Raspberry Pi Forums

As far as I can tell, setting the auto-exposure to 'off' in video mode gives only black output, until for stills. No fiddling with other switches seems to help. Has anyone had any luck with this?

Josh04 wrote:As far as I can tell, setting the auto-exposure to 'off' in video mode gives only black output, until for stills. No fiddling with other switches seems to help. Has anyone had any luck with this?

Yes, apparently setting exposure to off doesn't actually set it to off as I found out after I'd written the code. So I'm afraid there is no Off option for exposure.

Is there potential for this in the future, or is it a limitation of something which can't be changed?

If you think about it, having exposure processing off isn't of much use - the images will basically be rubbish, never the correct brightness except in very particular lighting conditions. You need some sort of exposure, and auto generally is the way to go.

There are some limited areas where you might want it off- in fact the production line for the cameras has a specially built version of the firmware where it's off, but that is in known lighting conditions and is used to ensure the cameras work, not to take usable pictures.

If you think about it, having exposure processing off isn't of much use - the images will basically be rubbish, never the correct brightness except in very particular lighting conditions. You need some sort of exposure, and auto generally is the way to go.

JAMESH, please! manual exposure is VITAL for a lot of projects. First of all a 3d laser scanner. I need to set ISO at 100 and choose the exposure time.
then, HDR photography, panoramas, night photo, infrared, etc etc.

axse wrote: HDR photography, panoramas, night photo, infrared, etc etc.

But this thread is about video isn't it?

axse wrote:

If you think about it, having exposure processing off isn't of much use - the images will basically be rubbish, never the correct brightness except in very particular lighting conditions. You need some sort of exposure, and auto generally is the way to go.

JAMESH, please! manual exposure is VITAL for a lot of projects. First of all a 3d laser scanner. I need to set ISO at 100 and choose the exposure time.
then, HDR photography, panoramas, night photo, infrared, etc etc.

Please don't use capitals. I find it annoying. I wasn't talking about manual exposure setting, I was talking about turning off brightness compensation completely - i.e. fixed gains. That's means no ISO either, although exposure times would still work.

You already have a load of different options for exposure e.g. night mode etc, try some of them out -they might already do what you want. Apart from Infrared unless you abuse the module.

ISO stuff isn't working (supposed to be there, but doesn't appear to work correctly), and there is no facility to set exposure time specifically as yet. Former I might be able to get working once all the more important issues are fixed - second I wouldn't hold my breath for.

Sorry for being imprecise - what I want is a manual exposure control, yes, not a strict lack of exposure control. The latter would be a bit useless.

I understand you work on this in your spare time - thank you very much!

Please don't use capitals. I find it annoying. I wasn't talking about manual exposure setting, I was talking about turning off brightness compensation completely - i.e. fixed gains. That's means no ISO either, although exposure times would still work.

You already have a load of different options for exposure e.g. night mode etc, try some of them out -they might already do what you want. Apart from Infrared unless you abuse the module.

ISO stuff isn't working (supposed to be there, but doesn't appear to work correctly), and there is no facility to set exposure time specifically as yet. Former I might be able to get working once all the more important issues are fixed - second I wouldn't hold my breath for.

Sorry for annoying you, i'm just very exited about the possibilities of a raspi with a cam, but i'm feeling a little bit frustrated because the settings I really need doesn't work. All exposure possibilities, as night, disco, sport ect. ect. are simply variation of 3 parameters. ISO, ex time and WB. (and saturation, contrast). To my eyes seams to be easier to let people directly set ISO, ex time and WB. good job!

It'll come. Reminds me of something I once heard in a different context.

You can have it cheap
You can have it good
You can have it quick
Pick any two of the above

Well the price is fixed on cheap. And it's going to be very good (already is in many respects). So, quick is off the table

axse wrote:

Please don't use capitals. I find it annoying. I wasn't talking about manual exposure setting, I was talking about turning off brightness compensation completely - i.e. fixed gains. That's means no ISO either, although exposure times would still work.

You already have a load of different options for exposure e.g. night mode etc, try some of them out -they might already do what you want. Apart from Infrared unless you abuse the module.

ISO stuff isn't working (supposed to be there, but doesn't appear to work correctly), and there is no facility to set exposure time specifically as yet. Former I might be able to get working once all the more important issues are fixed - second I wouldn't hold my breath for.

Sorry for annoying you, i'm just very exited about the possibilities of a raspi with a cam, but i'm feeling a little bit frustrated because the settings I really need doesn't work. All exposure possibilities, as night, disco, sport ect. ect. are simply variation of 3 parameters. ISO, ex time and WB. (and saturation, contrast). To my eyes seams to be easier to let people directly set ISO, ex time and WB. good job!

seems to me you should be using a proper DSLR and have the raspi connected to it by usb - ultimate control, ultimate picture quality

No seriously, being able to set exposure to be fixed at a pre-determined level is pretty crucial.

Big bonus points if the maths used correspond to APEX system.

towolf wrote:No seriously, being able to set exposure to be fixed at a pre-determined level is pretty crucial.

Big bonus points if the maths used correspond to APEX system.

Problem is the underlying code running the camera does what our major customers want - not what you might want. And remember that these mobile phones sensors do not have the same set of abilities you might find with a device that has a shutter, an aperture etc. So the maths does whatever Samsung want, as does the feature set.

That said, we should be able to get ISO working at some point. The Nokia 808 uses the same ISP and that allows you to set ISO. Not exposure time though.

I got the impression from my earlier experiments with CHDK hack firmware for Canon P&S cams.

My cam didn’t have an diaphragm aperture either, only an ND filter, but the exposure calculations were done internally in APEX system. So even though it was crappy, it evaluated light in the same way a light meter does.

But it may well be that this is not the case here.