Help with Orion Optics Dobsonian purchase....!

[TakMan]

I'm off to Astrofest next Friday, specifically to look at the OO stand and their dobsonian range.....see website link:

Dobsonian Range

I'd like your advise on which way to go....

a) 300s (1200mm focal length), or

300l (1600mm focal length)

both the deluxe versions, and why!

Both will be stored in the garage so it's only a very small walk to the back garden - I don't envisage transporting them once on-site!

This is to complement my photographic set-up (Tak FSQ106-EDX) and my visual grab and go unit (Tak TSA102s), and is for deep sky (obviously!) and the planets also....

I shall use it as a dobsonian to start with (may look to purchase a scope buggy like I recall 'JohninDerby' having), but may also purchase tube rings so I can mount it in the future on my Tak EM400 GEM (which if memory serves correct, can handle a 'visual' load of 35Kgs).

Any thoughts on the upgrades for each -

Optics upgrade

1/6 to 1/8 PV wavefront

£105

1/6 to 1/10 PV wavefront

£300

Optional Variable Friction Brake

£39

Optional 9 Point CNC Mirror Cell upgrade

£90

Optional Mirror Cooling Fan

£19

Optional Crayford Focuser Upgrade

Precision 10:1 Reduction Drive

£40

If there is a good deal on, I may place a deposit... or wait 'till summer to see if they offer the usual 'mirror upgrades'.

My biggest worry (being a refractor owner), is the dreaded collimation....!

I have included the Televue eyepiece charts that incorporate the Paracorr which I already have as this increases slightly the focal lengths.

Eyepieces owned are:

Televue 31mm Nagler T5

Televue 21mm, 17mm, 13mm, 10mm, 8mm, 6mm Ethos

I'd also like to attach a True-Tech Supa-Slim manual filter wheel as I have Lumicon 2" OIII and UHC filters - does anyone foresee this to be any problem?

Any thoughts or suggestions (especially from OO owners), most welcome!

Clear Skies

Damian

[mattifor]

Hi Damian.

I have a OO 250s Europa Deluxe 1/6 wavefront on OO UK Dobsonian,

I would have liked the 300, but I purchased the Europa to mount on EQ mount but changed my plans as I found it dificult to manage lifting on and off the EQ mount.

now fitted on the Dobsonian mount easier to set up, but has no GOTO amd needs nudging to follow images.

I fitted the friction brake to stop the scope moving when eyepiece changes.

I also fitted a set of locking casters this removes the need for the scope buggie.

Where are you located?

Ivor H

[arad85]

Someone posted on here a few days back that if you're buying OO, you need to go for the 1/10th wave upgrade. The reason was if you buy the standard range, they are only "as good" as the mass produced dobs where you can get a 12" for around £500 new.

As to which one to go for, given you have the full range of Ethos, I'd be basing my decision on what max mag you want. The 6mm in S will give you 100 degrees at 200x whilst in the L will give you 266x. Collimation will be more critical in the S though. Also, I'd go for the 10:1, 9 point and fans on both.

[TakMan]

Thanks for the advice so far!

keep it coming....

Damian

[barkis]

Whichever you choose, I envy you.

At f4 or f5.3 a 12" needs excellent optics, so buy the best they can offer. As for collimation, it's only a headache until you master it.

Best of luck.

Ron.

[davew]

Hi Damian,

I'd love to spend your money so here goes...

If it were me, I'd go with the f4. Slightly smaller tube and faster optics. ( Thinking about mounting on the Tak and possible photo use.) Remember to factor in price of a Losmandy / Tak mounting plate. Also I'd get the upgraded tube rings. The cheap metal bands don't cut it for me. I have a Gem mounted OO 250 and the whole tube clunks during a meridian flip !!

If you upgrade to 10th wave the 9 point mirror cell and 10:1 upgrade are pretty much mandatory. Why spend the extra cash on the mirror and not get the best from it ? With 6th wave I'm not sure. Ask Barry about the 9 point.

Cooling fan is cheap. Why not. It's a big mirror.

Ask about the filter wheel. I think it will be ok visually ( could be wrong ) but may make it hard to focus if using a camera. I'm sure they can move the mirror cell up for no extra charge if it needs it. I know you didn't mention photos but keep it in mind.

I would ditch the finder scope and fit a Telrad with dew shield. Both would be a good option if you like finderscopes.

A light shield opposite the eyepiece is a good idea. They can be velcro fitted. It's a big hole at the front

And finally, those upgrade prices you've posted look steep. I'm sure they were less than that. Have a long chat.

All the best which ever way you go.

Dave.

[johninderby]

Going for the 1/10PV optics makes it more of an all round scope, not just great on DSOs but great on lunar/planets as well. Definitely get the 9 point mirror cell and fan. The variable friction brake really works so you might as well get that as well.

You might however consider going with another focuser, say a FeatherTouch or Moonlite or Baader Steeltrack. OO will reduce the price if you don't take their focuser. If you send them your own focuser they will fit it for free and make sure the focuser is installed in the right place to keep the focal length correct.

If you don't mind spending another 58 quid they will also powder coat the OTA in any colour that you want.

John

[brianb]

Long.

Reasons: collimation far less critical, much more tolerant of eyepieces.