Astrophotography with 8" newtonian astrograph

[hisuv1909]

I want to buy an 8" f/5 newtonian-astrograph. Please advice whether it would be good for deep-sky images like galaxies, nebulae, etc.

[michael8554]

Bung the scope and your camera into the FOV calculator of your planetarium and try it on some of your anticipated targets.

I'd say the focal length is more suited to large nebula than all but the largest galaxies.

Michael

[MartinB]

If reasonably well made it has the potential to be excellent.   1000mm is a very useful focal length but will need more accurate tracking than a short focal length refractor.  The main issue you will face with a fast newtonian is coma.  This can be effectively managed by use of a coma corrector https://www.firstlightoptics.com/coma-correctors/baader-mpcc.html  Also, if it is being moved around it will need to be collimated before each session but this becomes a very quick and easy procedure with a bit of practice.  The scope will need quite a long time  to cool down to outside temperature if stored indoors (1 hour +) , less so if stored in an unheated outbuilding.  If not at outside temp air currents in the tube will affect the optical performance of the scope.

Suitable targets for imaging will also be dependent on your chip size.  If you are using an APS DSLR then the scope will be good for medium sized nebulae, globular clusters, smaller open clusters, medium to large galaxies (M31 won't fit) and larger planetary nebulae e.g. M27.

 

[ollypenrice]

When I started imaging I felt that a 1000mm focal length fell into a bit of a no man's land between nebulae and galaxies but, as pixels have become smaller, it is now a good length for galaxies and smaller targets because you have the resolution if you you use the right pixels size. About an arcsecond per pixel will bring you close up detail.

Olly

[MartinB]

I should also have mentioned, a newtonian is quite a bulky scope and needs a sturdy mount if there is any breeze about.  An HEQ 5 should be fine if it is calm, but an EQ6 would probably do better if conditions aren't ideal.

[CloudMagnet]

Subject to getting a HEQ5 size mount and above then yes. I find that pairing it with a APS-C sized sensor will give a good FOV that will give a decent compromise between galaxies that need high focal length and nebula which mostly favors shorter focal length.

Just bear in mind that the area of the sky that you can image will be very small, so no widefield shots and you will need good guiding as well for long exposures.