Quote:Is there anything like this available commercially ?Please note that my reducer can NOT work with cameras that have a CCD any larger than 1/3" ( 6mm diagonal).
Meade LS 8" + Watec 120N+ + SkyFi + visual accessories + video astronomy accessories tablet 7" + Vixen Polarie + Vixen Velbon tripod
Quote:Hyperstar is an option that gets down to F/2 .
Meade .33x gets down to F/3.3 .....The image below is shot with my home made reducer and my Meade 10 inch F/10 SCT .
The result is F/1.55 apparently ....
Nytecam 51N 0.1W Meade 30cm LX200 astrograph+C8+Ha+CaK PSTs+spectrographs SX M9+Lodestar-C+M CCDs/Canon 1100D DSLR My Meade astrograph-colour deepsky My supernova discovery My dome build/spectroscopes/DSO images/Lodestar colour images & videos
Quote:Hmmm... I wonder what a fast camera lens could do. Something like my 50mm f/1.7 Minolta. I can see some experimenting in the near future...
Quote:Maurice, I meant a fast camera lens used as a focal reducer in a long f.l. system, not by itself (which we know works quite well.)
I meant a fast camera lens used as a focal reducer in a long f.l. system, not by itself (which we know works quite well.)
Matt's absence after his initial teaser is keenly felt. Hint, hint, Matt!
Thank You, Matt - Astro-Video Systems http://www.astro-video.com/ Home of the NO AMP-GLOW Astro Video Cams
Quote:Matt,Have you verified that you're indeed working at or at least near to full aperture? Enquiring minds want to know! An image by itself will not tell you this.
http://www.astrobin.com/users/budman1961/ Meade LX3 8" OTA/IEQ45 Mallincam HyperPlus Color, QHY5L-II Mono Orion Mini Finder/Guider
Quote:To further build upon the thinking inspiring my doubts...Small-chip cameras have been around since the first CCD cameras. And Meade designed a suitable reducer for those small formats, it being the f/3.3 unit for f/10 SCTs. An even faster device would have been something of a Holy Grail, but seems to not have been easily achievable. And so the jump to 'extreme' speed was realized by the front-end corrector, whose current and most popular incarnation is Starizona's Hyperstar.Now comes along a hobbyist claiming to achieve a focal reducer of simply astonishing capability not heretofore seen. A reduction factor of 0.15X which delivers good correction and little vignetting. This is a *very great* amount of wavefront shaping; no mean feat to achieve. And we're given to understand (by reading between the lines) that such had been obtained at no great expense and with existing lenses.It might pose a difficult problem for an optical designer to come up with such a device, it requiring computation and numerous elements to deliver such performance. The chance of matching up a couple or few off-the-shelf lenses or existing reducers is not expected by chance to come close.And if the 0.15X worked well for the 10" SCT, why bother to make up a different (0.2X, or so was thought) version for the 8" SCT when the already proven 0.15X should work as well on the 8"?In the end, the numbers just seem to be *too* good, based on what has been achieved prior, and having some understanding of what it takes to perform such optical tasks.A number of questions are wanting answering.
LS60THa/B1200 Cerevolo 8" F5 MN Orion 11 SCT Tak EM200, Meade 6" F5 Newt, Starblast 4.5", ETX 90 C6 SCT, Meade 90 mm F9 refractor Meade 10"SN Canon T3, Mallincam Extreme
Gallifrey Observatory: http://devonsite.com 12' X 16' Observatory in OK, US + 12' X 16' NetWork/WarmRoom/WorkShop 12" LX200GPS Pier Polar Mount 12.5" Pier Fork Mount Newt For Outreach: C8 Deluxe and ES-152 6" Refractor on an AS5-GT Mallincam Xtreme + MISC Equipment.
Quote:Maurice, Wall's design you point to is a visual scope, primarily. It's speed is determined by the doublet objective (which works exactly like a focal reducer) which in the end gets no faster than about f/3. Moreover, there is significant lateral color present, due to the big singlet lens up front. I think that in this incarnation it's a dead end as a fast imaging system.