Back focusing SL1

Mike - wrote:

Has anyone found front or back focusing problems with their SLX cameras (or even checked) ?

Wondering what...if anything Canon might do to help with an older, bottom of the line body.

I've never been overly happy with my SL1. The detail/sharpness has not been very good. I chalked it up to a cheaper body and left it at that. I was checking the micro focus on a new lens on a Sony body, and the SL1 was sitting close by...I thought what the hell, I'll give it a go..! It has a zoom lens on it, so I tried f5.6 - f8 - f11. While f8 was by far the best, I also noticed that it back focuses by a large amount. I tried a second lens (also a zoom), almost as bad.

Unfortunately there is no adjustment in the SL1 like the higher end bodies..!

Experience anyone ?

Mike

I've had very poor focus accuracy, especially at wider apertures, with the 50mm f1.8 STM (two examples) on my 100D (SL1), and 750D (which I no longer have) and indeed my 200D (SL2).  The first two seem OK with kit-level zooms (i.e. smallish maximum apertures), whilst the 200D actually seems a bit questionable overall - I have some milder concerns with its performance with such zooms.  In all three cases, they were fine even with the 50mm lenses in live view mode, which does indeed point to the type of PDAF adjustment issues that would be helped/cured by micro-adjustment, if only they had that feature.  I have also observed a very similar problem with a 50mm f1.8 on a Nikon D5500 - again, it's fine in live view (which also suggests it's nothing to do with user error at the narrower depth of field of wider apertures), so it's by no means an issue confined to Canon DSLRs.  The Nikon also has no micro-adjustment feature (it also has some pretty strong shutter vibration interactions at certain speeds with certain lenses, which is something the Canons are inherently free of, since they use electronic front curtain shutter operation).  Once at a narrow enough aperture in SLR (i.e. PDAF) mode, the 50mm lenses on both brands of camera behave better as the increased depth of field helps to disguise it.

What's never clear with this focus accuracy issue with PDAF is how much is contributed by an issue in the body and how much by an issue in the lens, as it can be variable (presumably sometimes a lens could have its own issue that either compounds the problem, or in some cases lessens it, if the lens problem is in the "opposite direction", so to speak, of the one in the body; or of course there could be no issue at all with the lens itself.  Similarly there must be examples of bodies that have no issue at all as well - though sadly that doesn't seem to apply to any I've owned!).

Do you find that your lenses behave better on the Canon in live view mode too?

I'm old enough to have used film-based SLRs a lot too, and oddly, even when they had PDAF systems configured and designed similarly to current DSLRs, they didn't seem to have this issue.  Doubly strange given that they were full frame, with inherently narrower depth of field (though of course their 50mm lenses were 50mm, rather than equivalent to 80mm [on Canon APS-C bodies] or 75mm [on Nikon APS-C], so maybe that offset the narrower depth of field largely).  Maybe they simply checked them and adjusted them on the production line more stringently then, though some were very cheaply made, so I don't know...