In camera ND filters

[keithrsmith]

Can anyone think of a good reason why cameras can't implement in camera ND filter functions?.

It should be possible to dial in 'X' stops of ND at any F stop and the firmware to take 2, 4 etc exposures that add up to the required shutter speed, add the exposures together (in a larger number range) , divide the result by 2, 4 etc and hence simulate extending the shutter speed by 2, 4 etc. times.

All it needs is memory and a fast enough processor.

Actually it would be possible to do in camera grad filters as well - with the ability to adjust the grad and the position/ rotation - it is just  more processing.

[jonathanlung]

It would also require at least an instantaneous electronic shutter and data readout. It also wouldn't be equivalent to an ND filter because of read noise which, based on my understanding, would increase with a faster readout.

[hjulenissen]

What you are asking for seems to be closely related to in-camera HDR/exposure bracketing. Why not just do it manually afterwards if you want full control?

I would like in-camera physical ND-filters, just like pro video cameras. That could give the benefit of bright viewfinder/AF, and a gray filter that slid in in front of the sensor just before exposure, something that is impossible with screw-on ND filters.

Being able to use flash in bright sunlight (to even out shadows) together with larger apertures (for sharpness or artistic effect) would be the main usage for me. Being able to do long exposures in daylight without external equipment would be an added bonus.

-h

[keithrsmith]

But long exposures probably increase the noise level anyway.  Yes fast readout and electronic shuuter woul dbe necessary.
keith

It would also require at least an instantaneous electronic shutter and data readout. It also wouldn't be equivalent to an ND filter because of read noise which, based on my understanding, would increase with a faster readout.

[EduPerez]

I think the people at Magic Lantern are experimenting with similar: they use the video features of the camera, and average all the frames captured during a period of time to take a picture.

[steve owen]

My Canon G12, has a built in 3 stop ND filter. When you select it, the screen darkens down just for a moment, and then reverts to its usual brightness. You can see an adjusted shutter speed on the LCD screen, and when you take a picture the shutter time in the exif, is as it appears on the screen. And the selected aperture is not changed.

Now as to how Canon is accomplishing this, I don't know. But it appears to be a genuine ND adjustment, as in a real filter. Example: Metered exposure AV, F-4.5, ISO 100, = 1/125. ND filter on AV, F-4.5, ISO 100, = 1/15.

I don't think you could bias the ccd this low, that would require a ISO of 12. As far as I know!, this is not in the realm of possibility.  It seems at the time of exposure, the camera is slipping a real filter into the light path.

Unlike consumer line P&S cameras, the G12 has a real Shutter, and a real F-stop Iris diaphragm. So its also feasible a small ND filter, could be slipped into the light path, at the time of actual exposure.