High ISO on 5D (12800 trial)

EdBray

EdBray

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Edward Bray
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I decided to take some images today at 12800 just as a trial

I took the following shot at ISO 12800 (3200 ISO set and -2 stops EC) on my Canon 5D just to see what it was like. Shot 1/2 Taken in a darkish hallway with handheld 100-400L 400mm @ f5.6 1/30sec. I always shoot RAW and Large JPG.

The 1st pic is the large JPG with just auto brightness & contrast adjusted in CS3

The second pic is 100% crop from the RAW file of the same image in CS3 and all I have done is adjust the exposure back +2 stops in the RAW editor.

3rd image is Chloe (loves chocolate, well what girl doesn't?) from raw image, adjusted +2 stops, slightly rotated and cropped. yes I know the liight on the arm is a little hot, but this was just the light coming down the hall from the front door and it was a grab shot. 100-400L at 200mm 1/100 @ f5.6

Okay, I realise this is not for everyday shooting, but to get you out of a tricky spot? brilliant!


shoe.jpg


shoe100.jpg


Ilovechoccy.jpg
 
I am a little confused. You shot at 3200 ISO underexposing by 2 stops, you then brought back those two stops in the raw processing? so....it is 3200 ISO no?
 
So is this not the same as push processing film then?

You use the ISO to enable the shutter speed and aperture that you want to use and then bring it back in processing or have I got this wrong.
 
You can push a digital image by about 2 stops using RAW but the 5D doesn't have ISO12,800. I'm not sure you can claim its ISO12800.
 
petemc said:
You can push a digital image by about 2 stops using RAW but the 5D doesn't have ISO12,800. I'm not sure you can claim its ISO12800.
Click to expand...

Okay then, what would you call it exactly? Pseudo ISO 12,800

The corrrect exposure would have been 1/8 sec @ 5.6 @ ISO 3200
I underexposed by 2 stops which means that the equiv ISO would have been 12,800.

Call it what you want, but if you had set a normal light meter to get an exposure value which gave you a reading of 1/30th @ f5.6 for that amount of light it would show the ISO as 12,800.
 
I would say its been shot at ISO3200 and pushed by 2 stops in RAW. Thats the common way of describing it. I've never seen anyone say its ISO12,800.
 
Thats an interesting idea actually, I may have to do some experiments with my 40D now...
 
wait.....it doesn't sound right.

-2 stop exposure compensation on a digital camera does what ?, reduces the iso sensitivity to 800, then you take it back to 3200 in RAW ?

I dunno, I'm just guessing, it sounds like you can't manufacture iso 12800 sensitivity out of an iso 3200 sensor.

I don't even know what the camera actually does during exposure compensation...:shrug:
 
the exposure compensation has kept the same iso just underexposed by 2 stops, this has been bought back through pushing the raw file by the same amount. Its obviously not real iso 128,000 , but a great way to demostrate the detail you can be revealed back from the 5D images under high iso.

If you have maxxed out your iso setting and still cant get fast enough shutter speeds then underexposing the shot is a good last resort to get a suitable shutter speed.
 
joxby said:
wait.....it doesn't sound right.

-2 stop exposure compensation on a digital camera does what ?, reduces the iso sensitivity to 800, then you take it back to 3200 in RAW ?

I dunno, I'm just guessing, it sounds like you can't manufacture iso 12800 sensitivity out of an iso 3200 sensor.

I don't even know what the camera actually does during exposure compensation...:shrug:
Click to expand...

ISO stays the same at 3200 but the -2ev reading is giving the same reading as if you had set ISO at 12800.

So if you had iso 3200 and 1/60s for a reading, then if you shoot at -2ev at 1/250 the equivalent iso would be 12800 if you push processed in pp.

I think the equivalent in film terms is when you put iso 400 film in and set the film speed dial to 1600 with the intent to push process it to say iso 1600 during development. Do you say you have shot the images at iso 400 or 1600?
 
Underexposed

How ?, there are only 3 things you can mess with, since we want to keep shutter speed and app, it must be iso.

Or it does something else with firmware.
 
EdBray said:
I took the following shot at ISO 12800 (3200 ISO set and -2 stops EC) on my Canon 5D just to see what it was like.
[/IMG]
Click to expand...


I know what you mean and all considered, the the quality of, and the detail in the shots is amazing. Good stuff.
 
petemc said:
I would say its been shot at ISO3200 and pushed by 2 stops in RAW. Thats the common way of describing it. I've never seen anyone say its ISO12,800.
Click to expand...

