Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

Welcome to Stargazers Lounge

Register now to gain access to all of our features. Once registered and logged in, you will be able to contribute to this site by submitting your own content or replying to existing content. You'll be able to customise your profile, receive reputation points as a reward for submitting content, while also communicating with other members via your own private inbox, plus much more! This message will be removed once you have signed in.

  • Announcements

    SGL 2017 SP

JOC

How much Dob does a Dob Mob bod have if a Dob bod could have Dob?

132 posts in this topic

Posted (edited)

7 hours ago, Stu said:

Well, I hoped by saying that I recognize that it is not as solid as Damian's scope I was showing that I am not biased? I actually value honesty and have no problem with someone pointing out issues, in fact I do remember discussing the fact that it was a little sticky in its movement and how to remedy that.

Damian's scope is wonderful, but it is also significantly bigger and heavier than the Sumerian so is a different proposition I think.

You are right re the Tak, I do change stuff like the focuser to eliminate any image shift, but to be honest I found it quite easy to find and track small 'faint' galaxies with the Sumerian so did not have a problem with it.

I put faint in quotes to acknowledge that I was only down to mag 14.2 whereas I know you guys go a lot deeper.

Thanks for the acknowledgement Stu.

It is really difficult to build any scope and make it stable that is why the tried and trusted designs are so enduring. Like everything in life though they are not ideal for everyone. 

Anyone that has built a scope will realise the challenges it poses and the marriage of materials and ideas to build a useable and reliable instrument.

I spent a long time thinking mine through and even after all that I still had to improve and modify parts till I was happy with the stability and movement. 

If you ever read the mirror making book by Jean Texereau it states that to build a 20" scope rigid enough it will probably weigh 2 tons!!!! Not sure a thousand amateurs would agree with that, but mass does dampen vibrations and this was the point he was trying to make.

The lightweight, ultra compacts have to strike a balance and this is difficult to achieve. I have changed the spider on mine three times until I was totally happy from a functional and aesthetic point of view. 

I look forward to the next where I will incorporate all the learnings from my previous builds.

Edited by mapstar
7 people like this

Share this post


Link to post
Share on other sites

I agree with the above. Unless you use really exotic materials (in which case the compromise is either cost in sourcing them or time in sourcing them cheaply) there's always going to be some compromise somewhere down the line.Whatever the construction, if a scope is enjoyable to use (and it clearly was for Stu), reliable in the image quality and long-lasting then it's all good as long as it gets you out under the stars. I'd always encourage anyone looking at building a scope to think a long time first and then just go for it. As Damian says, every single builder makes mistakes along the way and learns from them. All of the scopes I have made have had to be changed en route and things improved and I doubt this will ever change. There's always something that could be better.

3 people like this

Share this post


Link to post
Share on other sites

Thanks both. Like everything I guess the range of dob options is a sliding scale in terms of aperture but also the design used. I'm not sure what the definition of a UC dob is, but I do know that a 22" UC is going to be a different proposition to a 16" UC and will naturally be more heavily engineered to cope with the weights involved.

As said, everything is a compromise, and everyone has different ideas about what will suit their requirements. With a young family and the demands that places on my time, I'm (unfortunately) not going to be in a position for quite a few years where I can get away every new moon so having a monster dob just doesn't make any sense for me. I do have a 10" mirror hidden away somewhere and have gradually built up the parts necessary to build myself a little suitcase dob so will try to make a start on that at sometime. That might be something I would use more regularly.

Horses for courses as they say :). As far as I am concerned, any scope that gets you out happily observing is a good scope.

7 people like this

Share this post


Link to post
Share on other sites

On my way to Reading... Just the Obsession to test as the Sumerian has been sold.  Hopefully the current patches of blue sky will translate into clear skies for testing.  Wish me luck!

Helen

2 people like this

Share this post


Link to post
Share on other sites

Hello, my name's Helen, and I have an Obsession 🤣

5 people like this

Share this post


Link to post
Share on other sites
26 minutes ago, Helen said:

Hello, my name's Helen, and I have an Obsession 🤣

Hurrah! Pictures! :) 

Share this post


Link to post
Share on other sites
13 minutes ago, Stu said:

Hurrah! Pictures! :) 

Just got home, so will do an uncrating thread... :glasses9:  Total cloud at the moment, but clearoutside reckons it might improve a bit later - here's hoping!!

Helen

1 person likes this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.