12 replies to this topic

[wuschel]

Hi,

I have been observing with binoculars for some months now and absolutely love it. But I want to see more than just gray blobs.

My issue is street lights around the house, I need to drive minimum 10 minutes over very bumpy gravel roads, uphill and downhill.

I would buy a skywatches dobsonian, but I am really woried if the mirror survives transport.

I have a Suzuki Jimny which has very constrained space. I would have to transport the OTA lying flat over the seats.

I am not sure if the mirror sits rigid enough to not fall out when it is shaken pointing nose down.

Or if the fixing will damage the edge of the mirror over time.

 

I really would appreciate your thoughts.

 

Also exact dimensions of the 10" Skywatcher classic dob ( for both tube and base) would be great to know, if it really fits.

 

Also how much would Pyrex help with large temperature difference?

Summer here has 40C and above during day and below 20C at night. Spring and Autumn shows only slightly less extreme differences. Would Pyrex keep up with cooling rates?

I found opinions differ on that topic.

 

Thank you!

[Tony Flanders]

My issue is street lights around the house, I need to drive minimum 10 minutes over very bumpy gravel roads, uphill and downhill.

Streetlights and gravel roads is an unfortunate combination! Somehow I get the sense that you don't live in the United States.
 

I would buy a skywatches dobsonian, but I am really woried if the mirror survives transport.
I have a Suzuki Jimny which has very constrained space. I would have to transport the OTA lying flat over the seats.
I am not sure if the mirror sits rigid enough to not fall out when it is shaken pointing nose down.
Or if the fixing will damage the edge of the mirror over time.

In my experience, solid-tube Dobs are always transported with the tube lying flat. The back seat has a lot more padding than the luggage compartment, which is where I usually carry the tube of my 7-inch Dob.

The mirror is held in with clips and cannot fall out when properly adjusted. And the mirror edge is pretty much impossible to damage. However, you're likely to have to re-collimate the scope every time you use it.
 

Also how much would Pyrex help with large temperature difference?
Summer here has 40C and above during day and below 20C at night. Spring and Autumn shows only slightly less extreme differences. Would Pyrex keep up with cooling rates?

The general consensus is that Pyrex makes no difference at all. The shape of the mirror changes less with temperature if it's made of Pyrex, but the real problem with a telescope that hasn't adjusted to the ambient temperature is air currents, not the glass itself. The only thing that helps significantly is a fan.

Edited by Tony Flanders, 03 February 2025 - 06:01 AM.

[ChristianG]

I have a Suzuki Jimny which has very constrained space.

My first car!!! Here they were called Samurai. Mine was a 1988. 62 HP of pure power, would not go above 90 km/hr unless the top was on, too much air resistance. Miss it!

 

--Christian

 

[sevenofnine]

Welcome to C/N! 

 

Tony has answered your questions really well. I'll just add that if the size of the Dob is concerning then you might consider the collapsible models sold by Sky-Watcher. The Dobs will gather the most light and that's a huge plus but there are other types of scopes that will show you a lot too. Their advantage is that they are more easily transported and may rarely need collimation. Also, know that collimation is a simple process once you understand the principle. A good astronomy guide book can help you decide what is the right telescope for you. Best of luck with your decision! 

 

https://www.skywatch...r-flextube-200p.

 

https://www.amazon.c...,aps,576&sr=8-1

[wuschel]

Thank you all for the replies! Really makes me worry much less.

 

@Tony The road just goes through the fields into the wood. Usually those roads have no asphalt here.

Lights are only in the village (where we have asphalt )

I assume it's similar in the US.

And thank you so musch for the detailed reply!

 

@sevenofnine I have considered the Flextube but points made me question if it's a good fit for me:

- While relatively sturdy (compared to cheaper ultralights like the explore scientific) it still seems to flex with normal usage so re-collimations are needed during a session, and especially in the beginning I wanted to avoid that.

- the lightshroud adds another 200 Euro

A little bit more and I could get a 12" Tauraus with a handmade premium quality mirror and a really solid truss and super smooth operation...

 

If you think the review that claimed the claimed lack of rigidity is an exaggeration and the scope can be used without a shroud (it has half a tube) or there are cheaper shroud options than the one offered by astrozap I would consider getting that as the transport would be much easier. I might even consider the 12" then.

 

I completely fell for deep sky so light gathering capability is the most important spec for me right now. And the cheapest way to get that is a dob.

[EsaT]

I completely fell for deep sky so light gathering capability is the most important spec for me right now. And the cheapest way to get that is a dob.

Globular clusters certainly become actual star clusters instead of round fuzzy blobs with proper aperture size.

