Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

Skywatcher 250px Flextube dob

DaveGibbons

Recommended Posts

DaveGibbons

DaveGibbons

Posted
Posted

I finally managed a couple of hours observing last night with my new 10" Flextube dob , enough time I think to give everyone my first real thoughts on it's performance. Because of the Moon being nearly full and the still not perfectly dark sky I concentrated on globulars open clusters and double stars.

The scope has been partially flocked and had a moonlite crayford added along with 9x50 correct image finderscope (never understand why they are not included with this type of scope). It has a flocked home made light shield on secondary assembly and I am in the process of making a light shroud for the open mid section not yet finished.

7153_normal.jpeg

(click to enlarge)

I chose the 10" over the 12" as I wanted a truly managable set up I could move indoors

easily , along with compactness of the collapsed tube (I removed the rubber stops from the 3 tubes) would mean I would never get in the "can't be bothered putting it out " mode!

Here she is in the collapsed position.

7154_normal.jpeg

(click to enlarge)

Just screw in the two handles in the side bearings and it's very easy to carry a long way. As you can seee I keep the hard dust cover on the lower sction and a simple shower cap on the top.

O.K. base and scope went out about 9.30 last night . I collimated using a baader laser to hit the centre spot on main mirror and a collimation cap for main mirror adjustment. I don't know if it's just me but If I use the return beam with a laser it never seems to give perfect collimation but the collimation cap does!

First target is the double double epsilon Lyra just to check all is well with optics and collimation. I used a 6mm uo orthoscopic that allows both double stars in the same field of view, Nice split but not showing diffraction rings as I expected, swing to vega de-focus to a nice large doughnut and see the problem of tube currents still evident, the scope needs a cooling fan. 30 minutes later all tube currents have gone and time to try some difficult doubles.

Please bear in mind that at F5 the problem is getting enough magnification coupled with a very small margin for error with collimation in order to get good results on double stars.

Target Delta Cygni, 2x ultima barlow and 6mm Ortho show a perfect split pair with diffraction rings around unequal componenets it is beautiful. I am up at x400 and hand tracking is not possible at this magnification. The trick is to make sure your finderscope is in perfect alignment and get ahead of your target using this and just let the star drift across the field of view in the eyepiece. It takes a little practice but can be done- and best bit is you don't suffer any motor vibration!

My collimation is perfect so now take a look at the challenging sub arc second double Lambda Cygni a real test for the dobs optics. Using the same drift method and magnification the scope split the components with a clean split in extended moments of good seeing, wonderful. I now decided to see just how good the optics are and double stack the ultima with a tal 2x barlow and a 9mm plossl giving 530x magnification. It gives the best image I have ever had of this pair , perfect diffraction rings with plenty of dark space between components , the stars being tight spots. It is similar to the very good C11 sct I owned and I think it actually shades it.

I decide to try something silly and put the 6mm ortho back in we are now up at 800x mag. It takes me half a dozen attempts to get the star traversing the field of view, it flies across in a few seconds. Amazed to see the diffraction ring still holding up and the gap between components even bigger although the stars not as tight and it is a less pleasing view with chromatic abberation from the tal barlow now spoiling the view.

The scopes optics are superb and a testament to the latest generation of optical machines knocking them out.

Over to M13 and m92 in Hercules. M13 is as good as anythong the c11 ever did with beautiful jewel like specks right across the structure, M92 is a much tighter ball of stars but in some ways even more beautiful than M13 to me.

I spend the next Hour doing what dobs do best just cruising around the starfields of Cygnus and Lyra with a 25mm tal eyepiece dozens of small clusters and asterisms beautiful colours . M57 is always a sight to behold in decent aperture and it appears more ghostly than ever with a hint of green colour to my eyes.

I forgot to ad it's been blowing a blumming gale all the time with huge white cumulus clouds skidding over the sky(actually pink sodium coloured clouds ) so much reflected moonlight and light pollution you can almost read a book.

The wind seems to have little effect on the dob structure and can't say I noticed any lack of contrast due to the open tube- it must be an issue though and even better views should ensue once I have fitted a light shroud. The movement in Azimuth and altitude is good and hand tracking up to x300 is no problem above that it just takes more care and practice.

Superb optics , superb design , great value for money .

I've not enjoyed myself so much for a long time and having owned 2 12" dobs before am glad I plumped for the 10" it really is an easier beast to handle both in operation and storage. It compliments my 6" refractor and as a serial scope junky I would like to announce that's it for me, I'm sticking with what I have-honest!

cheers

Dave

Link to comment
Share on other sites
rawhead

rawhead

Posted
Posted

That's a glowing review from what's obviously a very nice scope. Thanks for taking the time to post :thumbright:

I think a big(ish) dob will be my next purchase. You set out a great argument for the 10'' flextube.

Cheers

Jon

Link to comment
Share on other sites
John

John

Posted
Posted

Thanks for that very informative report Dave. I've seen the 12 inch version but I thought that was probably too big for me so it would almost certainly be the 10" that I would go for as well.

Sounds like it's an excellent scope :shocked:

Regards and thanks again,

John

Link to comment
Share on other sites
  • 1 month later...
  • 3 months later...
Mike Godfrey

Mike Godfrey

Posted
Posted

Hello Dave and all , I'm an occassional visitor to Stargazers, I have been looking at different scopes and I wondered if this Dob would be an ideal starter ,size being almost everything in Astronomy plus, lets be honest, it a cool looking scope!

Any thoughts ?

Cheers,

Mike

Link to comment
Share on other sites
DaveGibbons

DaveGibbons

Posted
  • Author
Posted

Hi Mike, Would this be a good starter scope ? Dobsonians are certainly a great way to get into visual Astronomy, you get the opportunity to learn the night sky and not have the complexity of a GOTO set up.

A 10" scope is a big scope for a beginner . With any Newtonian scope you will need to be patient and learn the dark art of collimating the optics to get the best out of it along with a myriad of other small issues such as allowing mirrors to cool down to ambient temperature and keeping the formation of dew at bay- none of these things are really a big issue as long as you are aware that running a telescope will take a little time getting use to! Also unless you have seen one in the flesh a 10 and 12 " dobs usually shock you with just how big they are.

Pound for pound though they do give maximum impact at the eyepiece for the smallest dent in your wallet!! I agree the Flextube dobs are beautiful in the flesh!

cheers

Dave

Link to comment
Share on other sites
ZOG

ZOG

Posted
Posted

Hi Dave, one slight problem I've found is if it gets dewy during an observing session, the tube gets very sticky when extending or retracting it.

I was thinking of giving the trusses a wipe over with WD40. Have you had this problem ?

Link to comment
Share on other sites
DaveGibbons

DaveGibbons

Posted
  • Author
Posted

Yes! In fact the trusses on mine were always a little stiff . A little wipe with wd40 on a rag does help no spraying :shock: . I also found that retracting whilst at a slight angle helped with mine. It must just be tight tolerences I think. Absolutely loved the scope regretted selling it so bought it back!

cheers

Dave

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.