Fumbled my 50D / 400L

[philthejuggler]

Hi all,

I think all is well, but just checking -

I fumbled my 50D with the 400L attached when picking it out of the drawer it lives in. It dropped about 2 inches & kind of rolled off the edge of the drawer & landed in a nice soft bin full of paper & stuff.

I've taken a few shots & all looks perfect - I've heard of Canon's surviving drops of several feet onto concrete so I wouldn't expect a problem, but is there anything in particular I should check for?

Many thanks

Phil

 

[HoppyUK]

If you're worried Phil, you might have knocked something off-centre. That will show up as one or more corners of the image being softer than the others.

Try shooting a distant target like a car number plate at the end of the road - high shutter speed, high ISO, lowest f/number. Tripod and mirror lock-up if you can't get 1/2000sec to be clear of camera shake with that lens. Lock exposure in manual, focus with deadly accuracy and lock that in manual too.

Then shoot four pictures with the target in all four corners of the frame - they should all look the same. You can do it on the LCD on max magnification as if anything is wrong it will probably stand out immediately. If you have to squint and scratch your chin wondering, it's probably fine. If you've knocked it out, you'll see it right enough. You're not looking for ultimate sharpness at all, and TBH you probably won't see it as it's a tough test especially on full frame, you're only looking for consistency.

Shoot quickly as if the light changes and the sun comes out/goes in, it changes everything as well as exposure.

 

[philthejuggler]

Thanks for the advice - will test later. I took a few shots where I focussed mid frame on an object and then shifted slightly to move it to the corners and all looked fine. I guess that focus / recompose is not the best plan as it can intoduce focussing errors. Actually, would a brick wall parallel to the camera back be a good idea?

Phil

 

[Canon Bob]

I believe that a skewed element causes the frame to drift as you focus. Find a nice, well defined target like a lamp post against the sky and then defocus each side of sharp. If an element is not perpendicular to the plane of focus then the post will drift left-right or up down as you turn the ring (do it in landscape and portrait for each axis).
IS lenses may exhibit this if the IS doesn't park perfectly so it's not a good test on these but should be valid for your 400L.

All that said, this kit is very robust and I doubt you've anything to be concerned about.

Bob

 

[HoppyUK]

Thanks for the advice - will test later. I took a few shots where I focussed mid frame on an object and then shifted slightly to move it to the corners and all looked fine. I guess that focus / recompose is not the best plan as it can intoduce focussing errors. Actually, would a brick wall parallel to the camera back be a good idea?

Phil

Not really. A two-dimensional surface is as much a test of field flatness as anything, which is very rarely a problem but might show up in that test, because you'd be at relatively close range. Having said that, if you have set it up dead right you would see more softness in one corner if things were out optically, but you'd also see the same thing if you weren't absolutely dead square.

When you think about it, shooting a distant fixed target and positioning it in the corners of the frame is exactly like shooting a massive brick wall, but with the benefit of distance you will minimise any field curavature and focusing errors.

 

[philthejuggler]

Many thanks both for the advice - I had a play and can't see any issues & a local camera repair shop has had a glance at it and all seems well. They said an obvious indication of likely damage would be loss of smoothness on the focussing ring (which is fine in my case).

I'll try your suggestion Bob but I think (and hope) all is well - it was a minor impact.

Phil