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nas76
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New telescope help

Post by nas76 »

It's been a while since my last post, so here's an extra long one...

It's about time I had a new scope, the 3" reflector that I've been using up until now has served it's purpose and now I want to got to the next level of viewing. The 3" scope was excellent for a beginner and gave stunning views of the moon; Mars, Jupiter and Saturn were decent too, but for deep sky it simply wasn't good enough but I probably haven't been helped with severe light polution with Watford in one direction the M25 in another and Warner Bros film studios in the other (although they don't do a lot of night filming).

This weekend the Optical Vision Ltd catalogue popped through the post and I spent many hours chewing over my choice for my next 'scope. In a nutshell my primary requirements are 5" reflector with an equatorial mount and to not spend any more than £350 maximum; also in the future I will want to have a stab at some astrophotography therefore a motor drive may be an additional benefit.

As OVL are only a distributor, they provided a separate document listing suggested prices. The catalogue is excellent and I've narrowed myself down to a handful of 'scopes and any assistance anyone on here could give me would be very much appreciated, I've listed them how they are ordered in the catalogue (note that all are Sky-Watcher Newtonian reflectors):

EXPLORER-130P SUPATRAK AUTO (5.1") SRP £249
PROS: It's motorised, its price.
CONS: Despite the mount being motorised it's not obvious whether in the future I'd be able to replace the scope with a larger one in the future.

EXPLORER-130P SYNSCAN AZ GO-TO (5.1") SRP £319
PROS: The GO-TO mount.
CONS: Same as the previous.

EXPLORER-130M (5.1") SRP £199
PROS: R.A. motor drive, price.
CONS: The EQ2 mount doesn't look sturdy enough and certainly not strong enough to carry a heavier scope in the future.

EXPLORER-130P (5.1") SRP £199
Is the same as the previous apart from the primary mirror is parabolic and there isn't a motorised mount, however no doubt there shouldn't be any reason why for a little extra I couldn't have the bext of both worlds.

EXPLORER-150P (EQ3-2) (6") SRP £319
PROS: Solid mount (which is upgradable), 6", it's advertised with "Direct SLR Camera connection", in my opinion the best value for money for final product.
CONS: There aren't really other than a condundrum in my head - it's got the largest mirror and best mount but it isn't motorised, it doesn't have GOTO so where do I go? Do I stretch the budget a bit further than planned and go for as large as possible scope (so I'd never have to buy a new one again) or as best a mount as I could afford but with a cheaper scope so I could upgrade the scope in the future without having to worry about the mount? Judging by the catalogue sometimes matching the same scope with different mounts sort of implies that I may be able to have some flexibilty with choice of scope with choice of mount but that of course wholly depends on the manufacturer/supplier.

EXPLORER-150PL (EQ3-2) (6") SRP £319
Same as above except that it has a 1200mm focal length as opposed to a 750mm f/l, which offers greater magnifications with the supllied eyepieces than the one above (max is 240x compared to 150x) but the max practical power of both is 300x. The main con is that its longer tube length would use up more storage space.

All my choices are Newtonian reflectors, I haven't included any Maksutov-Cassegrains as they are too expensive, Dobsonian's (because despite an 8" being listed at £299 the mount isn't too my liking and unless anyone that swears by them would convince me otherwise I doubt I'd ever get one); and finally refractors mainly because as a complete amateur I don't know what aperture size would be comparable to a 5" or 6" reflector (if I do have to get one with a similar aperture then this too becomes expensive), though I do have plans to get a small fairly cheap refractor for the next time I visit my in-laws in South America.
National Geographic NG76AZ
700mm focal length + 20mm, 12.5mm & 4mm eyepieces
51°40' N 0°24' W
nas76
Posts: 48
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Post by nas76 »

I forgot to mention that some of these scopes come with a red dot finder rather than a finderscope. My current kit has a finderscope, which I'm used to, but would I be right in guessing that a red dot finder is simply a laser? If so is it any good on a perfectly clear sky?
National Geographic NG76AZ
700mm focal length + 20mm, 12.5mm & 4mm eyepieces
51°40' N 0°24' W
David Frydman
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Joined: Mon Jan 18, 2010 9:25 am
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Post by David Frydman »

No a red dot finder as far as I know is a red circle image projected in front of your eye giving just a 1x finder. At least that is what I remember my telrad being.
A laser beam is quite different. But I think in the U.K. the beam will always be visible.
A 102mm refractor is about equal to a 5inch Newtonian although the Newtonian has little colour error and an f/5 refractor has some an f/8 less.
A 120mm refractor is almost equal to a six inch. It depends on personal preference. Some people like refractors, some reflectors, some both.
An 8inch Dobsonian is a very capable instrument but does not meet all your needs.
A refractor may be more maintenance free, but as you point out there is a very great choice nowadays.
Perhaps someone else will help as I am mainly a visual obserrver not used to computers.
Regards, David
astroeddie
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Post by astroeddie »

Nas,

Red Dot finders project a dot onto a glass scree in the finder, not into the sky. They also do not magnify the view, so you'll need a very clear sky to find your guide stars.

The Newtonian of 6" is the same as a 4" Refractorin glass wise, but, personally I'd have the refractor over the 5" newt any day. Refractors attain a much better contrasting look. Skies appear much darker in these scopes.
"Colin" has a good one for sale with an EQ mount for £150 here. A cracking bargin.

