D700 + Auto ISO + Aperture > 2.8 = Overexposure

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xil3

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Jon
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I was out taking some shots today, and had it set to Aperture Priority and Auto ISO on.

My minimum shutter speed setting with the Auto ISO on is 1/80 and max ISO is 6400. With that in mind, I was shooting fine with my aperture set at 4 (which was using an auto ISO of 200 and 1/125 shutter speed) and all was great...

As soon as I switched my aperture to 8, the shutter speed dropped to 1/80 (which is normal) and the ISO shot up to like 640 (normal, except that it went up too high...) - after taking the shot it came out overexposed, and I have no idea why it's not metering properly...

Is it expecting me to use a lower aperture because of the lighting situation (with auto iso on)?
 
Any Nikon experts out there have any clues?
 
Did you change your focus point between shots?

The D700 (overly IMHO) biases exposure towards the active focus point.

TBH I find the D700 meters too hot, I run mine at -0.3EV or often -0.7EV
 
Can't really comment without seeing your shots and which metering mode you were using....

PD seems to be correct about D300/D700 metering though - I am using a permanent -0.3ev adjustment on mine (another neat Nikon feature! - the adjustment, not the overexposure problem that is LOL)
 
I was using the matrix metering mode.

It just boggles me that this was only an issue when I bumped the aperture up to the point where the auto iso had to kick in and adjust itself...

But like I said before, it may expect me to be using the lowest possible aperture in low light conditions if I have the auto iso enabled, and therefore confuses the light meter...?
 
I've never been 100% convinced auto ISO always does the right thing.

Nevertheless if you plot out an exposure triangle - shutter, aperture and ISO, it generally IS correct.

Personally I suspect you just got a random over-exposure and the fact that you used AutoISO is incidental.
 
Yeah, it doesn't seem like a major issue, and I'm sure they'll fix it in a future firmware upgrade...
 
So ISO 200, 1/125th, f4.... you closed it down to f8, that is 2 stops which assuming the light remained constant (and the metering also thought it remained constant!)... now two whole stops of shutter speed would be down to 1/30, in fact one stop down would be 1/60 which is less than 1/80.

So the ISO needs to go up two (whole) stops to compensate, which is ISO 800. So its gone 1 and 2/3 faster. So there must be a change in light metering or its got it wrong :)

It becomes confusing because usually you are setting things by less than whole stops with shutter speeds and ISO....
 
Never used auto ISO, or auto W/B for that matter, every once in a while I got variation, its easy to set manually, I can't see the point in either really.
I did set my D70 @ -0.3 ev when shooting whites in strong light, all depends on the subject.
 
AutoISO is a superb feature and you are really missing out.

Think of it as ISO Priority (a bit like aperture or shutter priority), and it'll make sense.

One of the best (and most mis-understood) Nikon features IMHO.
 
I use it nearly all the time, as it allows you set your aperture for correct DOF and shutter for min lens length
 
puddleduck said:
AutoISO is a superb feature and you are really missing out.

Think of it as ISO Priority (a bit like aperture or shutter priority), and it'll make sense.

One of the best (and most mis-understood) Nikon features IMHO.
Click to expand...

Agreed, particularly with a camera like the D700 where you can add auto iso and iso settings to the custom menu so turning autoiso is very easy when you need to. I use it 99% of the time, lets me worry about aperture and shutter speed which are much more important to me.
 
I've never played with it until this evening after discussing this earlier.... You know I *think* this might be a winner for some stuff I do... but its impossible to tell indoors at night...
 
Another vote from me for the autoISO, started using it for my indoor stuff and in situations where the light suddenly changes I can keep on shooting without having to step up followed by the inevitable forgetting to come back down.
 
I think I found the problem!!

Out of curiosity I replicated the same tests with my 50mm f/1.8..

- auto iso on
- iso minimum shutter speed 1/60
- iso max 6400
- aperture priority on
- 1 shot at 2.8 aperture
- 1 shot at 4 aperture
- 1 shot at 8 aperture

All 3 shots were metered perfectly!

Now, I popped on my tamron 28-75 and tried the exact same shots...

It was fine at 2.8, tad bright at 4 and visibly overexposed at 8... and you can imagine how much worse it gets when i stop it down more...

So this is starting to look like a problem with the aperture on that specific lens... am I correct to assume this?
 
xil3 said:
I think I found the problem!!

Out of curiosity I replicated the same tests with my 50mm f/1.8..

- auto iso on
- iso minimum shutter speed 1/60
- iso max 6400
- aperture priority on
- 1 shot at 2.8 aperture
- 1 shot at 4 aperture
- 1 shot at 8 aperture

All 3 shots were metered perfectly!

Now, I popped on my tamron 28-75 and tried the exact same shots...

It was fine at 2.8, tad bright at 4 and visibly overexposed at 8... and you can imagine how much worse it gets when i stop it down more...

So this is starting to look like a problem with the aperture on that specific lens... am I correct to assume this?
Click to expand...

Not really :D Perhaps you have solved your problem, but I and others still have it. Not an issue for me, -0.7 is fine :D
 
EdinburghGary said:
Not really :D Perhaps you have solved your problem, but I and others still have it. Not an issue for me, -0.7 is fine :D
Click to expand...

