Cameras and eyepieces

[Freedom2099]

Hello,

I've been into astronomy for a while now and I decided that it is time for me to start trying to take some pictures... 

I don't have any cameras so I was considering buying the Atik Titan... but there is something I did not manage to understand so far:

In astrophotography the camera is connected to the eyepiece or not? And if not how can I change magnification?

Sorry for the dumb question but I'm a complete beginner!

[beamer3.6m]

The camera attaches directly to the focusser and is called Prime Focus.

In this manner it has fixed magnification but you can increase it by usuing barlow lenses (2x for example) or reducers to reduce it.

[Knight of Clear Skies]

Typically the camera goes straight in the eyepiece holder, it's very rare to use an eyepiece when imaging (although a few planetary imagers do). Magnification can be increased by using a barlow lens but this is usually only suitable for lunar, solar and planetary imaging, slowing down the optics is rarely a good trade-off when imaging DSOs. It's usually a case of choosing a target and framing a shot that is suitable for the focal length of the scope.

[Freedom2099]

ok, thx... I have a second question then:

How can I calculate the FOV of the camera?

Thanks for all your answers!

[Cornelius Varley]

ok, thx... I have a second question then:

How can I calculate the FOV of the camera?

Thanks for all your answers!

You can work that out using this FOV calculator http://www.12dstring.me.uk/fov.htm

[PeterCPC]

Try this http://astronomy.tools/

Peter

[ronin]

There is no magnification. The term is not applicable to prime focus imaging.

The scope will form an image on the sensor that is related by the object size and the scope focal length.

The relationship is fairly simple geometry.

The "simple" one is Image size = Focal Length x (Tan (Object size))

The more exact one is Size = Focal length x 2 x (tan (Object size/2)) but everything is generally small angles so they come out about the same.

Using say M42 and lets say it is 1 degree across then one you Evolution (2350mm) you get:

2350x(tan(1)) = 41mm.

Jupiter is average 40 arc sec so: 2350x Tan (0.6666) = 27.3mm.

It is a size and so magnification is incorrect with regards to it.

[Freedom2099]

Thank you to everyone!

Now everything is completely clear!

[Tommohawk]

Just a thought - you can use Stellarium software to show exactly what your scope/camera set-up will capture. I find i really useful.

[bitnick]

Jupiter is average 40 arc sec so: 2350x Tan (0.6666) = 27.3mm.

Just a little nitpick there: you calculated the size of an object 40 arc minutes across. Jupiter will be 2350 x tan(0.6666/60) = 0.46 mm. Just so noone gets false hopes of a jupiter that will fill the sensor nicely.