TAG FOV and other Calculation
birthday images 3 – aspect ratio and book thoughts
I’ve been thinking about printing out a book of my astrophotos. 8×10 and 16×20 are both 4:5 (1:1.25) sizes. So while the native resolution of the D70 is 3008×2000, the max 4:5 […]
birthday images 2 – resolution
This article is talking about magazine quality, 300dpi printing. It suggests that 6mp is good for 8×10, and about 4x the resolution is needed for 16×20. however, Kodak says 1600×1200 is sufficient […]
Trixie dovetail mounting holes
For the hole spacing of the for 23.75” and 19” plates, look up the DM14 and DM12 hole spacing. DP23.75 is Length 23.75” HS 23.00 1/4” 20 holes DP19 is Length 18.925” […]
Trixie dovetail mounting holes
Further research revealed that Losmandy sells DP plates in 17.5”/19” and 23.75” lengths without the curved radius blocks. They are a little cheaper than the DC plates (which include the radius blocks) […]
Trixie dovetail mounting holes, answers
According to my research, the “HS” (”hole spacing”) for the DC11 plate is 16” and 16.5” apart. The holes are at the ends of the plate only. I believe they are 1/4”-20 […]
Trixie dovetail mounting holes
I’m planning to use L-brackets to attach a Losmandy DC11 mounting rail to Trixie. I need to figure out: – how far apart are the holes on a DC11? – what size […]
Astro knowledge / Long Exposure Photography / Optics
Astrophotography: The "best" focal length
Astrophotography has a lot of legends and rumors floating around as regards focal length of scope. Since the focal length of the scope, size of the CCD, weight of the rig, and […]
Re: ASTROMART – Response to ad #562793
I asked the original owner of the 13” mirror for some information so I could start working up a .. er.. “balance” sheet for the scope. I’m not doing cost analysis — […]
Camera at the Newtonian focus
My D70 is 5.5”x4.4”. That’s a coverage of 24.2in^2. A 13.1” mirror has an area of 134.78in^2. That’s a 17% obstruction. Even if I mounted the thing on a 5.5” disc, basically […]
Astro knowledge / Deep Sky / Long Exposure Photography / Optics
Astrophotography in the slow lane
With most beginner astrophotography, a desire for fast optics (and the resulting short exposure lengths) is paramount. Unfortunately, fast optics necessarily mean wider FOV. This is not a problem when you have […]
RECENT UPDATE
Polar Alignment Calculations
Here’s a page that derives Polar Alignment Calculations. (update 5/2020: the original site is gone, so I found the text on Wayback and am inserting it below. This is by the original […]
Gear / Observatory / Telescope
Special Guest Star takes the mount at Hilltop O
The Astro Jedi needed somewhere to store his light sab—- I mean, bucket, and I was only too happy to accommodate him. I have decided that I need to come to a […]
General / Maintenance / Observatory
Dome shutter is motorized again!
I finally decided to bite the bullet and fix the shutter motor. Things went sideways last winter, and I’ve been opening the shutter manually (and tying it shut with rope, so we […]
Trixie 2017 – tube mods
I finally got around to cutting the MTA-UTA tubes to length; the only eyepiece that would come to focus with the focuser spacer in place is the Televue 55mm Plossl. If I […]
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Observatory
Observatory 2.0 – Time has come today!
General / Maintenance
First Light, a deeper look
Mount / Observatory / Telescope
Observatory 2.0 – Result!
Observatory
Observatory 2.0 – The Pier goes in
Gear / General / Maintenance
Martin Farmer Wormblock installation notes
Deep Sky / Long Exposure Photography
NGC2244, The Rosette Nebula
Deep Sky / Long Exposure Photography
Another beautiful night.