[Aavso-photometry] binning considerations

[David Trowbridge]

Thank you Gary and Arne for your very helpful comments.

Mike, yes actually I had been looking at the Meade LX200R series. I could
get a bigger aperture for the same money with the Meade. But I thought maybe
I could do better CCD photometry (presently BVR, but extending to U and I
filters) and possibly infrared photometry (Optek's SSP-4) or spectroscopy
over a wider range of wavelengths, on a system like the 10" Tak Mewlon which
has no glass secondary (Only two mirrors in the Dall-Kirkham Cassegrain). Do
you know anyone with experience using the LX200R for photometry? 

By the way, I'll be mounting the new OTA on my new Paramount ME, in parallel
with my Tak FSQ. What a treat that mount has been! With my old mount, I had
to discard maybe 30% of my images because of jiggles and shakes, now I can
keep nearly all the images I take! And no tangled cables anymore. Wow!

David

-----Original Message-----
From: mlfleenor at charter.net [mailto:mlfleenor at charter.net] 
Sent: Monday, June 11, 2007 7:28 AM
To: David Trowbridge
Subject: Re: [Aavso-photometry] binning considerations

Hi David,

Sold on those Taks are we?.. I have an FSQ and love it for pretty picture
imaging but for photometry I have to say that an SCT serves the need
admirably. Especially considering the new corrected LX200R series from Meade
I'd be hard pressed to recommend anything else-except maybe a large newt.

You'll probably discover that your seeing numbers will likely improve with a
bigger scope. Smaller pixels will also let you take advantage of good
nights. They will not seriously degrade photometry on poor nights either.
Binning 2x2 works  really well but I'd be cautious of 3x3 as a saturated
pixel or two can really throw your precision off.

I use a Meade 14 gps ota with an ST10XME and 2x2 binning running with a
telescompressor and achieve excellent photometric results.  ( I often
achieve 1mmag precision working with exoplanet candidates.) I highly
recommend this camera for photometry although you won't go wrong with the
ST8 either. You will need to watch for saturation when binned. 

The ST-9 depsite it's hype is better suited for astrometry and SN patrols.
The fov, lower noise and spectral response make the ST8 a better choice  for
photometry imo.


Mike



---- David Trowbridge <David at tinyblue.com> wrote: 
> When doing photometry, is it okay to freely use 2x2 or 3x3 binning to
> achieve the desired image scale?
> 
>  
> 
> Where I live, the seeing is generally not better than 2 arcseconds I don't
> think. 
> 
>  
> 
> The photometry I've been doing so far has been with an SBIG ST-7E camera
on
> a Takahashi FSQ-106 4" refractor which has been giving me 3.5
> arcseconds/pixel at f/5 or 2.2 arcseconds/pixel at f/8. 
> 
>  
> 
> Now I plan to upgrade to a larger scope for greater light grasp and a new
> camera for faster download times. I'm considering the Takahashi Mewlon 250
> and an ST-8XME camera. Using 1x1 binning this scope would give only 0.62
> arcsconds/pixel at f/12 and 0.80 at f/9.2. I think I'll need bigger
pixels. 
> 
>  
> 
> Will it work just fine to use 2x2 or 3x3 binning? Or should I consider an
> ST-9 instead? 
> 
>  
> 
> Also, will going to a camera with microlensing have any detrimental
effects
> on photometry measurements?
> 
>  
> 
> Are there any other issues I should be aware of?
> 
>  
> 
> David Trowbridge
> 
> Tinyblue Observatory
> 
> Whidbey Island, WA
> 
> _______________________________________________
> 
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> Aavso-photometry at mira.aavso.org
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--
Mike Fleenor
Volunteer Observatory
Knoxville, TN
www.mikefleenor.com