big scopes

Hello all.
I have a celestron C 150-HD newtonian and I am very unhappy with it.I have read reviews about it and it has got bad reviews.I am intrested in building a 14inch f4.1 or f5 in the summer.My question is, will a 14inch be much better than my 6 inch scope or am I expecting too much.I have never looked through a big scope before. I was going to buy the mirror and I do not want to waste my money if the 14 scope is not going to be alot better.

Also does anyone know how a laser collimater works, I will make one if I can.

Hi Brian ,
Depending on what you are looking at the 14 will be a big improvement in light gathering and obviously you'll have a longer focal lenght to use re magnification,which will then start to depend on seeing rather than the capability of the scope for deep sky it would be brill.
Re the laser collimator ,I personally dont think you'll need one a s this is only used in the final stage of collimation and especially with scopes with small "sweet spots" which yours wouldn't have,you'd be better off getting a "collimating tool" like the one ORION US sell for $39. This tool does allthe steps and is very easy to use it also saves you getting a Cheshire collimator try www. heavensandearth.com they deliver to Irl
Regards
Eugene

Hi Again Brian
Heavens &Earth dont have them in the Orion stock at mo, but you can check it out on www.telescope.com search in observing aids for item No 03640 Orion Collimating Eyepiece $39.95
E

Hello all.
I have a celestron C 150-HD newtonian and I am very unhappy with it.I have read reviews about it and it has got bad reviews.I am intrested in building a 14inch f4.1 or f5 in the summer.My question is, will a 14inch be much better than my 6 inch scope or am I expecting too much.I have never looked through a big scope before. I was going to buy the mirror and I do not want to waste my money if the 14 scope is not going to be alot better.

Also does anyone know how a laser collimater works, I will make one if I can.

Brian, like the folks said 14 inch will be a huge improvement on 6 inch. However at f4.1 you will get horrible coma at such a fast f ratio consider something closer to f/6 if you can. You could couple with a parracor coma corrector but these are expensive. If portability is the reason you are going for such a fast scope why not consider something like a 10 inch f/6 that will be a vast improvement on your 6 inch.

Remember the light gathering power of a scope is relative to the surface area of the mirror. remember pi x r(squared) (formula for area enclosed by a circle)

For a 6 inch = 28 square inches
For a 10 inch = 78 square inches
for a 14 inch = 154 square inches.

so a 10 inch has almost 3 times the light gathering power of a 6 inch and a 14 inch has 5.5 times the light gathering power of a 6 inch.

Dont bother with the laser collimator, buy a cheshire eyepiece, it will do the job just as well.

Brian, I think the conventional wisdom on Big Scopes should be ignored when viewing in Ireland.

The general rule seems to be if you can see the Orion Nebula clearly it is going to rain and if you can't see it clearly....... it is raining !

If yo are lucky enough to be able to set a 14" scope up in an observetory in your back garden you might get 15 good viewings a year. If you need to travel to a dark location you will need a van and you might get 4 or 5 good viewings a year.

Is this worth the expence and hassel? If you have dedicated your life to Astronomy and you realy need to see the two eyes in the Owl nebula... its well worth it, otherwise you will just get fustrated horseing this monster around and probably give up.

I think if you can't set it up and take it down in less than 10 min you will probably stop using it. I agree a 6 inch is to small, probably much happier with an 8" and I wouldn't bother with anything bigger than an 10".

Regards, Damon

Thanks guys for the advise.

Eugene, the reason I asked about a collimater is, I had to clean my mirror and when I went outside last night I could tell the mirror was off, but if collimaters are that cheap I might get one.

Dave the mirror I was going to get was at Oldham Optics and they sell 14 inch mirrors at f 4.1 or f 5.Do you think a f 5 be much better than a f 4.1?I might rethink the size.

Damon I live in fairly dark skies except towards the east(Cork city).The scope I was going to build was something like a truss design with most of the scope made out of aluminium.I was going to have a pier in the back garden and just disconnect the scope from it when going inside.I hope to make a mecanism so it would only take a few minutes to connect and disconnect the scope.

Thanks again for the advise.