Which type of telescope offers large OTA focal length

[mhc]

Hi,

Can someone please tell me which type (and, ideally, brand) of OTA offers a reasonable balance of focal length to price?

I understand that Newtonians are the cheapest to produce, but they seem to have quite short OTA focal lengths, and I'd like something longer for better magnification.

Thanks,

Mark

[Kaptain Klevtsov]

Maksutov Cassegrain, in the smaller aperture / price range, or SCTs in the bigger apertures.

Captain Chaos

[GazOC]

Don't get too hung up on focal length Mark, you need aperture to make effective use of the magnification you get from a scope. You can alway Barlow a Newt to increase the focal length but you can't increase the aperture of a scope with a small primary mirror/ lens.

[Kaptain Klevtsov]

Excellent point Gaz. It is possible to overestimate the amount of magnification required, what's the target Mark?

Captain Chaos

[GordonCopestake]

The OMC200 has a 4000mm focal length I believe. The Synta 200 f/5 Newt has a 1000mm focal length. What is it your after?

[mhc]

Hi Guys,

Thanks for all the responses.

I'm currently bouncing lots of kit ideas around in my head, hence my current posting frenzy.

My current target is Saturn. Visual observing, not photographing. Of course, I've left it a bit late in the season.

I've only just realised that my 6" Newt only has ~750mm focal length. So, it's an f/5 scope, needing tight collimation. Oh goody

My smallest fl eyepiece is a cheap 10mm Celestron (came with an 80GTL), that I use successfully with a Vixen Barlow. I don't know the Barlow's power - guess I should work it out through drift timings or something. Of course, a new eyepiece is in the pipeline, but being tied to my spectacles implies something expensive so that I get decent eyerelief. Not researched that yet.

Recently visited an astro club for the first time (Wilmslow, Manchester). Really helpful bunch. One guy (Mike Cook - big thanks!), taught me how to collimate the scope. I'd completely stuffed my secondary alignment! While talking OTAs he proposed that a long fl 8" SCT would be useful for, in effect, cutting through my heavy light polution by limiting fov. Sounded counterintuitive at first. Am open to opinions.

Don't worry, I am aware that practical magnification is limited by aperture (upto 50 x aperture in inches). See, I've been doing my homework

So many variables (OTA, mount, ep), so many choices. Too many choices! It's really doing my head in Maybe I should just stick to chess? Hmm, do I want to play white, or black. I know - flip a coin

Pass the asprin!

Mark

[GordonCopestake]

In your situation I would spend your money on a GOOD 2x barlow or powermate rather than a new OTA. What mount have you got at the moment? Thats probably the most important factor for planetary viewing.

[lunator]

Mark

I would see how you could get the best out of your current scope 1st.

It should give good views of planets with a decent barlow & plossl.

Cheers

Ian

[GazOC]

Another thing to remember is that every time you double the magnification of an object you make it 4 times fainter. Its a bit of a balancing act, don't think I'm trying to put you off long focal length scopes but they don't tend to make good all rounders. The OMC that Gordon mentioned is an example thats scope is pretty much limited to the Moon, the planets and double stars, its a specialised scope.

[lunator]

I have an OMC 200 on order but I would not recommend it as an all-rounder scope.

It is ideal for me but I have specialised in my viewing.

Cheers

Ian

[GordonCopestake]

I bet it's great on Saturn too though Ian as well as DS

[mhc]

Thanks for all the advice.

I'm in the process of buying a Televue 3x Barlow from astrobuysell. Impulse buy this morning. I blame lack of sleep

A new mount is certainly my primary concern, and I've received lots of good advice from y'all in a different thread. Hardest bit is making the choice - wifey has actually given me a green light to spend :shock:

Was playing with my old Celestron NexStar 80GTL last night. Had lots of fun with the goto but it wobbled sooo much every time I sneezed! Focussing was a nightmare, waiting for the vibrations to stop, but it reconfirmed my desire for a motorised mount. And possibly goto.

Hmm, HEQ5 vs CG5-goto... :?