New telescope advice

[schmourghenne]

Originally Posted by Gargoyle_Steve

Schmourghenne I'm not quite sure what prompted your sarcastic response to my genuine replies to your posts - you had asked questions, I was trying to reply and make a suggestion in a forthright and honest fashion, no disrespect was intended. I went to some effort to search for the thread on Dave's trolley, knowing that a picture was worth a thousand words. I now feel VERY happy that I went to such efforts to provide you with information.

Those here who know me, and there's more than a few, know that the portrait you have painted of me is far from correct. I am NOT self opinionated, in the habit of making snide remarks, a member of the grammar police, etc. My comments re carless, sociophobe, etc were directly taken from what you had said about yourself - except you also described yourself as lazy, I didn't repeat that for fear of giving offense.

As for the comment I made about most aperture for minimum price the fact is that MOST people want to achieve that (myself included) - unless you are in the habit of preferring to spend more money than is necessary to achieve a goal. Thats why I suggested a dob, that's why I have one myself. You had also mentioned how much having a shaky mount irritates you, again at the price there's no more stable mount than a dob.

From your original post I took it that you were a person who had a sense of humour - I was obviously wrong. I won't offer other suggestions, I'll simply hope that you find a scope package that suits your requirements.

Steve, from reading your reply, I see that I completely misinterpreted your reply and I wholeheartedly apologise for my aggressive response.

In most of the forums I visit there is a culture of treating new posters as second-class or unworthy. I react badly to this type of culture wherever it exists whether it is on the internet, at work or anywhere else.

From reading many of the posts on the Ice in Space forums, I see that this is not the case here and again I apologise to you and anyone else I may have offended.

[Gargoyle_Steve (Steve)]

No problem - we were ALL newbies here (except for Mike of course!) and members of this forum generally are all pretty much mature and considerate enough so that no one, newbie or pro, ever gets treated badly.

I was brand new to this forum and to astronomy only 18 months ago, and it was the wise advice that I received here that has guided me in most, if not all, of my astronomy purchases. I know I have a hell of a lot to learn yet, but from my perspective as a "recent" newbie who has been through the same sorts of questions that you're going through now, I thought my input as to an alternative suggestion may be valid to your decision making process.

I look forward to hearing what you end up doing scope wise, and of hearing how great your "first light" session with it goes.

Remember that there ARE groups of IceInSpace members who meet up regularly (each month around new moon) and that you would always be welcome at any number of these meetings should you ever wish to attend.

Cheers!

[ngcles]

Hi Schmourghenne,

I'd have to very much agree with the advice that Steve offered.

Have to admit up front I'm a big fan of Newtonian reflectors that offer by far the best value for money.

Specifically regarding the questions you are looking to get answers to.

The true power of a telescope (assuming good optics) is the light gathering power. You can compare different apertures simply by comparing the square of the diameter. The central obstruction is negligible in assessing light gathering power.

4" = 16

5" = 25.

Therefore the 5" will produce images that are nearly 50% brighter than the 4" and means you can see objects 50% fainter. It will also have slightly better resolving power meaning you will get a little more detail in the image too.

However the 8" aperture suggested has a light gathering power of 64 -- 300% more light that the 4" and 250% more than the 5" and has about twice the resolving power.

An 8" dob doesn't generally come with goto but as pointed out, if fitted with an AgroNavis (the best DSS in the world - and Aus made), you can have push-to. A dob with push to is _dead easy_ to use. The Autostar and Nextstar systems are good but the Argo is even better -- wouldn't be without it.

Unless you have a midget car (assuming you get it fixed one day or another), the tube will fit across the back seat, and the mount in the boot.

As you have already recognised, it will need collimation from time-to-time. I know this can seem frightening, but it is like riding a bicycle. I know I'm an old-hand but I've got a truss-tube dob that is more demanding generally than a simple hard tube. Out of the ute after an hour riding the road it takes 2 mins at most to get spot on. The first time you do it it will take 20 minutes, the second time 10, the third time 5 mins etc etc. It isn't hard I promise you if you have the right tool (also cheap). Owning a newtonian means you should also remove and clean the mirror occasionally, but if kept capped it only needs to be done every 12 months. Remember a Schmidt corrector plate also needs occasional cleaning.

Owning a Schmidt will not relieve you of the need to collimate occasionally and collimating a Schmidt is somewhat harder and there are no tools to help. You have to do it on a star or an artificial star.

In terms of price, the 4" Celestron and the 8" dob with push-to will be comparable. The 5" will actually be a bit dearer than the dob. You don't get tracking with the dob, but you do get a vastly better view due to the increased aperture. Which is most important to you?

In portability, the 5" won't be easy to tote around all in one go -- your hands will be very full. The 8" is certainly a bit harder and bulkier, but with a sling for the tube you can carry the whole lot short distances without too much hassle.

Yes the dob is heavier and bulkier but is not real hard to move around. It will take up more room at home but if stored assembled with the tube upright and capped it will only take a foot square of floor-space somewhere. All catadioptric telescopes are prone to dew build-up on the corrector so counter measures need to be taken. Attacking this problem properly can be a mite expensive.

In the end, buying a telescope is a bit like buying a car. It is a personal choice and is made with your personal needs in mind. In my opinion you should carefully consider the advantages a 8" with push-to has to offer. It's has some very considerable advantages. But it is after all your choice.

Re this light-pollution business, it is an urban myth -- aperture rules.

Hope this is some help.


Best,

Les D
Contributing Editor
Australian Sky & Telescope