Another One Bites The Dust- Aperture Fever Won.

[Suzy]

Hi everyone,
Though I've had fantastic views and many an enjoyable night with my 6" dob., the time has come for me to upgrade. I am planning on upgrading to an 8 inch dob. (after much brainstorming on a 10", I've concluded that I won't be able to comfortably handle this by myself, so I won't be going there).

The 8 inch collapsible dobs are on sale at the moment for only $550, compared to the solid tube at $500. May I please ask for your help with regards to the pros and cons of the collapsible dob (aside from the obvious 3kg lighter weight)?

Some questions that cross my mind are:

1) Does this need colminating everytime it's set up?

2) It seems strange to have the scope open to dust and elements. Even if you do cover with a shroud, can dust get in (I loathe dust on my scope).

3) Is dew more of a problem with these.

4) Is it fiddly to put together in the cold and dark.

5) Anything else I should be aware of.

I am leaning more towards a solid tube, however I want to make an informed decision before I go ahead and purchase, as this is the scope that I plan to keep for a very long time to come.

Many thanks for taking the time to help me out .

Regards,
Suzy.

[Liz]

Hey Suzy

I have the 10" collapsible Dob, and I think its/shes great. Easier to manage and transport and lighter, as you said. i have no problems. Easy to collapse and set up again.
They keep their collimation very well, which is great as I am a hopeless collimater person.
I had friends make me shroud to help protect from light and dust. You need a shroud as light can get in when viewing, esp public nights, whooaa!! they are dear to buy so get one made if you go down that track
After use, you collapse it, so no dust can get in anyway. It comes with (well mine did) a good Dob cap for the first section of scope, and a flimsy cap for top, which keeps falling off. A good protection for dobs is to snuggle thm into a sleeping bag for protection after use, and store them horizontal.
No more dew problems than normal, which is horrendous up here!!!
I love the look of the black diamond finish on mine, but whatever you like you can get girl.
Good luck, and keep researching.

[astro744]

An 8" f6 is exactly the same focal length as a 6" f8, just a little larger in diameter. If you can handle the 6, then the 8 will be manageable and much easier to just 'plonk' outside and be observing in minutes (planets will of course require mirror cooling). If you go with the 10" then perhaps the truss or semi truss is better from a weight point of view. The truss 'scopes do take longer to set-up and yes collimation should be checked and is often needed. You will also need a shroud of course. Note too that shiny aluminium truss poles will affect contrast.

The 8" will give you 1.78x the light gathering power over a 6" wheareas a 10" will give 2.78x over a 6". A good upgrade path is 6" - 10" - 16" with each jump giving over 2.5x a brightness increase. Another good upgrade path is 8" - 12" - 18" with each brightness jump being 2.25x.

You will notice a difference between your 6" and 8" particularly on globulars as you will be able to resolve more and the stars within the globular will be brighter. Planets will appear similar but the resolution gain can be detected in good seeing. The brightness gain is important on planets mainly at the high power end where you will get a larger exit pupil at the higher powers.

If you are set on an 8" then I would go with an 8" tube for general use at home or a trip to a dark sky and would only consider an 8" truss if I was travelling. Otherwise consider a 10" truss or semi truss design.

Note you can get a hand trolley and strap the dob base and tube to it with luggage straps to make it easier to move around. Get one with large pneumatic tyres rather than solid tyres to take the bumps better. This would work well with an 8" or 10" tube telescope.

If you have aperture fever then going from a 6" to 8" may be like taking one paracetamol when you should have taken two; the fever may go away but could just as likely come back with a vengeance. Whatever you choose, enjoy!

Note on f ratio: Your 6" is f8 and an 8" will likely be f6. A 10" will likely be f5 and will show more noticeable coma and also require premium eyepieces to perform well. You may even need a Paracorr at f5 if coma bothers you.

[Paddy (Patrick)]

Hi Suzy,

I haven't had a lot of experience with collapsible dobs, except for a friend's Saxon collapsible 8" which seems to work very well. I use a truss dob which collects no more dust than my former solid tube 12". The secondary does tend to dew up and I use a dew heater which works fine. But I don't use a shroud. If you have a shroud, there shouldn't be any difference dew wise compared to a tube. Collimation is actually a little easier on my truss dob than it was with my tube scope.

