Loose bayonet fitting on Canon lenses

Started Apr 13, 2007 | Discussions
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rlshep Senior Member • Posts: 2,112
Loose bayonet fitting on Canon lenses

How much play is 'normal' with Canon lenses - in terms of the bayonet fitting to the body?

My 300mm F4 IS has noticeable play in it - hardly life threatening but I can move it enough to see/hear it. I don't have this with my other 2 lenses or the TC.

I got it s/h mail order so can't actually demonstrate to the shop and I don't want to be over fussy but equally I've no idea if this is normal, acceptable or of any concern at all. Not something I've had with previous systems.
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Petteri Sulonen Forum Pro • Posts: 24,585
Probably normal...

The bayonet is designed to have a small amount of slop in it -- enough that you can feel it if you rotate the lens by the barrel. It has to do with the sweeping action on the electronic contacts, or so I've heard.

However, if the lens slops vertically or side to side, you have a problem: the slop should be rotational only.

Petteri
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rlshep OP Senior Member • Posts: 2,112
Thanks

I'm guessing it is just fine - it's not wobbling or anything - just I'm aware of it and it grates a bit as I'm not used to it - but no doubt I will be in no time!
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Lizzie
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netgarden Forum Pro • Posts: 10,770
Often wondered if it was the cause of...

btw, my 300f4 has a small amount of slack, and I wondered it it didnt play a role in the teleconverter +300 misfocusing alot. I now clean all the contacts, and make sure nothing is tweaked away from the contacts. I seem to get much better autofocus % with the 1.4x plus I had my 300 recently calibrated, which back focusing was exaggerated with distant shots. Now it all works smoother..
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cyberstudio
cyberstudio Regular Member • Posts: 493
Re: Loose bayonet fitting on Canon lenses

You should have no play perpendicular to the sensor plane (there are leaf springs to make sure the lens sits tight in that direction), but movement parallel to the sensor plane is normal. The idea is that while the optical axis of the lens has to be critically aligned within itself, it is not necessary to align that with the center of the sensor.

If they make everything perfectly tight, you won't even be able to attach or detach a lens except with great force.

rlshep OP Senior Member • Posts: 2,112
Re: Loose bayonet fitting on Canon lenses

Thanks all - any movement is very much lateral - it a little twist round rather than away from the body - so I think it is fine - I'm just a bit pedantic so I tend to notice these things...!

I'm still not 100% sure everything is focussing 100% as it could - but think it's either down to me or possibly the camera - doesn't seem to be particular to one lens. More likely it's due to the fact I'm trying new things (not having to worry about expense of film) and with my Pentax 645 I was manual focussing more often than not. Think it's just getting used to new gear.

I love the results when everything is right - just need to cut down on the things I'm doing wrong I think. Certainly the quality and intensity from the 5D and L lenses is way closer to my medium format trannies than I could get from my previous dSLR - which was the whole idea of changing....
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