Commercial truss dobs - Page 2

Starkler (Geoff) · #21 04-09-2006, 10:42 PM

Im making enquiries with Mr Suchting and Ed Taychart (Tscope) at the moment.
I have emailed Peter Read previously and he wasnt interested. I got advice hat might have changed now.

I could construct a kit, but I wouldnt attempt to build one from scratch for reasons previously stated

I'll give Peter another try. The more options the better

AstroJunk (Jonathan) · #22 04-09-2006, 10:55 PM

It turns out that the 15" optics are only $600 less than the 18", so there is as good as no difference in price for a much smaller aperture - all of the other components will be the same, just a little less wood and a little shorter truss tubes.

I think that given the costs involved that the 18" does seem to be the practical mimimum size for value for money. And from experience it is quite portable (relatively!) and only requires a single step near the zenith.

xstream (John) · #23 05-09-2006, 11:49 AM

Quote:

Originally Posted by AstroJunk

It turns out that the 15" optics are only $600 less than the 18", so there is as good as no difference in price for a much smaller aperture - all of the other components will be the same, just a little less wood and a little shorter truss tubes.

I think that given the costs involved that the 18" does seem to be the practical mimimum size for value for money. And from experience it is quite portable (relatively!) and only requires a single step near the zenith.

Geoff, I would have to agree with AstroJunk here. The 18" is a very portable scope. A 2 step stool would be all you need; Think of that extra aperture.

Starkler (Geoff) · #24 05-09-2006, 12:57 PM

Quote:

Originally Posted by AstroJunk

It turns out that the 15" optics are only $600 less than the 18", so there is as good as no difference in price for a much smaller aperture

I just had a look at the OMI website. Price difference between 18" f4.5 and 15" f4.5 mirrors is $950US !

I have seen and used an 18" obsession and its a big beast of a thing, i would think twice about dissassembling, loading, reassembling on site etc for a casual session away from home. especially single handedly.
A scope thats a bit smaller and lighter is likely to get more use .

I have seen a rough price, and the difference between the 15 and 18 is over $2000. For me its not about price, but usability.

AstroJunk (Jonathan) · #25 05-09-2006, 09:28 PM

Quote:

Originally Posted by Starkler

I just had a look at the OMI website. Price difference between 18" f4.5 and 15" f4.5 mirrors is $950US !

I think its the diference between 15" OMI and 18" Galaxy Premium (but i'm far from certain).

Quote:

Originally Posted by Starkler

I have seen and used an 18" obsession and its a big beast of a thing, i would think twice about dissassembling, loading, reassembling on site etc for a casual session away from home. especially single handedly.
A scope thats a bit smaller and lighter is likely to get more use .

The only issue with my 20" that I have is the lift into the 4x4 as it's too high for a ramp - that's a 2 strong people lift! otherwise, if you have a waggon or a box trailer then it's no problem for one.

Quote:

Originally Posted by Starkler

For me its not about price, but usability.

So true. And once you use a Krieg style dob, it's difficult to accept anything else - Obsession continue to sell 12.5" scopes when so many equal aperture dobs can be bought at a third of the price. That says a lot about their design and usabilitty - especially so as the GSO/Lightbridge et al scopes are fine machines themselves!

gaa_ian (Ian) · #26 05-09-2006, 11:16 PM

I have the same problem of the lift of the 18" into the back of the 4x4 Astrojunk, it is a 2 person lift, also the assembling of the trusses onto the seconarry cell.
I call it "wrestling with the octopus" & I have not succeeding in doing this on my own yet !
But I love the extra aperture

AstroJunk (Jonathan) · #27 05-09-2006, 11:28 PM

Luckilly for me, Krieg's truss tube clamps make one person assembly easy.

I hear that the 30" is the easiest of all, due to a light stiffening ring which is fixed when vertical, so the whole scope can be lowered to mount the cage with the scope horizontal. I wouldn't like to try lifting one though!

