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Is apperture really king?

am3x

By am3x
in Discussions - Scopes / Whole setups

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gary1968

gary1968

Posted
Posted

I have 3 scopes that I use / swap about for imaging, a ZS66, a C80ED and a Orion 8" F4 Newt. For wide field the ZS66 wins hands down, it's FOV is huge, then the C80 and lastly the Newt. For ease of use I would use the 2 refractors on a side by side bar, but for real faint DSO's I use the Newt guided with the ZS66, my mount is a HEQ5 Pro. I did use a CG5GT and for unguided imaging it was fine, upto about 2 min subs. I then started guiding and it was very hard to get the guide graphs smooth. I sold that mount on and bought a HEQ5, absolutely fantastic mount. If you are about to buy a mount for imaging then I recomend you hold off and go for the HEQ5, great mount, very easy to use and guides straight out of the box with no faffing about or 'tuning'.

Now, if you are considering the scope purely for imaging then I would recomend a refractor, so much more reliable in its build, much easier to transport and set up, and as has been said the smaller aperture makes little difference when imaging. The newt on the other hand takes a bit of looking after, mirrors get dusty (easily cleaned) and the faster the newt the more critical the collimation is (for planetary imaging collimation is VERY critical. I have read that Damien Peach collimates his SCT every time it flips on the mount). Again this is fairly easy and quick to do once you have done it a couple of times, a good reliable collimation tool is very important for this. I use a Hotech Laser as I have never got my head round all the circles and reflections while using a Cheshire Collimator, although some folks say this is the best, but the Hotech serves me well, I can have the newt collimated in about 5 mins.

Back to my point though, if it is going to be your visual AND imaging scope then go for aperture, thats why I bought my Newt, great for imaging as it is very fast and also good for visual as it has a fairly large mirror. ( I love Newts though, and the diffraction spikes add that little bit of 'special' to the image)

Just my 2p worth...... :-)

Gary

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sixela

sixela

Posted
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The 150 tube weight is 8kgs, so again you'd need the HEQ5 if the standard EQ5 has a 10kg capacity, plus, at f8, it's quite a long tube.

I'm talking about an f/5 Newt. These sit quite comfortably on an EQ5 or Vixen GP, even for imaging (unless you add a very heavy autoguiding setup).

A HEQ5 is, of course, better but that's well beyond what I consider even remotely portable (at least for schlepping through Africa).

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TheThing

TheThing

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It's quite obvious from my previous posts if you bother to read them.

I did have a long reply typed out, but I just can't be bothered anymore! It seems if you don't slavishly follow the 'norm' your experiences are ignored.

Never mind. I wont be bothering again.

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ollypenrice

ollypenrice

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You know, Thing, it is maybe just a tad ironic that you repeat the mantra 'aperture rules' and then accuse those who take the opposite view of being slavish followers. Historically, in imaging, the rise of the small refractor owes much to a number of very radical thinkers who broke away from the mainstream (which was SCT/Large Newt at the time) to explore what could be done with seemingly absurd little telescopes. In this country we must think of the early work of Ian King, for example. This can happen in all sorts of areas. Trials bikes used to be gigantic 500 singles and then Sammy Miller turned up on a ridiculous little Spanish pop-pop and wiped the floor (which was already his, by the way!). Now the tiny trials pop pop is the orthodoxy. The Americans laughed their socks off when Cooper turned up at Indianapols with a tiny rear engined minicar... And so on.

It is always best to stick to the merits of the case and certainly not worth becoming acrimonious on this amiable forum.

Olly

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saturn5

saturn5

Posted
Posted
It's quite obvious from my previous posts if you bother to read them.

I did have a long reply typed out, but I just can't be bothered anymore! It seems if you don't slavishly follow the 'norm' your experiences are ignored.

Never mind. I wont be bothering again.

I did read them,you made a short statement saying

Go for the 200. Apature is definitely king and the 200 will rule over a frac - just look at Steve Richard's pictures.

Nobody will argue about the quality of Steves images ,they are superb but the're are a lot of superb images posted here taken with much smaller scopes.

I was only looking for a reasoning behind the statement,not for a "spit the dummy out" reply.

The OP is looking for advice and probably would like that advice backed up by some sound reasoning,from the obvious vast knowledge bank of this forum,so they can make a balanced judgement based on the points of view given to them.It is of interest to me also because i would like to make a serious attempt at imaging.

Thankfully for us novices the're are many who can be bothered to take the time and explain things so we can understand the reasoning behind their opinions.

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OzDave

OzDave

Posted
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In my own experience as a beginner to imaging, I started out trying to image and guide with a longer focal length scope on a mount that wasnt really up to the job. The results were not reallt very pleasing due to inability to effectively control the tracking sufficiently to get longer subs. The longer focal length of the scope just acted to magnify every problem in a way.

When i switched to an 80mm refractor on the same inadequate mount, i immediately started to get some excellent imaging results although perhaps not by the standards posted here. The shorter focal length made tracking much easier and many problems i was having disappeared.

Therefore i would seriously recommend that someone beginning imaging consider a short focal length scope initially, if only to make things easier. When you're trying to learn a lot of new techniques anything you can do to make it simpler helps.

Not that longer focal length scopes are not good for imaging, just maybe better for when you get to a more advanced level.

David

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Tim

Tim

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Posted
Hey all,

Im going to be working in Kenya for 3 months or so and will come back with a little extra pocket money and im wondering which one of these scopes is the best for astrophotography. The sw 200p on eq5 goto, or the Sky-Watcher EXPLORER-150PDS same mount? obviously the 200p has the larger mirror but does the 150pds Dual-Speed 10:1 ratio focuser, and the tube length shortenning take presidence?

or could someone else recommend something else in the 600 - 700 price range?

Many Thanks

Alex

Hi Alex. Quite a storm in a teacup you have inadvertently brewed :(

In answer to your question re: the 200 v the 150, the 150 may be easier to use.

Could you just verify your mount type though please? Is it a HEQ5 or EQ5?

Most of the telescopes available for imaging will enable you to capture great images. The real trick is learning how to process them to get the best out of the equipment you have, and that is the real challenge!

If you plan to stick at the hobby, a smaller refractor is likely to come in handy for many things in the future, even if you upgrade to a more expensive scope in the long run. They are certainly easier to setup and run with, and you can achieve very nice results with a smaller tube. Please see SteveL's image here that was mostly taken with a 60mm refractor.

http://apod.nasa.gov/apod/ap101005.html

I have both refractors and reflectors. As you see, peoples experience and opinions will vary widely as to what is "best", but really the best scope for you is one you enjoy using. Personally I really enjoy using the MN190 reflector most of all, but that doesn't mean my refractors are any less capable :)

Cheers

Tim

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