Digital cameras 101

[Marc Parsons]

Let's say I'm shooting in a shutter-preferred mode, and I select a shutter speed that requires the lens to use its smallest aperture - but the exposure is still 1 stop too light. Will setting the exposure compensation to -1 do anything at all...? or, since in shutter preferred, is the aperture already at its limit therefor cannot stop down anymore to perform the compensation? Would the camera adjust my shutter speed against my preferred setting - or alter the ISO setting?

[Mike54]

Hi Marc and welcome to Digicamhelp,

I'm probably not the best one to try to answer this but I'll give it a go. If your shutter speed is set so low as to force the smallest aperture adjusting the ec probably isn't going to do anything for you. I don't believe the camera is going to adjust your shutter speed (as you've taken charge of that aspect). Since I don't know what you're using for a camera I can't say whether it would adjust the ISO, mine doesn't.  

I'd just adjust the shutter speed back up a setting or two to balance the exposure.

[Deb]

Hi Marc and Welcome to the Q&A Board!

Let me make sure I understand what you're asking ....

If, for example, I set my shutter speed to 1/100 (shutter priority) and the exposure is still too bright at minimum aperture (F29), will an EV adjustment of -1 actually darken my image? Where are the adjustments being made if I'm at the limit of my aperture range in shutter priority mode?

Super duper question Marc!

I've found that on my camera, the exposure settings (shutter speed and f-stop) are listed as remaining the same as does the ISO value. (This info was obtained from the EXIF data for the test images.) The images, however, do darken as I adjust the EV from 0 to -5. So in answer to one part of your question, YES, adjusting EV does affect the final exposure even when at the limit of aperture range (at least on my camera). Take a few test pix on your camera and see if it does likewise.

But what is the camera actually doing? Got me! I'm really intrigued! I suspect it's magic   but I'll put in a query to the Nikon Tech Support and see what they say. I'll post their reply when I hear back.

Cheers!

[Mike54]

Thanks for stepping in here Deb, that will teach me not to try actual pix before responding.

YES, adjusting EV does affect the final exposure even when at the limit of aperture range (at least on my camera).

[Deb]

Hi ya Mike!

I won't claim it will work on all cameras  , but it did on mine. I'm dying to find out what it's actually doing though. These digital cameras sure do have lots of tricks up their digital sleeves. Since I didn't notice any obvious change of depth-of-field, I wonder if it isn't overriding the shutter speed to a faster setting and just not indicating so in the EXIF data. The test shots I took were of a stationary light fixture. It's not bright enough outside here now for me to try it on a moving subject (Utah, my dog). Hopefully, I'll hear back soon.

Toodles for now.

[Deb]

Hello again,

My EV results had me puzzled! I couldn't sleep! Something just didn't feel right. So I ran the test again today using a tripod to ensure that I didn't inadvertently shift the frame. (That'll teach me to delete images. I didn't have them to double-check this morning.)

Here's what I got:
As Mike thought would happen, the shutter speed didn't change, the minimum aperture didn't change, the ISO didn't change ... and the image's exposure DIDN'T change! I suspect what I saw yesterday was a result of NOT keeping the subject perfectly in line with the previous shot. A slight shift (I was photographing that dern light) could have changed the exposure range slightly. I don't have the EXIF data of the old shots to double-check.

I agree with Mike that adjusting the EV won't accomplish any exposure shift (given shutter priority mode and set at minimum aperture). Sorry for the confusion!  

UPDATE: Nikon Tech Support ran a similar test (shutter priority, minimum aperture F22, EV=0) and found no exposure change when the EV setting was adjusted to negative values.