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How do I compensate by 50 ISO on a light meter?


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850ISO is the base iso on my camera where I get the most dynamic range.

The issue is that my light meter only has 800 ISO and not 850 ISO.

I can use the exposure compensation on my light meter (i can adjust by 1/10th of a stop at a time) to try and sort this (I hope) but I am not quite sure how to work that out,

Wondering if anybody could help me sort this issue out? Thanks!

 

 

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When I had a C100 I just rated it at 800 ISO. I was mostly using still lenses then though so I figured the t-stop f-stop difference was darkening the image more than the extra 50 ISO was brightening it. I notice when people shoot by eye on the C300 etc. they tend to overexpose (or maybe not I dunno) so I think overexposing a bit is fine. 

Edited by M Joel W
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Shot at 850 and metered at 800. The 850 ISO setting always seemed a little "off" to me. With the internal codec, shadows sometimes got blocky, and it was safer to overexpose than underexpose. And that is such a trivial difference anyway.

I suspect most  people using these cameras are overexposing more often than not. There's a whole school of thought (ETTR) that encourages it, but I don't buy into that. On the other hand, I used to rate the F5 around 800 ISO or 1250 ISO instead of 2000 ISO too.

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Posted (edited)
16 minutes ago, M Joel W said:

Shot at 850 and metered at 800. The 850 ISO setting always seemed a little "off" to me. With the internal codec, shadows sometimes got blocky, and it was safer to overexpose than underexpose. And that is such a trivial difference anyway.

I suspect most  people using these cameras are overexposing more often than not. There's a whole school of thought (ETTR) that encourages it, but I don't buy into that. On the other hand, I used to rate the F5 around 800 ISO or 1250 ISO instead of 2000 ISO too.

Thanks! Its interesting because I am wanting to expose to the right as I feel its useful for my c100 (its a camera that likes a lot of light) but first I just want to ‘calibrate my meter to my camera’  (make sure my meter’s middle grey and canons recommended ire for middle grey in Clog’ is the same).

 

I guess i dont really need to know how to compensate for 50iso, i can just meter it at 800 and just use exposure compensation till the meter gives me what I want. I just thought it might be something useful to learn though and cant find much info on it online!

Edited by imran qureshi
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If I'm not mistaken 850 ISO is almost exactly 1/10th of a stop faster than 800 ISO. 857 ISO?

But I just rated my camera at 800 ISO. 😕

So if you want to do things right my guess would be to correct by 1/10th of a stop. But in my experience the camera doesn't love underexposure and most photo lenses are slower than their stated f-stop so I just set my meter to 800 ISO and went with it. 😕

Edit: I don't really believe in ETTR but I do believe in slightly overexposing some cameras. I dunno, I don't shoot much anymore. I think you can find online where different cameras put middle gray and different log profiles place it quite differently. I really like the Canon Log image from the C100 a lot but do find the codec a bit thin in the shadows sometimes.

Edited by M Joel W
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41 minutes ago, M Joel W said:

If I'm not mistaken 850 ISO is almost exactly 1/10th of a stop faster than 800 ISO. 857 ISO?

But I just rated my camera at 800 ISO. 😕

So if you want to do things right my guess would be to correct by 1/10th of a stop. But in my experience the camera doesn't love underexposure and most photo lenses are slower than their stated f-stop so I just set my meter to 800 ISO and went with it. 😕

Edit: I don't really believe in ETTR but I do believe in slightly overexposing some cameras. I dunno, I don't shoot much anymore. I think you can find online where different cameras put middle gray and different log profiles place it quite differently. I really like the Canon Log image from the C100 a lot but do find the codec a bit thin in the shadows sometimes.

Ahh if it is 1/10th of a stop faster that is my answer! Thanks

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A difference of 50 ISO (ASA) doesn't actually mean anything without a reference point. 

50 ISO to 100 ISO for example is a whole stop difference, while 800 ISO to 850 ISO is a small fraction of a stop ( I calculate it to be 0.87 of a stop - so even less than a tenth). 

Here's a graph of ISO/ASA numbers showing third stop increments, which are normally the only ISO settings available in digital cameras:

photography-iso-chart.thumb.jpg.cc6fdd6621e1e0d1f76554c3f98a2cf4.jpg

I'm surprised Canon chose to have an non-standard ISO 850 setting in the C100, given how close it is to 800. Does it really make any difference to the DR? A tenth of a stop would be less than the assembly tolerance of even high end cine lens aperture scales, and many lenses would have more play than that just in the aperture mechanism. 

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44 minutes ago, Dom Jaeger said:

A difference of 50 ISO (ASA) doesn't actually mean anything without a reference point. 

50 ISO to 100 ISO for example is a whole stop difference, while 800 ISO to 850 ISO is a small fraction of a stop ( I calculate it to be 0.87 of a stop - so even less than a tenth). 

Here's a graph of ISO/ASA numbers showing third stop increments, which are normally the only ISO settings available in digital cameras:

photography-iso-chart.thumb.jpg.cc6fdd6621e1e0d1f76554c3f98a2cf4.jpg

I'm surprised Canon chose to have an non-standard ISO 850 setting in the C100, given how close it is to 800. Does it really make any difference to the DR? A tenth of a stop would be less than the assembly tolerance of even high end cine lens aperture scales, and many lenses would have more play than that just in the aperture mechanism. 

I get .087 stops too but rounded up to .1.

As I mentioned, I just rated at 800 ISO. Maybe it was something to do with fudging the over/under. Or just where something landed? I believe the camera has 800 ISO as an option, too, but 850 is considered native.

Anyway, it's a nice camera!

Edited by M Joel W
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