Back button focus

[bigbassloyd]

Originally Posted by JimThias

How can you even see this scale on TOP of the lens when you're looking through the viewer and focusing on the subject?

The same way I can see the timer on top of my 6d while mounted on a 6 foot tall tripod during long exposures at night?

Stupid of Canon to not include the back lcd timer on the pro bodies as seen on their cheap ones..

But I digress.

Loyd L.

[Dennis A. Livesey]

After I got the following shot by luck, I was telling Tom Nanos my woes about focusing and he told me of the Canon AF-On back button technique.

PhotoID: 386268 Photograph © Dennis A. Livesey-liveseyimages.com

You must set up in the camera menu to stop focusing via the shutter button and allow only for the rear focus button to do it.

In this type of shot, use a powerful flash light. The one I used was one of those cheap, large "million candle power" light you get at a hardware store. With it, light up the place on the track you want the engine focussed, use a camera focus point on that shot, cross hatched type focus point preferably, and press the AF-ON. Then do not touch that button or the lens again and viola tack-sharp image.

BTW, infinity and hyperfocus focusing depend entirely on several factors properly calculated. The size of the sensor, the lens mm, the lens aperture, and the focusing distance all determine what will be in focus.

At the distances, lighting conditions, and mm's we shoot out for a wedgie, you were pretty well set focus wise in the film days with setting your manual focus lens a little short of the Inf mark.

With my first auto focus camera, I learned on an expensive lesson. I whipped the 50mm all the way to infinity I thought. Well, i truly went "To infinity and Beyond" and those images were out of focus and quite worthless. I learned to not use the AF lens scale and just use the AF function and double check with looking in the viewfinder.

[Ron Flanary]

This is all over my head...

[Dennis A. Livesey]

But Ron I 'sprained it very simply.

THIS is over your head.

"Panavision Platinum with the 11-1, 100-275mm, 8'6" to 11'8", 85ND3, 24FPS, 180 degrees, T2.8, ECN 5219, Matte Box, Mienardus Sunshade, Panahead on the Hybrid. Later to the Arri 435 and 120 FPS on the OConnor, etc, etc, etc."

[JimThias]

Originally Posted by Ron Flanary

This is all over my head...

[bigbassloyd]

Originally Posted by Dennis A. Livesey

But Ron I 'sprained it very simply.

THIS is over your head.

"Panavision Platinum with the 11-1, 100-275mm, 8'6" to 11'8", 85ND3, 24FPS, 180 degrees, T2.8, ECN 5219, Matte Box, Mienardus Sunshade, Panahead on the Hybrid. Later to the Arri 435 and 120 FPS on the OConnor, etc, etc, etc."

What is filming an outdoor adult movie scene?

Loyd L.

[Ron Flanary]

Originally Posted by Dennis A. Livesey

But Ron I 'sprained it very simply.

THIS is over your head.

"Panavision Platinum with the 11-1, 100-275mm, 8'6" to 11'8", 85ND3, 24FPS, 180 degrees, T2.8, ECN 5219, Matte Box, Mienardus Sunshade, Panahead on the Hybrid. Later to the Arri 435 and 120 FPS on the OConnor, etc, etc, etc."

Sure...but can you transpose from Eb to Db on a Bb trumpet?

[JRMDC]

Originally Posted by Ron Flanary

Sure...but can you transpose from Eb to Db on a Bb trumpet?

Sure ... but can you ...

...

...

nope, got nothin'. I guess I lose the internet today.

[Dennis A. Livesey]

Originally Posted by Ron Flanary

Sure...but can you transpose from Eb to Db on a Bb trumpet?

I can say with some authority one should never B flat with any musical instrument.

[Ron Flanary]

I'll have to read up on this back button stuff. I'm sure it's within my grasp once I know what it is, and why it's important.

[JimThias]

Originally Posted by Ron Flanary

I'll have to read up on this back button stuff. I'm sure it's within my grasp once I know what it is, and why it's important.

Your pre-digital days...was the focus control on the shutter button of your film cameras?

[Dennis A. Livesey]

Originally Posted by JimThias

Your pre-digital days...was the focus control on the shutter button of your film cameras?

Yes.--------

[JimThias]

Originally Posted by Dennis A. Livesey

Yes.--------

The last 35mm film camera I used was in 2000 for a few days and I think it was manually focused. Prior to that, I think it was 1984 when I had last touched a 35mm camera.

[Ron Flanary]

OK....I actually went back and read this thread (well, most of it). I simply prefocus at a determined spot, as Jim explained. If I'm using a zoom and pull back, I do so to a point ahead of where the train is at the moment, and prefocus (on a specific spot on the track) to the point where I intend to trip the shutter. That's how I've done it for eons, even before auto-focus.

As for night shots (what few I've done), I used a small light placed at the focus point to establish focus. I then move the light, and do the shot. That's how O. Winston Link did it (though I'll quickly note, I'm no O. Winston Link...).

You can get in trouble, as Dennis noted, going to infinity on a 50mm lens. I have boxes of just slightly out of focus shots ("soft") shot on dark days (film) with a wide open or nearly wide open aperture. You should pull back a smidgen to get a crisp shot (or as crisp as you could get it under those conditions).

[denvillerailfan]

I got used to it from chasing my kids in various sports, now I use it full time no matter what - I love it so much I found myself pressing the back button to focus my manual focus lenses... then I'm like WTF...
AI-Servo back button only, want to focus, press the button, already focused, dont touch anything...

[lalam]

May be this is a dumb question for Nikon users. There are 5 options for AF-L/AF-E key. Which one is correct for back button focusing?. I have selected AF-ON(last one). But does it need AF-L key be pressed along with shutter release or press it just once and I can remove my finger from it while pressing the shutter release. Thanks in advance.