Dobsonian or EQ mount?

[Swamp Donkey]

I am looking to buy a second-hand scope and from reading through some posts the Skywatcher 200 seems to be very popular here and also widely available at reasonable prices. Now there seems to be a variety of flavours available EQ mounted  F5 (1000mm), Dobsonian F6 (1200mm) and I think I also saw a F4 (800mm) somewhere.

It is my understanding the for detail of Planets and other nearby objects greater focal length is an advantage. Is there any reason the 200 F6 couldn't be mounted on a EQ or HEQ (5 or 6) mount at a later time?

What are the advantages of F5 over F6 (or the other way around). 

The intention is to mainly observe visually Planets and hopefully some DSO and maybe some imaging with modified webcam. Eventually like to have the scope permanently mounted in a DIY obsy aka converted shed.

At this point in time budget is the main constraining factor.

[NGC 1502]

The tube of a 200 f4/5/6 could be remounted on a wide range of EQ mounts later on.

200 F5 - lower power wider field with a given eyepiece, good for deep sky, shorter tube a bit more easy to transport, you can perhaps get

away with a bit less sturdy mount. Good for planets / moon / double stars but 200 F6 a bit better for that (perhaps). Collimation a bit

more fussy than F6. A good all round scope none the less.

200 F6 - higher power with a given EP, longer tube a bit heavier and a bit less transportable and could do with a slightly more solid

mount, but still an excellent all purpose scope.

200 F4 - much more specialised, critical collimation, needs excellent eyepieces to perform well, but very transportable. Great for taking to a dark site for deep sky.

Neither F5 or F6 is a mistake, best to think hard before getting an F4.

I'm talking visual here, hopefully someone will comment on imaging.

Good luck in your choice, Ed.

[Ricochet]

For visual observations with a Newtonian I prefer a Dobsonian mount over an equatorial mount so I would favour the F6 as it tends to come as a dob. For photography the eq mount is a much better (necessary) choice but I would imagine that even the F5 200p is a bit of a sail.

[nightfisher]

If i were you i would look at the 200 f6 dob, then at a much later date look at EQ mount and smaller scope for any imaging work

[DRT]

If budget is the main constraint I would agree with the posters above that an f4 would be the wrong choice as you would need to spend lots of money on eyepieces and, ideally, a comma corrector/paracorr to get the best out of the scope.

I have an f5 Skywatcher Explorer 200 which I predominantly use on a giro (Alt-Az) mount. I have mounted it on an EQ mount and find it extremely awkward to use for visual as the eyepiece ends up in some very strange positions. I have also owned a 200P Dob, which I really liked but found the low position caused problems with my dodgy knees and back during long sessions. For visual use I think an Alt-Az mount of a tripod and pillar provides the easiest use and best flexibility in terms of eyepiece height/position.

[Gazabone]

The Dob is a great scope for visual, incredibly quick and easy to set and get looking at the sky. You are limited to finding faint targets by star hopping though unless you do the modification that was articled in July 2015 Sky at Night mag (did that to my 10" Dob and it works wonderfully.

With photography, it's very unlikely you'll get anything terribly worthwhile unless you have a good EQ mount and deep sky photography on any altaz mount (which includes the Dob) is out of the question.

Hope enjoy whatever you end up with.

[BritAngler]

As a slight alternative, you could buy the f5 plus EQ5 mount, and build a dobsonian mount so you have the best of both worlds (I will be doing that in the New Year if Santa brings me some 12mm plywood sheets....). There are plenty of plans on the net if you want to go that route.

[DRT]

A money saving option which would allow you to move on to astro photography when funds permit would be to buy an EQ5, set the Altitude adjustment to 0°, loosen the clutches and use it as a push-to Alt-Az mount

I have done this before and it can work well provided you spend a few minutes getting your scope well balanced.

[Swamp Donkey]

The Dob is a great scope for visual, incredibly quick and easy to set and get looking at the sky. You are limited to finding faint targets by star hopping though unless you do the modification that was articled in July 2015 Sky at Night mag (did that to my 10" Dob and it works wonderfully.

With photography, it's very unlikely you'll get anything terribly worthwhile unless you have a good EQ mount and deep sky photography on any altaz mount (which includes the Dob) is out of the question.

Hope enjoy whatever you end up with.

Can you give me a vague idea what this mod involved? There appear a few mods that are mentioned in various places, Lazy Susan bearing, Teflon patches etc.

[Gazabone]

Can you give me a vague idea what this mod involved? There appear a few mods that are mentioned in various places, Lazy Susan bearing, Teflon patches etc.

In brief it was fitting a 360 degree indicator (a sort of compass dial) in the base and some form of pointer (it has to be fixed in such a way that you can move the compass dial to orient it to the pointer but mustn't move as you rotate the scope itself (hope that makes sense). Then add a digital inclinometer to the OTA and it works very well to find faint objects very quickly and easily using altaz coordinates. Don't confuse the altaz coordinates with Right Ascension and Declination coordinates.

If you open the object panel on Stellarium, it will show both types, the altaz coordinates are the set that are constantly changing. I've found stuff in a matter of seconds using that system that would have taken me ages to find by star hopping (if I could have found them at all)!

[Charic]

Keep it simple, the f/6 Skyliner is a great telescope. No mods are required, just a dark sky, good collimation, an eyepiece of your choosing, and hopefully, some good seeing conditions, enjoy the view.

[Swamp Donkey]

Well availability and the right price. It looks like it's going to be a 8" Helios F5 on a  EQ5 style mount. I'll know more in a couple of days once I had a look at it and, all being well,  given it a new home.

Just gotta hope for some clear skies to follow on.

Thanks for all your thoughts and all the other advice available in the Lounge.

[Putaendo Patrick]

Sounds interesting - Helios was pretty much the predecesor of Skywatcher, and the scopes are generally of similar quality! Hope it works out!

[John]

As long as it's the F/5, 1000mm focal length Helios then it should be fine. The brand name Helios has also been used on an 8" F/4 Eq mounted newtonian which is really to be avoided. There was no connection between these latter types and Skywatcher.

[Putaendo Patrick]

Thanks John, I rather hastily assumed this would be a secondhand scope.

[Swamp Donkey]

This is the 8" 1000mm (F5) and it is used. As far as I can tell it is in reasonable condition, I'll find out tomorrow.

[Swamp Donkey]

Right, that's that sorted. Looked at, 't was an offer I couldn't refuse. The scope is in good nick, generally, the mount is solid and fairly smooth. Apparently it has been standing still quite a lot so maybe a clean and re-lube or just some use. Well here's hoping for some clear skies soon.

The mount only has rigid plastic knobs for RA and Dec adjustments, so I am thinking of flex cables to start with a view of adding some kind of motor drive (more research needed on that one) later, snag is there are no identifying marks that I can see on the mount. Are there any good resources available to help identify the mount with a view of getting the right accessories?

[faulksy]

your scope sounds great. if you need more info. irealy suggest you put some pics up, people can help i.d it and help no end