Posts Tagged ‘astrophotography image’

Is it really worth a blog entry?

Well perhaps.

I’ve been playing around with the controller I set up for my Pentax cameras and realized that I missed an option. I’d thought of it before, but hadn’t really worked out setting it up.

In short I have a ‘bulb’ mode on the camera. What does that mean? Well in short I have a mode where I can take a picture, and the shutter stays open as long as the shutter release is held down. Or in the case of what I’m doing, as long as the remote indicates the shutter should be open.

Most of the time that doesn’t matter. I’m looking to let the camera do as much automatically as possible. But there are situations where that’s not necessarily the case. Astro-photography. Which I’m going to try to do a bit of this evening and into the morning.

When taking pictures at night, I don’t want to rely on the camera figuring out what to do, I want to pre-set as much as possible.

So I’ve set the camera up with a f2.8 28mm prime lens, open to 2.8, focus on infinity, with a bulb exposure of just about 15 seconds. Or at least that’s what I’m aiming for. Part of the problem is that I live in a city, where there is quite a bit of light pollution. Apparently I can filter a good portion of that out, but I’m likely to be affected by the light a neighbor has on, which happens to be an incandescent bulb, and the filters really don’t help with that. So I’m not going to worry too much about it, and just set up to start taking pictures when it’s dark and clear enough. Which looks to be about 4 am Monday Morning for about 3 hours.

Ok, in looking at the timer I set up before, there were different ways I could work this out. I could simply set the pressed button state high for a longer period on each of the settings, (intervals have been set to 1 second, 10 seconds, 20 seconds, 30 seconds, 60 seconds or one minute, and 600 seconds, or 10 minutes.

However as I was considering it, I want an interval where if the camera decides it needs to take a black frame for noise reduction, that can happen. I also want to get as many shots as I can from the time available. So with an exposure of 15 seconds, I’m going to need approx 15 additional seconds. The 1, and 10 second intervals were out to begin with. No sense in fighting with an interval shorter than the exposure time. 20 seconds  doesn’t give the camera time to take a ‘black frame’ if needed, and 60 and 600 seconds means I’m probably going to loose most of the possible exposure time. That leaves 30 seconds. So I modified the software to press the shutter, check to see what interval had been selected, and if the interval is 30 seconds, hold the shutter open for just under 15 seconds. That gives the camera a chance to take the black frame, and save the image to memory.

All that’s left is to try it out. Tonight seems like a good possibility.

Be the first to comment - What do you think?  Posted by rusty - October 21, 2012 at 11:44 am

Categories: Blog   Tags: , , ,

Basic astrophotography image processing in GIMP – Part 1: image calibration « FlatPress

Basic astrophotography image processing in GIMP – Part 1: image calibration « FlatPress.


For those of us who are not going to see a copy of photoshop, or use the various photoshop related software any time soon…

Be the first to comment - What do you think?  Posted by rusty - September 14, 2012 at 9:02 am

Categories: Articles from Elsewhere   Tags: , , , , ,