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-   -   Focus problem (https://www.dvinfo.net/forum/canon-xh-series-hdv-camcorders/502150-focus-problem.html)

Philip Younger October 30th, 2011 05:34 PM

Focus problem
I've been asked to shoot a meeting and one sequence will require that two people be in the frame one sat close to the camera, he other approx 5 feet further back.

They want me to shoot seemlessly with narrow depth of field so that while speaker A is speaking, speaker B will be out of focus and vice versa. I will need to quickly and accurately move from one point of focus to the other without any visual sign of me peaking or otherwise getting it wrong in one go!

I've been practising marking points on the focus ring but I can't master quickly changing from one focus to the other, when I get the speed I inevitably get camera movement, furthermore if the guy in the background suddenly decides to lean forward and rest his arms on the table, my pre-marked positions will be out.

Is there a pro trick or tip in doing this with better results?

Matthew Amirkhani October 30th, 2011 06:53 PM

Re: Focus problem
Hi Philip,

Are you going to use a 35mm lens?

Chris Soucy October 30th, 2011 07:44 PM

Re: Focus problem

Originally Posted by Philip Younger (Post 1692650)
.............if the guy in the background suddenly decides to lean forward and rest his arms on the table, my pre-marked positions will be out.

A loaded .45 on the table adjacent to your right hand might solve this one.


...Is there a pro trick or tip in doing this with better results?
Without a non servo lens with proper focus stops, (which won't fit on any A1/ G1), no, not really, and even then, you'd still need that .45!


Les Wilson October 30th, 2011 08:20 PM

Re: Focus problem
Maybe you'll have better results with Olof Ekberg's zip tie and paper tape technique ... look closely at the focus ring on his EX3 in this photo


David Dalton October 31st, 2011 01:26 AM

Re: Focus problem
Have you tried the focus preset described at the bottom of page 35 of the manual?
If the camera is on a tripod, I've found it to work very well.
There are 3 focus speeds that can be used.
Of course, it won't work if the people move out of position.

Chris Soucy October 31st, 2011 03:04 AM

Re: Focus problem
Uh, David.............

If I may?

The "Focus Preset" is about as much use as an ashtray on a bicycle under the circumstances outlined, where one party can simply stop speaking and the other take over.

Do you realy think you'd have the time to reprogram it before the switch, for EVERY switch?

Jolly good luck, mate.

If they want "High Drama" video, they better have "High Cost" video written into the contract and "High Maintenance Talent" sourced as well.

You know, the sort that don't need the loaded .45 to keep them on their marks.

They want "Quality Video" they're going to have to pay way more than for an XH A1!



Richard Gooderick October 31st, 2011 04:29 AM

Re: Focus problem
I have an XHA1 but would use my 5D for this.

There is a very useful app for mobiles, ipods etc call pCAM. It costs about 20. You can use it to work out your field of view and depth of field with different combinations of fstop and lenses.

This will help you set the shot up the way you are being asked so pulling focus from one speaker to the other should be more predictable.

The 5D has a massive ISO range. If you use this, a fast lens and a Fader ND you should be able to cope with just about any lighting situation and still control your DoF.

The 12 minute maximum for each clip on the 5D might be a problem. Depending upon what you are filming and whether you can stop and start the camera in order to keep your clips to less than 12 minutes.

Bo Sundvall October 31st, 2011 05:13 AM

Re: Focus problem

Or film the talents in full focus and manipulate the focus shift in post...

Just an idea. :-)



Mark Ahrens October 31st, 2011 05:30 AM

Re: Focus problem
The focus preset would work for one position but the second focus target would have to be done manually. If you had an HD monitor hooked up, i would think you would be able to pull it off . . . depending on how quickly the dialogue goes back and forth.

Would one of the subjects have their back to the camera?

Roger Van Duyn October 31st, 2011 06:07 AM

Re: Focus problem
Bo's idea would cost the least and also simplify the shoot. And really, the subject matter is what makes or breaks talking head videos. If the target audience is interested in the subject, just make sure the person speaking is in focus and the audio is crisp and clear. Really for TALKING head stuff, the audio is most important, next to whether or not the audience finds the subject interesting, or boring.