But if you don't underexpose by 2 stops in camera what are you going to do with it in raw?

Lets put it this way then, if you have a Hassleblad and use a ISO400 film (say HP5) and then using a handheld light meter you underexpose the film by 2 stops (ie you are shooting at ISO1600), you then increase the development time to bring out the image. You have still shot at ISO1600 even though the camera/film 'does not do more than ISO 400'

So I have set the camera at 3200, which gave 1/8 sec @ 5.6 I have then reduced the exposure by 2 stops to give me equivalent of 12,800 ISO which the camera then set 1/30 sec @ f5.6.

If we do this at say ISO 800 for a different light condition then the combination may be 1/4 @ f4 if we then dial in -2 stops of EC and keep the aperture the same then the exposure will be 1/15 @ f4 , if we put the EC back to 0 and change the ISO to get 1/15 @ f4 the ISO will be 3200.

Okay, to prove it I have taken the following two images quickly, one was taken at ISO 3200 1/25 @ f4 and the other was taken at ISO 800 1/25 @ f4 with -2 stops of Exp Comp and the image boosted in the RAW editor by (strangely enough) +2 stops. Exif data is complete. This shows that ISO800 with -2 stops of exposure compensation gives near enough the same shutter speed/aperture combination as ISO 3200 without any compensation. You have to pull in back in the RAW editor though.

ISO1.jpg


ISO2.jpg
 
joxby said:
wait.....it doesn't sound right.

-2 stop exposure compensation on a digital camera does what ?, reduces the iso sensitivity to 800, then you take it back to 3200 in RAW ?

I dunno, I'm just guessing, it sounds like you can't manufacture iso 12800 sensitivity out of an iso 3200 sensor.

I don't even know what the camera actually does during exposure compensation...:shrug:
Click to expand...

Sorry, you're going the wrong way.

ISO3200 - ISO800 is +2 stops exposure compensation (2 stops overexposure)
ISO3200 - ISO12,800 is -2 stops exposure compensation (2 stops underexposed)
 
Where's the crosseyed smiley....:lol:

Knowing what actions the camera takes during EC, would help decide one way or the other.

Can you go further than -2 EC in camera ?
 
You could perhaps switch to manual if you can't go further than -2 ec.
 
joxby said:
Where's the crosseyed smiley....:lol:

Knowing what actions the camera takes during EC, would help decide one way or the other.

Can you go further than -2 EC in camera ?
Click to expand...

Okay, it depends on whether you have AV or TV set.

If you have AV set and you dial in -1 stop of compensation the shutter speed will double to give you a stop of underexposure, dial in -2 stops and the shutter speed will quadruple (-2 x -2) to give you 2 stops underexposure.

so 1/30 sec -1 stop = 1/60 sec -2 stops 1/125 sec

For TV dialling in -1 exposure compensation the aperture will close down by a stop giving you 1 stop of underexposure and if you dial in -2 stops of exp comp then the aperture will close down by 2 stops giving you 2 stops of underexposure.

so f8 -1 stop = f11 -2 stops = f16

For AV, If you dial in +1 stop compensation the shutter speed will half giving you +1 stop overexposure and if you dial in +2 stops the shutter speed will be 1/4 of what you originally had giving you 2 stops of overexposure.

so 1/30 sec +1 stop = 1/15sec +2 stops = 1/8sec

For TV, If you dial in +1 stop compensation the Aperture will open 1 stop giving you 1 stop overexposure and if you dial in +2 stops the aperture will open 2 stops from what you originally had set giving you 2 stops of overexposure.

so f8 +1 stop = f5.6 +2 stops = f4

I do not know what happens in program mode or any fully auto modes with EC as I have never used them in my almost 30 years of photography.

To go further than +/-2 stops you can do it in manual by just under/overexposing from the correct exposure by 3 stops, but in order for it to work your RAW editor has to be capable of bringing the exposure back (the CS3 Raw editor allows up to 4 stops either way).

Hope this helps!
 
Is the focus off on the first door shot or is that the result of the -2EC and +2EC in PP?
 
CraigDouglas said:
Is the focus off on the first door shot or is that the result of the -2EC and +2EC in PP?
Click to expand...

I suspect it's more a case of camera shake. 100mm macro lens at 1/25 no IS. It was only a trial of the exposure not my low light handholding skills. :)
 
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