Which would you recommend, an expensive 8/9inch or a cheap 12/14inch.

[focaldepth]

Which would you recommend, an expensive 8/9inch or a cheap 12/14inch?

I live in north east England with worse than typical English weather and typical town light pollution.

I am moving up from a 6inch Newtonian on a wobbly EQ mount.

Looking at Cassegrain variant for mainly astrophotography.

I already have some decent DSLR gear. (It automatically upgrades every 2 years or so)

It would be a pedestal mounted goto EQ at the bottom of the garden with limited views for the sky. ( It will never see mars)

I am leaning toward a remote controlled set-up, with the option of some hands on peeping.

It will be the classic set-up of the main scope, a smaller scope, and DSLR camera for through the scope and piggy back.

It will never be loaded into a car or plane to find clear skies. I have been in Arizona deserts looking at the crisp clear skys and can only imagine what it would be like to live there.

I am hoping to buy gear without the automatic upgrade feature all my other hobbies have.

So my question is really, Would you go with a small "PRO" scope or a cheaper bigger one? I am thinking about image quality for photography.

Also I am confused how to go about mounting on a pedestal. Do you buy a mount on a tripod and throw away the legs?

[NickK]

The bigger scopes (and more so the cheap larger scopes) are heavy. With this weight comes the need for a larger payload capable mount. Also the larger the scope, often the focal length increase which results in a requirement to have a steadier mount. A steady, high accuracy, high payload mount equates to an expensive mount.

On the good side (if that's the case) the mid & high range mounts are usually sold as the mount and then you buy either the pier/tripod etc to go with it.

I'd have thought a cheaper large scope will not have the same quality coatings that a higher cost small mount would have. Orion Optics clearly tout that their higher cost coating results in more light (thus shorter and more detailed/contrasty exposures).

I'd be tempted to stick with the newt, go pier and focus on the higher quality mount and then later go for the big mid range scope.

However I'm just starting out down the same path..

[focaldepth]

Thanks Nikk for your reply, I have a lot more research to do before I flex the plastic.

Sorry for the late reply. Not really trying to bump this damp squib of a thread.

[Demonperformer]

<Looking at Cassegrain variant for mainly astrophotography.>

Just a word of caution (unless you are solely interested in planets, in which case ignore me!). These scopes tend to be quite slow (~f.10) and so require longer exposures which in turn require better mounts. If astrophotography is your main interest, you may be better with a shorter focal length refractor.

[Whippy]

<Looking at Cassegrain variant for mainly astrophotography.>

Just a word of caution (unless you are solely interested in planets, in which case ignore me!). These scopes tend to be quite slow (~f.10) and so require longer exposures which in turn require better mounts. If astrophotography is your main interest, you may be better with a shorter focal length refractor.

Sound advice there. DSO imaging largely isn't dependant on aperture, focal ratio and focal length are the two numbers you want to bear in mind. Focal ratio being how quickly light gets onto the sensor and focal length determines your field of view. Another thing to take into account is the longer the focal length, the more accurate your polar alignment and tracking your mount has to have.

There are loads of great images taken with large scopes with long focal lengths but it can be an expensive and frustrating exercise taming that kind of setup. A short, small apochromatic refractor makes life a lot easier if you're just starting out. Short focal length, no collimation to worry about and it doesn't have to hugely expensive either. Something like an ED80 or Megrez 72 on a HEQ5 would be a great starting point. Add in some autoguiding kit and that should keep you happy for quite a while.

Tony..

[ollypenrice]

I too think an SCT is a bad idea if deep sky is your bag. F5 needs four times less time than f10. A focal length of 500mm is dead easy to guide. A metre is easy-ish. By 1.5 metres you are into the tricky stuff and from there on it gets very hard indeed. At long focal lengths you also need good seeing to make it worth bothering. So I will one day have a long FL for those nights and times of year (the springtime) when it is worth having. Otherwise I want the productivity and freedom from hassle and lost time that comes wth using fast refrators.

If you really want some focal length then the Skywatcher Mn190 blows the SCTs out of the water on speed, flatness of field and imaging optical quality. But it is big, it will catch the wind, need collimating and just not be all that easy to manage.

the EQ6 can be made to guide at 2 metres of FL but you can't expect to buy one and watch it do so straight from the box. My feeling is that by a metre it is at its comfortable 'out of the box' limit.

In your situation, short of clear sky time, I would go for a fast f ratio above all and save on the rest of the system in order to get a CCD camera. Then you can do narrowband in clear moonlit nights and have a faster camera than a DSLR. I thnk CCD is actually easier, as well.