Whichever you chose, you'll enjoy it immensely. But I wonder if it would be worth having a play with a 10" to see how hard/easy it would be to handle? 8" very good, 10" very very good (provided that it is easily usable)

[RobF (Rob)]

+1 for what Astro said - there's likely to be a much better "wow factor" going to the 10" from a 6" over 8" if you look at the area numbers. If at all possible would suggest looking at ways to save space and weight (collapsible), money (IIS classifieds....) and ease of use (small trolley if need be - many threads along these lines here).

Resistance to the aperture fever is futile - you will be assimilated (err sorry - Star Trek taking over there....)

[torana68 (Roger)]

Originally Posted by RobF

Resistance to the aperture fever is futile - you will be assimilated (err sorry - Star Trek taking over there....)

I feel a great disturbance in the Force, as if millions of voices suddenly cried out in terror and were suddenly silenced. I fear something terrible has happened. Suzy has bought an 8".....

[that_guy (Tony)]

hehehe... i upgraded from 8" to 10... you can see the difference immediately!! these guys have 'em cheap! also free shipping. http://www.theastroguy.com.au/telesc...obsonians.html

[leon]

Suzy, my goodness you have been captured, bugger, but i'm afraid you won't be able to get out of this one, but at this point I congratulate you, well done.

I say this for this reason, one goes, one enters.

Suzy, I have been doing Astronony forever, I just turned 60, on June 13th, and I have given it away, well my stuff, that is, I still like looking up so to speak.

Life changes, and I am going to do other stuff, I have plenty of nice L Glass to keep me happy.

One leaves, One enters, go for it girl.

Leon

[floyd_2 (Dean)]

Suzy,
if you can manage it, I would recommend upgrading to a 10" rather than an 8". An 8" seems like too much of an incremental upgrade. Go for the maximum aperture that you can handle / afford. There may be ways that you can handle a 10" without having to lift it here and there, depending on where you observe from vs where you store your scope. For example, as Astro mentioned, you may be able to use a hand trolley to move a 10" scope around. Alternatively, perhaps a set of handles with wheels might do the trick so that you could wheel the fully assembled scope around sort of like a wheel barrow.

In the case of my 10" LX200GPS - I find it too heavy to move around / assemble etc, so I have it permanently mounted on a custom wheely bar sort of set up with leveling bolts - so I just wheel the fully assembled scope to my observing pad, level it, and I'm off and running with zero effort. If I had to carry that scope and mount it on the wedge every time I wanted to observe, I think I'd end up selling it for something more convenient.

I've used tube dobs and truss dobs and have liked them both. I had a 10" f/6 tube dob for years and absolutely loved it. I think that 10" is the sweet spot before you really start getting into heavy / less convenient scopes. I'm a firm believer that the more convenient a scope is to use, the more it will be used.

My 15" truss dob was a little more trouble to move around and quite heavy. However, the views more than made up for the inconvenience. I made a set of handles with wheels for the rocker box of the 15" but could never bring myself to drill the female threaded sockets into the cabinet So, those handles were never used even though it meant that I could have left the 15" fully assembled at all times and cut the fuss down to almost zero. I guess the point here is that there was a way of increasing the convenience of using that scope that would have been perfect (if I wasn't so scared of drilling holes in an obsession).

I'm sure you'll end up with just the right scope for your needs regardless Suzy. If you think a larger scope would be better, I'm absolutely sure that there'll be a way for you to increase the convenience / ease of moving it and setting it up.

Dean

[ZeroID (Brent)]

Hi Suzy, I've been debating the 8" - 10" decision as well but I'm upgrading from only a 4.5". I am also building my own truss dob using only two poles ( according to current plans which may change ). From my point of view the build is only 50 mm bigger in the cell size but the same length as a 8" f6. It is also slightly dearer for the mirror but the deciding factor was the light grasp of the 10" over the 8". It goes from 841 to 1317, a significant factor. My 4.5" is 265 so I'm expecting to see a big change. Light grasp on a 6" is 472 btw.
I'm adding fan temperature control to the primary and heater to the secondary, we get the heavy dew here as well.
I'll investgate shrouding if it proves necessary but I have access to a good dark site.
Good luck with your choice but aperture rules as they say.

