SW Flextube 14" or Explore Scientific 16"...?

[emadmoussa]

So  the home purchase seems almost confirmed now and AT LAST I will have the chance of sparing some fund to get my big aperture Dob.

I'm torn between the Sky-watcher Flextube 350P and the Explore Scientific 16".

While the ES is a bigger aperture, the eyepiece is not very high and the optics seem very good, I find the Flextube 14" more suitable considering it's less maintenance (no assembly time or any of that). Plus I pretty much doubt for such aperture a 2" won't make a massive difference in 4-5 sky type.

I like the ingenuity and aperture of the Explore Scientific, but seems a bit  high maintenance. Let alone the price has gone back to £1999. I also like the Flextube 14", but not convinced of the focuser. I know I can change it, but this will mean stretching the budget too much.

Any thoughts or insights will be much appreciated!!

P.S. I'm perhaps buying in the end of July (no point buying next month with the days getting longer and will have more time to save up some more pennies) with a budget of about £1400 (the less the better ).
 

[John]

If you can make the step I think adding 4" of aperture will deliver a more satisfying improvement in performance over your 12".

[emadmoussa]

If you can make the step I think adding 4" of aperture will deliver a more satisfying improvement in performance over your 12".

Sorry, forgot to mention. I had to sell my 12" to fund the house purchase

[nmoushon]

I think you are right and that you might not be able to tell much of a difference with the 2" of aperture in your skies. BUT if you ever take it to a dark sky I think you will be able to find plenty of fuzzies you will find in the 16" and not find in the 14". But if you rarely go to dark sites then I would suggest going with what you feel you would use the most. Personally I would go with the ES as is looks much for solid and better built. IMHO I think the SW looks like it would easily flex and not support all that weight at the EP, especially if you upgrade the focuser. Now if thats reality I dont know as I've never been up to one but thats just what it looks like to me. Plus if you have to upgrade the focuser is there really any saving over the ES?

There will be assembly time for both scopes. Especially if you have to collapse either of them for storage. Though the SW assembly time will be less than the ES but I'm sure after a while you get it down really fast and but up and running in 15min or so with the ES. Just like when I got my first EQ mount. Would take me about 40min to setup and PA now it takes me no more than 10min to setup and PA.

[AlexB67]

Not sure what to suggest and only best known to yourself the pros and cons. If it is just for home use could you not leave the ES assembled ?    It is a nice comparison that shows how compact the ES really is though. That base on the SW are biiig. 

Just to throw it into the pot, but with that sort of budget  and I think since you mentioned you use it at home, you could also keep an eye out on the second hand market ?  Who knows, perhaps a nice used VX14 will turn up with a high grade mirror. 

Good luck with the house and your scope purchase

[emadmoussa]

I think you are right and that you might not be able to tell much of a difference with the 2" of aperture in your skies. BUT if you ever take it to a dark sky I think you will be able to find plenty of fuzzies you will find in the 16" and not find in the 14". But if you rarely go to dark sites then I would suggest going with what you feel you would use the most. Personally I would go with the ES as is looks much for solid and better built. IMHO I think the SW looks like it would easily flex and not support all that weight at the EP, especially if you upgrade the focuser. Now if thats reality I dont know as I've never been up to one but thats just what it looks like to me. Plus if you have to upgrade the focuser is there really any saving over the ES?

There will be assembly time for both scopes. Especially if you have to collapse either of them for storage. Though the SW assembly time will be less than the ES but I'm sure after a while you get it down really fast and but up and running in 15min or so with the ES. Just like when I got my first EQ mount. Would take me about 40min to setup and PA now it takes me no more than 10min to setup and PA.

The Flextube is very solid actually - I had the 12" and it was very good.

[jetstream]

Emad,the high relectivity coatings that OOUK ( and some others) use effectively add a bit of aperture and the HILUX process maintains the mirror figure after coating,others may not.Also the higher Strehl mirror keeps the light going to the right spot in the Airy disk.Less scatter,more contrast.It is kind of eye opening to run the numbers using accurate reflectivity numbers.My 10" HILUX performs like a standard reflectivity(.88%) 12",with a much better mirror figure.

Alex is making a good recommendation with the used VX14 or between the ES & SW go for aperture IMHO.Also a new VX12 OOUK won't be far off any of the listed bigger scopes and has a great mirror, good mechanics,mirror cell,fan, great focuser and is easier on eyepieces.

[scarp15]

The flextube 14" might be more logical to use if exclusively observing from home, fitted with a shroud, home made dew shield and eventually save up and change the focuser and  it ought to perform fine in terms of aperture gain with some light pollution to contend with. The ES 16" is surely designed with going into the boot of a car in mind and stretching the aperture reach from a dark site.

[scarp15]

Yet as Alex and Gerry have added (whilst I was adding my post), if you see a used Orion Optics UK or can go with one at retail, the solid tube, hilux coating and nice figured mirror etc will be a very good option for home use and for that matter if you are able to travel.

