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EOS 350D and Canon 50mm f1.8

Started Dec 14, 2014 | Questions thread
WilbaW
WilbaW Forum Pro • Posts: 11,643
Re: EOS 350D and Canon 50mm f1.8

ZX11 wrote:

WilbaW wrote:

Susan S. wrote:

my copy of the 50 1.8 generally front focuses a bit, but also will pick something infront or slightly behind the plane of focus-it is particularly fond of almost invisible stray hairs. or it will focus on nothing at all.

A typical 50/1.8 provides ambiguous light to the AF sensors (the most likely culprit is spherical aberration, which is high with that lens). It make it hard for the system to accurately and reliably determine where focus should be. Also results in the typical overall image softness we see with that lens wide open.

Could this ambiguous light thing be a problem with the canon 50mm f1.4?

I haven't tested one, but AFAIK the 50/1.4 is much better behaved.

I am trying to figure out what it needs to hit focus more accurately.

A typical 50/1.8 focusses in two places regardless of whether either of them is in "accurate" focus or not. To fix a genuine accuracy problem you generally need some form of calibration, either through Canon service or AF microadjustment.

I am starting to think I need to ditch the lens filter on it and install a hood as one step in improving the keeper rate when wide open.

Good first step.

If that doesn't fix it, post some images in a new thread and we can let you know how it looks.

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