But why would it be fine on the nikon 50mm and totally off on the tamron 28-75 (when stopped to 4 and past)

It just seems like the aperture isn't setting itself properly on that specific lens
 
Surely Xil's experiment would suggest the actual aperture value of the Tamron was cock?

ie it says its letting in f8's worth of light, but actually its wider than f8.

Obviously the metering is done by the body but if it asks the lens for a value but doesn't get it...

Never heard of a problem like that with a lens before, but am prepared to accept it might be the case...
 
It's funny that i just noticed this recently, cause I have mainly been shooting wide open with that lens (low light shots), so I never really got to test it properly at all apertures...

I think i'm gonna bring it back to Jacobs tomorrow...

This is the first time I bought tamron and it's not a very good impression - at first i thought it was great - the shots were really sharp and crisp wide open (2.8-4).. but past that all overexposed as I recently found out..

I need to more thoroughly test a lens before i buy it next time
 
Can you see anything like that though? Just out of curiousity...
 
puddleduck said:
AutoISO is a superb feature and you are really missing out.

Think of it as ISO Priority (a bit like aperture or shutter priority), and it'll make sense.

One of the best (and most mis-understood) Nikon features IMHO.
Click to expand...


Nope, I use ISO priority effectively, every time I shoot the thing, I can't think of a situation where noise was irrelevant.
I don't want iso buggering about into noise land under any circumstances, I think you'd need a low noise body to get any kind of use out of it at all.
 
iv,e just got the magic lantern dvd ,and the guy on this says DON,T use the auto iso! yet you guys say its great now i,m totally confused:shrug: surely not knowing what iso the camera was setting would be like walking around with a camera (film) and not kowing what asa film you were using
 
dinorock said:
iv,e just got the magic lantern dvd ,and the guy on this says DON,T use the auto iso! yet you guys say its great now i,m totally confused:shrug:
Click to expand...

Try it then? Its awesome, a fantastic feature. On the D700 and D3, the noise is not an issue for the types of photos I like when using this feature.


Some examples:

http://www.flickr.com/photos/scottishsnaps/3083628690/

http://www.flickr.com/photos/scottishsnaps/3077853697/

http://www.flickr.com/photos/scottishsnaps/3083991709/

http://www.flickr.com/photos/scottishsnaps/3103246953/

http://www.flickr.com/photos/scottishsnaps/3104076516/

http://www.flickr.com/photos/scottishsnaps/3103244857/


Go see Pete Carrs stuff, he uses it to great effect.

Gary.
 
EdinburghGary said:
Try it then? Its awesome, a fantastic feature. On the D700 and D3, the noise is not an issue for the types of photos I like when using this feature.


Some examples:

http://www.flickr.com/photos/scottishsnaps/3083628690/

http://www.flickr.com/photos/scottishsnaps/3077853697/

http://www.flickr.com/photos/scottishsnaps/3083991709/

http://www.flickr.com/photos/scottishsnaps/3103246953/

http://www.flickr.com/photos/scottishsnaps/3104076516/

http://www.flickr.com/photos/scottishsnaps/3103244857/


Go see Pete Carrs stuff, he uses it to great effect.

Gary.
Click to expand...

not having a go at you but, these are all night shots and, i would have adjusted my iso accordingly .or are you saying it just cuts out the need to do this and lets you get on with taking the shots (nice shots by the way).
 
EdinburghGary said:
Try it then? Its awesome, a fantastic feature. On the D700 and D3, the noise is not an issue for the types of photos I like when using this feature.


Some examples:

http://www.flickr.com/photos/scottishsnaps/3083628690/

http://www.flickr.com/photos/scottishsnaps/3077853697/

http://www.flickr.com/photos/scottishsnaps/3083991709/

http://www.flickr.com/photos/scottishsnaps/3103246953/

http://www.flickr.com/photos/scottishsnaps/3104076516/

http://www.flickr.com/photos/scottishsnaps/3103244857/


Go see Pete Carrs stuff, he uses it to great effect.

Gary.
Click to expand...

Dude, what sort of camera hax are you using?!
 
Like I said earlier, I've yet to test it in anger, but I have been currently doing the same thing manually - using manual mode and then adjusting the ISO to get the exposure, but with a sensible limit...

Works ok for motorsport...
 
desantnik said:
Like I said earlier, I've yet to test it in anger, but I have been currently doing the same thing manually - using manual mode and then adjusting the ISO to get the exposure, but with a sensible limit...

Works ok for motorsport...
Click to expand...

To be fair I used to do exactly that. Just with Auto, I can set a max ISO and a MIN shutter speed, and forget about it. Either way works, manual is fine. Just slower i guess?

I used manual for about 6 months, only recently started using Auto.

Gary.
 
puddleduck said:
AutoISO is a superb feature and you are really missing out.

Think of it as ISO Priority (a bit like aperture or shutter priority), and it'll make sense.

One of the best (and most mis-understood) Nikon features IMHO.
Click to expand...

I never understood why this wasn't a semi-automatic option like Av or Tv (or Sv for Nikon users I think). Setting 2 of the 3 factors and letting the camera decide on the third was the way I learnt about the effects of altering the different settings without screwing up too badly
 
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