[triton1]

Emad,for the extra 4" over the old 12" and the less weight and ease of mobility surely the 16 the is way to go.There will also be the benefit of never wondering or saying what if or should I have.This may be your last big scope purchase and should last you for many years to come,so why not.

Regards Jonn

[emadmoussa]

I like the 16", but I've heard a lot about how hassling to put it together and find a shroud (which I don't have a clue how to make )...is it worth it? I don't know to be honest.

Alex, the OOUK is a great option actually. If I can get a good deal on one, then why not?!

[triton1]

Exactly,and there is lightweight tent material out there so once you have your scope and can measure everything correctly making a shroud shouldn't be too hard surely.

[AlexB67]

It is quite remarkable what a high grade mirror could do. I had to sit and do some calcs during my cuppa.

If you take say a well used older SW mirror at 88 reflectivity, I do think that is a bit pessimistic, afer much research months ago, new I do think they are closer to 92 - 94, but lets say 88% for an old used Chinese mirror with strehl 0.8x, x being less than 5 usually for the chinese ones.  Now a high grade 1/10 PV where this will be well into the 0.9x with x closer to 5 and  higher.  Adding it all up. I'l not got through the math for the sake of boredom, but you can calculate the contrast factors, how much energy is lost in the central disk,  at least assuming it is on axis it is not too hard, the brand new 14 inch OO research grade mirror could get close to a standard well used 16 inch run of the mill  Chinese mirror.

These are some generalisation and assumptions, it will also depend what you are looking at,  for example planets, fine details versus faint fuzzies, and not even bringing seeing conditions into it.

As  a guideline, what drops out in such a comparison shows that the effectiveness of an OO research grade 14 inch, versus a more standard 16 inch Chinese run of the mill well used  one, the difference is significantly smaller that a simple ratio of light gathering comparison proportional to area, which would say it is about 34% going from 14 to 16 inches and many vendors flog as a selling point.

On the whole though, a new SW 16 inch, or GSO or one of those make mirrors versus a brand new 14 inch research grade 14 inch, the former will still bag more faint fuzzies I feel. If that is it primary use, even under modest skies.  How important that is, is something to consider.

[emadmoussa]

Ermm..interesting, Alex. Now I'm having more criteria to consider. On one hand I prefer a solid tube since I almost exclusively observe from my back garden, but on the other what if I want to go somewhere with the scope?! Here comes the dilemma, the good and bad points...16" with portability, or 14 inch of top class mirrors, or even 14-inch with the advantage of very short set-up time and less open space...I think there will be some sort of compromise eventually. For me personally, the price will surely be a major governing element. As far as I remember, I never saw a 14-inch OOUK up for sale...

[scarp15]

Here is a picture of the VX14 in the field for comparison.

[emadmoussa]

Here is a picture of the VX14 in the field for comparison.

Very nice indeed!! Is it up for sale in July?! :D

Did you buy brand new?

[AlexB67]

I saw one once not that long ago on AB&S or ebay, do not recall. I feel it is a bit of an if and but when do they turn up, perhaps not often, and  the cost of transport getting it, would you want to see it before buying , they may be in some other part of the country far away etc. etc.  

In my case I will buy one of those OO scopes at some point in the future, or something with high grade OO optics, but for me personally I am talking far ahead, not this year, that's for sure. Right now my feeling is more like 2 - 4 more years or so when the SW is getting a bit ropy and ready for a recoat perhaps  If you already have scope there is no rush and you can wait it out for the right one to turn up.

Typically when you have the cash and you want something, the item you are looking for is nowhere to be found. I can appreciate just buying something when you want is hard to resist when you don't have a Dob at all and are ready to buy.

Also my calculation is a rough guideline. I'd feel much more confortable if you actually could try both somewhere and compare, the best test of all  . That being said, there is an element of truth in what I said, but to quantify these things reliably is a big ask.

[jetstream]

Alex I think that  effective aperture reflectivity considered, makes things much closer for the 14" vs 16" than may be realized.I checked things out a while back too and I am also looking for more aperture,but I am being careful about the purchase.I understand that making a good large mirror is hard, and a fast one even harder,so it would be good to do as you say and compare the different apertures(OOUK,Nichol vs SW,ES) directly.Seems like the UK has top tier mirror manufacturers,a Nichol mirror would be very nice too.Even some premier US dob makers won't provide or guaranty their mirror specs and eventhough they can be great its reasuring to see some numbers.I can't wait to hear more DSO reports about the ES dobs,I'm thinking of one too possibly.

[scarp15]

Very nice indeed!! Is it up for sale in July?! :D

Did you buy brand new?

Second Hand, as Alex has pointed out, there were two up for sale at around the same time, one on ebay the other on ABS. Mike (Faulsky) got hold of the other. Keep looking out, the 10" and 12" versions come up more frequently sometimes complete with the OOUK dob mount.

