Flextube or Fixed tube?

[Stargazer_00]

Hi all,

I am settled on getting a 10 inch dob upgrade for this coming autumn/winter viewing session (clearly am not expecting any stars at the moment)

I am now wondering if there is any performance difference between fixed tube and flex tube dobs by Skywatcher.

I assume the flextube is mostly about keeping larger scopes more compact for storage and possibly also allows the scope to come to OAT more quickly. Are there any other benefits I am unaware of? Can afford both so money isnt really a problem.

Also, can anyone with practical experience give a rough idea what the difference would be like going from a 150p to a 250px dob? thanks

[SeedyF]

Easy storage and transport are the big pluses with the flextube in my view. But I've never owned a solid tube.

I went from a skywatcher 150 on an EQ3-2 to the 10" dob and the difference in what I can see is incredible, that's the only way I can describe it I have access to so much more in the way of faint objects and views of the bright stuff is enhanced significantly - the planets for example are way, way better viewed through the 10".

You really need a light shroud of some sort wrapped around the open mid section of the flextube to cut out stray light. The official one is £60 or you can improvise - I adapted a camping mat.

[SeedyF]

PS - I can't read your signature, but then I am colour blind

And where in herts are you - roughly? I'm in Hemel

[Stargazer_00]

Thanks for the response Can't wait to get it, ill get the Flextube then as you dont describe any inherent issues with a flex tube

I'm in Stevenage, just up the A1 from you

Are there modifications I need to make to the base? It'll be used in a garden, on grass so it might be good on some 'off road' adjustable caster wheels. Or maybe i just make a base with adjustable legs I put down on the grass and set the dob up on top? Giveit a few more inches off the ground as well?

Also changed signature colour, it does my eyes in on this new scheme as well

[Stargazer_00]

Also is it worth that bit extra to get the GoTo? I really enjoy finding things for myself but it has such a huge library of objects itll find things way after im done finding the things I can for myself.. I just know if i save up for the GOTO ill end up getting the 12 inch fextube instead...

[carlc]

Easy storage and transport are the big pluses with the flextube in my view. But I've never owned a solid tube.

On a related note: there are conflicting views with regards to the flextube dobs keeping their collimation between sessions (extending and retracting) some say they do and I've read some recently saying they don't (related to the 130 Heritage only though). What's your experience? I'm 'scared' of reflectors because of the collimation issue (I'm incredibly bad a fine motor skills - which I presume collimation requires). Yet that may just be the usual newbie fear of what looks like a technical procedure.

[Mike73]

I've had a 8" solid tube and now got a 12" flex SW.

Personally, if I was going for a 10" then I'd go for a solid tube because my 8" held collimation really well, I hardly ever had to touch it. Collimation is really easy to do though and I usually check both secondary and primary before observing, this usually takes about 5 minutes tops sometimes less.

Transporting a 10" solid tube will be easy in an average car so I can't see the advantage of getting the flex if you are mainly going to be viewing from home.

[swamp thing]

Id go with a solid tube too. The Flextube 10" just doesn't do it for me. It doesn't become small enough to be any real benefit IMO, instead it just brings issues with shrouds. I'm not sure the tube on it is short enough to stop tube currents either (one of the usual benefits of truss design) or help with cool down time.

Collimation isn't an issue with either for me. On a scope this size it should be checked anyway. Can't quite see why people are frightened of this but will happily opt for a Goto system that requires considerable faffing about with.

Trust me people collimating is a lot easier than setting up a Goto EQ mount, and no harder than a alt - az one.

[Stargazer_00]

Collimation doesnt scare me at all. I have a newt which I check the collimation on regularly.

Does the flex tube design make the secondary more accesible for collimation? One pain I have with the 150p is getting at the secondary to make fine adjustments. It seems to me that you could get to it alot easier in a flex.

[Mike73]

I think that the Flex tubes look a lot more sexy but if you are somewhere you can see your dob then your in the wrong place.

Seriously though, I think the 12" Flex is practical and personally if I was going for a bigger dob than that then it wouldn't be a Skywatcher anyway.

[Damo636]

Below 12" I personally wouldn't bother with a collapsable dob. They are more expensive and actually heavier than their solid tube equivalents.

[carlc]

Can't quite see why people are frightened of this but will happily opt for a Goto system that requires considerable faffing about with.

Trust me people collimating is a lot easier than setting up a Goto EQ mount, and no harder than a alt - az one.

It's a common anxiety as it looks like a technical procedure to be honest (despite every Dob owner's reassurance). I'm sure it is simple though.

[swamp thing]

It's a common anxiety as it looks like a technical procedure to be honest (despite every Dob owner's reassurance). I'm sure it is simple though.

