Canon EOS 1100D SLR, imaging the nightsky help.

[Cloengaa]

I just got me a Canon EOS 1100D and with light the camera works like a star.

Here is my problem. When I try and take a picture at the dark nightsky or lets say the moon ( with my 18 - 35mm objective normal objective) it will not let me take any pictures.

I have shutter on BULB and Iso 800 or above but it will not take a picture.

Can anyone please help me as I am interested in also taking nightsky pictures. What am I doing wrong ?

[Ags]

Do you have it set to autofocus? You will have to manually focus.

[swag72]

If you have the setting on bulb, you need to press the shutter to start the exposure and then press it again to finish the exposure. That is why people use a remote, as the action of pressing the shutter will disturb the camera and get camera shake.

For the moon, you won't need bulb. Set it to manual and live view. Point at the moon and just adjust the exposure time until the moon looks good in the screen. Then press the shutter!

[Cloengaa]

Ok I will try these and see if it helps. And yes I think I have autofocus on. I will disable that.

Thanks for the heads up

[Cloengaa]

The moon looks very small in a 18 -35mm lens though hehe. But as I dont have any tracking mount. I will try and just take about 30 sec max pictures.

[Cloengaa]

That is 30 sec max for the nightsky, not the moon.

[Ags]

Finding the focus point for infinity can be hard. What I do is focus on a distant street light to get approximate focus then point the camera at a bright star and refine the focus by zooming in on live view. A tripod is essential for this, at least for me. If the moon is up getting infinity focus is easy!

[Ags]

Take a series of 30 second pics and make star trails :-)

I think you will find the stars stop being points after about 5 seconds at 30mm, by the way.

[Cloengaa]

Oh okay so I should max take 5 second exposures ?

[Ags]

If you want to capture pinpoint stars get the aperture wide open and shoot for 5 secs or so. If you want to shoot star trails then shoot 30 or more 30 second shots and add them together. In Gimp you can just layer them up, setting each layer to lighten. There is a program called startrails.exe but I have not tried it yet. I've only done it once myself...:-)

[Cloengaa]

Ok sounds nice through

[Ags]

I should have added that when you shoot wide open you are likely to see distortions to the stars in the corners of your image. It depends on your lens but you can clear this up by stopping down by one or two stops.

I discovered that I seem to capture more stars at 55mm F5.6 than at 18mm F3.5. The reason is (I think) that the aperture is much larger at the long end of the zoom and it is aperture not F ratio that sets star brightness. As an added benefit, the slower F ratio also darkens the sky background!

[Cloengaa]

Ok. I am gonna get some money here soon, so am looking to buy a good imaging set. Was thinking of a Celestron CG-5 GoTo with an SW Explorer-200PDS and also a Guidecam and a Skywatcher Evostar 80ED DS. You think that would work AGS ?

[Ags]

I have my ideas but I am not the most experienced imager - I have just been messing about a bit over the past few months. I think you should post your question in a new thread under the imaging discussion subforum.

One thing you will definitely be told is that the HEQ5 Pro is a better choice for mount, if you can afford it.

[Ags]

I have found a rule for max exposure without star trailing: 600 secs / focal length. So 20mm would give 30secs exposure without star trails by that formula. That's not been my experience (I would say it is half that), but look at these photos taken on that basis - which seem to indicate I am being too conservative, or too finnickity:

http://stargazerslounge.com/imaging-widefield-special-events-comets/168363-comet-lovejoy-south-africa.html#post2089435

[carastro]

Looks a super scope, but I am wondering whether it is a bit heavy for the CG5 GT. They always say you should halve the load for Astro-photography, and you'll have lots of accesories to mount onto this with guidescope, guide camera/imaging camera etc etc.

Carole

[Cloengaa]

Yeah I know. My problem is I want a big reflector as I will also use it for Visual use, and in my world the bigger the better.