Overexposure at higher ISOs

[arun_seetharam]

<p>Just searched the forum and didnt find this issue discussed.<br>

What I am finding is my D700 overexposes a bit at hier ISOs. More so at ISOs greater than 800. I know there is a bit of a loss in the dynamic range but some seem a bit too much. It is a new D700.<br>

From what I understand, The pictures at should look somewhat similar in exposure as you increase the ISO. For convenience sake, Lets take the apperture or shutter priority mode and 3D Matrix metering. Colors may change slightly.<br>

Is this an incorrect understanding? Do I need to watchout for something else or adjust some setting apart from this? Does the camera need calibration?<br>

Indeed appreciate your thoughts on this.<br>

Thank you<br>

Arun</p>

 

[rodeo_joe1]

<p>Firstly check that you're just not running out of shutter speed. If you use Aperture Priority mode and the camera reaches 1/8000th of a second, then anything brighter than that is going to overexpose. Similarly there's a limit to the minimum aperture available in Shutter Priority mode.</p>

<p>Although the D700's metering does have a tendency to overexpose IMO (see thread below), I've never noticed a variation with ISO speed. But then I never use active D-lighting, which may well interfere with how bright the image is rendered as the ISO setting is changed.</p>

[eric merrill]

<p>Use manual mode. Make sure you're comparing apples with apples instead of some other fruit. :)</p>

<p>If I were concerned, I would keep the shutter speed constant and change aperture and ISO. Then, keep aperture constant and change shutter speed and ISO. This will help rule out variations in accuracy for shutter speed and aperture.</p>

[arun_seetharam]

<p>Basically, pictures taken with different ISOs should all look alike, assuming the lightmeter is zeroed in and metering is matrix.<br>

Upto ISO 6400 at least.<br>

Isn't that a correct assumption?</p>

 

[SCL]

<p>It's only correct if you have the range of shutter speeds and apertures available to you, as noted above, but if you're photographing the same object with iso 200 & 6400 (5 f stops), you may have run out of either shutter speed or apertures depending on your initial settings, and then the camera will expose the shot as best it can.</p>

[mike_halliwell]

<p>My D700's exposure 'accuracy' seems to falter when ISO goes over 1600 AND the shutter goes over 1/2000. Now those circumstances are pretty weird, but I begin to doubt my shutter at those speeds and higher.</p>

<p>It's done over 90000 actuations and I think the high end is 'slowing down', leading to over-exposure.</p>

[bebu_lamar]

<p>very high shutter speed are generally not accurate and tend to be longer than marked speed. The modern shutter although electronically controlled at high speed the mechanical elements play the major role in accuracy.</p>

[rodeo_joe1]

<p>Maybe I've been lucky with my D700 shutter, but setting the aperture and shutter manually I get consistent exposures right up to 1/8000th; i.e. if I set f/2 and 1/8000th I get the same image brightness as at f/2.8 and 1/4000th, f/4 and 1/2000th etc. Making a small allowance for lens vignetting of course.</p>