dslr photos help

[scubaian]

Hi all, advice please???!!

I've got a dslr, and want to tak esome deep space photos (orion nebula and andromoda galaxy)

Apparantly i need to open the shutter for 30 seconds ish. Surely with the spin of the earth, any pic will be streaked across my photo?

I dont have a tracker, Am i right with the streaking? or what do i do?

Bit confused!!!

Please keep it simple, i'm a simple lad!!

Ian

[barkis]

Are you going to use your scope at prime focus for this?

If so, depending on the f/ratio of the system, 30 will be abit too long. The Nebula is at a point in the sky that star trails will be at their longest on a trail image.

Try experimenting, using the highest ISO setting possible, for a noisless results, combined with various exposure times.

If you get some decent subs, you can stack them to build a decent Image.

Ron.

[LukeSkywatcher]

How long you leave the shutter open for and what ISO settings all depend on the level of light pollution in your area. To find the right balance for you, you will have to experiment. Without any tracking, the longer you leave the shutter open the longer star trails become.

Without any tracking you CAN take many short exposures and use DSS (Deep Sky Stacker) to combine them all into one single image.

Obviously if you are seriously into astro imaging then some kind of system that allows tracking is a MUST. But you can get some great results by using a non tracking system and software such as DSS or Startrails.

[scubaian]

Cheers, i've dowloaded the DSS and am going to have a play with lots of 1 sec images.

[LukeSkywatcher]

Cheers, i've dowloaded the DSS and am going to have a play with lots of 1 sec images.

You can do better then a single second exposure. Try 10 seconds to start with.

[jgs001]

The focal length of the lens/scope will determine the maximum shutter speed you can get away with on a static tripod. At 18mm, you can probably squeeze 30 seconds out of it. At 50mm, 8 seconds is pushing it. At about 400mm, you'll be lucky to get 1 second. If you take a very large number of exposures on a static tripod, you will start to get smearing in the corners due to field rotation when the images are combined... I'm not sure after how many/how long this occurs, but it's probably something in the order of about 10 minutes.

[jleach29]

You could build a simple Barndoor mount, on a good day when I am actually paying attention to turning the knob at the correct speed I can manage exp of several min with little to no trailing. 2 pieces of wood a hinge and a screw.

[continuum]

For straightforward DSLR photography i.e., no mount, no barn door etc, this site has a very good video on night sky photography

The Star Trail

RonJ