From: Mark Gaffney <markgaffney@mac.com>
Date: April 10, 2009 5:13:44 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Meade f3.3 FRs...
Milton, It says in the "Dome Flats" section of the linked article that vignetting is present & that a shadow was cast on the chip but that..."In practise this isn`t a huge deal as it is only on the upper 5% of the image & can generally be flat fielded out without a problem.." This is surely a good application of your "Flat Frame Correct Movie" option, although obtaining a flat frame the same size as the movie in question may be difficult- I don`t know- I was hoping you`d have some insights..! As for the back motion, can`t this be solved by having an extender tube on the nosepiece of the imaging camera as I`ve already been using with the Flea 2 & the f6.3 FR? You may be right I`ll have further problems with co-inciding the focus of the 2 cameras? I was going to buy one of these f 3.3 FRs to experiment with it unless I heard a good reason I`d be wasting my money & I think the expenditure going on these parameters (above) may be OK after all. I guess I`ll never know unless I try it in practise! Mark.
On 11/04/2009, at 6:38 AM, Milton Aupperle wrote:
Mark;
On 10-Apr-09, at 10:21 AM, Mark Gaffney wrote:
Hi Milton, following on from my message to you privately today I`ve been re-investigating f3.3 focal reducers. I got a good deal of advice on these on the SCT user group a while ago & I think the consensus was that the new version of the Meade f3.3 FRs were OK but the older version was a bit suspect?I may have it the wrong way around. I`ve been looking at this link I believe you sent me;http://benedict.isomedia.com/homes/cvedeler/scope/focal_reducers.htm
This is the place I got my Antares f6.3 FR & looks like a good deal for them; http://www.agenaastro.com/Meade-f-3-3-Focal-Reducer-and-Variable-T-Adapter-p/ofr-me-3.3fr.htm
What do you think? Mark.
What do I think? About what am I supposed to offer an opinion on? Pricing?
It's pretty clear the drop off on the edges of a F3.3 adapter is excessive, and you get a lot of distortion too. And you may not have enough back motion to get both cameras into focus. Lasltly, the drop off on the edges will negatively affect the star brightness of the Pick Off Prism on the OAG too for an F3.3.
Hope that helps..
Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
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