[rmcpb (Rob)]

Suzy,

If you haven't committed to the 8" already really consider a collapsible 10" and a luggage trolley for movement. It will really grab you hard.

What's next, a 16"................................ ..........

[astroron (Ron)]

Suzy, I understand that you may be going to AstroFest?If so and you haven't ordered a scope yet why don't you put it off till then as you will be able to see lots of scopes and get a feel for what is available
Also you may Pick up a Bargain from the Vendors who are there for the last couple of days
I to reckon that with a bit of thought in the way you move the scope in and out of storage can make the 10" a better proposition
PS the collapsible Dob seems a great idea.

[sejanus (Gavin)]

get something like a lightbridge and put it on wheels

my 16" LB was quicker to setup than my 8" dob - it literally rolled out of the garage and that was it.

The exception is if you need to put it in a car.

I reckon get a 12" LB

[marki]

There will not be a great enough difference between the 6" and 8" to make it worth the hassle IMO. Best follow Ron's advice and check out as many different options as possible. That way you can get a better feel for what overall performance you want and what you can physically lug around. If the dob breaks down you will only have to manage the mirror box which will be the heaviest component.

Mark

[Suzy]

Thank you all for your input towards helping me make the right decision. I’m so very grateful (though utterly confused at the same time!) I have in fact tried out a 10” dob- I loved the view. The notable difference was on the Jewel Box Cluster. In my 6” the gold star is very tiny and you can just make it out, on the 10” it’s bright and very much there-you can’t miss it. Never tried an 8”, so was happy to compromise and settle in the middle of these two scopes. Size wise- the 10” really didn’t look that big to me, I could easily handle the size, the weight is another story. Say we put the weight issue aside and utilize a trolley, there are other concerns that I regularly come across reading, and these issues add to my issues of weight/transportability. Will the following be big issues for me…..


1)Collimation. I hear the 10’s need this regularly, especially after every car trip?

2)Dew problems. More of a problem with a 10”?

3)Cooling down period takes longer?

4)This is a fast scope at F5. How will this impact on my current premium eyepieces (Vixen lvw 22m, Petax xw10mm)?

5)The planets get very picky when it comes to less than desirable seeing conditions through larger apertures, as large apertures can magnify poor conditions that smaller apertures don’t reveal (as they don’t show as much detail). I regularly come across this point. Do I have to carefully pick my nights when I view planets?.

6)Lastly, a valid point I’m about to raise. The only other two females on here that I know of that have got 10” dobs: JJJnettie sold hers, and Liz went for collapsible. This isn’t giving me much confidence.

7)There doesn’t seem to be much of a difference between and 8” and a 10”, than
There is from a 6” to an 8”. I have detailed the differences below:

6” Resolving Power: 0.74 Faintest Stellar Magnitude: 13.6
8” Resolving Power: 0.56 Faintest Stallar Magnitude: 14.2
10” Resolving Power: 0.56 Faintest Stellar Magnitude: 14.7

From what I see, I see a whole magnitude difference between the 6 and an 8 (that’s 2 and a half times brighter, right?), but not even a mag. Difference between the 8 and the 10. I don’t doubt the 10 will give a better view on top of the 8, but from what it looks like there is a bigger jump from the 6 to the 8, than there is from the 8 to the 10. What do you’ll think?

I’m trying to keep in the forefront of my thinking, the classic line “the best scope is the one you use the most”. If the 10” ends up being quite a bit of maintenance (regarding the above points), I have to ask myself, would I really use it as much as I do now, in comparison with my 6”(despite stunning views).

I understand and appreciate that you'll are trying to give me the best advice, and believe me,I am taking everything you'll say into heavy consideration.

Regards,
Suzy.

[Suzy]

Originally Posted by RobF

Resistance to the aperture fever is futile - you will be assimilated (err sorry - Star Trek taking over there....)

Aaaaaahhhh Sheeeeez! I knew the force would try and get me on this thread too. Seems I can run but can't hide.

