Venus
Venus again
Venus yet again
Crescent Moon
Wednesday, March 17, 2010
More Digital Imaging with Quattro
Nightly images with Sony DSC-W1 and Quattro 4.25" unguided Dobsonian:
Mirror Cell Construction: Day 1
I started the Mirror Cell today, beginning with the three cross bar supports that will sit under the triangles. It was just your basic drill 5/16" and tap 3/8-16 threads job. 21 more holes to drill and tap!
I also picked up most of the hardware as well.
More to follow. Here's the pics:
I also picked up most of the hardware as well.
More to follow. Here's the pics:
Tuesday, March 16, 2010
CCD Imaging with Quattro
So, I'm trying to squeeze some better performance out of my junky Sony DSC-W1. It's not a Canon 5000, but hey, I'm experimenting.
Check out this shot of the Pleiades (it's not bad for a 3 second exposure at F2.8 with a hand held shot against the 20mm eyepiece):
I'm hoping a t-adapter on the 18" will reveal wondrous images, but we'll see.
More to follow. Tomorrow, we're cracking on the primary mirror cell at Horizon Industries.
Check out this shot of the Pleiades (it's not bad for a 3 second exposure at F2.8 with a hand held shot against the 20mm eyepiece):
More to follow. Tomorrow, we're cracking on the primary mirror cell at Horizon Industries.
Mirror Cell Redux
Round 2 on the Mirror Cell:
Work is progressing. The PLOP calculations are complete, and I'm scrounging the local scrap yards for 1/4" Aluminum plate and 1" x 1/2" key stock for the bar joist.
I'll be using 3/8-16 Weld Nuts as the supports, as indicated by the awesome Bino-scope engineer Bruce Sayre on his website:
http://www.foothill.net/~sayre
Overall it should look something like this:
I'll post more pictures as I get things accomplished. I'm off to the scrap yard!
Work is progressing. The PLOP calculations are complete, and I'm scrounging the local scrap yards for 1/4" Aluminum plate and 1" x 1/2" key stock for the bar joist.
I'll be using 3/8-16 Weld Nuts as the supports, as indicated by the awesome Bino-scope engineer Bruce Sayre on his website:
http://www.foothill.net/~sayre
Overall it should look something like this:
Sunday, March 14, 2010
Working on the Mirror Cell
So, I've been working on the Primary Mirror Cell Design, and these are some of the candidates:
I think I've settled on the 18-point flotation design commonly used for a mirror this size, but I have had concerns about stability and mirror retention. After speaking with Dennis at Dobstuff, he assures me I don't need retention clamps or a sling, so I'm thinking about a basic bar-triangle design.
Here's what PLOP says:
I have plenty of metal, so either way, fabrication begins tomorrow!
I think I've settled on the 18-point flotation design commonly used for a mirror this size, but I have had concerns about stability and mirror retention. After speaking with Dennis at Dobstuff, he assures me I don't need retention clamps or a sling, so I'm thinking about a basic bar-triangle design.
Here's what PLOP says:
I have plenty of metal, so either way, fabrication begins tomorrow!
Thursday, March 11, 2010
Meet the Mirror!
In an awesome development, I have come to an arrangement with a prominent telescope parabolic mirror maker (think one of the Big 3), and he is going to make an 18" f/4.5 mirror for me from one of his blemished stock in exchange for a 17" BK7 blank I have laying around.
Since I've been carting the thing around for 6 years now, I figured it was a fair trade, and although I'll probably never see another 17" x 1.35" chunk of BK7 in my life, I think it's making a good sacrifice in the name of project success.
Here's the BK7:
So, without further adieu, meet the mirror!
Since I've been carting the thing around for 6 years now, I figured it was a fair trade, and although I'll probably never see another 17" x 1.35" chunk of BK7 in my life, I think it's making a good sacrifice in the name of project success.
Here's the BK7:
So, without further adieu, meet the mirror!
It's a 2" thick 18" blank with a chip and a scratch on it, and although it looks rough now, the optician is going to do a great job getting the mirror up to snuff! Besides, with a mirror this big, you're not even going to notice the slight decrease in gathering power. When properly finished, it will be just like having a perfect 17.5" mirror! As soon as everything is finalized, I will let you know who we have to thank for this AWESOMENESS!
Now to find the remaining needed parts!
Down to Business on the 18" Scope
Okay, now that I've been able to assess my resources and gather the proverbial troops after the 4.25" rebuild, the time has come to buckle down on the 18" dobsonian telescope.
My main concern has been a potential cost overrun, one that I would have to foot out of my own pocket. Granted, I am willing to cover some operating expenses on this project, but having built two of these sort of telescopes before, I know how quickly things can get out of hand. So, I've done some brainstorming to cut costs but not corners.
My first concern has been tools and workshop capacity. Living in an apartment with a pregnant wife, I've had to rely quite heavily on the generosity of my in-laws and their ample garage and basement workshop space. However, niether they nor I have significant woodworking tools, namely jigs and dovetail stuff, and I have no real money for wood.
I did get some donated for the secondary cage rings, but that didn't go very far when it came down to it.
So, in the interest of efficiency, I looked around online for a kit or some similar shortcut to a traditional Dob. What I found was quite amazing, actually!
Dennis Steele at Dobstuff ( http://www.dobstuff.com/ ) sells reasonably priced, unfinished kits for this sort of project, and after talking with him on the phone, I think I'm going to go with one of his kits. This will save some invaluable time and could have me observing at local schools by the end of May. All I have to do is provide the following parts:
The scope would look like this:
Since Moonlite was so generous in providing the focuser, all that remains for me to obtain are the optics and the spider!
More updates soon! I've got work to do!
My main concern has been a potential cost overrun, one that I would have to foot out of my own pocket. Granted, I am willing to cover some operating expenses on this project, but having built two of these sort of telescopes before, I know how quickly things can get out of hand. So, I've done some brainstorming to cut costs but not corners.
My first concern has been tools and workshop capacity. Living in an apartment with a pregnant wife, I've had to rely quite heavily on the generosity of my in-laws and their ample garage and basement workshop space. However, niether they nor I have significant woodworking tools, namely jigs and dovetail stuff, and I have no real money for wood.
I did get some donated for the secondary cage rings, but that didn't go very far when it came down to it.
So, in the interest of efficiency, I looked around online for a kit or some similar shortcut to a traditional Dob. What I found was quite amazing, actually!
Dennis Steele at Dobstuff ( http://www.dobstuff.com/ ) sells reasonably priced, unfinished kits for this sort of project, and after talking with him on the phone, I think I'm going to go with one of his kits. This will save some invaluable time and could have me observing at local schools by the end of May. All I have to do is provide the following parts:
- Crayford Focuser
- Secondary Spider Mount
- Secondary Mirror
- Primary Mirror
- Primary Mount
The scope would look like this:
Since Moonlite was so generous in providing the focuser, all that remains for me to obtain are the optics and the spider!
More updates soon! I've got work to do!
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