Improve my Skywatcher 300P flex tube

[Jam_70]

Hi guys, 

Having just stepped into astronomy with the purchase of a skywatcher 300P flex tube, I'm wondering what you can to make a good telescope into a great telescope.   I've found that the focuser can slip a little and can take a few attempts to get onto focus and would it be prudent to upgrade the focuser ?  I'm also thinking of getting a tel rad rather than using the spotting scope    

I also purchased two celestron eye pieces (32 mm and 15 mm).  

If you guys can think of any other upgrades that would help, please advise and  many thanks.    

Btw it's cold up in moray at the mo so I'm getting warm gloves, thick socks and a a thermal boiler suit lol.   

[John]

Hello and welcome to the forum !

Congratulations on an excellent telescope

There are loads of upgrades and improvements you can make to dobsonians but it's probably best if you get some experience using the scope before "splashing the cash".

That said, things that spring to mind would be:

- A cheshire eyepiece to help with collimation.

- A Telrad finder to use alongside the optical one.

- A red torch

- A good star atlas or two

With some experience of the scope you will be able to make better decisions on further improvements. You can easily spend as much as the scope has cost on a couple of really nice eyepieces and a focuser, more in fact !

 

[Avocette]

Hi there - good choice of scope!

As John says, get some experience whenever you can with it as it stands. I find personally that I need some help in getting to the right bit of the sky to look for particular objects unless it's Venus or the Moon for example. So I have added a 'setting circle' to calibrate the azimuth angle and I attach a Wixey magnetic angle gauge to the steel tube (alongside my Rigel Quikfinder and my RACI finderscope) to measure the angle of elevation (Altitude). I look up the instantaneous Alt/Az angles for the object I am seeking on my iPad running a planetarium program App (Sky Safari 5 in my case).

There's more info also in this thread written about the 200p (and 250px) Dobs I owned before the 300 flextube.

 

[Jam_70]

Thanks John,  as reference I've bought a few books to aid my knowledge of the sky.   Turn left at Orion to orientate the stars, planets and constellations.  I have a skywatcher laser colimator and have found it easy to use.  ( you tube helped there )   The telescope seems to hold its colimation unless I put it down. 

Still waiting to view the moon tho, (crescent at mo) by Friday it will be in a good position if the sky is clear. 

Looking forward to many a night watching the heavens. 

[Jam_70]

Thanks Avocette,   I have downloaded Stellarium also as a reference which is hand held as a guide.   Will look at your thread thanks 

[Ricochet]

I believe the Skywatcher focusers have a grub screw on the underside of the focuser (next to the focus lock thumb screw) that you can tighten to increase the tension on the focuser. If you have a play with that you might be able to stop the focuser slipping so much. There might also be similar screws at 120° separations that increase the friction from the bearing sides as well. 

[westmarch]

Hi Jam,

I got a Meade 250 Lightbridge - a similar flex tube and through trial and error ended up with the following mods:

(1) Got a Cheshire collimation tool - the flex tube design means that collimation is often disturbed when moving the scope.

(2) If you need to use tools like a screw driver and allen keys to collimate the mirrors then buying and fitting Bob's Knobs makes this so much easier.

(3) Finder: found the red dot finder good for general pointing but fitted a Celestron RACI finderscope to allow me to zero in on fainter objects.  Unfortunately this unbalanced the scope, so fitted a lump hammer to the mirror fan fixings and that seems to have balanced things out. You can alternatively use magnetic weights.

(4) Altitude adjustment:  still had a bit of stiction, The bearings are basically an aluminium ring sat on a felt base. Brantuk suggested that I replace the felt with the loopy side of a velcro strip - ingenious and fixed the problem.

(5) Stray light and dew ingress:  found that the open truss design needed a shroud to protect the light path and main mirror. I have put together a shroud with old tarpaulin and a black foam yoga mat to stop the shroud sagging into the light path. 

(6) Dew still forming on finders and secondary mirror:  cobbled shrouds for the finders out of plastic pipe and made a foam collar out of the rest of the camping mat. 

(7) Nudging: Fitted a small cupboard door handle to the upper tube segment to allow easier nudging of the scope.

You may find you encounter none, some or all of the above.

The main thing is to enjoy your scope and use the flex tube advantage to get it out to a dark sky site - worth more than many expensive modifications and lenses.

John

 

 

[Jam_70]

On 01/02/2017 at 00:00, westmarch said:

Hi Jam,

I got a Meade 250 Lightbridge - a similar flex tube and through trial and error ended up with the following mods:

(1) Got a Cheshire collimation tool - the flex tube design means that collimation is often disturbed when moving the scope.

(2) If you need to use tools like a screw driver and allen keys to collimate the mirrors then buying and fitting Bob's Knobs makes this so much easier.

(3) Finder: found the red dot finder good for general pointing but fitted a Celestron RACI finderscope to allow me to zero in on fainter objects.  Unfortunately this unbalanced the scope, so fitted a lump hammer to the mirror fan fixings and that seems to have balanced things out. You can alternatively use magnetic weights.

(4) Altitude adjustment:  still had a bit of stiction, The bearings are basically an aluminium ring sat on a felt base. Brantuk suggested that I replace the felt with the loopy side of a velcro strip - ingenious and fixed the problem.

(5) Stray light and dew ingress:  found that the open truss design needed a shroud to protect the light path and main mirror. I have put together a shroud with old tarpaulin and a black foam yoga mat to stop the shroud sagging into the light path. 

(6) Dew still forming on finders and secondary mirror:  cobbled shrouds for the finders out of plastic pipe and made a foam collar out of the rest of the camping mat. 

(7) Nudging: Fitted a small cupboard door handle to the upper tube segment to allow easier nudging of the scope.

You may find you encounter none, some or all of the above.

The main thing is to enjoy your scope and use the flex tube advantage to get it out to a dark sky site - worth more than many expensive modifications and lenses.

John

 

 

Many thanks John.  

 

[JOC]

Interesting - just a comment about using a Yoga mat - I have a goto 200P flextube and I personally found that the dew shield I tried to make for the end of the OTA was too heavy even with a thin mat.  I have now got a nice Astrozap shield to try and hope it won't be as heavy - there is a lot of length on the pivot points when you start adding extra length and I found that I needed to keep things at that far end fairly 'light weight'