dark current noise

alexisgreat wrote:

Astrotripper wrote:

alexisgreat wrote:

It's still been mostly cloudy around here so I haven't been able to test it- but basically what I'm looking for is if the noise is fairly low up to ISO 3200 and 1 minute exposures for pictures of constellations like Orion?

ISO 3200 might be too much for 60 second exposures. You might end up with the core of the nebula blown, at least when using a fast lens. For exposures that long, you can use lower ISO. Here's a shorter, 40s exposure at a very small aperture:

See it on flickr

Very nice image! I think you can see stars down to about 14th mag in it, no?

Nah, I don't think so. 12 mag for sure, maybe even 13, but 14 would require some stacking and most likely a longer exposure. But in general, I'm always pretty amazed how "deep" you can peek even with a single exposure.

Thanks about dark frame subtraction, I did not know that. It sounds like what we have to do for CCD cameras, you need to take a "library" of darks at different temperatures.

It's the same for modern consumer cameras as well. I have a whole library of darks taking space on external hard drive

If you'll have some time on your hands, I would recommend having a go at stacking. Even if you don't have a tracking mount, you can do some interesting things as long as you have a fast lens. The closer you stick to the area near the celestial pole, the longer the exposures you can take without any tracking. It's unfortunate that this area is lacking in impressive objects, at least in northern hemisphere. But pointing your camera at Polaris and taking a bunch of shots is the easiest way to have some material to practice stacking and subsequent post-processing. And if you want some Milky Way, Cassiopeia is probably the best choice for starters.

You can have a look at my recent thread on astrophotography here .

I haven't used Live Composite mode yet- is that only for star trails?

For astro, yes, that's pretty much it. Normally, it's also fantastic for light painting. Or you can combine both.

This is the peak time for astrophotography here, arctic air is finally here! It would be nice if the wind lowered a bit though lol.

I've been lucky in this regard. Not only did new year start with clear skies, the winds died out at the same time. And I have not seen a clear night sky in months previous to that. Not to mention crazy winds for the past two or three months.