DOBS .....
Write these off at your peril. You get a lot more glass, that's what astronomy is all about, for your money. You can get a 6" EQ mounted newt for say, £500. You'll get a 10-12" dob for that. I'd say buying a 5-6" newt would soon have you itching for that bit extra glass.

www.astrobuysell.com/uk usually have tonnes of scopes for sale at excellent prices, same for Stargazers, but you need to be a member to view their section now.
I started with a Taso Refractor (60mm) around 15 years ago. Crept upto a Celestron C11 GoTo, sold all and now have a 300mmF5 Dob auto.
Dobs are the bizz for speedy obs sessions. If your serious about astro imaging, your EQ alignment needs to be spot on. This can be troublesome, so imagine having to set up each time if you have to bring your stuff in.
Mak 127 GoTo,s do not track the objects in EQ style they use stepper motors, so you cannot use these for long exposures. The stars will look like a set of steps

Do not rush into your next scope. Check everything twice on the net and then decide and check again. Buying a setup and getting frustrated is the last thing you want.

JUST MY TEN BOB'S WORTH...

Eddie
20x80 bins
127 SW Mk
Usual odds an sods
gary1968
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Post by gary1968 »

If you want to try imaging at some point then the dobs and az mounted scopes are not for you.
You are right in saying a motorised mount will be required. For imaging the bigger the mount the better, I would not recomend anything less than a HEQ5, but an EQ5 might do for a while.
With your budget in mind I would not consider imaging at the moment, either concentrate on visual or save a bit more and get a 2nd hand HEQ5 and use it with your current scope until you save yet even more to buy another scope.
Reflectors do give the best bang for your buck, but take a bit of looking after, which isn't difficult. A refractor will give more pleasing contrsty views, is more expensive but if handled carefully takes next to no maintenance.
For imaging the mount in next to gad, the bigger the better..... and good motor drives are essential.

HTH,
Gary
56N / 3.5W
HEQ5 Pro. Skywatcher ED80, William Optics Field Flattener III, Canon 1000d - Imaging Rig. Guided with Orion 8x50 & QHY5.
Control Via Ascom, EQMod, Cartes du Ciel and PHD.
Everything will be OK in the end, if its not OK, its not the end..............
nas76
Posts: 48
Joined: Sat Dec 29, 2007 10:37 pm
Location: Watford
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Post by nas76 »

Thanks everyone for your help. I fully understand that in the case of Dobs one can have a larger mirror than a Newtonian for the same cost but the mount is quite off putting; and as I suspected, not suitable for imaging unless motorised.

I did see the scope that Colin is selling, and whilst it looks excellect value for the asking price, astroeddie gives good advice insofar as not to rush my decision. Also he has "UNDERSTANDING WIFE" in his signature, which I empathise with, as a South American she can't understand why anyone would want to go to the shops when the temperature drops below 5C in the winter let alone stand in the garden in such temperatures looking at the sky! But while she has agreed to allow me to get a bigger scope I wouldn't be able to push my luck and get an intermediate sized one and then a larger one later. I will probably follow gary1968's advice and go for as large scope as affordable and then later upgrade the mount, I'd probably get away with that with the missus!

Referring back to the OVL catalogue, on the opposite page of the scope I have my eye on is this:

EXPLORER-200P EQ5 8" NEWTONIAN SRP £449
PROS: Even better mount, 8" mirror only for £100 more than I am prepared to spend.
CONS: The wife and the rolling pin.


Cheers,

Neil
National Geographic NG76AZ
700mm focal length + 20mm, 12.5mm & 4mm eyepieces
51°40' N 0°24' W
David Frydman
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Post by David Frydman »

A tin helmet shouldn't cost much extra. You could line it to keep out the cold. Dual purpose.
Regards, David
astroeddie
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Post by astroeddie »

Nas,

Good choice for the 8".
A bit baffled though. You are upgrading the mount later ?
If you get the EQ5 mount with the 200P (advised) you only need motors. If the mount is less stable, no good for imaging, GET A BIGGER DOB.
a 10" scope can be handled with an HEQ5 later in life. These go for sale, mount, for @£400 2nd hand.

MY Undertsanding wife told me to get back into astronomy instead of reading forums all the time, Ermm ok Jackie, but I need a scope ..... :lol:

Eddie
20x80 bins
127 SW Mk
Usual odds an sods
nas76
Posts: 48
Joined: Sat Dec 29, 2007 10:37 pm
Location: Watford
Contact:

Post by nas76 »

Thanks Eddie,

As I said in my first post, imaging isn't high on my priorities at the moment, primarily due to additional cost of the equipment required. The 3" Newtonian I have now would be useless for the job hence my desire to get a larger telescope now. Once I can see deep sky objects and learned to navigate my way around those, then I would then fork out for imaging kit when I can afford it.

Obviously I wouldn't get a 6" or 8" to sit on an EQ1 because it would be too heavy, and such combinations are not available as one package for that reason. The question arises, if I were to go for the 6" with an EQ3-2 mount, what's to stop me selling the mount at a later date for an HEQ5 in order to do astrophotography? I suspect part of the answer lies in Eddie's first reply is that once I see what's possible with a 6" I would be salavating for more, in which case going for the 8"+EQ5 makes the most sense; also ask Sky-Watcher if I could have any tube offcuts to make an effective helmet!

Final question though, if I bought an 8" or 10" Dob, would I be able to detach the tube from its mount and attach it to an HEQ5 later on?

Cheers,

Neil
Last edited by nas76 on Tue Jun 07, 2011 12:21 pm, edited 1 time in total.
National Geographic NG76AZ
700mm focal length + 20mm, 12.5mm & 4mm eyepieces
51°40' N 0°24' W
astroeddie
Posts: 1111
Joined: Thu Dec 16, 2004 5:06 pm
Location: Hartlepool
Contact:

Post by astroeddie »

Yes,

Just remove the two "discs" on either side of the scope tube and buy tube rings for said scope.

I DID exactly that a few years ago. Sold it all for a C11. To me, a big mistake. My 254mm F5.7newt shown much better detail for visual obs of the planets.

Eddie
20x80 bins
127 SW Mk
Usual odds an sods
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