[Aavso-photometry] Focal Reducer

[Tom Richards]

On a related point, has anyone any experience of photometry with Celestron's
Fastar assembly?

Tom Richards
Woodridge Observatory, Melbourne, Australia.
(CBA Melbourne)
www.WoodridgeObsy.org
Carpe noctem!


> -----Original Message-----
> From: aavso-photometry-bounces at mira.aavso.org [mailto:aavso-photometry-
> bounces at mira.aavso.org] On Behalf Of Walt Cooney
> Sent: Sunday, 23 January 2005 13:28
> To: 'Greg Spear'; aavso-photometry at mira.aavso.org
> Subject: RE: [Aavso-photometry] Focal Reducer
> 
> Greg,
> 
> I have used the Celestron 0.63 focal reducer and the Astro-physics 0.68
> focal
> reducer on my 12" LX-200 with an AP-7.  Using the 0.63 focal reducer and
> Ted
> Agos's variable distance adapter, I had some troubles.  There was a large
> circular area in the middle of my images in flats that was a couple of
> percent
> off.  It looked like a scattered light phenomenon.  I was never able to
> pin it
> down.  I have since swapped to the AP reducer operating at about 0.74x and
> have
> not seen the problem.  The 0.33x reduction is pretty extreme.  I have not
> used
> one but would not be surprised if there aren't some issues with it.
> Really good
> flat fielding techniques will hopefully solve any issues.  If you have a
> scattered light phenomenon as I did with the 0.63 Celestron, you won't be
> able
> to flat out that problem.
> 
> Clearest skies,
> Walt Cooney
> http://members.cox.net/waltc/BLACKBERRY_OBSERVATORY.htm
> 
> -----Original Message-----
> From: aavso-photometry-bounces at mira.aavso.org
> [mailto:aavso-photometry-bounces at mira.aavso.org]On Behalf Of Greg Spear
> Sent: Saturday, January 22, 2005 12:45 PM
> To: aavso-photometry at mira.aavso.org
> Subject: [Aavso-photometry] Focal Reducer
> 
> 
> 
> I am in the process of configuring a setup for Transit Search which
> consists of an Meade LX-200GPS and a SBIG ST-7XME. I'm looking for a
> good focal reducer suitable for high precision photometry (< .01 mag)
> 
> So far, I've found:
>    Optec NextGEN MAXfield 0.33x
>    Meade Series 4000 Focal Reducer .33x
> 
> Does anyone have any recommendations or other reducers?
> Does anyone have any experience with these or comparison information?
> I have found some information on the Internet but would like to hear
> something from those doing photometry.
> 
> Thanks
> 
> Greg Spear
> gspear at ucolick.org
> 
> 
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