Focal reducer on SCT6SE

[Martin Meredith]

Indeed Olly, it is definitely worth restating this often, because the idea that a fast focal ratio is a necessary condition for EAA has become perhaps too firmly embedded (*). We typically make this compromise in the interests of getting a bright image of the target quickly enough to tell ourselves that we are observing in near real-time, but other tradeoffs are possible e.g. binning at the native focal ratio, which might be preferable in some situations. I don't think we explore these alternatives nearly enough. As you say, we are indeed aperture-limited and its just a matter of how we want to sprinkle the photons we collect.

Martin

(*) speaking as one who has spent half the afternoon recollimating his f4 Newt....

[Look left]

Bilbo it's either the Altaire 183c pro or then ZWO 533 c pro .

i,ve  put The ZWO 533 on the ASIair and took image with this set up with 110 mm back focus or a little bit more and get focal length to be 1023 mm fl.

not the 948 mm I was expecting so I,lol redo with different spacers to get the f ration down a bit.

[bilbo]

24 minutes ago, Look left said:

Bilbo it's either the Altaire 183c pro or then ZWO 533 c pro .

Its the Altair (purple) The pro & pro tec use up different amounts of your back focus.  12.5mm on the pro, 17.5mm on the protec (as I annoyingly found out)

So the pro needs 97mm spacers, The pro tec 92mm.  Back of reducer (not threads)  to face of camera T connection.   Or at least it would in a perfect world. Then there is reality.

At least you've got things on the right track.

Steve (waiting for the rain to stop nr west auckland so I can take the dog out)

[Look left]

Sorry Bilbo they are both Protec versions so will check out the distances.Bilbo it's either the Altaire 183c pro or then ZWO 533 c pro .

i,ve  put The ZWO 533 on the ASIair and took image with this set up with 110 mm back focus or a little bit more and get focal length to be 1023 mm fl.

not the 948 mm I was expecting so I,lol redo with different spacers to get the f ration down a bit.