First view through Orion skyline 12” Dob

[0030]

Well, clear skies and after physical therapy for shoulder surgery felt up to moving my beast outside for the first viewing. Checked the weather Chanel’s website as weather can change here in a heart beat. Looked like I had at least a couple more hours of clear skies.  Base moved…. Telescope moved…. Cue clouds. Sky was not opaque, but far from clear. Still made out the moons and a few bands on Jupiter. Very happy with my purchase and can’t wait for eyepiece upgrades. One question: not even a hint of diffraction spikes on Jupiter or any of the stars I was briefly able to see, what gives?

[Dave In Vermont]

First off, diffraction-spikes only appear on images, and images take longer exposure times than the human eye. They keep saving and adding the light from objects to create the images you see of stars with the spikes. With our eyes alone, what you see is what you get. Blame DNA.

I know about weather and the way it can change real fast. "If you don't like the weather, just wait a minute." But you might find the fast updates available through local Doppler radar a bit better than the TV. This has saved me and my gear quite a few times:

http://radar.weather.gov/radar.php?rid=dtx&product=N0R&overlay=11101111&loop=no

Give this a whirl!

Clear & Dry Skies,

Dave

[0030]

I have heard the mantra of diffraction on Newtonians for so long, I was kind of looking forward to seeing them. Joke’s on me, because I have utterly no interest in imaging. I like your guys’ photos and I’m sure you guys have lots of fun (and torment) with that side of astronomy, but it’s just not for me.

Thanks Dave.

Clear skies, -John

[0030]

Thanks for the link also

[alan potts]

Sorry Dave can't agree with that not in your face buy I saw diffraction spikes on Sirius with my new 18 inch and there is nothing wrong with the mirror, can't say I remember anything on Juptier apart from it was incredible.

I am sure I didn't dream it but will have a closer look next time out on fainter stars, Sirius is rather bright.

Alan

[Dave In Vermont]

Sorry Dave can't agree with that not in your face buy I saw diffraction spikes on Sirius with my new 18 inch and there is nothing wrong with the mirror, can't say I remember anything on Juptier apart from it was incredible.

I am sure I didn't dream it but will have a closer look next time out on fainter stars, Sirius is rather bright.

Alan

With Sirius I can see why. I see spikes and rainbow colours and plumes. And that with just my eyes! That thing is like a celestial jewelry-store.

You looked at it with an 18 inch? Hope you wore sun-glasses. Or welder's goggles.

Please do have another go. That's worthy of it's own thread: The Optical-Illusions of Sirius.

Clear Skies,

Dave

[swamp thing]

The lack of diffraction spikes is interesting. Unlike above I see them on all bright stars and planets when using a newt It's certainly not an image only feature as suggested.

Perhaps it was due to the weather conditions as you stated the sky wasn't clear. Thats all I can think of TBH.

[Charic]

I've never been able to rid the  4 spikes with my reflector telescope, in-fact I don't think it would look right without them?

[Moonshane]

I think it is due to a relationship between area of vanes to area of mirror. At learn for planets. I hardly see any spikes on Jupiter with my 12" but they are obvious in my 6". On bright stars they are generally always there.

[0030]

I figured it might be the sky conditions or maybe the low magnification. I will definitely check back in after upgrading eyepieces. Thanks and clear skies everyone-

[starlogborg]

Congrats on your new scope, 0030.  With my 8" dob, I can definitely see diffraction spikes on bright stars (Sirius, Vega, etc.) but never on planets or dimmer stars.  They do add a certain beauty.  I purposely bought a 4-vane spider on my telescope so that I would see 4 diffraction spikes, rather than a 3-vane (where I would see 6), simply because I thought it looked cooler. 

[0030]

Thanks starlogborg. I love my new dob, but I am definitely planning on buying a smaller scope as I haven’t yet built an observatory and I have missed some good opportunities for star gazing because I couldn’t be to move my dob outside for just a half hour of viewing. Thinking of getting a Celestron AstroMaster 130EQ.

[0030]

Sorry that line should read "because I couldn't be bothered"