Question About Light Meters

[DogHeadGod]

I just bought my first lightmeter, a Sekonic L308s

I shoot with a Nikon D70s and after taking a while to figure out the camera's inbuilt meter I always go two bars (thats LCD bars, not stops) higher than the camera states is the correct exposure as I always found images to be underexposed if I didn't.

Now with the Sekonic light meter I took a reading for my desk and then set the camera to the indicated exposure, pointed the camera at the desk and hey-presto the internal light meter showed 2 bars higher than the camera would suggest, so I'm not crazy after all.

Now onto the serious question... are light meters set for a specific lens focal length? The onboard camera changes it's exposure setting as you zoom in or out. Surely less light reaches the camera sensor at high focal lengths and therefore a longer exposure would be required?

[candidrachel]

Hey! I got the Sekonic L-358 for Christmas! Still trying to get my head around it. Sorry I can't help with your question but will look forward to your reply.

[Jim Bryant]

I have a Minolta three light meter that I purchased in the early 80's. I use it for my studio work and to double check my cameras' meter when I'm shooting outdoors......sometimes.
It's just a way to make sure the camera meter is reading the light as I think it should be. Then again, God gave us Adobe Photoshop, and digital RAW images to fix our under or overexposed shots. But, after being in this business for 40 years, old habits don't go away so easily, or bad ones as a matter of fact

[candidrachel]

Actually Jim has a point that with photoshop and raw its not so important to have an external light meter nowadays but I'm not sure my canon 40d is metering properly thats why I persuaded my hubby to buy me an external light meter just to double check! (Also it looks more "pro" when your out and about

[RustySterling]

I've had the Sekonic L358 with the Pocket Wizard module for awhile. I love it. It is invaluable in the studio. I don't use it too much outdoors. But like the OP I know my cameras and can compensate for the quirks of the internal meter. Still, I love the Sekonic in the studio for my strobes.

The Minolta 3 is a great meter. But I remember a segment of a Dean Collins' lecture at Brooks where he said it is "the best meter in the world -- until you drop it. Then it is the stupidest. Once you drop it then it says 'wow, that's bright'. It gives you all kinds of numbers. It's the only meter that will read 'bracket.'" It was a pretty funny segment.

[Jim Bryant]

Originally Posted by candidrachel

Actually Jim has a point that with photoshop and raw its not so important to have an external light meter nowadays but I'm not sure my canon 40d is metering properly thats why I persuaded my hubby to buy me an external light meter just to double check! (Also it looks more "pro" when your out and about

How true, I've managed to fool many throughout the years

[DogHeadGod]

I don't mind using photoshop on my images in general, but because I'm shooting microstock the exposures have to be perfect ...anything other than the slightest tweaks will get rejections on most microstock sites for "artefacting" or "excessive level adjustments".

If anybody knows about the relationship between light meter readings and focal length I'd appreciate your input.

[LoveDSLR]

Originally Posted by DogHeadGod

Now onto the serious question... are light meters set for a specific lens focal length?

Not with the incident meter. Your L-308S reflective meter measures 40 degrees (slightly wider than the viewing field of a normal lens).

Originally Posted by DogHeadGod

The onboard camera changes it's exposure setting as you zoom in or out. Surely less light reaches the camera sensor at high focal lengths and therefore a longer exposure would be required?

That's why L-758 has build-in one degree spot meter.

Originally Posted by Jim Bryant

I have a Minolta three light meter that I purchased in the early 80's.

I have the Minolta IIIF and Gossen Profisix system meter.

[DogHeadGod]

Originally Posted by LoveDSLR

That's why L-758 has build-in one degree spot meter.

Mine came with a little disc attachment, I take it that will allow spot readings? ...(wanders off to find the manual)

[kencaleno]

Originally Posted by DogHeadGod

I don't mind using photoshop on my images in general, but because I'm shooting microstock the exposures have to be perfect ...anything other than the slightest tweaks will get rejections on most microstock sites for "artefacting" or "excessive level adjustments".

If anybody knows about the relationship between light meter readings and focal length I'd appreciate your input.

I believe this is what you want:

How zoom lenses can affect metering

There are two distinct types of zoom lenses
a) Constant aperture zooms, that maintain a fixed aperture when zooming
b) Variable aperture zooms, where the aperture changes as you zoom

Therefore metering with a type b) zoom lens, is trickier than a type a) where the aperture remains constant, when in manual mode
So when you zoom away from the original metered scene, you will need to change the settings, because the aperture will have changed while zooming
So, with an 18-55 zoom lens, which aperture varies from F3.5-F5.6 as you zoom, If you get a meter reading at the 55mm (F5.6)setting, then zoom back to 18mm, your aperture will have changed to F3.5 .
Those two stops difference in exposure will make a noticeable effect on the final image.

Regards, Ken