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Video for DSLR and Point and Shoot Cameras
Revisiting Auto vs. Manual
Aug 12, 2020 21:25:28   #
sjb3
 
When I started the first thread, the last word on it was that I was convinced that my camera's video function was in fact full auto, though I was also pretty sure the sensor's reading could be affected if there was a Neutral Density filter on the lens. I'd made some test footage doing that, but it was sloppy and disorganized, so this afternoon I did it over, so to speak, shooting about 10 minutes of footage which I then trimmed down and organized into a sequence. It was about 5 in the afternoon and still very sunny & bright.

There are a total of four 45-second clips , each with a title bar at the start; I edited them in Premiere Elements and made a single 3-minute long video. I started out shooting in Manual with the shutter set to 1/125th to match the camera's default 60 fps for Full HD 1920x1080, and the aperture wide open at f/ 2.8. Since the day was so bright (and I started out facing West) the footage should have been overexposed with completely blown-out highlights, and the exposure meter was in fact pegged at the far right up against the + sign.

The next was with the Mode Dial set to Auto. The 3rd one was back to Manual, same shutter & aperture, only this time I had a 6-stop ND64 filter attached. The exposure meter wasn't pegged at the blown-out side anymore. I didn't fiddle with the setting because I wanted to stick with the test settings (wasn't looking to take a photograph!) The last clip was in Auto, with the ND64 filter still attached.

Looking at the finished clip, I still think the video function is fully automatic, irrespective of the Mode Dial setting, but the sensor's perception of the scene is affected when it's looking through an ND filter. Comments and opinions solicited; thanks!

Here's the YouTube Link: https://www.youtube.com/watch?v=fiOIcH96Ee4&t=37s

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Aug 13, 2020 06:06:30   #
kymarto Loc: Portland OR and Milan Italy
 
With the Sony A7 series you can set up what mode you want when you set the camera to video. I imagine it is the same on the Panasonic. None of your videos appear to be in manual mode, as the relative brightness of the grass changes as you include more and less highlight areas. You can easily tell by pointing the camera towards the sky, and then towards something dark.

My guess is that the camera is varying ISO. It would not blow highlights if it could stop down, but even at lowest ISO it will blow the sky at f2. 8@1/125. The ND gives you an effective six stops down, the equivalent then of f22. My guess is that then in both cases the camera is boosting the ISO then to maintain what it thinks is correct exposure.

Again, point the camera toward something very bright and then very dark, and you will immediately see if the camera is adjusting exposure or not. One thing I can assure you is that the metering is not affected by the ND. The ND only allows the scene's brightness to be in metering range with the aperture fixed at f2. 8 and shutter at 1/125.

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Aug 13, 2020 10:40:55   #
sjb3
 
[quote=kymarto]My guess is that the camera is varying ISO.

Good call! Thanks very much. You are exactly right, right down the line. When I did my little test shooting session, switching between manual and auto, with and without that ND64 filter attached, I hadn't even messed with ISO. I always shot mainly outdoors; years ago I'd just set the ISO to 200 and forgot about it.

According to the owner's manual, in the Fuji S1, available ISO adjustments are shown as the first item in each of the Shooting Menus, with a separate menu for each position of the Mode Dial. With the mode dial at M, ISO is also a completely manual function, allowing one to set it from 100 up 12800 (with the appropriate warning that photos will most likely be grainy and of low quality at these really high settings).

In Full Auto mode, ISO is greyed out in the shooting menu, which tallies with your assessment that the camera, in Auto setting at least, will adjust aperture, shutter and ISO as needed for the lighting conditions.

With A, S and P mode there are manual ISO settings allowed from 100 to 12800, but also AUTO settings: 400 max, 800 max, 1600 max and 3200max. I didn't use any of these Mode Dial positions during the test.

The camera has a fixed optical superzoom (50x) lens but it was not zoomed out at any time during the shoot, so the available aperture range was from wide-open f/ 2.8 to all-the-way-stopped-down f/ 11. I did the light-to-dark test in Manual and Auto modes, filter on and off, same shutter & aperture in manual as in the test, and as you predicted, the camera adjusted exposure immediately in each case.

I fully understand about how that happened in Auto, but I'm not quite grasping how it happened in manual since there's no provision for auto ISO adjustment in that Mode Dial setting. Yet the camera acted exactly the same way going from bright light to dark both with filter mounted and without.

Anyway, all my long-winded (sorry) verbiage aside, in the end I'm still satisfied that the video function is just a push-button, on/off function, with no real creativity possible, though I'll probably continue to experiment with ND filters since the test video did show at least some difference with and without them. Thanks again for your interest and valuable information.

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Aug 13, 2020 17:04:51   #
kymarto Loc: Portland OR and Milan Italy
 
Since the S1 is not a professional camera they may have decided not to actually give you full manual on video. The problem is that you would need a way to vary aperture while filming to keep correct exposure and that is a problem on all video cameras without an actual mechanical diaphragm ring that you can turn. Even prosuner videocams cannot vary aperture steplessly unless they are in auto mode. That is why many filmmakers use variable ND filters, to give them a way to smoothly change exposure.

You should either use a smaller aperture in bright situations or use you ND so that you bring the amount of light down to where the camera will not blow highlights at its lowest ISO setting. Alternately let the camera vary exposure via the aperture unless you have a good reason to stay at a certain aperture, such as for shallow DOF.

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