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How is a 3.3 Reducer good for CCD but not observing?

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#1 AstroChampion

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Posted 24 January 2020 - 03:15 PM

The title pretty much sums up the question.
How / why is it that a 3.3 Reducer is good for CCD imaging but not observing? Isnt it “what you see is what you get”?

#2 AhBok

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Posted 24 January 2020 - 03:21 PM

If you do not mind looking through a fuzzy tunnel, the F3.3 is fine. You can crop the vignetting out from an image or mitigate the effect somewhat with flats, but it is pretty awful to see visually. Try it and you will see what I mean.


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#3 einarin

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Posted 24 January 2020 - 03:24 PM

Actually it's not that good for imaging either - well the EAA people use it because they like fast optics and short imaging times (and image quality is not that important).

And it's really meant for tiny imaging chips (back in the days when people just started using ccd imaging).


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#4 photoracer18

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Posted 24 January 2020 - 03:24 PM

The secondary shadow using a 0.33x reducer gets insanely large. That means when you look thru the scope when its out of focus all you see is a big black blob. Also causes the effect if you move your eye around behind the eyepiece.

 

It works fine for imaging if you are using some kind of C-mount video camera or small chip still camera like some of the old converted PC camera imagers.


Edited by photoracer18, 24 January 2020 - 03:26 PM.

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#5 AstroChampion

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Posted 24 January 2020 - 03:27 PM

Thanks. I guess I need to get one first. :). I plan on testing with an LPI-G advanced planetary imager but not sure of this is a good combination.

Edited by AstroChampion, 24 January 2020 - 03:28 PM.


#6 AstroChampion

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Posted 24 January 2020 - 03:32 PM

Actually it's not that good for imaging either - well the EAA people use it because they like fast optics and short imaging times (and image quality is not that important).
And it's really meant for tiny imaging chips (back in the days when people just started using ccd imaging).



Hrrrmmm. Or maybe I shouldn’t get one?

#7 AhBok

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Posted 24 January 2020 - 03:41 PM

Ha! I would not waste my money. I had one years ago with a tiny ccd chip camera. I couldn't wait to unload it, with a warning, of course. There is always someone wanting to try one, so they continue to be sold. I think its a P.T. Barnum sort of thing, LOL!


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#8 TOMDEY

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Posted 24 January 2020 - 03:49 PM

Eyepieces can't handle the fast input cone and pupil displacement. The view will be somewhere between bad and absolutely terrible. Simple as that!    Tom


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#9 vtornado

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Posted 24 January 2020 - 04:33 PM

Hi,

 

I just bought a .63 reducer for my C5, and visually I'm happy with it.  Increases my TFOV.  Image still looks sharp.

 

VT


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#10 AhBok

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Posted 24 January 2020 - 04:38 PM

Yep. The 6.3 does a fine job. I keep one on my SCT full-time!
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#11 Jeff Lee

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Posted 24 January 2020 - 04:59 PM

if you have a 224 the FR3.3 works well. Not so good on my 294:)



#12 bdyer22

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Posted 24 January 2020 - 09:28 PM

so, if you have good glass in the 6-8mm FL range and smaller, you might be ok with it.  But that's probably antithetical to what you're after.

 

What your eyes really care about exit pupil.  the bigger the exit pupil the brighter it will look to you until you reach the extent of your eye's ability to dilate.

 

What works good for sensors isn't necessarily what works best for you. smile.gif

since your after wider field, try a 6.3 reducer and wide field EPs.  good luck!

 


Edited by bdyer22, 24 January 2020 - 09:29 PM.



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