Stuck on which scope to buy

[Irvine6]

Hi

I have now saved up and have £300 to spend on a new scope.

After reading many reviews im now looking at the Skywatcher Explorer 150PL or 150P, what is the diffrence? i would like better views of saturn and jupiter etc as from my last scope they were tiny dots.

I have also now come across a Dobsonian skywatcher skyliner 200P which also gets good reviews, what is a Dobsonian?

Thanks

[Capricorn]

150 is the mirror diameter in mm.

P is parabolic, the mirror profile is parabolic as opposed to spherical, creates a better image.

The L is simpl Long, the 150PL has a longer focal length then the 150p

Dobsonian is actually just the mount. John Dobson came up with a simple cheap mount for a newtonian reflector (scope) some years ago. So succesful that people now refer to the scope as a Dobsonian, whereas it is actually just the mount.

The 200P is as above, a 200mm dia mirror with a Parabolic profile.

In general terms the 150PL will be less critical of collimation then the 150P.

Owing to the longer focal length eyepieces may be easier to use on the PL, additionally the PL will allow more magnification to be obtained without resorting to possibly more costly eyepieses.

[Cornelius Varley]

The difference between the 150P and the 150PL is the focal length. The 150p has a focal length of 750mm and the 150PL 1200mm, which makes the 150PL a better scope for planetary viewing. It should also be more forgiving on collimation and lesser quality eyepices than the shorter focal length 150P. Try out this Field of View calculator to see how big jupiter will appear in the eyepiece.

A dobsonian telescope is one which has a simple alt-az mount such as the Skywatcher Skyliner range. The dobsonian telescope is named after the man who made this type of telescope popular in America, John Dobson. His telescopes were homemade out of reinforced cardboard tubes with a simple alt-az mount. He would set them up on street corners and invite passers-by to look through the eyepiece.

Peter

[Quatermass]

go for the 200p if you can afford it or better still get yourself to one of the stargazing live events and have a try on some scopes but dont rush whatever you do.

Sent from my GT-S5670 using Tapatalk

[nightfisher]

I would suggest the 200 dob, a really good piece of kit

[Irvine6]

Thanks for the quick replies

Good info, learning something new everyday on here.

[todd8137]

hi there the 200p is a great scope and works well of deep space stuff,the planets will be a bit bigger but not massive i have a SW 300p and it looks about the size of a pea i could use a barlow to make the pea bigger ,but i can see the great red spot and the bands and its moons but were these scopes get going ,if you have a darkish back garden ,you will see clusters,double stars, nebula,galaxies the moon will blow you a way at high power

they are easy to set up no cables wires or batteries and the views on a night will keep you hunting and busy for years

[Irvine6]

Thanks ive just been using the field of veiw calculator theres alot to see out there! lol.

Ive seen alot of pics on this site that people have taken of saturn etc that look close up and clear, how are they doin this?

[John]

Ive seen alot of pics on this site that people have taken of saturn etc that look close up and clear, how are they doin this?

They will be using either a converted webcam or a dslr (more likely the webcam). The basic method is to take an AVI movie of the planet then to use special software to select the best frames and stack them on top of each other. There is then subsequent processing done to get the final image.

Images are generally not representative of what can been seen visually through a scope as our eyes can't compete with the above processing.

[SplintUK]

Never confuse what you can see visually with what a photograph can show. In that respect the wonderful FOV site can be very misleading.

The photographer has many tricks in their arsenal which allow for long exposures for deep space objects or stacking multiple (sometimes hundreds) image frames using clever software to get a lot more out of the telescope than the mark 1 eyeball is capable of.

You can run a webcam at many frames per second on a planet using a large Barlow (5*) to effectively increase the focal length of the scope by 5* and stack the results in registax to get a clear well defined single image (after photoshopping) much larger than you can achieve with an eyeball.

And other objects like the horse head nebula are invisible to the eye and need long exposures and post processing before they magically appear in the image.

There is still a great deal of joy to be had visually, just don't expect to compare the views with competition winning photographs or Hubble shots like on the FOV website. The images are for representation only.

[Irvine6]

Ok thanks

I will be happy to see a hint of saturns rings and jupiters moons, i think i may go for the Dob if its easy to store and i may have to build something in the garden do put it on or is the idea it just sits on the floor?

[SplintUK]

I saw a good view of Saturns rings in my explorer 130, not big, but clear and magical. A 200p Dob should be perfect, and if you buy an EQ mount later on, you can still use the 200p dob tube in that.

In fact for my second ever scope earlier this (last) year I went for an EQ mount (HEQ5) and an Explorer 200p ds which is basically the same optical tube as the 200p dob, just with a different colour paint and a different focuser on it (a Dual Speed focuser hence the ds in the name).

