as an example focal length.

85mm/16 = 5.31
85mm/11 = 7.73

7.73 /5.31 =1.46

Verify
5.31 * .46 = 2.44 + 5.31 = 7.75

100-46 = 64

+.64 stop light.

Alexajlex wrote in post #5941654
That is true and of course some variations would be needed.

Something like .64 would probably work better on paper.

In reality +.64 exposure will clip red a bit so .60 would work a bit better.

I'll use 85 as an example focal length.

85mm/16 = 5.31
85mm/11 = 7.73

7.73 /5.31 =1.46

Verify
5.31 * .46 = 2.44 + 5.31 = 7.75

100-46 = 64

+.64 stop light.

I guess you missed the point of my previous post. The shot made with the Polaris metering was already starting to clip the red channel. Increasing the exposure even slightly would just make it worse, not better.

PacAce wrote in post #5941675
I guess you missed the point of my previous post. The shot made with the Polaris metering was already starting to clip the red channel. Increasing the exposure even slightly would just make it worse, not better.

If there is something wrong with my calculations to reflect the difference between f11 and f16 at the same ISO and focal length please let me know.

I took the JPEG in ACR and it confirmed to me that +.65 is about what is needed.

The question comes down to which pic looks better exposed overall.

There is not doubt the 40D came closer.

Can I ask in your opinion what would be needed to have the red channels not clipped?

I think we can all agree that we are pushing the limits @ .65.

If in your opinion we need -1 stop of light to bring the reds in complete check then we have to play with fill light, recovery and such.

The pic will look quite flat IMO at that point.

I'm sure the fact that -1 stop even in RAW is getting close to the limits of what is possible.

I think to truly get it perfect and zoned up right you'd need:

A) additional light shaping, white soft screen to soften the harsh sun light or a reflector + a screen to cut down on direct light.

B) Wait for the sun to go under the clouds and use fill flash or a reflector.

C) Shoot 3 frames (or more) bracketed @ -1, 0, +1 or -2,-1,0,+1,+2 and combine them in PS

Alexajlex wrote in post #5941720
If there is something wrong with my calculations to reflect the difference between f11 and f16 at the same ISO and focal length please let me know.

I took the JPEG in ACR and it confirmed to me that +.65 is about what is needed.

The question comes down to which pic looks better exposed overall.

There is not doubt the 40D came closer.

Can I ask in your opinion what would be needed to have the red channels not clipped?

I think we can all agree that we are pushing the limits @ .65.

If in your opinion we need -1 stop of light to bring the reds in complete check then we have to play with fill light, recovery and such.

The pic will look quite flat IMO at that point.

I'm sure the fact that -1 stop even in RAW is getting close to the limits of what is possible.

I think to truly get it perfect and zoned up right you'd need:

A) additional light shaping, white soft screen to soften the harsh sun light or a reflector + a screen to cut down on direct light.

B) Wait for the sun to go under the clouds and use fill flash or a reflector.

C) Shoot 3 frames (or more) bracketed @ -1, 0, +1 or -2,-1,0,+1,+2 and combine them in PS

Given the two images presented by the OP, I'll take the underexposed picture over the one you consider as properly exposed but which I considered to be overexposed (after all, the flower would be the primary subject, no, and not the foliage around it). I can always "fix" the underexposed background but there would be no way for me the recover the highlight info that's lost in the clipped red channel. Just my 2 cents.

PacAce wrote in post #5941891
Given the two images presented by the OP, I'll take the underexposed picture over the one you consider as properly exposed but which I considered to be overexposed (after all, the flower would be the primary subject, no, and not the foliage around it). I can always "fix" the underexposed background but there would be no way for me the recover the highlight info that's lost in the clipped red channel. Just my 2 cents.

I prefer the image having secondary objects still reasonably exposed.

I'm not a big fan of the "bat cave look" that would occur if you tried to reduce the exposure so the flower would be properly exposed.

While using the fill and recover functions in ACR can help you get a compromise I think it will look fake (more like a slightly saturated Dave Hill look type of image).

Rather than relying upon the on-board JPG processing programmed into the camera, one could also shoot RAW, hold the flower at the right intensity point, boost the shadow area with the Fill Light function, and set the Saturation and Vibrance levels which closely match what reality provided but digital imaging could not capture with today's technology.

In the disputed red flower example photos, it appears the plant was in very different light at different places. When the meter reading was taken, was it positioned right at the bloom?

Alexajlex wrote in post #5941569
To me the 40D did a outstanding job.
The Polaris underexposed by nearly 1 stop (~.75).

For f16 to work @ ISO200 you'd need 1/80~ shutter speed.

First off: I agree with PacAce: The second shot is a bit blown, the first is way overexposed (the flower that is).

Second: From f/11 to f/16 is one full f stop. So 1/125; f/11 at ISO 200 equals 1/60s f/16 at ISO 200.

Alexajlex wrote in post #5941654
100-46 = 64

I'm not sure what you are trying to calculate here, but as said, f/11 is one stop faster then f/16.
Each aperture stop is a factor of SQR 2 (1.41 and a bit) bigger then the next:
f/1; f/1.4; f/2; f/2.8; f/4; f/5.6; f/8; f/11; f/16; f/22 and so on.

Well rather than all this math and technical stuff, which one looks more like what your eye saw without the camera?

Right Cranium Imaging wrote in post #5953926
Well rather than all this math and technical stuff, which one looks more like what your eye saw without the camera?

Neither. In the first picture, the red flower is overexposed so it'll look much lighter and a different shade of red than what the eyes would see. In the 2nd picture, the red is truer to life but, because of the exposure, darker than what the eyes would see. The eyes has a wider dynamic range so both the flower and the green foliage would look brighter than what's recorded in the 2nd image. But, having said that, the 2nd image can be post processed to come closer to looking like what the eyes would see than the 1st image can be.