[torana68 (Roger)]

[QUOTE=Suzy;604835]

1)Collimation. I hear the 10’s need this regularly, especially after every car trip?
shouldnt be worse than anything else? the faster you go the harder it gets to get it right, F4 can be not a lot of fun, F8 easy

2)Dew problems. More of a problem with a 10”?
here EVERYTHING has a dew problem

3)Cooling down period takes longer?
bigger bit of glass takes longer yes but most 10's have a fan , if not get one

5). Do I have to carefully pick my nights when I view planets?.
I can only say when a 4.5" sees a planet as a blurry spot the 8" see's a planet so i would assume ,and its what I hear, a bigger scope is less effected than a smaller one as it gets more light to your eye

Maybe someone here has a 10 they could lend Suzy to try?
Buy what makes you happy! (no that does not mean new shoes instead)

my 2c worth...
Roger

[that_guy (Tony)]

Will you be keeping your 6"?? I have a 10" and i had an 8". You can see the difference when looking at nebuli and clusters.. I don't find the weight much of a problem. just take time setting it up. Would there be other people who might be able to help you?? I'm not a fit person nor am i the strongest. (i have nerve damage in my hand) but i can still lift it fine...!

[astroron (Ron)]

Hi Suzy see my input


1)Collimation. I hear the 10’s need this regularly, especially after every car trip?
Why is everyone afraid of collimation? after you have done it a few times it becomes second nature.

If you pack it in the vehicle well enough and the roads are not too rough, then there shouldn't be much of a problem.

2)Dew problems. More of a problem with a 10”?

The more glass there is the longer it takes to due up IMHO.

3)Cooling down period takes longer?

Set up a bit earlier, look at say Nebular/ galaxies until it as cooled enough to look at Planets

4)This is a fast scope at F5. How will this impact on my current premium eyepieces (Vixen lvw 22m, Petax xw10mm)?

Not to sure on that one?

5)The planets get very picky when it comes to less than desirable seeing conditions through larger apertures, as large apertures can magnify poor conditions that smaller apertures don’t reveal (as they don’t show as much detail). I regularly come across this point. Do I have to carefully pick my nights when I view planets?.

A small Fuzzy Planet is just as bad as a large Fuzzy Planet.
You take your nights as you find them.

6)Lastly, a valid point I’m about to raise. The only other two females on here that I know of that have got 10” dobs: JJJnettie sold hers, and Liz went for collapsible. This isn’t giving me much confidence.

There is a lady who is on iceinspace, but doesn't post who takes her 10" scope out as often as she can ( more than most males I know.
Liz and Jeanette can come in and give their reasons for doing what they did.

7)There doesn’t seem to be much of a difference between and 8” and a 10”, than
There is from a 6” to an 8”. I have detailed the differences below:

6” Resolving Power: 0.74 Faintest Stellar Magnitude: 13.6
8” Resolving Power: 0.56 Faintest Stallar Magnitude: 14.2
10” Resolving Power: 0.56 Faintest Stellar Magnitude: 14.7

From what I see, I see a whole magnitude difference between the 6 and an 8 (that’s 2 and a half times brighter, right?), but not even a mag. Difference between the 8 and the 10. I don’t doubt the 10 will give a better view on top of the 8, but from what it looks like there is a bigger jump from the 6 to the 8, than there is from the 8 to the 10. What do
you’ll think?

The 10" scope well out performs the 8" scope, an increase of nearly a magnitude is considerable.


I’m trying to keep in the forefront of my thinking, the classic line “the best scope is the one you use the most”. If the 10” ends up being quite a bit of maintenance (regarding the above points), I have to ask myself, would I really use it as much as I do now, in comparison with my 6”(despite stunning views).

That is only for you to decide.
there is a price to be paid for everything
cheers
Ron

I understand and appreciate that you'll are trying to give me the best advice, and believe me,I am taking everything you'll say into heavy consideration.

Regards,
Suzy.[/QUOTE]

[Suzy]

Originally Posted by that_guy

Will you be keeping your 6"?? I have a 10" and i had an 8". You can see the difference when looking at nebuli and clusters.. I don't find the weight much of a problem. just take time setting it up. Would there be other people who might be able to help you?? I'm not a fit person nor am i the strongest. (i have nerve damage in my hand) but i can still lift it fine...!

Hi Tony,
I will be selling my 6".
As mentioned I've got a 6" and looked thru a 10", and you've had an 8". Say with the Jewel Box Cluster for example, what notable difference do you make between the 8" and the 10" performance on the gold star with these scopes?
Thanks,
Suzy.