Maximum time for a Canon 20-D AV mode

[RacePhoto]

Canon 20-D what is the maximum auto exposure duration Aperture-priority mode? Canon says Max. is 30 seconds, but I only get 4 seconds? I had to dig around quite a bit to find that 30 seconds number.

I thought maybe there was light leaking in through the eyepiece and tricking the meter. I tried a lens cap on, and then a body cap, no lens. If you are wondering why I'm out in space on this question, that seems to have no useful purpose or reasoning. I'm trying to set up a time lapse camera, to run 24/7 and I need it to be fast enough for the daylight, so the shots aren't over exposed and slow enough at night, so I still see the stars.

My base point is f/4, 1600 ISO, if that will allow a "normal" exposure at 1/4000th of a second. (so far) And the same setting, AV f/4, if the camera would go up to 30 seconds, would also make a reasonable star shot.

Anyone have any ideas why Canon says the maximum automatic exposure duration is 30 seconds, but I only get 4 second exposures? Something I'm doing wrong or is there something I'm missing in the specifications?

By the way, this is an example, using the older camera, the newest have the same automatic time limit in the software as far as everything I could find. It's not just an irrelevant old camera question.

Update, I covered the eyepiece and that does make a difference, but still, no Max. time. I had an idea, I turned off the protection, and also tried changing the ISO. Funny thing, as soon as I went to 800 it flashed 30" and then switched to 8 seconds. When I change to 400 it flashes 8 then changes to 15 seconds. (or if I turn off the camera and start again, it flashes 30 and switches to 15 seconds) This is no lens, just a body cap. The camera is somehow sensing the ISO and adjusting the Maximum exposure duration.

 

[wfooshee1]

When I shot this star trail I used a sequence of 15-second exposures at f:3.5 and ISO 200. I think your camera is realizing that 40 seconds at ISO 1600 is just seriously overexposed, even on a dark scene.

This is the first image of the sequence, not cropped. (I didn't crop until the image was stacked.) You can see that while it wasn't absolutely black, being in my back yard with my neighbor's yard lights on, the stars are still plenty visible without any exposure enhancement at ISO 200 and only 15 seconds. I think your camera is simply protecting itself by not allowing excessive time at high ISO.

 

[RacePhoto]

Yes, to all of that, but the point is, the camera specs say, a maximum of 30 seconds in AV, but the camera doesn't do that. It's apparently dependent on the ISO, and somewhere in the software, that changes the actual maximum. Maybe next week. Since you do these, maybe you'll find the fireflies photobombing my pictures amusing?

 

[wfooshee1]

Actually, they are kind of funny. Maybe annoying, but funny.

In that star trail I have four or five aircraft trial which appeared as a sequence of red or green lights, as the lights blinked while the airplane moved across the frame. I can't begin to express the tedium of finding those frames and removing the from the stack (although I probably could have used a spot healer to remove the lights... Still tedious going through all the frames to find them!)

Back to your camera... at "reasonable" ISO settings, it WILL give you 30 seconds max exposure time, so I don't consider it a misleading claim at all.

 

[RacePhoto]

AV Mode and the camera still doesn't go longer than 15 seconds, even with the over exposure protection turned off. But as I suspected, if I lower the ISO and cover the eyepiece, it will start to shoot longer exposures. Then the problem is, if I'm trying to get something at night, with a longer exposure, but I've turned down the ISO, I'm going to start missing lighter objects. Lets just say, a meteorite for example.

Still working on it, this hasn't been, all I've been doing. I also have been collecting ankle weights from resale shops, to duct tape to the tripod legs, getting the power and timer and enclosure determined. I picked up a dandy 30-D, but I'm not sure if I want to burn that one down with the 24/7 camera in a box project.

Asking for a setting that can be left unattended, adjust from daylight to night, is pretty demanding. I could use a GoPro, but they lock up and have heat issues, where the Sunshine will make them shut down. Also, the sensor is tiny and only gets the brightest stars. 30-D for this project, set to Medium, is "good enough" to make FullHD timelapse and at the same time have potentially useful still images. The main goal is Time-Lapse.

How about this one? Not your usual airplanes and satellites. Starlink? It's not an error from the camera.

 

[wfooshee1]

Asking for a setting that can be left unattended, adjust from daylight to night, is pretty demanding.

That's the first I've seen you mention daylight to night with a single setting. That's not just "demanding," it's not possible. Looking at the exposure differences for a daylight shot compared to one of the frames for my star trails, between differences in shutter speeds, ISO, and aperture, the night-time shots might require 10 or 15 THOUSAND times more exposure than daylight, about 14 stops! One of the Program modes would be your only hope, and that would be inconsistent and completely beyond your control.

 

[RacePhoto]

Yes, going further, I did finally get things set and did a sequence. It works, but also yes, it's pretty demanding and didn't really end up with what I had hoped. The stars just don't make it. Or I should say, only some of the bright ones. The daylight was "good enough" for that kind of project. A whole bunch of other things, that are good and worked out. Shooting Medium with a 32GB card, worked and I can set a camera (this one is a 30-D right now) and leave it for over 30 days.
The previous version of this, I had to go out and connect the USB and download the images, which was time consuming. New version, I can flip open the box, take out the memory card and restart the project.
Otherwise another new discovery. Aiming the camera up, meant rain and snow got onto the filters and window, which is fine, except, aimed down it's not a problem as much. Shooting up, the filters are not waterproof or sealed. If I make a version for the stars, that's only for Night Sky, it needs a weatherproof dome. I bought one for a security camera, now I need the motivation to build a new waterproof box, with the camera mount and step forward.

Here's to projects and experimental fun.