How to lock exposure on XF300 - Newbie questions

[Milton Perrin]

I'm primarily a still photographer slowly learning the XF300. I've learned the hard way about the Auto Gain Control button ... what IS the purpose of that when it makes so much noise?

So I'm shooting high-pressure nozzles in a factory. The spray moves around a lot, resulting in annoying flicker which can be seen here:

sb49_28_2000psi.mp4 - YouTube

I imagine that simply locking the exposure will stop the constant exposure adjustment - assuming that's what's causing the flicker. I've read the manual but I'm still not clear on how to just manually lock the exposure for the duration of a clip - is it manually controlling the iris essentially manual exposure? Seems to me like something that is easily done but I'm not clear on it.

Thanks

[Alan McCormick]

Milton, what settings did you use when shooting this?

I would have thought manual exposure would have been sufficient, in such circumstances auto anything would be a problem. I posted a few weeks ago about the same "exposure lock" option as I was used to using it on previous cameras, I have moved into relying on manual iris and clever use of ND filters.

Alan

[Tim Bakland]

Yeah, same here. I'd go with all manual -- maybe with ND to keep the shutter where you want it.

[Jeff Anselmo]

Hi Milton,

As Tim and Alan mentioned, use your iris wheel to change exposure. Your exposure is locked all the way through, UNLESS your zooming in (changes to f3.5 at the full telephoto range, I think. Sorry don't have the cam in front of me.)

Make sure you lock in your shutter speed (60i/30p at 1/60th; 24p at 1/48th; or 180 degrees), adjust your ND filters, and adjust your iris for exposure (but try not to go beyond f5.6 for HD).

If you haven't already, check out Doug Jensen's XF tutorial Mastering the Canon XF305/300 Camcorders training DVD

Best,

[Noa Put]

Originally Posted by Milton Perrin

I've learned the hard way about the Auto Gain Control button ... what IS the purpose of that when it makes so much noise?

They still included a "auto gain" button on the xf300? My xh-a1 also has that magical button as well and that must be THE most useless function ever invented for a camera, maybe oke for a "one button all auto" camera but for a xf300, wonder what the technicians must have been thinking. My guess is that the flickering you see has been caused by that auto gain which is constantly making gain adjustments so the best advice I can give is to never, ever use it.

I have blocked my xh-a1's autogain button with a piece of tape, tried to rip the button off but didn't work :) Last year that autogain button got activated by accident and ruined a lot of shots, couldn't see it during recording on the small lcd until I got home and watched it on my 22 inch screen.

[Alan McCormick]

I just had a few clips where the gain was set too high (9dB) but could not see any obvious noise on the LCD.

Was going to dump them but I applied NeatVideo denoiser and was amazed by the results, worth considering but doubt it will be a be all end all solution if the auto gain kicks in.

Alan

[Nigel Barker]

The XF300/305 has a very effective 'Auto-everything' mode that makes a pretty decent job of shooting video for the complete novice. This is one of the reasons why this camera is so popular with news-gathering & other broadcast organisations as it allows them to dispense with a professional cameraman & have a producer/cameraman or journalist/cameraman. I'm not saying that someone who knows what they are doing won't do a better job than this auto mode but there are good reasons why Canon put such a mode on a professional camera.

[Alan McCormick]

Originally Posted by Nigel Barker

The XF300/305 has a very effective 'Auto-everything' mode that makes a pretty decent job of shootingfor the complete novice. This is once of the reasons why this camera is so popular with news-gathering & other broadcast organisations as it allows them to dispense with a professional cameraman & have a producer/cameraman or journalist/cameraman. I'm not saying that someone who knows what they are doing won't do a better job than this auto mode but there are good reasons why Canon put such a mode on a professional camera.

Probably explains why a LOT of interviews on the news channels nowadays have the subject out of focus but the background looks fantastically in focus (they are not using professional cameraman - just someone who points and has everything in AUTO).

[Graham Bernard]

Nigel & Alan, yes.

Wanting the bg in focus, for the narrative=news-story, the Operator has the camera far too close. Kinda basic, really?

Maybe that's why there's face detect on a 422, 50mb/s, 1920x1080 BBC approved camera?

Grazie

[Chuck Fadely]

That looks like the flicker you get with some industrial lighting when the light's cycling with the AC line voltage hz. It's usually at 60 cycles in US, 50 cycles elsewhere.

Try dropping your shutter speed down to 1/30 and see if it stops. You should be able to see lighting flicker in the viewfinder.

To lock the exposure, you have to turn off the auto gain, the auto-everything switch, and the auto-iris switch. Tape those three down so they don't come back on by accident!

Originally Posted by Milton Perrin

I'm primarily a still photographer slowly learning the XF300. I've learned the hard way about the Auto Gain Control button ... what IS the purpose of that when it makes so much noise?

So I'm shooting high-pressure nozzles in a factory. The spray moves around a lot, resulting in annoying flicker which can be seen here:

sb49_28_2000psi.mp4 - YouTube

I imagine that simply locking the exposure will stop the constant exposure adjustment - assuming that's what's causing the flicker. I've read the manual but I'm still not clear on how to just manually lock the exposure for the duration of a clip - is it manually controlling the iris essentially manual exposure? Seems to me like something that is easily done but I'm not clear on it.

Thanks

[Milton Perrin]

Thanks for all the info. I bought the dvd but haven't watched it yet.

So if I turn off auto gain and auto iris I'm essentially in manual mode.

I didn't think of the lighting in the lab where I shot this, it has large mercury-vapor-looking lights in there. I'm adding light with some Lowel tungsten lights. Color balance is difficult but the camera seems to deal with that ok.

So dropping the shutter speed is worth a go. I swear I didn't see the flickering in the original but with all the commotion I didn't perceive it.

On an unrelated note, If I connect an external monitor (Apple 27-in) via HDMI, can I playback and watch it on the monitor, or even better watch real-time?

Thanks again for all your help.

[Alan McCormick]

Milton, regarding the colour balance I would advise you set manual white balance using Kelvin if possible as once again you will get a better result.

You can definitely connect your Cam via HDMI to your external monitor provided you have an HDMI connection and use it realtime or for playback.

Have Fun

[Al Bergstein]

I thought that on the dvd I remember that there is a flicker setting in the menus, folks. I believe that if you turn that on it will minimize flicker. Haven't needed it yet, but remembering that.

[Steven Davis]

I wish Canon would have made the gain adjustable via the scroll wheel. I've run into situations where the three presets don't quite work based on weather, clouds, sun changes etc.

[Graham Bernard]

You probably know, but for others, you can fine tune gain in increments: Select [Fine Tuning] to adjust the gain in 0.5 dB increments.