My C8 vs Orion 8" f/4 Astrograph???!!!

[AlexxxAA]

Hi everyone.

I was looking online and have come to a dilemma about my equipment...

My C8 doesnt seem to gather as much light as i thought i should and compared to other peoples' 30" exposures. DSS wont even recognize any stars in my many attempts at M81, and this will not stack any pictures. Im waiting for clear skies to try out my autoguider to see if longer exposures will help with this issue since even 1min exposures wont get recognized by DSS either.

I have come across the fact that Orion Telescopes sells a very inexpensive 8" Newt Astrograph for around $500 US. The next option is a 8" Ritchey-Chretien style Astrograph for around $1200 US.

-Is the 8" Newt a good option for my set up?

If i trade in my C8 and other store credit i have, i come out pretty much even with the Newt. What do you guys think? Will it add more weight to my rig???

I really want to get better astrophotos... What should i do guys???

[angusb1]

The C8 has a focal length of 2032mm and a focal ratio of f10 which makes it hard to autoguide and also slow at f10 so longer exposures are needed in comparison to a faster scope to get the same brightness. What might work better is using your Zenithstar ED80 to image through piggybacked on the C8 if you are imaging DSOs. The Zenithstar is much faster at f6.8 so you will get much more depth for a given exposure. If you want to try guiding you could use the C8 as the guide scope and image through the ED80. Keeping the C8 for planetary and lunar observing and imaging would work really well.

An astrograph at f4 will be very sensitive to collimation too, the Zenithstar would be much simpler to use all round.

[AlexxxAA]

You are very right! i think i was just getting too excited with the price of the Newt and getting something new lol

I think i will invest my store credit on a reducer/flattener for my zenithstar?...

I think i will save up and buy and Astrotech Ritchey-Chretien in the future to avoid all that collimation too...

[AlexxxAA]

Oh and by the way, i had been using an f/6.3 reducer/corrector on my c8, but i would still get severely vignetted image subs...

Thats why i was getting somewhat frustrated and was inclined to the appeal of an astrograph

[angusb1]

A reducer/flattener would certainly be a good step. I'd like a RC too but there are so many shiny things I'd like to spend my money on

[E621Keith]

The SCT is F10, so in theory it will image around 2.5stop slower than a F4 Newt. Hence your 30" will look much darker than other people's 30" exposure with a faster scope. You can try using a f6.3 reducer with your C8 to speed up exposure. There is a also a Hyperstar system for C8 which will allow you to image at F2 (4 times (2 stop) faster than the Orion).

[angusb1]

Oh and by the way, i had been using an f/6.3 reducer/corrector on my c8, but i would still get severely vignetted image subs...

Thats why i was getting somewhat frustrated and was inclined to the appeal of an astrograph

Did you try to correct the vignetting with flats? Its something you will need to do with the ZS80 as well.

[E621Keith]

Regarding vignetting, have you taken any flats?

edit: got beaten to it again. Flats can be used to compensate for vignetting. Some people uses electroluminescent panels or light boxes, but I find sky flats to be sufficient for my need. Handbook of Astronomical Image Processing by Barry and Burnell is a good guide and should be fairly easy to get in the States. Steve Richard's Making Every Photon Count is also highly recommended, but I don't know whether it is available across the pond.

[AlexxxAA]

thanks guys. i knew about darks. but i havent done my research on flats yet since im still struggling to get my autoguider to work on my mount. and there havent been clear skies these days... hopefully soon. and ill try to post some test shots from my zenithstar

for now ill start with getting the reducer or flattener for my refractor. thanks alot guys!!! :)

[ollypenrice]

It is just so much easier with a short fast refractor.

The 8 inch RC tempts me but for special occasions on small targets. F8 is slow, slow. Most of the time the fast little refractor gets the work done.

Olly

[AlexxxAA]

I just spoke to a rep at the dealer and they dont know what kind of flattener i can use with my ED80ZS...

Will i definitely need a reducer/flattener for my 80mm??? any suggestions on what will work? or will it be easier to just image and crop out edges?

[ollypenrice]

Post a separate question on this because, though I don't know the answer, plenty of people will tell you straight off. I thought Skywatcher did a dedicated one, no?

The one at the bottom of this page?

Pro Series - Skywatcher Evostar 80ED DS-Pro OTA

Ollyt

[dph1nm]

DSS wont even recognize any stars in my many attempts at M81

Have you tried DSS superpixel mode? This creates one pixel out of the 4 Bayer ones (essentially reducing the resolution by a factor 2) which might help in star detection. DSS is not very good at picking up stars which are fuzzy or trailed.

NigelM

[E621Keith]

... Will i definitely need a reducer/flattener for my 80mm??? any suggestions on what will work? or will it be easier to just image and crop out edges?

