To Flex, or not to Flex

[BruceUK]

I'm definitely going to get hands on with a few scopes before I buy anything, but I need to get my post count up to see the buy/sell section, so you guys get the benefit of my daft questions for a bit longer...

What are the pros & cons of flex over solid tube? Obviously a Flex is smaller in storage/transit, but is it also lighter? If so I might stretch to a 250

[Telrad]

Portability is an advantage of having a Flex system.

There are actually a few small disadvantages, but nothing that can't easily be overcome. Using a shroud will help you with the ambient light of course, but maybe more importantly will keep your primary mirror from dewing up quickly. If and when you do store the scope by collapsing it, you may find that, after reassembly, the collimation might be out of whack on a Flex. Again, nothing to stress about, collimation is fast and easy with a laser.

[BruceUK]

Obviously it would remove the option of mounting it onto an EQ at some point too I guess.

TBH I'm leaning pretty heavily in the direction of a 200p solid tube, but those extra 50mm keep winking at me.

The 250 is f4.7, whereas the 200 is f5.9, I guess that means the 200 will have a more flexibility in eyepieces?

[Tinker1947]

I think i have seen quoted "bigger is better" so go for the biggest you or your wallet can manage..

[Telrad]

Well, we all know aperture rules - as Tinker1947 said "bigger is better". I would have to go with the 10", which has 56%, or half a magnitude more light output, and for resolving power the 8" is about .68 arcseconds, and the 10" is .45 arcseconds, so that should be thought about also.

[John]

The Flextubes are actually a little bit heavier than their solid tube versions. Personally I'd go for a solid tube up to 10" and think about Flex / Truss tubes above that aperture. You will need a light shroud with the open tube designs. Remember that the 8" versions are F/6 wheras the 10" is F/4.7 - the latter means that accurate collimation is more critical and they are harder on low cost wide field eyepieces. Additional aperture is good but you ought to be aware of the other factors too.

If anyone has managed sub-arc second resolution regularly with the UK seeing conditions it will be a miracle !. The additional aperture would show itself on deep sky objects more than planetary / lunar viewing.

[Omega]

I'm also thinking about the 200P Flex version and did consider the 250P also, but have been told the f6 of the 8" will perhaps be better for a newbie. The extra 2" i guess will be better noticed on DSO...

[BruceUK]

Roughly how heavy are we talking for a 10"? I'm a fit and healthy 34 yr old so I don't see it as too big a deal. Also we're moving from a 2 bed flat to a 4 bed house, so my wife can suck it up that I'm stealing a few square feet of the conservatory

I think the collimation and eyepiece factors might well seal the deal for me though.

[BruceUK]

Whereabouts in Worcs you from Omega? I'm a Malvern boy returning to the Midlands from exile in London

[Earl]

Having owned a 300 solid 250 flex and a 250 solid.

Flex is really only of use 12" + and thats if your going to be moving it about.

The 12 inch solid tube is very big even for a 6'4 brute like me LOL

[Omega]

Whereabouts in Worcs you from Omega? I'm a Malvern boy returning to the Midlands from exile in London

Ombersley originally, now in the city! I'm sure your move back home to Malvern will help with your views of the sky!

[Chris H]

I (37yrs old, fit, healthy I think) can carry my 10" Dob (solid tube) scope plus base in one piece no problem. I don't move it very far though just about 10m in separate parts it's a doddle.

If you can observe from your garden the best place to keep it is in a shed, then it's ready to go and when you get a spell of bad weather it well out of the way.

[Omega]

I (37yrs old, fit, healthy I think) can carry my 10" Dob scope plus base in one piece no problem. I don't move it very far though just about 10m in separate parts it's a doddle.

If you can observe from your garden the best place to keep it is in a shed, then it's ready to go and when you get a spell of bad weather it well out of the way.

Would you suggest keeping it under a blanket or some sort of cover?

I think most of the Flex versions come with Auto tracking which may be worth considering Bruce. It is certainly one of the selling points that appeals to me.

[Chris H]

I just put a shower cap over each end once the dew has dried off and thats it don't have any problems with dust or insects.

[BruceUK]

Not quite making it back as far as Malvern actually, I'm heading to Leamington Spa but yes, definitely better viewing than London although Jupiter was pretty stunning here Sat night with the mark one eyeball.

I've thought about Auto, I was wondering if it's available as an upgrade on the solids?

[BruceUK]

I (37yrs old, fit, healthy I think) can carry my 10" Dob (solid tube) scope plus base in one piece no problem. I don't move it very far though just about 10m in separate parts it's a doddle.

If you can observe from your garden the best place to keep it is in a shed, then it's ready to go and when you get a spell of bad weather it well out of the way.

Is shed better because you don't have cool down time? There's actually a covered BBQ area that might suit, probably with a tarp thrown over in case rain gets blown in.

[Omega]

I'm not too sure whether it is. I presume the base units are different which incorporate the servos and the encoders, so not to sure whether you can change them later or not?

Like yourself I'm waiting to hit the magical 50 post landmark and check the buy/sell section too as some of the larger Celestron Nexstar units look nice, particularly the 8", but are quite expensive new!

[BruceUK]

I think that when I get to wanting tracking, I'll probably go EQ, so that really rules out the flex

[Omega]

One thing is for sure, I've changed my mind about 100 different times now! THe Flex AUTO is about £200 dearer, but for that you get Auto tracking, the storage space benefit and the black coating (if that is of any preference). Other than that they are pretty much the same scope. I have considered myself whether it is worth the extra £.

[BruceUK]

Me too, once or twice my credit card started sweating

[Omega]

lol, likewise. Btw, if you do opt for the FLex then a shroud is highly advisable. If I get the Flex myself I'll be getting the Astrozap shroud which is convenient as it stays on as the telescope is collapsed.

Perhaps some of the more experienced members could shed some light on how difficult it is to track objects without the AUTO? Is it just a case of simple nudging? Is the Dob quite sensitive and liable to easily stray out of focus?

[Per167]

I have the 200p flextube auto and really like the tracking ability. For deep sky tracking is not that much of an issue but for high mag on planets it's really a deal breaker to be without it as far as I am concerned. Maybe you could get used to the "nudging" but i never did - that's why i got the auto version when i upgraded.

[frogdr1ver]

Ive been considering one of these as well and wondered if it would be possible to retrofit to an eq mount later. So you've answered a couple of my questions!

[Omega]

Ive been considering one of these as well and wondered if it would be possible to retrofit to an eq mount later. So you've answered a couple of my questions!

Another benefit of the solid tube version! I'm not sure whether you can with the Flex or not?

[Chris H]

Is shed better because you don't have cool down time? There's actually a covered BBQ area that might suit, probably with a tarp thrown over in case rain gets blown in.

Cool down yes, if you take the dob out of a house to the garden the mirror needs to cool to ambient temp this can take a while like an hour or so. If it's in a shed then it nearly as cold if not the same as outside so you can use the 10" as a grab and go which is handy with the weather we have.

The base is chipboard so I would not let it get wet or even damp so BBQ area is a no no IMO.