Mirror Slap

My 50 mm lens the focus ring is so sensitive, while using it in live view I get focused and just removing my fingers from it can sometimes throws focus out of whack.
I was wondering if the mirror moving out of the way of the sensor (mirror slap) could be throwing the lens out of focus.
T3i.

I decided to do a test, set my camera on a sturdy tripod, camera set to AV mode, camera auto focus off, turned the adjustment ring, perfect focus in live View, I pressed the shutter button half way and the news paper moved in the live view screen, let off the button it moved again, what's up with this

Well if you are actually pressing the button on the top of the camera, I don't care how good your tripod/head combination is you will be moving the camera a little. When using LV there is zero possibility of mirror slap though, the mirror is already up to enable the LV to work, so there is no mirror movement.

Alan

If you're getting movement is might be from the shutter, although I find shutter to be dampened really well on DSLRS. On mirrorless cameras it is more severe since they dont have a mirror box to take the sudden movement, also makes them really loud. on my 7D I can handhold 1/5 no problem but on my EOS M 1/30 is pushing it.

BigAl007 wrote in post #18115852
Well if you are actually pressing the button on the top of the camera, I don't care how good your tripod/head combination is you will be moving the camera a little. When using LV there is zero possibility of mirror slap though, the mirror is already up to enable the LV to work, so there is no mirror movement.

Alan

Thanks BigAl007
Forgot to mention I was using wireless triggers, I was pressing the button on the camera at first then I switched on the triggers

Update I tested LV and you are right the mirror is locked in LV.

maverick75 wrote in post #18115883
If you're getting movement is might be from the shutter, although I find shutter to be dampened really well on DSLRS. On mirrorless cameras it is more severe since they dont have a mirror box to take the sudden movement, also makes them really loud. on my 7D I can handhold 1/5 no problem but on my EOS M 1/30 is pushing it.

Thanks maverick75
In the custom settings I set it to mirror lock up, the thing I've noticed when I press the button to take the picture I hear the mirror flip up then I have to press the button again to take the picture, I'm still wondering if the mirror opening could cause the sensitive focus ring to move focus ever so slightly.

DigitalDon wrote in post #18115713
My 50 mm lens the focus ring is so sensitive, while using it in live view I get focused and just removing my fingers from it can sometimes throws focus out of whack.
I was wondering if the mirror moving out of the way of the sensor (mirror slap) could be throwing the lens out of focus.
T3i.

I decided to do a test, set my camera on a sturdy tripod, camera set to AV mode, camera auto focus off, turned the adjustment ring, perfect focus in live View, I pressed the shutter button half way and the news paper moved in the live view screen, let off the button it moved again, what's up with this

From this description......is IS turned off? I have seen this kind of behavior when I forgot to turn off IS and had the camera on a tripod.

saea501 wrote in post #18116378
From this description......is IS turned off? I have seen this kind of behavior when I forgot to turn off IS and had the camera on a tripod.

Thanks, I hadn't though about that, I will give it a try, just turned off IS and that fixed it imagine doesn't move, problem solved, thank you, thank you, thank you.

DigitalDon wrote in post #18115934
Thanks maverick75
In the custom settings I set it to mirror lock up, the thing I've noticed when I press the button to take the picture I hear the mirror flip up then I have to press the button again to take the picture, I'm still wondering if the mirror opening could cause the sensitive focus ring to move focus ever so slightly.

One would think that if mirror slap shifted lens focus enough to be an issue, we would have a lot of out of focus shots...after all, even when AF with no manual focus intervention, shots should be shifted out of focus then, too.

DigitalDon wrote in post #18115713
My 50 mm lens the focus ring is so sensitive,

Shouldn't the focus ring be a little tighter and require just s bit more effort, to stabilize it?

chuckmiller wrote in post #18117022
Shouldn't the focus ring be a little tighter and require just s bit more effort, to stabilize it?

I would think so, I don't know how to explain it, nearest thing I can think is, its not as severe as a lose filter or filter holder but it close to it. My other two lens the rings are snug.
The 50mm is a canon I bought it on eBay from China I think at the time I bought it the American Canon was a lot more expensive.
Thank You chuckmiller for replying to my post.

Wilt wrote in post #18116645
One would think that if mirror slap shifted lens focus enough to be an issue, we would have a lot of out of focus shots...after all, even when AF with no manual focus intervention, shots should be shifted out of focus then, too.

Makes sense to me thanks Wilt

DigitalDon wrote in post #18116386
Thanks, I hadn't though about that, I will give it a try, just turned off IS and that fixed it imagine doesn't move, problem solved, thank you, thank you, thank you.

Most welcome. Glad you got it sorted out.

saea501 wrote in post #18117428
Most welcome. Glad you got it sorted out.

There's probably a simple explanation for why the image moves, but, nothing is simple for me ߘ

DigitalDon wrote in post #18117432
There's probably a simple explanation for why the image moves, but, nothing is simple for me ߘ

It's not very simple. The IS system can cause minute vibrations of it's own when operational. Sitting on a tripod the only vibration would be caused when we touch the camera or tripod. IS responds within .0002 of a second and as the lens group moves to make the correction it generates minute vibrations of it's own thereby triggering an additional correction and a sort of feedback loop which can be seen through the lens as movement.

That's odd. I didn't think that any of Canon's 50mm lenses had IS on it.