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Newtonian Astrograph vs refractor


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Hey guys,

I was thinking of purchasing a telescope, primarily for astrophotography. I as unsure as to what kind of telescope I should get. I have heard good thing about the Orion astrographs (8" http://uk.telescope.com/Orion-8-f39-Newtonian-Astrograph-Reflector-Telescope/p/109883.uts?keyword=astrograph 10"http://uk.telescope.com/Telescopes/Reflector-Telescopes/Reflector-Optical-Tube-Assemblies/Orion-10-f39-Newtonian-Astrograph-Reflector-Telescope/pc/1306/c/1315/sc/1350/p/109882.uts) but do not know if it would be better to get something like these or a refactor (preferably APO).

Mount - wise, I will most likely purchase used (if that is recommended) but am unsure of exactly what would be recommended for these wider telescopes.

Sorry for any "rookie" errors, as I am new here :help:

All help appreciated!

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If you are starting out in astrophotography then you need to keep it as simple as possible. Most start with an 80ED refractor on something like an HEQ5 (Usable) or EQ6 (better).

What is most important is the mount. As focal length increases so does the difficulty of tracking. Large astrographs require a larger mount and, a lot of skill from the user.

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firstly check these out http://www.firstlightoptics.com/skywatcher-quattro-f4/skywatcher-quattro-f4-imaging-newtonian.html  i had one and liked it very much. 2nd buying a mount from here or http://www.astrobuysell.com/uk/propview.php is fine. ideally you would need a HEQ6 by the time you add imaging equipment the weight adds up.

 

do you have any ideas on what imaging equipment you are likey to be using. 

 

 

 

 

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An f/3.9 reflector is pretty difficult to collimate, do you have any experience with collimating reflectors? A refractor, like Michael says above is pretty much plug & play. What mount do you have in mind, all successful DSO imaging rigs are built from the ground up. Mount first, rest later!

Edited by johnrt
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6 minutes ago, Daniel-K said:

also with the F4s you will need a coma corrector and as john and micheal said collimation at this F ratio is a little tricky even for the experienced astronomers.  

Its not a black art Colimating a scope, just needs a little bit of practice, coma corrector for a Reflector, focal reducer flatterers for Refractors, go for a 130P-DS in the reflectors easier to use and cheap......

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45 minutes ago, Tinker1947 said:

Its not a black art Colimating a scope, just needs a little bit of practice, coma corrector for a Reflector, focal reducer flatterers for Refractors, go for a 130P-DS in the reflectors easier to use and cheap......

Your quite right it's not a black art & is certainly possible, but for someone just starting out when they want to be capturing some images I think fiddling with collimation would be very frustrating and off putting.

I think the 130P or an ED80 is a good shout. 

Edited by johnrt
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WOW guys thanks for the fast feedback!

Yes I was unsure if the astrograph would be a good idea and am now looking more at a refactor. You say 80ED, is this some sort of standard? Also i was thinking of maybe a used advanced vx from celestron, would this and an 80ed be good for astrophotography (specifically nebulae)?

http://www.astrobuysell.com/uk/propview.php?view=108096

also, are there any recommended 80eds?

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If you are new to astro imaging can I suggest that you just stop for a moment before spending a penny and take a deep breath. Get hold of the book Making Every Photon Count from the book section of the FLO website..... read it once.... twice..... thrice..... then stop and think again. Do you know then what you need and more importantly why? If not, go back and read it again :)

Astro imaging is all about the mount ...... mount ..... mount ..... Did I say that imaging is all about the mount? :D

Get that right and life becomes easier, not easy by any means! But a short focal length refractor coupled with a decent mount is the easiest way to start off and to start gathering data and learning about what it all entails.

Hope that helps :)

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Maybe you should look at the mount first, because whatever telescope you choose - sticking it on an insufficient mount wont be any good. The HEQ5 would be considered the minimum requisite for good imaging. The pecking order for AP is mount>camera>optics.

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I agree, either the 130 PDS or 80ED is the way to go. I recently bought the 130 PDS and put it on a second hand HEQ5 Pro. I was worried about collimation but once I'd had a read online and got all the necessary bits it became fairly straight forward and I do it now as part of my routine (or when i'am bored of the clouds and want to do something with the scope).

