What is the native ISO of a Canon 5D Mk3 ?

[jimsphotography]

Hi,
Does anybody know the native (true) ISO of a Canon 5D Mk3 ? Im not talking about its base or lowest ISO but the ISO at which there is no electronic manipulation of boosting (or decreasing) the output image signal. I have a figure of approx. ISO 400 in my head but Im not sure if that is true or not.
Thanks
James

[Papathanassi]

Re: What is the native ISO of a Canon 5D Mk3 ?

I may be wrong but I think I read it was 160!

Papa.

[Tigger]

Re: What is the native ISO of a Canon 5D Mk3 ?

Hi,
Does anybody know the native (true) ISO of a Canon 5D Mk3 ? Im not talking about its base or lowest ISO but the ISO at which there is no electronic manipulation of boosting (or decreasing) the output image signal. I have a figure of approx. ISO 400 in my head but Im not sure if that is true or not.
Thanks
James

never heard about this - would be interested to hear the outcome. I'd like to think it was 400 but I suspect lower, maybe 200

[jimsphotography]

Re: What is the native ISO of a Canon 5D Mk3 ?

never heard about this - would be interested to hear the outcome. I'd like to think it was 400 but I suspect lower, maybe 200

Shooting at (or near) the native ISO produces the least artefacts and noise. Turning up (or down) the ISO does NOT alter the sensitivity of the camera to light ( this is fixed by physical factors) but merely amplifies the signal - rather in the same way if you turn an amplifier up too much you get distortion.
Hope this helps
James

[Tigger]

Re: What is the native ISO of a Canon 5D Mk3 ?

very clear thanks James

[AndyMulhearn]

Re: What is the native ISO of a Canon 5D Mk3 ?

This may be of interest...http://photo.stackexchange.com/quest...anon-5d-mk-iii

[Sarawak]

Re: What is the native ISO of a Canon 5D Mk3 ?

There seem to be similar questions being asked elsewhere on the interweb. You're not thinking of going over to Fuji are you?

[Papathanassi]

Re: What is the native ISO of a Canon 5D Mk3 ?

This might be of interest,

http://home.comcast.net/~NikonD70/Charts/RN_ADU.htm#EOS%201D%20Mark%20IV_14

Papa.

[jimsphotography]

Re: What is the native ISO of a Canon 5D Mk3 ?

There seem to be similar questions being asked elsewhere on the interweb. You're not thinking of going over to Fuji are you?

Yes - that was me ( I think) - I own a Fuji XT-1 as my carry everywhere camera. The images from it a truly astounding despite its small weight and size and the optics of the lenses are up their with Canon L lenses.
I tend to keep my heavier Canon gear for extreme weather conditions, wildlife / action shots and where the end result must be totally spot on. The Fuji system although brilliant ( even at high ISO) - it is not so well weather sealed and does not focus as fast as a good DSLR. I feel sure Canon will be significantly upgrading its M system to see off these contenders from Fuji and Sony - they tend to be the sort of company that likes to be top dog etc.

As for the links to further information some of you provided - a big thank you for that - very interesting indeed.
James

[Sarawak]

Re: What is the native ISO of a Canon 5D Mk3 ?

We have been away over Xmas with some friends who have a XT-1. Like you I think the images are astonishing.
I didn't try it where fast focus was needed, but I am really impressed with it as a second camera. I'm so impressed that I've started looking for where to get one, although His Lordship will probably want one as well!

[antoeknee]

Re: What is the native ISO of a Canon 5D Mk3 ?

Full review of the Fuji here http://www.dpreview.com/reviews/fujifilm-x-t1

Sounds quite a good piece of kit. Body is also described as weather-restraint.

[DrJon]

Re: What is the native ISO of a Canon 5D Mk3 ?

100
(Which DXO measure as 80 but that is the way the work it out rather than a fact - not that there is anything wrong with that either.)

http://www.sensorgen.info/CanonEOS-5D-Mark-III.html

http://www.clarkvision.com/reviews/evaluation-canon-5diii/index.html

Happy New Year
John

[DrJon]

Re: What is the native ISO of a Canon 5D Mk3 ?

The more technical version is either look at the full well capacity (which goes down with amplification as otherwise it would go over the top of the digitiser) or with Canon just look at the read noise. Canon adds a lot of noise off-sensor but the effect of this goes down with ISO amplification, so just look for the noise peak. (BTW ISO 50 is a synthetic mode made by throwing away highlight room, note the measured ISO doesn't change from ISO 100. A lot of cameras also do this at high ISOs, where as ISO climbs they hit a point after which they keep shooting at that high ISO and just underexpose more and more then compensate for it when making the JPEG or in the Raw converter.)

The even more technical version is you can see the noise is added after the (off-sensor) ISO amplifier by the way the read noise reduces at higher ISOs. What happens is the signal gets amplified more and more as ISO goes up so the noise gets to be a smaller part. For example if you have captured 1,000 electrons and have (say) 10 electrons of noise added after the amplifier that gives about 1% noise to signal (10/1010). However if you crank the ISO so the 1,000 electrons is multiplied by 16 then it's still 10 electrons noise so about 0.06% signal to noise (10/16010).

DXO has 33.6 electrons of read noise at ISO 100 and 3.1 electrons at ISO 3200 (they are the sum of the sensor read noise and the off-sensor stuff).

P.S. A number of Canon cameras make the intermediate ISOs by just under/over exposing the full-stop ISO so they aren't real either. Hence ISO 160 is ISO 200 over-exposed and ISO 250 is ISO 200 under-exposed (the Raw pixel data would be identical for all three, the Raw file just contains a different note about the ISO to use when processing).

P.P.S. There is an argument the 5DmkIII native ISO is a little bit away from 100 rather than exactly that. I wouldn't worry about it as you'd have to use Magic Lantern to get any closer to it.

[jimsphotography]

Re: What is the native ISO of a Canon 5D Mk3 ?

Thanks - that was a very detailed account & very much appreciated.
James