70D AF Problems?

[unistudent1962]

Hi all,

Is this a problem any Australian 70D owners have experienced?
http://photography-on-the.net/forum/showthread.php?t=1354075

Reportedly it's only an issue with Large Aperture lenses, so it's not something I've had a problem with yet.
While it's popped up on a number of overseas forums I haven't been able to find anything about it on the local forums.

Thanks,
Mark

[ricktas]

You do realise that most cameras will have this issue with lenses at 1.8 etc. The sweet spot for best focus with MOST lenses is the f8-f14 range. Outside that pure optical physics come into play and no lens will be sharper at f1.8 as it will be at f8 if the images are put to pixel peeping.

Also unless you have your lens and camera calibrated to one another (professionally) then discrepancies in focus are bound to happen. Seems to me the people on POTN are seeking out a problem with their camera, that is not really the camera at all, but known limitations of physics and lens manufacturing. Also lenses have minimum focusing distance, if they get objects closer to the lens than that distance, they will not be in focus.

63 pages of chat that is probably about an lens optics issue that has no relevance to the 70D at all, but rather they need to learn more about the basics of lens design, optics, etc.

[ameerat42]

OK Mark, it looks like you might have a legitimate issue here - though limited in its range so far to specific camera models and lenses - but,
could you please present a precis of the problem and save us from having to trawl through umpteen pages of questionably presented posts on another
forum.
Am.

[unistudent1962]

As I said in my original post it's not a problem that I have experienced, but one that I had read about on overseas forums and was left wondering if any Australian users had experienced this problem with their 70Ds.

This thread was directed at 70D owners who may have experienced the problem is outlined in the opening post on POTN.
Unless you have a 70D with that particular problem, or you suspect that you may have that problem, I don't see that there's any need to "trawl" through anything.

If the moderators of this forum consider that it is not relevant, I am more than happy for it to be closed.

Mark

[ricktas]

If the moderators of this forum consider that it is not relevant, I am more than happy for it to be closed.

Mark

Of course it is relevant, if only to keep those newer to photography, informed about lens design and that wide open apertures will generally not produce the sharpest results. I was just surmising that the 'problem' is not really one related to the camera body at all, but to a lack of understanding of lens optics and physics in general. After all I could start a thread that says the D800 has an issue cause my lenses are not as sharp at f1.8 as I had hoped. It is not the D800 that is the issue, it is wide open large aperture lenses.

[johntorcasio]

The 70D suffers from soft center point focusing other focus points seen to be okay ..

[Phil777]

John, do you have a reference for this "soft center point focusing" at all? (Whatever that actually means)