I've never used a Dob mount myself, but there are times when I am spending 30 mins trying to get my EQ mount level, and polar aligned, then star aligned for the goto, that I can really see the benefits of a dobsonian mount ;-)

[Irvine6]

oh right i didnt know the tube could be used in another mount. Thats good to know and making the Dob seem a great choice.

Think i may also try and find a group to go to and try a few diffrent scopes as was suggested earlier.

[swamp thing]

I've never used a Dob mount myself, but there are times when I am spending 30 mins trying to get my EQ mount level, and polar aligned, then star aligned for the goto, that I can really see the benefits of a dobsonian mount ;-)

One of the principle benefits about a Dob mounting that is often forgotten, is, the inherent stability and vibration dampening offered by the design.

Very few affordable EQ mounts offer anywhere near the same properties of this simple mount.

Most small EQ mounts wobble like mad after the focuser is touched taking ages to settle down. They even wobble like crazy when the slow motion control is handled.

A well made Dob dampens after being touched almost at once. This enables you to move the scope easily whilst looking through the eyepiece without the image dancing wildly all over the place.

IMO most EQ mounted small scopes are given woefully undersized wobbly mounts.

Regards Steve

[rickygoespop]

I'm a beginner and I have the skyliner 150p 6" dobsonian , it's £190. If your budget is £300 I would do the following.

150p dobsonian scope £190, turn left at Orion book £19, collamating tool £25, x2 Barlow £15 , higher quality eye piece £40, moon filter if required £10ish. Total £300.

You have to take into account the extras as a £300 budget soonturns into a £400-£450 budget if you spend the hole budget on scope only.

My budget was the same and that is my set up so I'm biased but I'm extremely happy and my passion for astronomy has blossomed and my gf is quite worried at how much I enjoy reading about it and fiddling with the scope. I ran her a nice hot bath with music and candles yesterday so I could do some more reading.

[Irvine6]

ok thats another way off looking at it thanks,

can i just ask what is a collamating tool ?

[rickygoespop]

With the Newtonian scopes the mirrors can become misaligned and your scope will not perform at its best,the Cheshire collamating tool sits in your eyepiece part of the scope and helps you check to see if the mirrors line up or not so you can correct them.

[SplintUK]

Collimation is bringing your mirrors into alignment, and it's something you have to do if you have a reflector. It sounds harder than it is, and there are lots of guides all over the web telling you how.

There are Laser collimators and Cheshire collimators, I have one of each. The laser does a good job of your secondary mirror alignment and gets you a good starting point on the primary, the Cheshire is best to finalise the primary alignment. You can do the whole thing with either tool, but I find the above gives me the best result for now. I'm only a year into this hobby, and collimation is starting to be a routine and simple thing to do. Astro_baby has a good article on it. It sounds a lot harder and scarier than it is.

A laser collimator is about £30 upwards, a Cheshire is about £20 upwards.

If you buy a new scope, you will have to collimate it before you can use it as they tend to screw down the mirrors before shipping, and since the factory is (usually) in China, collimating in factory for use in the UK isn't an option.

[Irvine6]

Thanks for everyones input, i have gone for the Dob 200P

Cant wait for it to arrive and for a clear night

[SplintUK]

Cool. What collimation tool did you go for?

[Irvine6]

i went for the laser

watched many vids and read a few instructions so i feel i can have a go now.

It arrived today do now im just waiting for the scope, hopfuly monday.

[Catweazel]

I tried the FOV calculator for the scope I have been thinking of buying and Jupiter appeared about the size of a pin-head? Why, in that case, is it 4x that size in my 15x70 bins? Maybe I didn't put enough detail in? I put in scope details and without Barlow!

[twotter]

Thanks for everyones input, i have gone for the Dob 200P

Cant wait for it to arrive and for a clear night

Congratulations, it's a cracking telescope

[SplintUK]

i went for the laser

watched many vids and read a few instructions so i feel i can have a go now.

It arrived today do now im just waiting for the scope, hopfuly monday.

When you get it, check the laser is collimated itself. The easy way is to set up your scope inside and put the laze in backwards so the laser points at the wall. Put a post it note on the wall and draw a dot where the laser is. Rotate the laser a little in the focuser and see if the do starts moving. If it does it will describe a circle, and that means its out of collimation. You can then either start mucking about with adjustment screws on the laser, or send it back as it really should be right when you get it. My first laser was out, but it took me ages to work out that it was out, so I was having the most frustrating time trying to collimate with a dodgy laser. Worth checking up front to save some stress. ;-)