[OneCosmos (Chris)]

OK, now that you have all stopped laughing at the silly notion that a puny 6" refractor could possibly provide any kind of competition against such a large mirror, let me explain. Yes, any 16" scope would leave a 6" refractor for dead on just about any celestial object, but the exception are those object bright enough to mitigate the obvious advantage of the big scope. Size not withstanding, I have always maintained that my views of Jupiter and Saturn have been better than any views I've ever had through even very large dobs.



Now I know many of you will put your faith in physics (and rightly so) and argue that 16" resolution must always win out and show more detail than a smaller scope and any other impression is subjective wishful thinking on the part of refractor owners, possibly fooled by the contrast such instruments are famous for.



Well last night I had the SDM 16" f4.5 set up side by side with the APM 152mm APO refractor both looking at Saturn which was about 30 degrees up in the east.



I was able to perform a very good test where as many of the parameters as possible were similar to not completely void the results. I should say though, right up, I don’t yet have a collimator tool but Jonathan Bradshaw bought his over the previous evening and it was collimated at that time and I haven’t moved it since so it should still be OK but I suspect a little tweaking wouldn’t go amiss.

In the SDM I had the dokters 12.5mm – probably one of the finest eyepieces ever made giving 144x whilst in the refractor I had the vastly inferior Meade 8.8 giving 136x. I was not using any planetary filters.

Both were beautiful views but there isn’t a person alive, (not even Jonathan) who could look through both one after the other and not award first prize to the refractor – no ambiguity no caveats at all; the refractor view was hands down many times better. To say it was pin sharp doesn’t do it justice, it looked etched on to the glass with the finest virtual chisel ever not made. Cassini’s division was more than obvious, it looked so sharp and contrasty that you could cut your fingers on its sharp edges – and that goes for the planet too. There was obvious detail on the surface and beautiful colours to boot. There is simply no finer view possible. The physics isn’t wrong it is just that there is more to it than the maths on the page imply - that must be true.


Yes, I do love refractors but am fully aware of their limitations due to size and I absolutely love large dobs and SDMs especially are the Mozart of the telescope world, simply magnificent. The DSO views are second to none and ease of use, pride of ownership etc all come in to play, but for viewing Jupiter and Saturn I defy anyone to come to Nundah and prove me wrong. By the way, the seeing conditions in Nundah - high up as we are with nothing to disturb the air flow is excellent. On thew refractor I can push magnification to its limits.


Whether a refractor is really worth the money for relatively few objects is another question - but since I already have it I can enjoy the views.


Has anyone done a similar test?



Chris