You may well be right Carl. I guess being a practical type things like this never put me off.

OTOH setting up a computer every night! Eek! I fear I would end up throwing the mount into the nearest ditch. Mr patience me.......not lol!

[Mike73]

I used Astrobabys guide to learn how to collimate and although it teaches you everything you need to know and imo is the best place to learn it does seem a bit bewildering when you first read it.

[carlc]

Ah! Well there's practical and then there's me (about as practical as a disabled sloth)- just ask my wife about my DIY attempts....

[Moonshane]

Either scope will provide super views compared with a 6" scope. personally, up to a point, I prefer more aperture to more gadgets for the same price and if you can afford and move/carry the 12" this will make an ever bigger difference.

above 10" though the SW scopes start to get very bulky.

collimation of any newtonian is straight forward. broadly if you can turn one thumbscrew for left right and another for up down, and remember what you have just done a few seconds ago then you can do collimation - you just need the tool for the job.

[carlc]

I used Astrobabys guide to learn how to collimate and although it teaches you everything you need to know and imo is the best place to learn it does seem a bit bewildering when you first read it.

And that's the best one I ever read before jumping from bins to scope (hence the Tal - but don't get me started on EQ mounts - I keep using the wrong control to track after centring - Doh).

As I say - desperately not practical (just practically stupid really).

[SeedyF]

Some good points made above.

1. I don't feel the flextube cools down any quicker to be honest
   
2. It callapses enough to hide behind an armchair in my living room and to get on the back seat of my car where I can get a seatbelt round it.
   
3. I check collimation everytime and mostly it needs a minor tweak
   
4. I got something similar to bobs knobs and it takes less than 5 minutes.
   
5. I like the Goto. It's easy to set up and I spend less time getting frustrated looking for faint objects. Your sky will be a lovely orange just like mine and the goto takes some of the pain out of hunting a patch of sky with the finder - sometimes giving up. Now I can quickly assess if it is worth trying to see an object by telling the goto to find it then a quick look in the eyepiece will tell me if the LP is likely to be too bad. Having said that I did really enjoy the excitement of findng things manually. I miss that a little but not as much as I enjoy actually observing.
   
6. I usually take about 15 minutes from taking the scope to the door to finishing set up, even if I star align to use the goto.
   
7. I made a platform with adjustable feet to stand the scope on & get it accurately level - if you get the goto I think its essential to have it level.
   

Just in case it helps the scope and base wheigh 32kgs (I stood on the scales holding it one day). It's worth making sure you can happily cope with that, although its really easy to separate and then it's really manageable.

[scarp15]

The 10" flextube would be worth it if you require the compact storage at home, otherwise as has been mentioned a solid tube would be fine for both home and travel. IM quite new to collimating tecniques myself but I have overcome the initial fear factor and now just get on with it. Really is no trouble at all, besides Astro Babys account, I printed off 'How to Collimate Your Newtonian Reflector' - www.SkyandTelescope.com

Bobs Knobs on the secondary help a lot to.

[Hals]

I've never owned a flextube so I can't really comment on them, all my scopes have been solid tubes and I've not had any bother with that design at all in 25 years observing.

My 10" 250px is relatively easy to move about, just pick her up by the two handles and do the dob-shuffle out of the shed and across the garden (depends on your general fitness but unless you have a bad back or such shouldn't pose many problems), fits in the car ok when OTA & base split and is very robust. Holds collimation very well (I'm always checking it).

It's a purely personal thing both flextube or solid have their pro's and cons.

[Stargazer_00]

thanks for all your replies

You cant buy the fixed tube 12 inch anymore can you? The one from Skywatcher. It seems FLO has recently started stocking the 10 inch again which is looking good but the 12 inch is not to be seen anywhere :/

[cotterless45]

I'd go for a 10" solid tube. Flexi tubes are a pain for muck getting in. Anything above 10" , you might get into portability issues.

I can see 95% in an 8" Dob compared to a 10". Really depends if you're going to be a dedicated fuzzy finder. If you are then GOTO is the only way.

Nick.

[RikM]

Optically, the solid and flex-tube scopes are identical. I have the solid 10". I wouldn't consider a collapsing design much of a benefit until you get to 12". I compared the views through a 10" and 12" and the difference, to my eyes, wasn't worth double the money. I don't have space to store or transport a solid tube 12" but I am very happy with my solid 250PX.

[SFlowers]

We have a lightbridge and we have a lip sticking up from our door then a drop out of the door into the garden. My husband can't pick it up assembled and we take it outside in 2 bits. I think it would be more awkward with a solid tube but having never owned one I can't say for sure.