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Can Focal Reducers be Stacked?

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msheald
Can Focal Reducers be Stacked?

Hello! As I consider upgrading my Meade 8" LX200 and SBIG 402 combination, I wonder about purchasing components consecutively in order to manage the costs.

    As a result, would it be possible to use two 0.63 focal reducers stacked on a C14 in order to bring the focal length consistent with the ST402, and use this combination till I purchase a more appropriate camera with photometric filters, such as a FLI ML1001? Thank you and best regards.

Mike

lmk
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I would think the "Fastar"

I would think the "Fastar" (Now "Hyperstar") prime focus attachment to the C14 would be the better way to go.

 

spp
spp's picture
another way to go.

Mike,

The problem using a C14 with an ST402 is not just image scale.  That could be managed (somewhat) with a focal reducer and binning.  (I don't think stacking reducers would be a good idea.)  The worse problem is FOV.  The CCD is just too small.

Here is another idea.  Use a 0.5X focal reducer with your current camera and telescope.  With a 1000mm effective focal length the ST 402 would have an image scale of ~1.85 arcs/pixel and a FOV of ~24 X 16 arcmin when using the Meade 8.

I have had very good results using my ST 402 with a C5 and SBIG FR247 (AKA eFinder). This is a very nice combination, and it would serve you well while you save your money for more expensive equipment.  Actually, I think the 8 inch would be an even better match, better sampling for average seeing conditions.  (Search web for "SBIG efinder".)

The advantage of the FR247 is that it is small, and works well with the small chip of the ST402.  This makes it light, inexpensive, and more important, it doesn't result in a long train of equipment hanging off the back of your telesscope.  (It just screws into the sky end of the 1 1/4 inch nosepiece on the camera).

SBIG dosen't offer the FR247 eFinder anymore, but they come up occasionally on Astromart and Cloudy nights.   Some retailers may also have them still in stock or in a box of miscellaneous gadgets in the back storeroom. 

The SBIG ST 402 photometric filter wheels are still available from relailers.  You get the very good quality B,V,Ic,Clear filters and wheel, specifically designed for the ST402, for less than you would normally pay for just two new 1 1/4 inch photometric filters.

Phil

 

spp
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Correction FR 237

It's an SBIG FR237 eFinder.

Ed Wiley_WEY
Ed Wiley_WEY's picture
I found my Schmidt-Newtonian

I found my Schmidt-Newtonian (8", F4) and St 402 to be a great combination. I agree with Phil's comments. If you want a truly ugly 8" S-N with a good focuser (Moonlite) and rings, let me know. Mine is now surplus.

Ed

spp
spp's picture
8" F4 + ST402

Mike,

That does sound like a pretty good fit to me (if your mount is beefy enough).

Phil 

 

spp
spp's picture
8" F4 + ST402

...accidental duplication.

msheald
Thank you all for your

Thank you all for your comments. I appreciate them.

    Thank you for the offer of the 8" SN. I'll defer for the time being, but I appreciate the offer. Best regards.

Mike

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