Questions about Beginning Astrophotography

[Perseus (Kobe)]

Hey,

Just wondering what affordable telescope would be sufficient for both astrophotography and viewing (Planets and some galaxies/nebulae). Currently looking at a Go-To Dobsonian (8-10inch), would this be a suitable Telescope for a beginner astrophotographer?

Cheers.

[billdan (Bill)]

Hi there Perseus,

Welcome to IIS, A Goto DOB is fantastic for viewing but for astro-photography there are some issues to overcome first.

The first issue you may encounter is the focus position has been optimised for eyepieces. So this may entail minor modifications to the OTA to achieve focus with a camera. i.e moving the primary mirror closer to the secondary and depending on your camera could be over an inch.

The next issue is field rotation, the DOB is on an Alt/Az mount and this means you will be limited to planetary photographs and short exposures on DSO's, max about 30sec's depending on the part of the sky you are looking at.

If you are serious and want to go longer in exposures you will have to buy a De-rotator which are not cheap $1500 - $2K. Also some way of guiding the DOB precisely.

For a first time telescope it's great choice.

Cheers
Bill

[raymo]

If you get a Skywatcher [ Saxon is same scope], Dob, [Go To or not],
collapsible or not, you won't have to worry about whether you can use a camera with it, as all Skywatcher Dobs can be used for basic photography. Most other popular brands do need modding, as mentioned by Bill.
raymo

[Perseus (Kobe)]

Thanks for the advice guys. Is an 8 inch enough or is it worthwhile spending the extra money to get a 10 inch dob ?

[billdan (Bill)]

The 8 inch is definitely good enough, the 10 inch will give better magnification.

The 10 inch is heavier and harder to move around, and it's also taller so you may have to stand on a box to see things when its near vertical.

If you have the bucks I'd go the 10.

Cheers
Bill

[Somnium (Aidan)]

If you are keen on getting into astrophotography as well as visual use you can't go too far past an heq5 mount with an 8" Newtonian telescope. A dobsonian will have serious limitations in astrophotography, you will only be able to shoot really short exposures

[raymo]

You have to make a decision. The set up described by Somnium will
allow you to learn, and produce much better results than the Go To Dob
will, but at the price of a much longer gear set up time[unless it is permanently placed], and the time needed to learn how to set up and polar align an equatorial mount like the HEQ5, and later learn how to use an autoguider. So I suppose it comes down to how seriously you want to
pursue astrophotography.
raymo

[Somnium (Aidan)]

Originally Posted by raymo

You have to make a decision. The set up described by Somnium will
allow you to learn, and produce much better results than the Go To Dob
will, but at the price of a much longer gear set up time[unless it is permanently placed], and the time needed to learn how to set up and polar align an equatorial mount like the HEQ5, and later learn how to use an autoguider. So I suppose it comes down to how seriously you want to
pursue astrophotography.
raymo

I think if you want to do astrophotography it is a given that you will have to spend time setting up, be keen to learn, get frustrated and work your way through issues. if you are not willing to do that then you can expect average results. if you are looking for something straightforward then astrophotography is not it. perhaps you can get away with some moon and planetary work, but not many DSO objects. you definitely need to weight up the easy set up and visual use of a dob to the better AP results of an EQ mounted Newt. not an easy decision but making the right one for you can be the difference between finding a hobby for life or just getting frustrated resulting in your scope gathering dust.

[Perseus (Kobe)]

Due to the fact that i live near a city with some light pollution, will i still be able to get shots of DSO? or will i have to venture out west to get some clearer shots?
Also, i kind of have an idea of what exposure times are, but could someone pls give me a brief overview of what they are.

Thanks heaps guys, really appreciate the responses.

[Somnium (Aidan)]

Originally Posted by Perseus

Due to the fact that i live near a city with some light pollution, will i still be able to get shots of DSO? or will i have to venture out west to get some clearer shots?
Also, i kind of have an idea of what exposure times are, but could someone pls give me a brief overview of what they are.

Thanks heaps guys, really appreciate the responses.

You can but it becomes harder to get good results, more imaging time is needed and post processing to remove gradients. Some people from Sydney still get great results, Peter ward comes to mind. You can also do narrow band imaging which means that you are imaging very specific wavelengths of light. The costs go way up though.

[Perseus (Kobe)]

Will the Nexstar 130slt have the same tracking problems? im also worried that the aperture would be too small.

What 8" Newtonian telescope would you suggest to mount on the HEQ5 ?

Cheers.

[Somnium (Aidan)]

Originally Posted by Perseus

Will the Nexstar 130slt have the same tracking problems? im also worried that the aperture would be too small.

What 8" Newtonian telescope would you suggest to mount on the HEQ5 ?

Cheers.

Yes , the same issue, the problem being that they are alt az mounts rather than an Equatorial mount. This means that as the night goes on, the image slowly rotates. If you are after long exposure astrophotography you will need an eq mount. If you have some time watch Forrest tanaka' series on YouTube. He goes through the differences between scopes and mounts , guiding and polar alignment

This is part one of three, should answer most of your questions https://m.youtube.com/watch?v=9d0292TBMHo

[skysurfer]

For AP you can rather buy a good ED or APO refractor. Avoid the much cheaper achros as they have too much color errors for AP.

Look on this page to get idea of prices.

For about $1000-$1500 one can get a good ED80. I have an ED110 on a Vixen SP (equivalent to a SW EQ5) which works very good for AP.

For scopes under 5kg (or SLR+telephoto) even a $600 Star Adventurer suffices.

[jenchris (Jennifer)]

I'm sure that your enthusiasm will help with the learning curve.
When you're photoing, it isn't the aperture that is important.
It's the focal ratio.
F5 is great. You can get an f5 scope that is 3 inch diameter. Though an f9 is cheaper but then you need longee exposures
Exposures vary, but I usually limit mine to 5 or so minutes and stack say 5 or 10 images in my laptop to give me a viable image.
I'm a bit raw because I can't afford amazing software or scope but I get some interesting pics.
I mostly use a 4 inch refractor and a dslr mounted on a eq6 mount. Coupled with a guide scope and a laptop to give me some added accuracy.

[xelasnave]

Jennifer offers very good advice.
I would like to add that if you are going to do astro photos the quality of your mount is very important.
I started with a very poor mount and even when I tweeked it I could not get more than 90 seconds reasonable tracking but with stacking I could produce a reasonable image.
Back then I had to guide manualy using an illuminated reticle.
The scope is somewhat a secondary consideration but for starters go for a 80 mm as good and as fast as possible.
You should get reasonable results unguided with some effort and later get a better imaging scope and use the 80 mm as a guide scope.
Good luck.
Alex

[Somnium (Aidan)]

Refractors are great grab and go tools, no collimation, few issues (apart from chromatic aberration ) if it gives you the fov you are after then go for it. There is enough trouble learning this game, fiddling with a scope is just an added pain point

[Perseus (Kobe)]

Im thinking of a HEQ5 or EQ5 and a SW ED80. I already have a cannon dslr.

Also, any tips on computer programs and imaging techniques ?
Cheers.

[xelasnave]

Start reading up on drift alignment.
When you get your gear I will let you in on a secret method.
I won't suggest software I am not familiar with the latest.

[xelasnave]

http://deepskystacker.free.fr/english/index.html

have a look and download.
place your canon on a tripod take some shots of the sky and start stacking...
you should be able to produce a decent wide field.

[Somnium (Aidan)]

use;
backyard eos for image capturing,
DSS for stacking,
PHD2 for autoguiding if you go down that way
cartes du ciel and EQMOD if you want to control via computer

that should get you started