aperture priority, min shutter speed, auto iso, +exposure comp possible?

Started by outlawrocketman, March 29, 2017, 06:50:46 PM

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outlawrocketman

Hi, saw a 2012 discussion about this but nothing more recent. New to ML and trying to figure it all out.  Appreciate any help.
Trying to do this:
Canon 6D
Set Aperture to F8 (for best photos from Tamron 150-600)
Set min shutter speed (say 200)
Have camera meter and have ISO float to the point that the exposure is correct.

Sounds a lot like manual mode with auto iso, BUT, I'd like to be able to exposure compensate (for example birds in flight where I want 1/2 or 1 stop more light).

Appreciate any thoughts on how to do something like this!

--Peter

simonm

Have you tried ETTR? I haven't used it yet, but it sounds like just the tool for the job.

I can see where you're wanting to go with this, but there are several things that mean auto-ISO may not be as necessary as you might think:

If your birds are in flight, at a rough guess, you probably need 1.5 or 2 stops extra exposure (over average metering, NOT spot measurements), BUT the lighting against the sky will be pretty constant. So your actual exposure won't change a great deal.

I have a 6D too, and its low light performance is outstanding. Given that, I'd just set the ISO somewhere in a sensible middle range for this sort of thing, say around the 2000 mark, use aperture priority and try some test shots with static subjects like the tops of trees, in similar light conditions to what you expect with a moving target. You might even find you can still get decent image capture at f/8.

And try ETTR, obviously. Note that it's about getting the best image file technically: it will probably look over-exposed initially - you need to post-process it properly into a good printable (or whatever) image. The whole point of it is to make best use of the sensor and file's dynamic range, so as to preserve shadow detail (which is what you are after, in this case).

Key thing is to experiment where/when nothing matters. You'll be concentrating on the bird's behaviour when doing it for real, so you don't want to be thinking about the technicalities.

PS:i find I'm using zebra exposure bars with live view more and more doing stills work. It's a great way to understand how bright the highlights are, and what I can safely allow to go 'over' - might be worth playing with too, but live view does thump the battery rather hard.

garry23

This is always worth a read: http://www.clarkvision.com/articles/iso/

The fact is that above a certain ISO our (Canon) cameras enter the ISOless region.

Exposure strategies below that are different to those above it.

Cheers

Garry

outlawrocketman

Thanks much for the feedback.

Simon yes I usually shoot as you suggest (aperture with ISO sent reasonably).
Sounds like I shouldn't let ISO totally float, thanks Garry will give that a read.

Haven't spent much time in live view but will play with that eventually.

I tried ETTR about a year ago (maybe it's better now). I recall that it would keep shooting until it had the right shot?  Drove me nuts as I wasn't sure when it was done shooting...

--Peter

garry23

With the latests 4K announcements from A1ex I think we will see a lot of video related posts. I don't do video so it's great to have this past to talk about still photography  :)

If you read the Clarkevision info, you get drawn to the following ML exposure strategy/hiearchy, at least on my 5D3.

1. Use ISO 100 with ETTR for as long as you can, then
2. Use ETTR with higher ISO up to, say, eg 1600, also
3. Consider using Dual up to X/1600, then
4. If you find yourself needing to go above ISO1600 for your base ISO, then adopt an ISOless exposure strategy.

It would be great to hear if other still photographers, have other thoughts.

Cheers

Garry