John

3 hours ago, Piero said:

I feel the thread title should change. Currently, it is not really informative and this might affect searches.

Probably something like "Lukehurst-Nichol classic dobsonian mods" would be more appropriate? If happy with this, could @John or @Stu change this, please?

 

Change made Piero

Thanks for the responses Piero and Gerry.

My Orion Optics 12 inc dob mirror cell is so basic compared to all this. I'm amazed that it does a reasonable job at all !

I think if I was going to replace it, I would have to put the replacement together myself now to be confident that the design was really up to the job.

This thread is becoming a great resource that will be valuable to those considering a reasonable sized newtonian either DIY or through one of the smaller manufacturers

Stunning aren't they ?

The animations are particularly weird to watch. Imagine what forces are going on to create such features and changes

I was just thinking that with the positioning of the sling around the primary being so critical in terms of where it sits around the mirror edge, the pressure it exerts on the support points beneath the mirror, remaining perpendicular to the optical axis etc, etc, ideally the sling would move together with the mirror and mirror cell if the primary collimation is adjusted to avoid changing the position or angle of the sling

But perhaps such movements are so slight that they would make no meaningful difference ?

Good to see you back in action observing-wise Geoff

I hope Marvin gets better luck than I did when I visited Oz in November 2018. Great trip and weather generally but out of the 27 days we were there I got just a couple of clear nights !

Did manage to see a few of the southern sights with my binoculars but plenty more left over for another trip

Very interesting Piero - it's like detective work, eliminating one cause after another

Just out of interest, does your whole sling mechanism, attachment points included, move with the primary cell and primary mirror when collimation adjustments are made ?

Amazing new images and movies from the Inouye solar telescope in Hawaii

https://www.nso.edu/press-release/inouye-solar-telescope-first-light/

Very nice !

When I'm doing outreach I find that the younger observers do have a habit of grabbing the eyepiece with one or both hands before putting their eye to it. I always try and explain up front why this is not a good idea but there are always a couple whos enthusiasm runs away with them a little !

I've tried the newt / mak-newt + alt-az T mount thing a couple of times. it worked quite well too

Should be worth the wait I reckon Chris

Quick deployment, portable setups make so much sense if you are trying to pursue astronomy in the UK.

My astro society (Bristol) has regular public viewing sessions as do many other astro societies throughout the country.

Currently Venus, Neptune and Uranus are visible from the UK but the other planets will put in an appearance as the months progress.

1 hour ago, Alan White said:

New Baby??? Tel more Mr H ???

I'm buying GavStar / Gavin's T-Rex from him

It's my 60th birthday next month so I've decided to treat myself to something really nice. When Gavin put his T-Rex up for sale I knew that I had to act fast. These things rarely become available and production stopped back in 2016 when the chap who exclusively built the mounts in Japan sadly passed away.

I'm really rather excited

I'd bet that the plans for human space flight would be given new impetus if really strong signs of life were to be picked up elsewhere in the solar system or, alternatively, if a significant and accessible valuable mineral or energy resource was discovered.

Wow !!!

What a great selection of alt-az joy there Stu

I'm picking up my new baby on Sunday all being well

Thats why my mind has been on alt-az mounts of course !

1 minute ago, johninderby said:

Just out of curiousity went and weighed the Bresser 10” base and it’s 11.5kg including the twin wheel castors I’ve added. The OO 10” base is 12kg. 🤔

My base weighs 10kg.

5 minutes ago, Barry-W-Fenner said:

I really like the "dob knob" under the chin of my 200p It really helps me maneuver the scope around. I think I will certainly keep an eye out for one of these bases.  Is there any known mod to increase the alt bearing on the Skywatcher base?

 

Baz

 

I'm sure there are mods for practically everything on the Skywatcher and other mass produced dobs. It has often been said that a dob is a "work in progress" out of the box

There is a well known mod for the azimuth bearings which involves washers cut from plastic milk cartons - that one works because I've used it !

Having a large alt bearing (like Bresser, OO and my mount use) is the best approach to controlled but smooth motion I think. Thats the challenge with dob bearings - you want smooth movement but also you want the scope to stay where it's pointed.

Orion Optics used to make schmidt-newtonians many years back.

From what I've read on the Meade ones, the optics have always been pretty good but sometimes the accessories such as the focuser have been lower quality.

I believe that one of the benefits of the design is that is has around 30% of the coma that a similar specification conventional newtonian produces. Popular with imagers for that reason.

An added benefit of either plywood or OO's aluminum bases is that they weigh considerably less than the MDF that is used for many dob bases. My 12 inch dob weighs about the same in total as the Skywatcher 10 inch does.

1 minute ago, Barry-W-Fenner said:

One thing I cant understand though. When turning the scope what do you hold on to. My current Sky Watcher mount has the handles on the alt bearing to hold, i cant seem to see anything on the OO Base.

Baz

I have a "dob knob" somewhere that I was going to fit to my dob but I didn't bother. I just hold the lip of the end tube ring and move it around.

4 minutes ago, johninderby said:

OO dob bases

https://www.orionoptics.co.uk/MOUNTS/dobsonianmount.html

I really like the OO dob bases but they aren’t cheap. Prices shown are without VAT.

Moonshane (Shane) designed the dob base for my 12 inch along similar lines to the OO ones but made it in 18mm baltic ply. I did approach OO for one of their bases originally but the price was off putting. Moonshanes build was somewhat less expensive and I could have it made to my specifications. Its a superb design and works exceedingly well 

SN 2020ue is a Type 1a supernova I believe. How long is it likely to stay relatively bright ?

14 minutes ago, Telescope40 said:

Hello Chris. 
This has been a very informative read. I’m getting a trigger finger issue about this scope. Saw one as IAS last year and some plans are afoot. Presume it’s still living up to expectations. 
can I ask if you got around to fitting a Moonlite focuser. 
My current big frac, a 127, has a Moonlite and I would be looking to switch it to this scope if I become an owner. 
Thx in advance.  John 
 

I'd be interested to hear what Chris says on the scope now as well.

On the focuser upgrade, I'm not sure that Moonlite have developed a flange for the Evostar ED150 as yet. You might have to have one specially made up ?

Well done Neil

I can't observe tonight due to a back injury (flares up from time to time) but it's good to know that you got this SN. That is a bright one as SN go. Good chance for those who have not seen one before to tick that box

I've found a couple more that I'd forgotten about

Vixen Porta Mk 1:

Tele Vue Gibraltar: