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  #21  
Old 24-01-2014, 02:36 PM
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Originally Posted by SkyViking View Post
Interesting thread. I usually experience between 2" and 3". I have seen below 2" on occasion, but it's rare. If it's over 3" I switch to taking colour, binned 2x2. I rarely see it higher than 3.5-4" though (only on a few nights per year).
Hi Rolf,

I'm a bit curious about this. what software did you use for the above measurements?
I'm struggling with constant above 4 FWHM as reported by Maxim, ccdstack and ccdinspector but I thought it could be my guiding/mount performance/scope rigidity all of which could smear the stars over a few pixels increasing the overall fwhm. I use an OAG with the lodestar and guiding is pretty flat.
I constantly get blurred images, with my F4 I get pretty good details, but compared to others, its blurred.
I even tried with a refractor, but ended up with 3.9.
would this mean that this is basically due to poor seeing?
if it is, then I'm moving to the hills.

Cheers
Alistair
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  #22  
Old 24-01-2014, 07:57 PM
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Hi Alistair,

Here is an example of a good night at my site, FWHM ~2":
http://www.rolfolsenastrophotography...g/i-bNVbbNZ/X3
That is measured with PixInsight. I get similar results in Maxim for the same frame, so expect it to be reasonably accurate.

First of all I'd suspect that your image scale is set incorrectly so FWHM is not reported properly, but if you say images are also blurred compared to others then maybe not. Just something to double-check.
And secondly, collimation could be off.

I don't know if your site has particularly poor seeing. If it's always 4 or above then that sounds odd, but I'm really just guessing
What is the experience of others in your area?

Cheers,
Rolf
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  #23  
Old 24-01-2014, 09:41 PM
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I throw out everything over 3" fwhm in luminance, over 3.5" in colour.
Geoff.
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  #24  
Old 24-01-2014, 10:28 PM
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Tonight's seeing is pretty good here, below 2" in both axes: FWHMx 1.9" and FWHMy 1.7"
I'm currently making the most of it but my target will go behind trees in about 10 mins. And the Moon is also coming up soon... I think it's time to go to bed
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  #25  
Old 24-01-2014, 11:21 PM
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Tonight's seeing is pretty good here, below 2" in both axes: FWHMx 1.9" and FWHMy 1.7"
Officially jealous...
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  #26  
Old 25-01-2014, 11:27 PM
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Officially jealous...
Yip, me to. Forget about the quality of seeing, I'd settle for a clear sky. We've had clouds for weeks now. Next week looks promising though.
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  #27  
Old 04-03-2014, 05:26 PM
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Quote:
Originally Posted by Logieberra View Post
Peter, how do our TheSkyX HalfFluxDiameter HFD figures correspond to FWHM? The same? If so, in the burbs of Canberra, I never see below 3. Evenings start at mid 5's and get marginally better over time.
With the ATIK and 80mm, I can get down to 1.6 late at night in Canberra on a good night. No hope earlier in the evening or with the SCT. Usually around 2-3 earlier in the evenings on good nights.
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  #28  
Old 04-03-2014, 07:10 PM
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Funny you say that, Grant. I ran an experiment shortly after my post, above, last September. I found that my Kendrick dew controller heater strap was ruining my focus! Bumped the heater settings way down and saw instant results, with HFDs in high 1s and 2s!
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  #29  
Old 04-03-2014, 09:32 PM
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Originally Posted by Logieberra View Post
Funny you say that, Grant. I ran an experiment shortly after my post, above, last September. I found that my Kendrick dew controller heater strap was ruining my focus! Bumped the heater settings way down and saw instant results, with HFDs in high 1s and 2s!
No coincidence that my SCT usually uses a dew heater then!
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