looking for a good spec compact scope

Merged. Cheers Dave

BTW I have the 4" skywatcher mak and I find it a great scope. Very portable. I've taken it and a sturdy tripod on holidays a couple of times with no problems. That was before the recent airport restrictions mind you.

The 5" would still be backpackable I'd imagine.

Hi there,

I would second Dave's recommendations having owned a 70mm ED refractor and the same Skywatcher 5" Mak.

I found that the Mak was fantastic, but the lack of wide fields made it harder for me to find my way around the sky when I started into the hobby. In the end I replaced it with the refractor and have not looked back. In fact, I use the refractor more than my SCT!!!

A decent ED type refractor is very easy to use, compact, quick to setup and has hardly any cooldown time. One thing that will drive you mad with the Mak is the cooldown period and it's suscepibility to dewing up.

+ the 5" mak would barely fit in my large camera backpack. The refractor fits in with loads of space to spare.

So in short I think an ED refractor in the 70-80mm range is the most flexible solution. It was for me anyway.

Skywatcher, Scopos, Celestron, Astronomica and Antares among others make fine refractors in this class which are not too costly. Then there are the more costly william optics, televue, etc.

You may be able to pick a second hand one up on

www.astrobuysell.com/uk


Hope that helps

Trev

technically, how do i compare these scopes?

i mean, will an 80mm lens on a refractor give more magnification than a 4 inch mirror in a makustov or Cassegrain ?

whats the best way to compare these different types of scope?

Ok firstly stop thinking about magnification. Every time that word enters you're head smack yourself:) In theory every telecope can magnify as much as you like, you jsut pop in an eyepiece. The key points to consider when considering a scope are aperture, design and quality.

When viewing something in space your goal is to make something very faint become bright enough to see. Most objects only require minimal magnification to see well, in fact many cannot be seen if the magnification is too high. If someone tries to sell you a scope based on magnification, walk away because they don't know what they're about.

As a general rule you would be wise to go for as large an aperture as you can afford. For example an 8 inch reflector will see much fainter objects than a 4 inch one. Next to aperture is the quality of the optics. Astronomical telescopes will only give good views if the optics are made to a VERY high level of precision. This is another reason to steer clear of cheap department store scopes, because they are not made to this level of precision. All tghe telescopes from the major manufacturers like Meade, Celestron and Skywatcher are well made so no need to worry with these brands (with the execption of the very cheapest models).

So to you're question about the difference between an 80mm refractor and 127mm maksutov. A primary difference is design, a refractor is more like the classical telescope non-astronomers imaging with a lens on one end and a rear end for looking through. The benefit of a refractor is that the optical design allows for much higher contrast when viewing. To explain why you need to look at other designs. Cassegrains are a class which include maksutovs, they emply a mirror (like a reflector) but also need another (smaller) mirror placed in the light path to work, this reduces contrast a little.

Now the benefit of reflectors (incl cassegrains) is that they are much more cost effective to make than refractors. This means you get far more aperture for your money and remember, aperture = light gathering power = seeing fainter and farther.

Specifically the two telescopes mentioned, the 80mm refractor and the 127mm maksutov. The refractor although smaller offers higher contrast views. It also offers lower magnification and a wider view so you can see more of an object more of an object. The maksutov inherently magnifys more and as such you get a narrower view but a bigger image scale in the eyepiece also it is of course a 5" scope so you get more aperture two.

From owing both scopes and if you put me on the spot, I'd say the maksutov would be the better choice for an all rounder. The refractor will give nich views of star clusters but wont be so good on planets and the moon.

hope some of this helps.

I found that the Mak was fantastic, but the lack of wide fields made it harder for me to find my way around the sky when I started into the hobby.

Trev makes a very good point which I had forgotten about.

you say that any telescope can get any magnification ( within reason). what is max useful magnification ? how do you know the max Useful is, and what is max useful resolution? 5" skywatcher mak is availiable on these boards for sale. was thinking of looking at this, but might hold out for a 6" one.thanks all

Magnification makes things bigger and dimmer. While that's often what you want on the planets and the moon, it's almost never what you want on DSOs (deep space objects). There you want brighter (so that you can see the detail in them), which is a function of aperture.

But to answer the magnification question, under Irish skies I'd say a good rule of thumb is 20x to 30x per inch most of the time, with a few nights a year worthy of 40x to 50x per inch. (So the 5" Mak would top out at 100x to 150x most nights, while allowing 200x to 250x on a few rare nights.)

-- Jeff.