what's wrong with my lens?

sturisoma

sturisoma

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my nifty fifty is no longer focusing...not sure if it's the lens alone or the lens-camera combined. the camera is fine with my other lenses.

questions

1. is it a focusing fault
2. is it something I could fix
3. what about calibrating the lens
4. other ideas

thanks in advance

:(


error by moominmama, on Flickr
 
If your camera is working with other lenses I'd say it's a pretty safe bet that the problem is just with the one lens you have a problem with.

If it's the really cheapo Canon 50mm I'd be asking myself if it was worth fixing but you could always get a quote and then decide.
 
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yeah it was 2nd hand too, so not worth an expensive repair, was just hoping it might be calibration or something. I could always just use manual but I'm short sighted and the dioptre isn't strong enough to compensate lol; I can't shoot with my specs on...
 
Is that the full frame or a crop?
 
Have you put a uv filter on the front of the lens? It could be that the filter glass is not sharp.
 
the picture is as it came out of the camera - using a 50D so not FF if that's what you mean David. I didn't have a filter on. The camera/lens started misbehaving part way through a shoot so something must have gone 'ping' if you know what I mean :(
 
No.. that's not what I meant. I mean is the image cropped at all.... is that a part of the image blown up, or is that the entire image?

If it's the entire image, then yes, looks like it has a focus issue. How does the camera focus with other lenses? If it's fine, then it's probably a lens issue. You could try AF fine tune, or whatever the Canon equivalent is. There are loads of threads on here about how to go about that.

It's probably not economical to repair a used 50 if it turns out to be a lens fault though.
 
It may sound silly, but have you flicked the AF/MF switch to MF?
 
thanks David -

the camera is fine with my other lenses.

the pic is as it came out of the camera


I tried flicking the AF/MF and also cleaned the contacts on the lens. It makes 'I am focusing' noises, and the focus looks fine in the viewfinder (not forgetting my poor eyesight), but when I look at the 'playback' in camera it looks awful :(

I think something must have malfunctioned tbh - wish I knew what.
 
That's at 1.8.. is it still as bad stopped down?

Either way... should be better than that. If it's not been dropped, banged or otherwise abused, I've no idea.

Have you updated camera firmware? Maybe it's changed AF adjust settings.... I@m clutching at straws now though.

As it was a used 50... I'd just replace it if AF adjust can't fix it.
 
I haven't tried changing the aperture tbh - will give it a go when I get home :)
 
If it's no better at different apertures I would think it's the lens that has gone. Might be worth looking at a replacement, you could even have a look into a 50 f1.4. They have a far better build quality and mine is very good, even wide open. You could also have a look into the equivalent Sigma lens as that's very good as well.
 
Is it the same with a more contrasty surface? eg an edge of something with a background at a further distance?

If it's the cheapo canon 50mm then bin it and get another. They're notorious for being not very durable.
 
Yeah, doesn't the 50D have Micro-focus Adjustment? Give it a whirl, you may be surprised! Use one of those focus test grids.

[EDIT] Also, from which part of the image is this crop taken from? The 50mm f/1.8 is very sharp in the centre but softer around the edges.
 
this isn't a crop Eddy

it's the same for other contrasts too Suz

thanks for all replies so far - am away to check other f stops
 
ok it seems to be a problem only at f3.0 or wider, which is annoying because the reason I bought the lens was so I could use it at 1.8 (*sulk*). however, it used to work fine at this level...
 
liveview, mmm, you mean through my PC? will give it a go. If it does what would that imply?
 
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