Astrobaby's guide to collimation was a god send;

http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

 

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Thank you so much guys

Am now thinking of a sky watcher 80ED and a HEQ5 as I feel an EQ6 may be a bit too expensive

With regards to collimation, how often must it be done on a refractor?

 

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As far as I'am aware they hardly ever need collimating, which is obviously one of the big advantages of refractors. There are guides on how to collimate them if needed but I'am sure people on here with far more knowledge than me can advise you. Can highly recommend the book 'Making every photon count', has everything you need to know and more.

R

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Seriously, as has been said don't spend a penny on hardware until you've bought, and read *thoroughly* "Making Every Photon Count* 

Here; http://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

AP is so counter-intuitive it's very easy to spend a silly amount of money, only to find you have to go back to the beginning and start again. Then again, even when you do know, it's even easier to spend a silly amount of money :eek:.

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The fast F4 Newtonians are interesting scopes (I have four!) the caveat being that unless you love a really steep learning curve- they're not the best scope for starting out on.

Collimation is fairly easily mastered- again the caveat is practice and the right tools to make the process fast and accurate.

As others have said- the mount is fundamental, if you're already thinking about largish scopes then it might make sense to invest in the bigger EQ6 from the go. That way you'll be fairly future proof even if you start out with a small refractor.

BTW- the Telescope House GSO/Revelation Astro F4 Newts are good value

http://www.telescopehouse.com/telescopes/telescopes-by-brand/brand-revelation-telecopes/revelation-8-f-4-m-lrn-optical-tube-assembly-ota.html

The monster 12" is steal at £575 but only really suited to observatory use.

 

 

 

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  • 6 years later...

I really don't understand the perception that collimating a Newtonian is difficult.  I have been using a 10" f/3.9 for years and I check/adjust collimation prior to EVERY imaging session.  I even do it during sessions if the temp changes much.  It's done on the mount and I don't even take it out of the tracking mode.  What is it that folks think is difficult?  Seriously, when it comes to a Newt I don't even consider it.  On a refractor, although they rarely need it, collimating is a major project that usually requires removing the telescope from the mount and heading for the "bench".  Some years ago I went with a 130mm triplet that I never COULD get perfectly collimated.  I finally took it to the Small Optics Lab at Steward Observatory to have it done.  Again, once it is done it will probably never need it again.  The "big three" for astrophotography is MOUNT, MOUNT, MOUNT.  Old saying, "you can compensate for a nominal scope with a good mount but you can NEVER compensate for a bad mount with an excellent optic".

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What kind of imaging do you want to do? I have two imaging setups, one with a 102mm achromat and the other with a 8" SCT + focal reducer.

They address different field widths.  If you want to capture wide (ish) fields, you want a short focal length and a small scope.  If you want to capture detail on small planetary nebulae and diatant galaxies, you'll want a longer focal length and a bigger scope.

The 102mm achromat is set up to plate-solve and re-sync, but that does not work so well with the SCT and its narrower field of view.

You don't mention a camera - many people use a DSLR.  You may already have one. Note that using an older model of DSLR can be a severe pain for various reasons. Dedicated astro cameras are easier to use but those with chip sizes comparable with a DSLR are expensive.

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I'm just getting started in astrophotography, I ended up going through a wide range of permutations of potential kit.  In the end I sunk the bulk of my funds into the mount and got a GEM28 (second hand) as it has a decent payload and is also 'portable' and lighter than many alternatives.

For my 'scope' I went for a takumar 200 f4 telephoto lens for £40.  There is loads to learn with astro imaging, I'm going to learn my equipment at a short focal length then get something 'better'.  I can see myself producing garbage images and not knowing what the issue is.  At least by simplifying everything as much as possible to start there will be less steep a mountain to climb.

Have a look at stellarium with it setup with a 200-300mm focal length and the camera you plan to use.  There are loads of decent objects to image at that range.

Oh and have a look on astrobin.com and search for images with whatever scope you are planning.  Keep in mind that the camera will also have a big impact.  It will give you an idea of what you can achieve.

Edited by Ratlet
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