best place to get telescopes etc cheapest

[sam mayo]

i am currently looking at buying a ssw 10" dob or the Zhumell Z10 Deluxe Dobsonian Reflector .

if i can make the decion between the 2,i have found that flow has been the best rated and cheapest anywhere but would welcome any input,thanks,sam

i am mainly looking at planets but i know the fancy pics u see of dso are not what u see through a telescope so what do u see ,help plz

[Bart]

Sam

I have 3 Dobs/Reflectors and am a fan. However if planets are your main target, maybe a Dob wouldn't be the best choice. Saying that, my love is galaxies, but I still get good views of the planets.

Someone more knowledgeable than I will offer more advice soon.

My choice of astro shop will differ from yours due to geography/exchange rates/delivery charges etc

Good luck

Bart

[jonathan]

From what I can gather you want a fast scope for planets so that you can use a higher magnification eyepiece (the more mag, the dimmer the view.. so you need more light coming through the scope faster). It is related to camera f stops - the faster the f stop your camera can do (lower f number), the faster shutter speed you can use in lower light. In this case, your eyepiece is like the shutter - faster f stop allows you to use higher mag (smaller mm) and thus see more detail. Some of the planets such as Mars, Venus, Jupiter and Saturn are very bright and can be seen in almost any scope, it's the dimmer ones that are much more difficult to see.

I hope that made sense!

(and I hope it was accurate)

Dobs are usually not fast scopes, for that you are probably looking at a high quality refractor or imagining newtonian. Look at the f number to find out the speed - lower f the better. You also need to factor in the size of the scope - larger refractors let in more light, but are not necessarily fast so might be better for wide field or DSO.

I don't know if it is good for planets, but the Skywatcher Quattro f4 is a fast newtonian. http://www.firstligh...-newtonian.html

[pete_l]

i am currently looking at buying a ssw 10" dob or the Zhumell Z10 Deluxe Dobsonian Reflector .

if i can make the decion between the 2,i have found that flow has been the best rated and cheapest anywhere but would welcome any input,thanks,sam

Since you have decided you want to buy a Dob, we'll leave that part up for discussion by others.

However, given the two examples you are asking about I'd offer this personal opinion.

My view is that I'm cautious about new technology (an attic full of stuff that was described as "ground-breaking", "fantastic new ... ", "revolutionary" and other phrases that mean untried, untested, unproven and "not properly thought out" is testament to this and has provided an expensive lesson that I was slow to learn ;() and nowadays I want to see independent reviews and trustworthy vendors before I start waving money around.

As a consequence, I'd go with the Skywatcher product. I did a quick search and apart from one reference from eBay, there's no mention of Zhumell dobs in this country (the OP shows a UK location). So buying a no-name dobsonian from an unestablished vendor with no reputation in the astronomical community gets my risk-aversion alarm ringing. Maybe the product is the astronomical equivalent of discovering The Beatles but until it establishes a solid record of being a good product I'd pass on it.

[willdabeast182]

Hi there,

I know this forum is sponsored by FLO (First Light Optics) but after using them several times I can honestly say they are the best place in my humble opinion for your equipment needs. They have the best prices I could find in the UK and there customer service, which to me is the most important thing, is brilliant. The one product I had a problem with that I bought from them was replaced within days without any hassle and they will do anything to make sure you have a first class experience.

Hope this helps!

Cheers,

Will

[Grotemobile]

I wll second that.Orderd a saddle on Tuesday

for my scope.Delivered Wenesday.

Spot on.

Steve.

[ollypenrice]

From what I can gather you want a fast scope for planets so that you can use a higher magnification eyepiece (the more mag, the dimmer the view.. so you need more light coming through the scope faster). It is related to camera f stops - the faster the f stop your camera can do (lower f number), the faster shutter speed you can use in lower light. In this case, your eyepiece is like the shutter - faster f stop allows you to use higher mag (smaller mm) and thus see more detail. Some of the planets such as Mars, Venus, Jupiter and Saturn are very bright and can be seen in almost any scope, it's the dimmer ones that are much more difficult to see.

I hope that made sense!

(and I hope it was accurate)

Dobs are usually not fast scopes, for that you are probably looking at a high quality refractor or imagining newtonian. Look at the f number to find out the speed - lower f the better. You also need to factor in the size of the scope - larger refractors let in more light, but are not necessarily fast so might be better for wide field or DSO.

