Couple questions

[Sunwind]

ok so I understand that having a 2" will cover me if I ever get a 2" EP, but on the most basic level I still don't really get how barlows are used in conjunction with EP's, they magnify the view right? does the size of the barlow, 1.25" or 2" effect the magnification or is that simply just the physical size?

is a 1.25" barlow the same magnification as a 2" barlow just larger or smaller physically?

[alfi]

hi

it is just the size that is different,

what it does is go in infront of the eyepiece, and with the lenses that are in the barlow, it changes the lightpath, and give you double the magnification your eyepieces give when you dont need a barlow.

to find the magnification of a eyepiece, you take the focallenght of the scope, in mm, and divide it on the size of the eyepiece, 10mm, 25mm, etc. the result of that, is your magnification with that eyepiece.

what the barlow actually does, is to use some glaselements to effectivly double the focallenght of the scope.

alfi

[alfi]

a 2X barlow is a 2X barlow, nomatter the size.

there are also 1,5X, 3X, 4X, 5X.

i have a 2" 2X, with a extention i can use, and then it will be a 2,7X

the most used is 2X and 3X barlows.

alfi

[Sunwind]

I see, so I should get the 2X 2" Barlow which can fit both 2" and 1.25" EP's if I ever decide to get a 2" EP in the future, but I should try to stick to 1.25" EPs?

[alfi]

hi

i would have done that, and have done that.

normally the 1,25" eyepieces are cheaper then 2".

you normally dont find 2" eyepieces in smaller then ca. 20mm, so they are more for low magnification, and widefield wiewing.

you can get some cheap 2" eyepieces, from skywatcher, orion, and others.

here are some examples: Skywatcher - Skywatcher Ultra Wide Angle (UWA) 2" Eyepieces

Skywatcher - Skywatcher PanaView 2" eyepieces

Okulare mit 2" Steckhülse ab 60° Gesichtsfeld - Teleskop-Express: DER Astroshop + Fotografie + Naturbeobachtung

hope this helps you a little

alfi

[Sunwind]

hi

i would have done that, and have done that.

normally the 1,25" eyepieces are cheaper then 2".

you normally dont find 2" eyepieces in smaller then ca. 20mm, so they are more for low magnification, and widefield wiewing.

you can get some cheap 2" eyepieces, from skywatcher, orion, and others.

here are some examples: Skywatcher - Skywatcher Ultra Wide Angle (UWA) 2" Eyepieces

Skywatcher - Skywatcher PanaView 2" eyepieces

Okulare mit 2" Steckhülse ab 60° Gesichtsfeld - Teleskop-Express: DER Astroshop + Fotografie + Naturbeobachtung

hope this helps you a little

alfi

what is the difference in 125 and 2" eyepeices apart from visual size, do 2" ones usually give better images? sharper, clearer or something?

This is what i'm planning on buying so far:

Scope - Skyliner 250PX 10 Parabolic Dobsonian Telescope by SkyWatcher - Skyliner 250PX 10

Barlow - Skywatcher - Skywatcher ED Deluxe 2x two-inch Barlow Lens

Books -

Turn Left at Orion: A Hundred Night Sky Objects to See in a Small Telescope - and How to Find Them: Amazon.co.uk: Guy Consolmagno, Dan M. Davis: Books

Philip's Planisphere: Northern 51.5 Degrees - British Isles, Northern Europe Northern USA and Canada Philip's Astronomy: Amazon.co.uk: Books

Norton's Star Atlas: Amazon.co.uk: Ian Ridpath: Books

I need a filter for looking at the moon right? how about this one Moon & Neutral Density Filters - Variable Polarizing Moon Filter and since the eyepeices supplied with the scope are 1.25", I should get that one and not the +£10 2" one (even though I can use it? or not? do filters go "above" EP's or "below" them?)

Should I also pick up a light pollution filter? are they worth it or just some kind of gimmick thing that doesn't really work? where I live could probably be considered light polluted Light Pollution Reduction - Baader Neodymium Filter

just need some more people to say "yes good choices" or something before I commit to spending the money, don't want to make any bad choices here as i'm sure you guys can appreciate.

[alfi]

hi

the 2" arent any different, they just give you a larger lens to look into, and good field of wiew.

your selection of equipment looks very good to me, lots of readingmaterial, and that is a good idea.

the variable polaritation filter is good, i have one to, it is made of two filters, and when you put them together, and twist one of them, you change the amount of filtering, darkening, of the filter.

as you only have 1,25" eyepieces, you need the 1,25" filters. you can only use 2" filters with 2" eyepieces.

you screw the filters in on the bottom of the eyepieces, they are threaded.

the light pollution filters seems to work quite well from reports people have written on them.

where i live in norway, there are almost no LP at all, so i dont have one.

i would say you have selected a nice, balansed setup.

there are always new stuff you will be wanting after a while, but it seems to be a good start.

alfi

[pvaz]

you can only use 2" filters with 2" eyepieces.

True. But he can buy a 2" extension tube, threaded for filters on the bottom end. Then screw the filter to it, then put a 2" EP on, or a 1.25" with also the 2" to 1.25" adapter.

Theoretically it haves 2 advantages:

- Save money, only 1 filter of each type for all your eps.

- Since the extension tube takes the filter, you screw it once and then switch EPs quickly without having to move the filter from 1 ep to the other.

I ordered the 2" extension tube from Astronomica last week, when it gets here I'll tell you if it works as well as in theory or not.

[acey]

I figure I could put the mount in the car boot and lay the scope across the back seats I don't think it would fit any other way.

The mount certainly won't fit in your boot (as has already been said) but the scope might.

I used to use an 8-inch f6 which went easily in the boot of my Vectra. The Skywatcher 10" is an f5, I believe, in which case the tube length must be about the same (around 4 feet).

[kniclander]

my tuppence worth - if you get a star atlas get something like Sinnott and Tirion Sky Atlas (2000) - I note that the one you're thinking of getting only shows stars to mag 6 which won't give you much more than the Philips guide. The Tirion & Sinnott shows stars to mag 8.5 . Or you could just run off your own star charts form CduC...

otherwise, great kit - much like my own;)

[pvaz]

Ok, I always heard "An image is worth 1000 words!". So how about a video with 24 frames/second?!

Crappy jokes aside, here are some videos that helped me get a sense of "what is what" before I bought my 1st scope:

(ignore the diagonal part of the video, thats used for cassgrain scopes, yours is a reflector and uses a focuser and it already comes with a big 2" one)

(you don't need to see this one, your choice is great for observing)

All videos explain things well and quicly (about 3 min each).

[pvaz]

True. But he can buy a 2" extension tube, threaded for filters on the bottom end. Then screw the filter to it, then put a 2" EP on, or a 1.25" with also the 2" to 1.25" adapter.

Theoretically it haves 2 advantages:

- Save money, only 1 filter of each type for all your eps.

- Since the extension tube takes the filter, you screw it once and then switch EPs quickly without having to move the filter from 1 ep to the other.

I ordered the 2" extension tube from Astronomica last week, when it gets here I'll tell you if it works as well as in theory or not.

Well tube's here and I just wasted money.

I can attach the filters to it and then change EPs freely while keeping the filter, problem is the damn tube is too big (high). It increases the distance between the EP and the secondary so much that, even with the focuser full in, I can't achieve focus on any of my EPs.

I guess I'll have to go to option B, and get a threaded 2" to 1.25" threaded adapter so I can use my filters on 1.25" EPs.