Quote:...Where the DSLRs do well is high signal...
...C11 with HyperStar... This is the configuration DSLR cameras made possible
...they really need fast optics... how much energy you get on the detector versus f/# of the optical system
I lost count of my scopes. Now I just want mobility. I came, I saw, I bought some interesting accessories, and put names to faces: NEAF 2012, ASAE 2012, SWAP 2013, ASAE 2013.
Quote:I don't know if the Canon cameras are the end-all. That's why I'm using a Pentax K-5.
Far less aggressive native IR filter inside. Very large dynamic range. Bigger detector than Canon's APS sized offerings. Last, but not least, ISO 51,200.
PeteGallery: http://www.astrobin.com/users/pmumbower/CGE Pro | modded C9.25 | 8" f/4 newtSBIG ST-2000XM, CFW-9 Astronomik type2c LRGB, Baader 7nm HaQHY5L-II mono, PEMPro2, Sequence Generator Pro, PixInsight, RegiStar
Quote:Is it about avoiding dedicating multiple nights to a single object to go deep or overcome LP
Bored? Peruse my website: http://www.samirkharusi.net/
Quote:with existing cameras and OTAs: 30sec subs and one hour integration time using a current model Canon crop DSLR is about as "agile" as it gets. Cut down the size of the final image to 600x400 pixels and you can cut down the integration time to half and still be very happy with the apparent SNR. Use an f2.8 OTA and you need to double up. Use a slow OTA, say, f6 or slower, and you are no longer in agile territory.
Quote:I think the traditional refractors have just about had their day as astrographs.
Quote:If you are Imaging @F1.9 with the C14 Hyperstar the focal-lenght is only 675mm.... You gain short exposure, you lose possible resolution.
Quote:APOs are getting overtaken by mirror scopes.
Quote: I feel this... discussion may have reached a different conclusion?
David Cotterell Toronto, Ontario "If an observer actually sees an object, there is no point in referring to a formula to find out whether he ought to see it; and if he fails to detect it, no formula will ensure his success." - W.H. Steavenson 8" f/15.5 TEC Maksutov 16" f/5 Teeter/Zambuto Dob 66mm WO SD AT 65EDQ APO Refractor Astro-Physics Mach 1 GTO Mount iOptron ZEQ25 mount Canon 60Da
Mach1GTO / G11/G2 (stock) / AT6RC / AT10RC / TMB92SS / Astrodon 50D / STT-8300M / FW8G-STT / PixInsight / etc, etc. Astrobin - Flickr
Quote:I understand the idea of getting a flat 'library'
Quote:Yes, dark library. I have corrected my post.The question remains: If it is 4C when a set of subs is taken how close to 4C must the dark frame be? +/- 1C? +/- 2C?THXDave
Quote: Quote:I think the traditional refractors have just about had their day as astrographs. If you are Imaging @F1.9 with the C14 Hyperstar the focal-lenght is only 675mm.If the pixels of a CCD camera are 5,5 micron wide, the smallest details you can capture is just 3,36 arc/ seconds wide (including 2x Nyquist criterion) with a color ccd camera it is even worse: 4.5 arc/ seconds (2,7x Nyquist).You gain is short exposure, you lose possible resolution.If the seeing is about 2 arc/ seconds, and the CCD camera has 5,5 micron black and white pixels the focal-lenght should be 1120mm to capture every detail.( 206265* (0,0055/X)= 1 arc/second )*2 X=1120mm.The TEC APO 160 F7.0 is just what you need: 1120mm focal-lenght.F 7.0 is slow, if you want speed take a 16 inch Newton Astrograph fit a 0.73 reducer and you have a (optical) ideal F2.8/ 1110mm imaging telescope.With 9 micron black/white pixels the focal-lenght is 1850mm: a very large APO or a small RC telescope.But never forget: ' There is no such thing as a perfect telescope' Garret van der veen
Quote:if you are using an astrotrac