Never had a refractor

[pat]

I've decided to get a Celeston 90mm LCM 660f/l. Already have a 10" dob. Just a grab and go to view the sun, moon, planets. What can I expect? And what is the top useful magification for its size. Thanks, Pat

[rowan46]

maximum magnification is usually aproximated at 50x per inch or 2x per mm so max magnification is aprox 180x. Generally in the uk except at times of great seeing anything other than the moon is limited to 150x aprox

[breezy]

^{should be good for the moon and jupiter, my fracs pretty good for them and it 90 mm 910 fl,}

^{a 10mm in yours will give 66x mag , 90 in mine and i dont push it much more than that.}

^{im sure someone with more knowledge will be along to give you some more indepth info cos im fairly new to this}

[Qualia]

I'm not sure, so bear with me on this one. By way of reference, I'm looking at this

You might find that the tripod is a tad lightweight and if its payload capacity is only about two and half kilos I can imagine that in the future its going to cause you some issues. Also, due to its very limited load capacity, I can't really see how useful this mount would be if you wanted to get some upgrades like a bigger viewfinder or heavier, higher magnification EPs etc. Just a 9x50 viewfinder and a 5mm Hyperion, for example, is already weighing in at about a kilo. Moreover, other than using the mount with the supplied OTA, I feel you're restricting yourself if ever you fancy getting yourself another frac, for example, but not wanting to fork out on another mount.

Again, a lot of the money is probably going into the computer driven system, so unless it is really necessary for you to have, I'd prefer to put that cash into the optics and just learn the art of star hopping - which really isn't that difficult.

Also, you say you want to a frac to get into planet, solar and lunar viewing but I'd imagine a short-tube refractor would be more useful for scanning Milky Way star fields, open star clusters, and other large astronomical objects and generally a poor choice for high-magnification viewing, such as Lunar and planetary observing. It is at this junction that I would really want ot know how this scope performs on these solar system objects, to what degree is the false colour etc and doing a quick hunt about, I haven't found anything here or at Cloudy Nights which suggests that this is a good frac within its price range.

What may be key here, then, is that ellusive term of 'grab n go' and yes, I imagine a small short-tube model is extremely portable. But sayng that, so is my set up which with just the mount and OTA weighs in at around 15kgs. That is, I grab the gear and go, lumping it onto a public bus and heading out to dark sites. Others may not find this such a grab and go set up, prefering to pack their gear in a car and driving off to a dark site, so in that case, I imagine an 8" dob or cassegrain is also grab n go. So, as you can see, I'm really not too sure what the term means, unless qualified.

With these thoughts in mind, I'd personally suggest that you check out something like a Tal 100rs - which must be one of the best quality fracs to price ratio on the market and to be honest, I haven't witnessed a single bad word about it - and a decent, lightweight Altazimuth mount which can be used with other OTAs if ever you decide to change your set up.

Okay, it's probably going to cost you around €550 brand new, a couple of hundred more I imagine, but I think saving for this kind type of set up is going to pay back a hundred-fold in the furture, so the extra time needed to save will be worth it. And in the mean time, I really don't know if it works, but you could always try stopping down your 10" dob to something like a 5" and see if this gets the depth of focus for planetary viewing?

I'm sorry if this post has put a wobble into the enquiry, but I really do hope it helps?

[90mm]

I am a long time 90mm refractor owner and in fact it is often my telescope of choice for moon, solar (with proper filter) double stars and brighter deep sky objects. I have observed the entire Messier catalog and many NGC and IC objects under dark skies and under light polluted skies a 90mm refractor is well suited for the brighter planets.

[cantharis]

http://www.teleskop-express.de/shop/product_info.php/info/p3431_Skywatcher-Startravel-80---80-400mm-Autotracking-Telescope.html

This is my grab ´n go. Just pick it up and the legs collapse, very light, just sling it in the car. AltAz mount is not GoTo but tracks.

[Carbon Brush]

+1 for Qualia's comment.

All too often supplied packages have the flimsiest mount that can be used.

Just look at the packages often offered by the retailers, who are in turn pressured by the importer & manufactuerer.