 

For collimation check needed after transport on rougher roads Barlow and laser is the easiest for primary mirror:

http://www.smartavtweaks.com/RVBL.html

Unless you have neck of giraffe or arm length of gorilla, traditional collimation tools need you to jump back and forth between focuser and tube's rear for trial and error...

 

Also exact dimensions of the 10" Skywatcher classic dob ( for both tube and base) would be great to know, if it really fits.

SkyWatcher's USA page has specs, though have to use some online converter to get metric numbers.
https://www.skywatch...er-classic-250p
 
Anyway in solid tubes would be better to look for GSO made Dobsons, which have major amount better equipping than SkyWatchers:

Starter level 2" wide view eyepiece to actually fit in Pleiades and Andromeda Galaxy. 25mm Plössl/what ever of SkyWatcher and others is just bad fit for full size Dobsons.
Dual speed focuser to give actual fine focusing for lunar/planetary observing magnifications. For those single speed focuser is like parking car stuck at second/third gear.

There's also primary mirror cooling fan.

 

https://teleskopy.pl...roducts_id=2038
 
Levenhuk branded ones seems to be available in some countries where Teleskopy.pl doesn't ship.

Edited by EsaT, 05 February 2025 - 05:27 AM.

[SeattleScott]

Gravel roads won’t hurt a Dob, other than perhaps knocking it out of collimation .

You will see more details with a Dob, but little color. Still a lot of gray blobs. A Seestar would give more colorful views and make transportation super simple, but a different experience.

[AlamoBob]

We drove Suzukis for 30 years - but they stopped selling them in the US, and they're all aging.

I'm currently building a Telekit truss-tube dob.  With a 333mm primary, it would easily fit in your Jimny.

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[dnrmilspec]

Making a good shroud only requires a very quick trip to the fabric store, a needle and thread and Velcro if you want to get fancy.

 

£200 is a great price if it is made from rare black ermine.   Otherwise it is an absurd price for a square piece of black cloth and some elastic. 

 

There is some debate as to whether a shroud is needed at all. Certainly at a dark sky site it s mostly for protection from the sort of clumsy mistake I might make.  In light polluted areas it is a nice to have thing.

[Dave Mitsky]

You may want to read the section on the first infamous telescope myth at https://skyandtelesc...elescope-myths/

[triplemon]

Wrt the sturdyness of a telescope mirror - as long as you can avoid its front surface getting scratched - your're all good.

These mirror are annealed, i.e. relived of internal stresses. That makes them the opposite of tempered glass - which (intentionally) shatters into a million pieces when hit hard with a sharp object.  One point of reference: What happens if you empty a whole magazine of 9mm ammo at ploint blank range at a big mirror ? Answer: pretty much nothing. A few divets.

https://en.wikipedia...andalism_damage

 

Edited by triplemon, 07 February 2025 - 02:25 AM.

[wuschel]

Thank you all, again!
I do know about the limitations of visual observing. I enjoy the experience with binoculars (especially the euphoria when I find a really dim object) and I want to keep that. So no GoTo mount or photography.
I plan to get the Dwarf 3 at some point, but not now.

I also want to start building telescopes. I like the idea of building one with a meniscus lens with big aperture Already found info how to build a kiln....

But that will take very much time and I wanted something to start with.

 

I think I will go with the GSO. The price on telescopy.pl is VERY good. I was thinking for a moment about getting an Omegon ProDob because it comes with a dual speed focuser and a good general purpose eyepiece, but for the extra money I could also get a cheaper dob + Televue 24mm.
The GSO costs the same as the Skywatcher solid tube, and the eypiece is much better.

 

I will get a laser collimater and maybe a better high mag eyepiece. I think that should do it for the beginning.

 

Thanks again, have a great night!

[Jon Isaacs]

You may want to read the section on the first infamous telescope myth at https://skyandtelesc...elescope-myths/

 

From the article:

 

"Since a commercial firm presumably wants to minimize the time spent on an individual mirror, some amateurs assume that a Pyrex mirror will turn out better than one made from plate glass.

 

This sounds logical enough, but I have seen no evidence of it in the dozens of mirrors I have tested over the years. In any case, these attributes are more of an issue for the optician than for the mirror user. If you're making a mirror, Pyrex does have its advantages, but if you're simply buying or using one, these characteristics really shouldn't come into play."

 

I have a hard time believing he has seen no evidence that Pyrex mirrors are superior.  The people that make the really good mirrors, Royce, Zambuto, Lockwood, Ostahowski, etc, they use Pyrex or something even better.  The article doesn't discuss the annealing of the glass, it's an important because a poorly annealed mirror will have internal stresses which can cause it to warp with temperature. I believe Pyrex blanks come annealed, plate glass, you need to anneal it.

 

Jon