Olly

[MartinB]

Imagine you had a DSLR and wanted to buy a lens for it. At the moment you are trying to decide between a 200 and a 300mm telephoto. A telephoto might be great but on it's own it's going to be pretty limiting both for FOV and the light level you can use it at - longer focal length = more wobble.

Although you have to be careful translating daytime photography with night time astro the same principles apply. As has been said you would be much better off with a shortish focal length refractor. Actually, you could just get that 200mm telephoto after all and use it in place of a scope. Check out Olly's recent Rosette and Cone. These telephotos are fantastic astroimaging tools.

[ollypenrice]

A couple from the Canon EF200l lens. I like it a lot! I was using it at a conservative f3.5 but I think f3.2 will be no problem and even wide open at f2.8 it works, according to Dangerous Dave.

Olly

http://ollypenrice.smugmug.com/Photography/Widefield-images-including/SIMEIS-147-HArgb/1182345194_8j8Pv-X2.jpg

http://ollypenrice.smugmug.com/Photography/Widefield-images-including/HaLRGB-WEB/1178234480_v4Rid-X2.jpg

[focaldepth]

Thanks for the comments.

I guess I was wanting an SCT just because they look cool.

I do have DSLR lenses from 10mm up to 500mm(800m APS) although at f2.8 I can only go to 100mm(160mm APS) by 500mm I am down to f6.

I have tried very wide angle shots from a tripod and played with stacking and pp.

So based on this thread (and many others I had read but some how failed to accept) I may have a plan of attack.

1) Keep playing with my static tripod and DSL pushing the focal lengths as far as I can.

2) Get hold of a decent EQ mount (NEQ6 Pro is in budget) and stick the DSLR on it.

3) Get more practice.

4) Get a decent refractor.

5) Now I have choices that involve CCD, Guiding etc.

6) The sky's the limit...(hopefully)

I have learned so many times that small steps is the way to go but it is so easy to get pulled in and want to buy loads of shiny gear from the outset.

Thanks I'm off to re-think.

[focaldepth]

Oh, just seen "A couple from the Canon EF200l lens", Wow, now if I could reach that standard I could die a happy man.

[smudgeball]

I guess I was wanting an SCT just because they look cool.

And so do their owners !

Imaging is not really the domain of an SCT

(well not on an ALT/AZ anyway)

(not impossible though)

I can attach my 40D to my scope and get some cracking planet imagery.

Tried M42 the other day on a 40sec exposure, but I was then off to do a lot of "photoshop" to make it presentable.

I think by now you've got the idea of what SCTs ARE good for.

Anyway, good luck with your choice

Neil

[ollypenrice]

I think SCTs are a con as described by their marketing and count myself as a victim. No telescope on the market is in need of more additinal accessories than these to work and even then you are far from sure to get a result.

If you fancy giving the camera lens a try, get an EQ5 or EQ6. There is no dfference in accuracy, the 6 just carries more. Fit an ST80 on it and screw a camera and lens on that. Guide with the ST 80 and one of the modern autoguiders. That is how my camera lens images were taken. By astrophoto standards it does not get much easier and certainly no faster.

Olly

[Space Hopper]

Hi Focaldepth,

A suggestion...

Forget the big imaging set-up (SCT + EQ mount etc) and buy a quality 3 or 4 inch flat field refractor.

Then have a look at an Astrotrac system to go with it for your DSLR astrophotography. I think this is a much more attractive system, with plenty of versatility.

If you want something for visual, go for a Dob. Masses of choice, good value for money.

TB

[michael.h.f.wilkinson]

I think SCTs are a con as described by their marketing and count myself as a victim. No telescope on the market is in need of more additinal accessories than these to work and even then you are far from sure to get a result.

If you fancy giving the camera lens a try, get an EQ5 or EQ6. There is no dfference in accuracy, the 6 just carries more. Fit an ST80 on it and screw a camera and lens on that. Guide with the ST 80 and one of the modern autoguiders. That is how my camera lens images were taken. By astrophoto standards it does not get much easier and certainly no faster.

Olly

For deep-sky astrophotography you have a point (though with a focal reducer you can get a reasonable F/6.3 at 1260mm FL, good for small DSOs), but they are among the best planetary photography scopes around. I also don't quite see what extra equipment is needed to make them work? Apart from the field flattener, I only needed an OAG and T2 adapter, which I would also need for an APO.

Their real strength is in portability for a given aperture: compare taking an 8" SCT with EQ mount on holiday in the back of your car (with camping equipment and all the paraphernalia for a family of four) with taking an 8" Newt. Looking at the solar eclipse in 1999 through my C8 from France was a treat I will never forget. Visually, they are excellent all-rounders, and much less prone to collimation issues than fast Newtonians.