I don't know if it is good for planets, but the Skywatcher Quattro f4 is a fast newtonian. http://www.firstligh...-newtonian.html

Sorry Jonathan but I'm afraid most of this is incorrect. In visual use the brightness depends on the aperturre and magnification. For a given aperture it makes no difference how you brew up a given magnification. You can use a short FL EP in a short short FL scope or a long FL EP in a long FL scope. If they give the same magnification (have the same effective focal length) they will give the same brightness. Actually, in the case of Newtonians, the slower scope will have a smaller secondary and therefore have a slightly brighter, more contrasty image.

Since fast optics are harder to make and harder to collimate many planetary observers prefer to go for a slow, long focal length scope. Per pound this is likely to have finer optics than a fast one.

Most Dobs are, in fact, what amateur astronomers would call 'fast' - ie F4 to F6. F7 to F8 tend to be called medium and below F8 the term 'slow' tends to be used, though there is no formal definition.

As for where to buy, don't buy only on price. With optics this would be madness. Optics involve care, experitise, advice and after sales service. Buy from FLO or Ian King or one or two other places and stay well away from anything with 'planet' or 'R us' in it!!!!

Olly

[murphy]

From what I can gather you want a fast scope for planets so that you can use a higher magnification eyepiece (the more mag, the dimmer the view.. so you need more light coming through the scope faster). It is related to camera f stops - the faster the f stop your camera can do (lower f number), the faster shutter speed you can use in lower light.

I hope that made sense!

(and I hope it was accurate)

I usually see slow scopes recommended for planetary use, due to the higher magnification obtained from the same eyepiece and increased contrast, I think? Very fast reflectors are usually sold for imagining, aren't they? The back focus being better than slightly slower, more common reflectors of f5 +? Then faster scopes introduce more problems with coma, collimation and show up eyepiece aberrations more.

Never mind, Olly posted while I was typing!

[John]

To answer your original question, buying used is a great way to get good equipment at a reasonable price. The UK Astro Buy & Sell website is a great resource until you can access this forums classifieds (50 posts required to read them) and many of our members , including myself, have bought successfully from that site. Here is a link:

http://www.astrobuysell.com/uk/

Ask lots of questions here though before you buy - telescopes and astro equipment is a specialised area and it's not always obvious to the novice which the "good buys" are.

It's best not to hurry the decision - ask questions, decide what you want then look out for one for sale. You should save 40%-50% of the new price for one in good condition.

[umadog]

I usually see slow scopes recommended for planetary use, due to the higher magnification obtained from the same eyepiece and increased contrast, I think?

Yes, you see that all the time but it no longer holds. When we only had simple eyepiece designs available this would have been good advice. This is because eye relief is proportional to eyepiece focal length for many of the more simple eyepiece designs. It's not pleasant for most people to have to glue their cornea to the eyepiece to see anything. Now we have access to eyepieces with generous eye relief and wide apparent fields at all focal lengths. Barlows are of better quality too. So there is always an eyepiece (perhaps with a barlow) that will allow you to hit the seeing limit with whatever telescope you have. The views will not suffer either.

As for contrast, an obstruction under 20% by diameter is indistinguishable from unobstructed at the same aperture. Once you start to pass about 25% obstruction you seen an effect on contrast. However, it's possible to make a fast scope with a small obstruction if you're careful. My f/4 has a 20% obstruction and the field illumination is adequate.

Very fast reflectors are usually sold for imagining, aren't they? The back focus being better than slightly slower, more common reflectors of f5 +? Then faster scopes introduce more problems with coma, collimation and show up eyepiece aberrations more.

Yes, that is one use for fast scopes. They are, however, appearing more and more as visual scopes. The main difference being that fast visual scopes have a smaller obstruction than fast imaging scopes. The idea behind a fast visual scope is portability. Take this little guy here, for instance: http://www.bbastrodesigns.com/ZipDob/ZipDob.html It's f/3. As you say, you will be wanting a coma corrector, good collimation tools, and quality eyepieces. However, gear for making a fast scope work is now available since we have access to all those things on the commercial market. What's needed from the scope manufacturers right now is good optical quality and stiff structures. When well made, there's no reason a fast scope can't produce killer planetary views.

[sam mayo]

thanks v helpful (slightly confusing),but got a better idea of it all thanks