People don't usually watch talking head video stuff, no matter how well we shoot it, unless they have a compelling reason to watch it, such as their employer requiring them, or a test being given after the lecture.

You could work yourself to death trying to nail all that pulling focus, for nothing. That's the closest I can give to a "pro trick." I'm in business, charging for the work, so in that sense, I'm a professional. If they want me to work that hard, it's going to cost a lot more. I might even need to tack on a rental fee for another camera, since I really wouldn't even want to attempt that kind of shooting with my A1.

Actually, I do have a pro tip for you. Offer them two bids, one with all the focus pulling, and one without it.

I find pulling focus to be difficult. When I need a clip or two with that effect, I simulate it in post. Plus at my age, with my eyesight, I don't enjoy even watching clips going in and out of focus. I get that effect all the time in real life with my progressive lens glasses every time they slip a little on my nose. Very annoying.

Don Palomaki October 31st, 2011 07:44 AM

Re: Focus problem
Maybe try two camcorders in very close proximity, one focused on each, and cross disolve as necessary?

Philip Younger October 31st, 2011 06:43 PM

Re: Focus problem
Thanks for all the replies.
No, not using 35mm just a 'out-of-the-box' G1.

I did think about two cameras but there is the perspective shift swapping from one 'head' to another. I did do a practise shot and will give this as one option to the company commissioning the video, but I wasn't impressed. Although I've just thought maybe having the cameras further away from the subject and zooming in may narrow the perspective sufficiently....... I'll play with that idea tomorrow.

Today I have been working with post production techniques and found a compromise effect which I will also present.

Fortunately, the company are aware of the technical difficulties as they got an astronomic quote from another video production company which is why they came to me - so that has worked to my favour. What is annoying is that this is really quite a short section within the film and I can't see why it is so necessary - I think perhaps someone saw the technique used somewhere and thought that 'That looks good'.

Unfortunately I live in the UK so getting my hands on a .45 is not going to be easy :-) We Brits do not have the right to take up arms - Oh no, if we are confronted by a crazed junkie wielding a large blade we have to make do with saying "Now look hear old man, kindly place that weapon down and we'll chat about your needs over a nice cup of tea". Always works! but if you Yanks start adopting that idea police dramas just won't have the same impact! so you carry on as you are!

Les Wilson October 31st, 2011 09:02 PM

Re: Focus problem

I took for granted that you knew that camera has to be moved away and zoomed in to get a shallow depth of field. Here's an article explaining the issue:
Depth of Field Myth

Your challenge I think is more the distance between the subjects. That is, once you've gotten the shallowest DOF your camera is capable of, the OOF subject needs to be further away than the area in focus.

Roger Van Duyn November 1st, 2011 02:33 PM

Re: Focus problem

Maybe I'm misunderstanding the issue. Are you just pulling focus once for each of the two speakers, or is it a sequence where you need to "ping-pong" back and forth between the two, pulling focus each time? If so, how long a sequence are you talking about? 30 seconds? Five minutes? Longer?

Pulling focus is something to be used sparingly. Like once per presentation. It can be very impressive. But the second time it's used, it loses that "wow" effect. Used repeatedly, it will get old to the audience viewing the video very, very quickly. It could even make some people feel "seasick." Does the client understand this, that it could ruin the entire video?

So the other company gave an astronomical quote... as in they were hoping the client would go somewhere else?

Philip Younger November 1st, 2011 06:15 PM

Re: Focus problem
Les: Yes I've been practising today and have got much better results being some 20-25 feet from the nearest speaker and by blacking out the background - that really improves the effect, I've also played with he idea of a little zap of slo-mo in post which absorbs the motion shift further.

Roger: The sequence is not being over used that would make people dizzy - if not sick! During a conversation of approx 5 minutes the focus will change from the main to secondary speaker no more than 3 to an absolute maximum 4 times.

Chris: I had another idea for the .45 (assuming I could get one) that being to use it on the art director who's idea this shot sequence is!

Seriously though I think that with a little bit of post and two cameras I am getting a pretty good compromise

Tobin Strickland November 2nd, 2011 12:39 PM

Re: Focus problem
I wonder if you could just simulate it in post with Andy's region blur... just move the blur back and forth...

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