All this does suggest they are not the most suitable scopes for the given purpose

[Dave-Ryan]

I think SCT's get some unfair flak. I've had one for nearly seven years and it's never needed collimating once and I wouldn't dream of getting rid of it.

They are far from ideal for DSO imaging but great for lunar and planetary imaging and give some fantastic views.

[ollypenrice]

For deep-sky astrophotography you have a point (though with a focal reducer you can get a reasonable F/6.3 at 1260mm FL, good for small DSOs), but they are among the best planetary photography scopes around. I also don't quite see what extra equipment is needed to make them work? Apart from the field flattener, I only needed an OAG and T2 adapter, which I would also need for an APO.

Their real strength is in portability for a given aperture: compare taking an 8" SCT with EQ mount on holiday in the back of your car (with camping equipment and all the paraphernalia for a family of four) with taking an 8" Newt. Looking at the solar eclipse in 1999 through my C8 from France was a treat I will never forget. Visually, they are excellent all-rounders, and much less prone to collimation issues than fast Newtonians.

All this does suggest they are not the most suitable scopes for the given purpose

I think they are great for planetary fast frame imaging. Given Damian Peach's results you'd have to be daft to argue otherwise!

But for deep sky you will first need a reducer (which will probably not give the claimed f6.3 but something rather slower.) Next comes a focuser. The moving mirror is a horror. Then maybe a mirror lock or spring loaded do-dah like mine to help keep the mirror located. Then if you are fork mounted you will need a system of balance weights and brackets.

To guide them effectively an off axis guider is to be desired and that comes in dearer than an an ST80 guidescope and is more complicated to get the hang of. Not impossible, don't get me wrong.

What gets me angry is the marketing which says things like Periodic Error Correction is a boon for astrophotography. It isn't, though, is it? You can't get unguided imaging out of a proprietory SCT fork mount and if you are guiding you are better off without PEC. Or so most of us find.

A newcomer reeading SCT ads is going to get the impression that they are all set for astrophotography and they are not. They are about as far as you can get from 'ready to go.' I really do find this marketing dishonest and unfair but I risk becoming a great bore on the subject and will probably soon shut up about it. I am just glad that when I started imaging Ian King put me straight before I had entirely wasted a fortune trying to sort out an SCT imaging setup.

I have had SCTs for about fifteen years and still have one. They have their virtues.

Olly

[Hawklord]

16 years ago I was about to buy an 8" sct. Then I saw an advert for a scope from Vixen, a VC200L. It looks a bit like an sct but the image plane is fantastically flat. At F6.4 it does everything I want it to do. It is worth considering as an sct alternative but far more suited to imaging.

[michael.h.f.wilkinson]

I think they are great for planetary fast frame imaging. Given Damian Peach's results you'd have to be daft to argue otherwise!

But for deep sky you will first need a reducer (which will probably not give the claimed f6.3 but something rather slower.) Next comes a focuser. The moving mirror is a horror. Then maybe a mirror lock or spring loaded do-dah like mine to help keep the mirror located. Then if you are fork mounted you will need a system of balance weights and brackets.

To guide them effectively an off axis guider is to be desired and that comes in dearer than an an ST80 guidescope and is more complicated to get the hang of. Not impossible, don't get me wrong.

What gets me angry is the marketing which says things like Periodic Error Correction is a boon for astrophotography. It isn't, though, is it? You can't get unguided imaging out of a proprietory SCT fork mount and if you are guiding you are better off without PEC. Or so most of us find.

A newcomer reeading SCT ads is going to get the impression that they are all set for astrophotography and they are not. They are about as far as you can get from 'ready to go.' I really do find this marketing dishonest and unfair but I risk becoming a great bore on the subject and will probably soon shut up about it. I am just glad that when I started imaging Ian King put me straight before I had entirely wasted a fortune trying to sort out an SCT imaging setup.

I have had SCTs for about fifteen years and still have one. They have their virtues.

Olly

So the gripe is very much with the fork mount supplied with many SCTs. I much prefer the German mounts (hence the GP-C8) which are much easier to set up. I do get something very close to F/6.3 with my focal reducer (measured it on my old 35mm camera donkey's years back), but on some set-ups mileage may vary. On my GP mount I can either use the AOG I have (only used that manually, a bit fiddly, but it works) or my 70mm F/5 finder/guide scope. When I upgrade the mount to an autoguider set-up, I will certainly be using my 80mm F/6 for deep sky, not the C8, that would require a much heavier mount, and only be suitable for small galaxies or planetaries.

You are right about marketing blah from many companies selling SCTs and the like, but the same can be said for Skywatcher when they sell a 12" Newt on a NEQ6 mount. I have heard several stories that the mount is not quite heavy enough for that scope, especially for imaging.