Another Focusing Issue - Snap Zooms

[Matt Sturns]

I have another focusing problem with my camera. I had the dreaded backfocus issue, my EX3 has since been brought in and fixed (given a new lens which fixed the problem). Now I am having a different focusing issue. When I am doing snap zooms I go in on the object focus, pull out, and then when I go back in on the object it is drastically out of focus again. Tried powering down camera but having same problem. Any ideas. thanks

[Serena Steuart]

Do you have the lens in AF or MF setting? In snap zoom will hold focus in MF but not in AF

[Duncan Craig]

Seconding what Serana suggests.

Leaving the lens in Full MF on my EX1 is the only way to get the zoom effect to work properly, I can see the image going soft in the middle of the zoom at medium speeds so I have to do it quite fast or much slower.

But it's effective enough for my needs: Here's an advert going to air today in the UK: http://www.duncancraig.co.uk/Burgess...3-040-h264.mov (the zoom out is the penultimate shot)

[Matt Sturns]

Thanks guys that seemed to do the trick. Stupid question what is the difference between the the different focusing modes. On the lens you can pull out for different focusing modes? What does pulling out the lens do? There is an asterisk in my viewfinder, thanks for the help :)

[Martin Mayer]

Originally Posted by Duncan Craig

.....Here's an advert going to air today in the UK: http://www.duncancraig.co.uk/Burgess...3-040-h264.mov (the zoom out is the penultimate shot)

Duncan, if I may go off-topic briefly: can I ask what you use for your H.264 encoding? It looks very good for a 3.5Mbps stream at widescreen PAL-SD resolution.

[Duncan Craig]

Martin, it's nothing special.

I'm on Mac OSX using compressor and had a play for a few minutes with the basic built in h264 settings, making the video 1024x576 (custom 16:9 size). Some of the spec is here:

Name: YouTube H264
Description: QuickTime H.264 video with PCM audio at 48 kHz. Settings based off the source resolution and frame-rate.
File Extension: mov
Estimated file size: unknown
Audio Encoder
AAC, Stereo (L R), 48.000 kHz
Video Encoder
Format: QT
Width: 1024
Height: 576
Pixel aspect ratio: Square
Crop: None
Padding: None
Frame rate: (100% of source)
Frame Controls On:
Retiming: (Fast) Nearest Frame
Resize Filter: Linear Filter
Deinterlace Filter: Better (Motion Adaptive)
Adaptive Details: On
Antialias: 0
Detail Level: 0
Field Output: Progressive
Codec Type: H.264
Multi-pass: On, frame reorder: On
Pixel depth: 24
Spatial quality: 74
Min. Spatial quality: 25
Key frame interval: 24
Temporal quality: 50
Min. temporal quality: 25

And then, frame controls 'ON', resize filter set to 'BETTER'

Hope that help, sorry if your not on a Mac.

[Martin Mayer]

Duncan - I am on a Mac, so that's very useful, thanks very much. As you say, the encoder is nothing unusual, and I already have those facilities. I suspect it shows the quality of the original EX footage compared to what I'm used to: Z1s and HDV, which I am beginning to find less and less acceptable....

You realise this is all pushing me towards upgrade time? :-)

Many thanks again. Now: back on topic:

[Andrew Stone]

Really nice piece of work Duncan! I really liked the way you kept the energy going with stuff moving in and out of frame.

I would say the "secret sauce" of Duncan's Compressor settings are controlling the keyframes in the video settings and activating "Frame Controls" and tweaking the individual settings there.

-Andrew