Being very much a used kit buyer means I choose the mount for the job, rather than be dictated to by the supplier.

[sologuitarist61]

Unlike a lot of people on SGL, I am of the opinion that in many ways the mount is more important than the optics. You can have a really expensive scope on a rubbish mount and you will always be disappointed, but a cheaper scope on a really good mount will pay dividends. With a good mount you can always upgrade your scope later if needs be.

[pat]

I rechecked with Celestron and they said the LCM mount is a "Go To" three star alignment system. Also it shouldn't be a problem for my 12.5 oz. Spears Walter eyepiece. My calulations show that the top useful magnification is 90x for this size lens (after that the views become dim). Good to hear that you can also view DSO. Maybe I should wait and let the scope surprise me, hopefully I can see the Cassini division. Your replies have been very helpful -Thanks. I'll never forget viewing througt a friends 2.4" Unitron! Pat

[sologuitarist61]

I rechecked with Celestron and they said the LCM mount is a "Go To" three star alignment system. Also it shouldn't be a problem for my 12.5 oz. Spears Walter eyepiece. My calulations show that the top useful magnification is 90x for this size lens (after that the views become dim). Good to hear that you can also view DSO. Maybe I should wait and let the scope surprise me, hopefully I can see the Cassini division. Your replies have been very helpful -Thanks. I'll never forget viewing througt a friends 2.4" Unitron! Pat

Yes, DSO's show well in the wider field of a fast-ish refractor and don't need much in the way of magnification - much of course depends on the quality of the light where you intend to use the scope.

[brantuk]

"Unlike a lot of people on SGL, I am of the opinion that in many ways the mount is more important than the optics"

I disagree Richard - I reckon a lot of folks on SGL would agree with you that imaging starts with the mount lol

[glowjet]

"Unlike a lot of people on SGL, I am of the opinion that in many ways the mount is more important than the optics"

I disagree Richard - I reckon a lot of folks on SGL would agree with you that imaging starts with the mount lol

+1 for that Kim, although your optics, webcam, camera etc, may not be quite the very best one can buy, if the mount is not fit for purpose, success won`t be a word in the operators vocabulary

John.

[KevUU]

I have an ST80 and get on well with it - although I've not looked through anything bigger yet so can't speak to what you will find after your 10"...

Saturn is good albeit small, Jupiter blew me away (more than Saturn, which might put me in the minority?).

The moon is good but I do sometimes wish for more magnification here. But at least it's bright enough that you can put the masking cap on and get less chromatic aberration from the narrower aperture.

And I'm doing fairly well on DSOs so far

One comment on magnification: x100 is about the usable limit on the ST80 (infact some retailers suggest you stay to x80) so unless the optics are significantly better on the LCM I would be wary of expecting to get upto x180.

HTH

[Polar Bear]

I've decided to get a Celeston 90mm LCM 660f/l. Already have a 10" dob. Just a grab and go to view the sun, moon, planets. What can I expect? And what is the top useful magification for its size. Thanks, Pat

I would steer clear of a small refractor as a grab n go scope as you will still need a good mount for steady views. The one you have mentioned has most of the cost in the goto mount which is not really needed for your chosen targets. For the Moon and Planets I would use a small Mak on a manual alt-az mount. I recently had a Skymax 102 Mak and it was equal to my much larger / heavier 120mm Evostar refractor. The small Maks can also be mounted on a good quality photo tripod with a fluid head mount for ease of use and quick setup.

The Skymax 102mm can be pushed up to 200x with good seeing conditions, plus it makes an excellent solar scope with a full aperture filter and if you add a 45 degree prism it is great for birding and terrestrial viewing.

Paul

[ollypenrice]

I'm a refractor fan but, to be honest, a fan of the posh ones! Good refractors cost a lot to make. On a smaller budget I too would be thinking 'Mak' for high magnification, colour-free observing of the solar system.

Olly

[LukeSkywatcher]

My Celestron 90EQ (f/l1000mm~f11) was an absolute planet killer. I got the best views ever of Saturn and Jupiter with it. Maybe that was just down to seeing and the like. Havent seen much of anything lately with any scope.