My idea for a new "auto-Av" mode

Instead of inputting an f-stop value yourself, input the depth of field that you want to achieve and let the camera figure out what the distance to subject is. You'd also need to input the output size, viewing distance and viewer's visual acuity.

How would it work? Let's say that you want to end up with 16x24" prints viewed from 3' by a person with 20/20 vision, so you enter those numbers into the camera. The camera will know the distance to subject and the circle of confusion already. You just select that you want a 6' depth of field, for example, and the camera will figure out the f-stop for you.

Benefit? When I am photographing an individual that is not stationary, I need to constantly change the f-stop based on their distance. If I want just the person to be in focus to get that awesome background separation, I'll use f/1.4 for full body shots, f/2.8 for half-body, and f/5.6 for head/shoulders. If there was a mode like the one described above, I could just set all the variables ahead of time and not have to change any settings as the person moves closer or further. If another person joins the first and I need a 3' depth of field, I just make that change once and continue shooting.

What do you think? Would this be a useful feature?

So, what was in Eye Controlled Focus (used on some mid-1990 EOS cameras) as described below would be the next step?

There was another feature within ECF and without getting out my manual or Elan I may be sketcy on the details. There was a way that when you looked through the viewfinder and "eye" selected a focus point on the furthest point, then the nearest point, and then looked at a symbol in the upper left corner, the camera detected a range of focus. The camera would then automatically set the aperture for the needed depth of field as defined by the two points (near and far), assuming the lens could deliver the aperture computed. There was some special way to do this; not sure but it may have been as simple as selecting aperture mode.

I'd rather have pizza slot and a coffee spigot.

The problem is that the reported distances from the lens are NOT very precise! I took a series of distance measurements at ever increasing distances with 70-200 f/4 L IS lens, with at least 2-3m more distance between each point measured.

1.6.3m
2.8.76m
3.8.76m
4.10.3m
5.12.6m
6.12.6m
7.16.3m
8.16.3m
9.16.3m
10. 25.3m
11. 25.3m
12. 4294967295 (virtually infinite)

Then I took another series to determine how far is Infinity
Continuing the experiment, nine shots
1. 16.3m
2.-5. 25.3m
6.-9. virtually infinite (first of these readings was at about 190')

You idea itself is OK, but what about the already existant DOF mode?!

John from PA wrote in post #16627976
So, what was in Eye Controlled Focus (used on some mid-1990 EOS cameras) as described below would be the next step?

There was another feature within ECF and without getting out my manual or Elan I may be sketcy on the details. There was a way that when you looked through the viewfinder and "eye" selected a focus point on the furthest point, then the nearest point, and then looked at a symbol in the upper left corner, the camera detected a range of focus. The camera would then automatically set the aperture for the needed depth of field as defined by the two points (near and far), assuming the lens could deliver the aperture computed. There was some special way to do this; not sure but it may have been as simple as selecting aperture mode.

Isn't that exactly what A-Dep mode does in Canon DSLRs?

I never use it myself, but doesn't that work by selecting the near and far focus points and letting the camera set the aperture etc., for the correct DoF?

I always wondered what a dep was

I will stick with the pizza holder and coffee spout and selecting aperture as well.

No, at least not by tracking eye movements. In ECF when you looked through the viewfinder at a point, the camera automatically focused on that point. Look at a different point, then focus changed. It wasn't perfect but worked very well for many of us.

John from PA wrote in post #16628093
No, at least not by tracking eye movements. In ECF when you looked through the viewfinder at a point, the camera automatically focused on that point. Look at a different point, then focus changed. It wasn't perfect but worked very well for many of us.

Well, no, not by eye movement obviously, because we don't have ECF (which I tried but hated as I habitually look around the viewfinder to check for intruding objects when shooting).

What I meant was it does the same thing using the AF points, except for how you pick the points. You still select near and far points to get the camera to set the required DoF.

Wilt wrote in post #16627993
The problem is that the reported distances from the lens are NOT very precise! I took a series of distance measurements at ever increasing distances with 70-200 f/4 L IS lens, with at least 2-3m more distance between each point measured.

1.6.3m
2.8.76m
3.8.76m
4.10.3m
5.12.6m
6.12.6m
7.16.3m
8.16.3m
9.16.3m
10. 25.3m
11. 25.3m
12. 4294967295 (virtually infinite)

Then I took another series to determine how far is Infinity
Continuing the experiment, nine shots
1. 16.3m
2.-5. 25.3m
6.-9. virtually infinite (first of these readings was at about 190')

You idea itself is OK, but what about the already existant DOF mode?!

I was afraid of that Wilt. I wonder how Canon actually calculates distance...

So what is this DOF mode? Where do I find it?

Have you tried looking up A-Dep mode in your user guide?

Wilt wrote in post #16628257
Have you tried looking up A-Dep mode in your user guide?

Yes, it's not there. I think Canon abandoned this mode on the 5D series.

I think with enough experience you'll know instinctively what aperture you need to use for adequate depth of field. If not (or you think you need to be more precise), get yourself an app or keep a chart in your pocket.

Personally, I tend to fall into the camp of needing either very little, some, or a lot. Those approximations mean I can guesstimate and say to myself, "okay f/2 will work here..." or "I think f/5.6 is good" or "dammit I need the tripod."

I have NEVER thought "I need exactly 12.75 feet of depth of field in this here photograph and it'll only be printed at 8x10 and I'm at 35mm...etc etc." Maybe it's because I never know what the final output size will be. Or maybe because it's IMPOSSIBLE to know what someone's visual acuity is. Maybe it's because there will be more than one viewer so even if I know one person's visual acuity, that doesn't mean anything for everyone else. People also look at the same photos from different viewing distances so that blows precision right out of the water.

So basically try to get everything in focus that you want in focus and don't worry about it.

xarqi wrote in post #16627987
I'd rather have pizza slot and a coffee spigot.

Extra-sharp cheddar and Glenlivet 18.

Doesn't CA (creative-auto) sort of work like that? I've never really used this mode, but from what I gathered from reading the manual that's sort of what it's for.

EverydayGetaway wrote in post #16628406
Doesn't CA (creative-auto) sort of work like that? I've never really used this mode, but from what I gathered from reading the manual that's sort of what it's for.

No, Creative Auto (CA) is sort of a "wizard" mode... the camera gives you brief tutorials to walk you through the settings. It's a good learning tool initially, but too slow for regular use.

A-Dep worked... sort of. The problem is it tends to be overly conservative. That was because of Canon's definition of the "circle of confusion", which was smaller than it needed to be.

The way you used A-Dep was to focus twice... once on the closest subject you wanted in sharp focus and the second time on the more distant... then the camera would determine what aperture was necessary at those working distances with the focal length being used.

However, because of the parameters programmed into and used by the camera, DOF usually ended up greater than I wanted. I could have "kluged" it a bit... setting the closest focus a little farther away and the farthest focus a little closer to compensate. But it was easier and a lot faster to just learn how particular apertures perform at various distances with different focal lengths and to eyeball the hyperfocal focus point. Doing that I blow it sometimes, but usually those times when it's really critical I know to check what I'm getting and can reshoot if I need to.