[scarp15]

I saw one once not that long ago on AB&S or ebay, do not recall. I feel it is a bit of an if and but when do they turn up, perhaps not often, and  the cost of transport getting it, would you want to see it before buying , they may be in some other part of the country far away etc. etc.  

Mike was able to collect his as he did not have a big commute, I took a chance with a courier, as the seller still had the original packaging. My scope was sold compelte with the mount, I believe that Mike purchased his in addition.

[Mike73]

My opinion differs from Gerry's, for DSO's I'd always go for the biggest light grasp I could afford even if it was a standard Chinese mirror. My 16" GSO mirror is 1/6pv and 93% strehl, exactly the same mirror from OOUK would cost an extra £1000 but it would be tested so you'll know exactly what you are getting unlike Chinese mirrors.

I had to cancel meeting the lads at Dobfest this week, we would of had Dans 14" SW, Mikes 14" high grade OOUK, my 16" Sumerian, Calv's 18" Nichol with high lux and Steves monster 20" with standard coatings. Now that would of been an interesting comparison!

[jetstream]

Now those will be some comparisons!Can't wait to hear about it.Mike I hope you are right as it will save me a pile of cash!lol! How does the new VX10L perform for you?

[AlexB67]

My opinion differs from Gerry's, for DSO's I'd always go for the biggest light grasp I could afford even if it was a standard Chinese mirror. My 16" GSO mirror is 1/6pv and 93% strehl, exactly the same mirror from OOUK would cost an extra £1000 but it would be tested so you'll know exactly what you are getting unlike Chinese mirrors.

I had to cancel meeting the lads at Dobfest this week, we would of had Dans 14" SW, Mikes 14" high grade OOUK, my 16" Sumerian, Calv's 18" Nichol with high lux and Steves monster 20" with standard coatings. Now that would of been an interesting comparison!

I would agree, that is what my calculation had indicated but it was a quick job and that is not to say I am right, but what I believe to be the case. I've never even looked through one of the things that size.

With that mirror you got a nice sample there too Mike, that helps, I would be chuffed to bits considering their cost    , but even with the 1/4 PV assumption, which is sort of to be the common believe as an average for those scopes, the 16 inch china made inch would win over the research grade 1/10 PV 14 inch I feel for fishing out faint fuzzies, just not by as much as it would be if all things were equal , reflectivity, strehl, etc.

Gerry, coming back to the reflectivity I think 88%  is not a bad value for a used average Chinese made mirror from what I read, but the Hilux one will also degrade over time and not deliver that 97% , it will just degrade much less quickly, so as times goes on, a 5 year old GSO or synta would probably perform worse in comparison to a Hilux OO. I think John told me this once as well, new the synta ones are in that 92 - 94 range  IIRC, and the GSO explicitly advertise similar figures in many places.

As Mike said, Emad, get to a star party and ambush a few people to look through theirs

[GuillermoBarrancos]

I like the 16", but I've heard a lot about how hassling to put it together and find a shroud (which I don't have a clue how to make )...is it worth it? I don't know to be honest.

Alex, the OOUK is a great option actually. If I can get a good deal on one, then why not?!

Don't rule out Orion USA either. Their truss dobs are also great!

As I see you want manual with no GoTo, you could look at the XX14i as well.

http://www.teleskop-express.de/shop/product_info.php/info/p3567_Orion-SkyQuest-XX14i-IntelliScope-14--f-4-6-Truss-Dobsonian-with-Object-locator.html

I personally always liked the construction of that one better than the SW ones. Especially since the base is also easy to completely dissassemble / reassemble. Making it even more compact for Storage / Transport.

I also think the default supplied EP's are better. A 35mm widefield and 10mm, instead of the SW standard 25mm and 10mm.

But I Guess you still saved your "better" EP's and / or buy better ones quickly anyway. But still.

What I also like is, that you can get a Complete transport case set for these truss dobs for easy and safe transport to dark sites and star parties. Not cheap, but still a nice option to have.

I really like this video. The guy just relaxing with setting up the 14inch.

http://www.youtube.com/watch?v=8LCvHx_skIs

[Mike73]

Now those will be some comparisons!Can't wait to hear about it.Mike I hope you are right as it will save me a pile of cash!lol! How does the new VX10L perform for you?

The VX10L hasnt seen first light yet Gerry as its had some teething problems, it had some parts missing when it first arrived then when the replacements turned up I found that the whole focuser sagged under the weight of a Delos so that was sent back to be fixed, the focuser should be here tomorrow though so fingers crossed for its first light soon.

Emad

I went from a 12" to 16" and from home with moderate LP the difference between the two isnt that great infact if I bought the 16" just to use from home I would of been pretty underwhelmed TBH but take that same scope to a dark site and its worth every penny!

I like the other suggestions of going for a OOUK scope. Great optics and alt/azi movements, quick set up and pack away times and if you get one used you'll save a few quid on a new SW or ES.