Here is one of my attempt with a 80mm without flattener, 10x1 minute unguided, stacked with DSS, taken with a DSLR-Fuji IS Pro (APS-C). No other processing apart from a bit of colour balance. Yes, a flattener will make it better, but I am happy with the current result. A bit of cropping will clear the worst of the elongated stars around the corners. I need to improve my processing and guiding skills before I can justify blowing another £250 on a flattener.

Stargazers Lounge - E621Keith's Album: Astrophotography attempt - Picture

The question is, whether the unflatten result is good enough for you?

[AlexxxAA]

Wow keith. Thats pretty freakin' awesome on its own. Cant wait to get a clear night and try it myself...

Lets see how I come out in the end

Thanks for all the great info!

[gary1968]

I know there are a LOT or refractor fans on here, and while they are great they are expensive, IMO.....

Now, I love newts, I love diffraction spikes and most of all I love the mechanical simplicity of a newt. Theu do need a bit of looking after but as they are sooo simple they can be looked after by the owner. Although unlikely, if a refractor looses colimation then its probably best to go to a specialist for adjustment. SCT's are great for imaging when used with a reducer, Blinky gets great results with his.

So with that in mind when I was upgrading to a Astrograph I bought the Orion 8" F4 newt you are talking about.

It has proven to be a good scope so far, although due to the terrible winter we have had it aint seen much use. It is well made, has a great slop free sturdy 2 speed focuser. It has the larger secondary mirror optimised for DSLR cameras.

Collimation, it holds very well when used at home. If I take it somewhere in the car it usually needs a little tweek, this only takes a few mins with a Hotech collimator. As I siad, when at home, if I build up the kit, then take it down, collimation is still fine. If there was one improvement I would make to it it would be better, stronger springs in the mirror cell, this will get done some day.

Anyway, thats my 2p worth...... Gary ducks n runs for cover....

Gary

[AlexxxAA]

Hi gary

Thanks for your input in the matter. Is there maybe a pic you can post here from your Newt?

You're getting me exited for the astrograph again hahaha

[gary1968]

Andromeda Galaxy

scottishastronomers.com - DSO Photos/M31-Kielder-Autumn 2010

Rosette Nebula

scottishastronomers.com - DSO Photos/Rosette Nebula-21/02/10

Sadr region in Cygnus

scottishastronomers.com - DSO Photos/Sadr Region in Cygnus

Veil Nebula- Eastern Section

scottishastronomers.com - DSO Photos/Veil Nebula-East.

These are some images taken with my unmodded 1000d and the Orion 8" F4 Newt. I am still at the bottom of the very big learning curve that is astro imaging but I am fairly pleased with these. As I said earlier, the newt aint seen much use, I am hoping that the weather improves before darkness goes completely again, else it will be packed away until next winter.......

If you bought the same scope you will need a coma corrector and a dew shield, it is a very short tube and mine has suffered dew when used without the shield, just something else to factor in when you are setting out the budget for it......

Keep us updated on your decisions.....

Gary

[AlexxxAA]

Wow those are awesome gary!!!

Can't wait to give my equipment a try like it is right now, and convince myself of which way to go...

I do think however that I will go with the astrograph since it is so affordable

[gary1968]

Cheers Alex, remeber though, you will need a coma corrector, I use the Baader MPCC, about £120 new..... Or, if you want to wait before you buy that you just have to pick smaller targets and crop the image down to get rid of the stretched stars in the corners of the field.

thanks again,

gary

[AlexxxAA]

Hi everyone.

So I went to the largest dealer closest to me yesterday. I took my C8 and traded it for the Astro-Tech 8" f/4 Newtonian. I'm pretty happy with the purchase. Especially for the great price ($499 US)

Now I'm just waiting for this storm to go away. It's suppsed to rain the rest of the week

But I'll try to post a pic of my new setup later on this thread.

Hope you're all having clear skies.

[gary1968]

Nice one, I'm sure it willl serve you well.

Clear skies mate......

Gary

[AlexxxAA]

Thanks Gary. Here is what my equipment looks like now

[gary1968]

Sweet.... its the same scope as my Orion, only you have the extended tube and baffles, mirrors are the same though...... All you need now is some clear sky. We are well into spring here, my gear will be packed away in the next month or so until Autumn.

Looking forward to seeing some images from it.......

Gary

*edit* although with the cameras on there I think you will need more weight, I have to use 3 large weights on my HEQ5 to balance my Orion, ZS66 & 2 cameras.....

[Deneb]

Not to rain on your parade mate, but I don't think that orion is a proper astrograph, more of a marketing gimmick if you ask me..

As others have said, imaging with a refractor it's a lot easier...

Just my 2p's worth..

Nadeem.