Starkler (Geoff) · #28 09-09-2006, 12:39 PM

I have been corresponding with Peter Read and he is able to help at a very competetitive price.

Theres some issues to be worked through though as the more I look into it, the more I want to be difficult and get a scope that "fits me" instead of taking a cookie cutter scope solution. This raises other issues with mirror sourcing and getting everything balanced.

I'll let you all know when a decision is made.

wavelandscott (Scott) · #29 09-09-2006, 04:52 PM

While I have not completed a similar search myself I would expect that creating a "custom" scope is like building a custom anything...

Although there are a number of fabulous handmade/handcrafted professional scopes available they are not "custom" made and will be built from "similar" materials and to a defined pattern...changing the "pattern" could quickly add up...like many, I am curious as to how you go...

Someday I too will move to a slightly bigger scope but I want to keep my feet on the ground...Based on that fact I reckon 15 inches will be about my limit...maybe something a little bigger can be done with a very fast mirror but that "project" is a ways away...

Good Luck!

janoskiss (Steve H) · #30 09-09-2006, 10:50 PM

... or you could go a folded 3-mirror Newt if you want to go bigger.

Starkler (Geoff) · #31 14-09-2006, 12:28 AM

Quote:

Originally Posted by wavelandscott

Someday I too will move to a slightly bigger scope but I want to keep my feet on the ground...Based on that fact I reckon 15 inches will be about my limit

This is pretty much what I have decided to do also.

After corresponding with Peter Read of SDM telescopes, he has agreed to build a 15" obsession style truss dob for me. Peter has a reputation for excellent workmanship and attention to detail in scope building.

I'll be getting a custom scope made to my specs including feathertouch focuser, encoders and wiring for argonavis, telrad, shroud, dew heater for secondary, powered groundboard and wheelbarrow handles.

My spec is that the eyepiece height at zenith matches my standing eye height. This means that the mirror will be at f4.8 and will be 1.6" thick pyrex provided by Mark Suchting of Deep Sky Optics

People have asked why not an 18"? and, If your getting a 15, then why not a 16? My answer is that I want the size and weight to be manageable, easily hauled around and set up single handedly. An 18" is a big beast, and if its too much effort to set up it simply wont get used as much

I won't talk about price here, but rest assured that for only a few hundred dollars more than it would cost me to import a kit, build it, and add those goodies, Peter will build one for me far better than I could ever build myself.

This will be my dream scope

Now for the long, long wait......

janoskiss (Steve H) · #32 14-09-2006, 12:41 AM

Glad to hear you've picked a scope even if it does not exist yet. I'm sure you'll love it once it's finished and in your hands.

iceman (Mike) · #33 14-09-2006, 06:19 AM

Excellent news, Geoff.. i'll PM you re price, because something like that would be great in my future.. with an added servocat of course

I expect it will be 12-18 months for delivery though?

xstream (John) · #34 14-09-2006, 06:56 AM

Congratulations Geoff, I'm sure you'll be happy with it.
A mirror from one the best; It will blow you away on those rare nights of exceptional seeing.
What time frame did Mark give you?

Starkler (Geoff) · #35 14-09-2006, 08:26 AM

When I first started talking to Peter, he said he had a lot on his plate and gave an initial date of "early next year" . Then I asked Mark and he said "about four months", so my guess is something like 6 months?

I should have set the wheels in motion a few months earlier

wavelandscott (Scott) · #36 14-09-2006, 09:17 AM

[QUOTE=Starkler]

My spec is that the eyepiece height at zenith matches my standing eye height. This means that the mirror will be at f4.8 and will be 1.6" thick pyrex

People have asked why not an 18"? and, If your getting a 15, then why not a 16? My answer is that I want the size and weight to be manageable, easily hauled around and set up single handedly. An 18" is a big beast, and if its too much effort to set up it simply wont get used as much
QUOTE]

Starkler,

Congratulations on what I think is a fine choice (from description) and matches my thinking very closely in terms of size and manageability...you must be a real smart guy

Good Luck!