Are 1/2 EV stops 'real'?

eoren1

My Canon 50D offers two options for exposure steps: 1/3 and 1/2. I've always stuck to 1/3 but wonder if there is a reason to not switch to 1/2. My main reason for doing so would be to bracket more easily for HDR shots. In order to get a full range of exposures, I figure I need to shoot at -3 EC at +/- 1 EV then at 0 and at +3. With 1/3 increments, that means 'spinning the wheel' 9 clicks between each set (and potentially moving the camera). With 1/2, I can cut that down to 6 clicks - faster and possibly less movement :dunno
So, any data out there on this 1/2 step?
Thanks,
E

cab.in.boston

You haven't ordered the Promote yet? Or better yet, a Nikon (set 9-shot bracket at 1EV steps, turn on continuous shooting, and hold down button on remote release - shooting stops when bracket is finished)...

Seriously, I can't see why 1/2 stop intervals would be bad, why do you think they might be? You lose granularity, but sounds like for what you need, that's no big deal at all. And you should be pretty solidly locked down on that new tripod, I'd think, so there shouldn't be too much danger in moving the camera.

rsquared

I'm not sure what you mean by asking if it's real... Your shutter speed and aperture are very real measurements (one in time, the other in the diameter of the opening between the aperture blades). There is no reason other than it being unnecessary that they couldn't be adjusted in 1/10th stop increments. Your camera chooses to give you 1/2 and 1/3 options because they are the most practical choices...

So instead of (for instance) shutter speed moving in full stops from 1/60 to 1/30, or in 1/3 stops from 1/60 to 1/50, 1/40, and 1/30 it would go from 1/60 with one inbetween step of 1/45 and then 1/30. Changing aperture works pretty much the same way...

eoren1

Thanks guys
Realized I was thinking aperture the whole time when I should have been thinking shutter speeds!
Of course changing shutter by 1/2 stop would be fine
I was imagining the aperture changing from the standard: 4.0 - 4.5 - 5.0 - 5.6 to 4.0 - 4.8 - 5.6 and was thinking there would be something physically wrong with that concept. I need to look at my camera with each setting and see if i have completely misthought how this would work. On that note though, is there anything 'wrong' with 1/2 stop apertures? In the same line as many believe 'in between' ISO steps are 'not real' and can introduce more noise.
E

ziggy53

I've not heard of any issues with 1/2 versus 1/3 step aperture or shutter settings.

Some (cheap) lenses have apertures that do not necessarily follow the 1/3rd steps reliably. That applies to both aperture automation as well as manual settings however.

eoren1

Actually, never mind those further questions. I'm going to plead temporary, post-lunch insanity and let this thread die

cab.in.boston

eoren1 wrote: »

On that note though, is there anything 'wrong' with 1/2 stop apertures? In the same line as many believe 'in between' ISO steps are 'not real' and can introduce more noise.
E

I can't see why there would be. The aperture adjustment (at least on my lenses, not sure how Canon's mount works) is just a tab that is slid up or down and the blades close with the tab. There are not fixed "stops." The camera should know exactly how far to move it to create any size aperture. As you stop down, I don't see why it couldn't create a circle with 3/4 (1/2 EV) the area instead of 5/6, 2/3, or 1/2...

Matthew Saville

The discussion of the mechanical validity aside, I use 1/2 stops for exactly the reason you quoted originally - why dial three clicks when you can dial two? I like to be able to crank my exposures faster, and I've never really felt a NEED for something as precise as 1/3 stop increments. Heck, my FM2 has WHOLE stop increments!

=Matt=