Losing patience with a DSLR...

Ray Heath said:

yeh, isn't most of that what i said?

why your "never" recompose comment?

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Recomposing after focus lock is to move the focus plain, and therefore cause less then critically sharp focus. The whole point of multi focus points is so that one does not have to recompose. Recomposing can also throw off metering too. Of course if one shoots at F5.6 or down from there, recomposing is less an issue, because of the fatter depth-of-field.

Most DSLR users don't know how to use their multi-point cameras. Even those having 10+ years with Nikon or Canon. Strange.

Hi

Rob Ruttan said:

I've had an EVolt 500 for about a year. Truth to be told, it's the first auto focus camera I've ever owned,

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ok ... its a paradigm shift I know. I still remember my first conference shoot with an EOS 630 and being frustrated that I had to center everything to focus and make damn sure that I didn't put someones cheek in the AF spot or it'd hunt and not even allow me to take a shot!

Rob Ruttan said:

Here's what's bugging me: in what I consider to be reasonable low light conditions (early evening, cloudy, aiming toward stuff in my garden...so I'm pointing away from the sky) it won't manual focus.

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I guess that you mean it won't Auto focus?

Rob Ruttan said:

Would any auto focus DSLR behave the same way, or is my EVolt sort of wimpy in this regard? The answer -- switch to manual -- is pretty obvious, but I find that the manual focus ring does very little.

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well, perhaps its because you're looking at a much smaller viewfinder and using a much wider angle lens than normal? I mean that I find it hard enough hand focusing my 24mm (even on my old Pentax MX) let alone try this with a 18-55 zoom.

Rob Ruttan said:

In bright daylight conditions, the camera does wonderful stuff. But take a small step away from the norm and it seems to call it quits. My ancient Minoltas -- film and manual focus that works -- do what I want when I want. Why not my EVolt?

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one reason is the point about the wider angles and the darker smaller view finders. Another is that some cameras AF sensors work differently with different f lenses. The wider the aperture the more contrast they can get. Also were you working with live view (focuses with a different system altogether if I recall).

If the light is low, then perhaps use just the central AF point
Just a few suggestions.

Hi

SilverGlow said:

Most DSLR users don't know how to use their multi-point cameras. Even those having 10+ years with Nikon or Canon. Strange.

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most people don't know how to change gears in a bicycle properly but that's not the bike makers fault

wrt the multi point AF, well do some tests and don't be stunned if you don't get focus exactly where you want it. I've found that (with my 10D and Tokina 12-24) that multiple 1/2 presses of the shutter (and the camera not altering focus anymore still result in less than optimal focus in the off center points. Heck with my 20D I got different results even with just the EF50 on different focal points.

Back ages ago (like 1990's) I tested my EOS 630 with only a single focal sensor and then checked focus with a ground glass on the film gate and found that I could do better by eye in the screen than it could at f1.8 This issue resolved itself when stopping down to f5.6 or smaller. I could not do follow focus on a runner (approaching me) with my USM lens anywhere near as well as it could though.

so ... swings n round abouts

I know this doesn't help, but perhaps it helps to manage expectations?

Hi

jens g.r. benthien said:

That means that digital is no real progress:

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if you mean digital in terms of AF systems well ... yes and no. Its like having an assistant, you have to learn to work with the assistant. Some people can't do that and are always over worked / late / missing things. I find that for some applications I use AF (sports and kids) and for others use manual focus.

I've leand to use my multi af points as if they're a moving split image, but to be honest I don't think its soooooo different to using my center and recomposing. The difference may be there but there are other potential errors that may make it similar anyway.

pellicle said:

Hi
I've leand to use my multi af points as if they're a moving split image, but to be honest I don't think its soooooo different to using my center and recomposing. The difference may be there but there are other potential errors that may make it similar anyway.

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When shooting close to your subject, and fast in aperture, you can be sure that locking focus then recomposing will throw off critical focus. If one has low standards one does not see much difference. For me, critical focus is very important. Do you know how thin the DOF is with a 50mm prime at 20 inches from the subject and at F1.4 or F2? Too thin to recompose and expect critical focus. Why not just learn to manually pick & choose the appropriate FP and use the camera as intended?

As to digital and progress wtih AF, well DSLR's often use the same logic and/or mechanism for AF as SLR's for respective companies.

Hi

SilverGlow said:

Do you know how thin the DOF is with a 50mm prime at 20 inches from the subject and at F1.4 or F2?

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I do ... but then I rarely use it at such, I often stop down to f5.6 or 8 because at 20 inches the background will still be blurred

and (as I mentioned conferences) I was thinking of a 200mm at 8 meters.

SilverGlow said:

Why not just learn to manually pick & choose the appropriate FP and use the camera as intended?

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I guess you didn't read what I wrote then ... I'll post it below even though you already quoted it.

I've leand to use my multi af points as if they're a moving split image,

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pellicle said:

Hi



I do ... but then I rarely use it at such, I often stop down to f5.6 or 8 because at 20 inches the background will still be blurred

and (as I mentioned conferences) I was thinking of a 200mm at 8 meters.



I guess you didn't read what I wrote then ... I'll post it below even though you already quoted it.

I've leand to use my multi af points as if they're a moving split image,

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Ok, but are you MANUALLY picking the appropriate focus point? And if so, are you not recomposing after locking focus? Even at F5.6 and 20" from your subject, recomposing can soften critical focus.

Hi

SilverGlow said:

Ok, but are you MANUALLY picking the appropriate focus point? And if so, are you not recomposing after locking focus? Even at F5.6 and 20" from your subject, recomposing can soften critical focus.

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yes, that's correct, I move the focus points with (on my camera) a thumbpress and a quick wheel to get the one I want. But I only do this to move to the extreme focus points as the cluster more or less around the center is of such little arc that its hardly worth it.

Also (for what its worth) I find that my camera occasionally front or back focuses anyway, something not obvious in the puny APS sized finders of my 10D or 20D ... I prefer the finder on my trusty old EOS 630 (which only has one focus point anyway ;-)

I've found USM lenses lessen this effect, but (say) on my EF 50 1.8 its quite notorious for it.

Well, front/back focus issues with even L lenses and all the Canon DSLR's are an on going problem. This is the bane of Canon, and perhaps the other makes. I've finally got my stable of lenses spot on, but it took years, and packages to Canon service. My 50L F1.2 still has issues however. I think no amount of calibration will mitigate it's issues; a design flaw that started during the blueprint drawings. Unlike the other L primes, the 50L does not use a floating design (idiots).