Posted 26 September 2010 - 07:51 AM
Here's a drawing I made of Jupiter in average conditions. To be honest I only really went out to align the telescope with polaris now that the new concrete floor is down- and what a difference that concrete floor makes!!!!
Even in these conditions, the bright rift in the NEB is unmistakable, as is the white oval in the SSTZ which seems to be effecting the SSTB.
Posted 26 September 2010 - 08:53 AM
Posted 26 September 2010 - 09:01 AM
A beautiful and accurate observation of Jupiter. You have recorded the bright rift in the NEB very nicely. The bright oval over the SSTB/STZ looks interesting. Thank you for sharing it with us all.
I hope that the concrete floor helps in your observations.
Posted 26 September 2010 - 01:20 PM
a very detailed , nice sketch of Jupiter.
Posted 26 September 2010 - 03:03 PM
Posted 27 September 2010 - 01:02 AM
Posted 04 October 2010 - 07:50 PM
Great sketch and observations, much color and detail. You are lucky to have tracking. My 8" and 10" Newts are both Dobs. The repetitive nudging can be distracting. I've tried mounting them on my CG5 GEM, but I haven't found that to be a good solution, even for the 8".
You've skeched a lot of detail for an 8" scope.
What f number is your scope? Do you know the CO percentage by diameter? Do you use any special filters or techniques?
Posted 05 October 2010 - 04:14 AM
Mike: My 8" telescope is f/5. It's a Skywatcher telescope but I do not know the CO percentage. I don't use any filters when observing.
Getting the results I do is more about the many years I've clocked up as a visual observer rather than using elaborate expensive equipment.
Posted 05 October 2010 - 06:20 AM
Experience is the most overlooked factor of the observing equation. I notice, for instance, that many Jupiter observers have experimented with different color filters over the years but end up using just one or two favorites or often none at all. That is what happened to me. If I use any filter on planets, it's usually the Baader Moon & Sky Glow filter. It increases the contrast but leaves the natural color largely unaffected.
I also notice that you use "only" 200x for your observation. I find that if I do everything else right, take my time and actually look for the fine detail, I don't need high power on Jupiter. I seldom take it above about 200x. That works out well for me, because at a midrange magnification I don't need to nudge the Dob as often and my eye floaters are not as obvious. IMHO, it is a good thing to avoid high magnification whenever possible.
Clear & Steady Skies,
Posted 05 October 2010 - 06:34 AM
I totally agree. I tend to spend about half an hour just looking before I make any drawings. Some planets like Mars and Saturn work well under high power. I was able to take my 8" up to 400x and make some high power drawings of the Martian NPR. Similarly, if I want to make a high res drawing of Saturn's rings say then I will use 312x or 400x if seeing permits. But most of the time I use 200-250x.
For Jupiter, I found that the giant planet does not tolerate high power well, and over the years I've learned to make observations at 111x-200x. If I want to make a strip drawing, then I sometimes go up to 312x.
In general I rarely use filters. Sometimes to enhance a spot on Saturn for transit times, but I don't like them in general and prefer to examine the planets in unfiltered light.
Posted 05 October 2010 - 07:33 AM
Mars and Saturn do respond better to magnification than Jupiter does. Last opposition, I sometimes used 300x to 480x on Mars. I haven't tried a strip drawing for Jupiter yet. If I do, I might try 300x or so.
An apodizing mask works very well to bring out the contrast on Jupiter. I use one all the time for that planet. I did not notice any improvement on Mars, and I haven't tried it on Saturn. From what I've read by Suiter on the subject, he is still not sure if they really work or not, and if they do work, why they work. He acknowledges, though, that there is a lot of "anecdotal" evidence to support their use. But he claims that an apodizing mask is only useful for magnifications 200x-300x or higher. That contradicts my own personal experience. I find it improves the contrast on Jupiter at all magnifications. He also says it should only improve the image of objects that can fit within the inner, empty annulus, and that it should not help lunar observation, for instance. For me, the mask is better than any lunar filter for cutting down glare and increasing contrast away from the terminator, regardless of any theoretical assertions that it should not work on the Moon.
Posted 05 October 2010 - 07:37 AM
Posted 05 October 2010 - 07:39 AM
Binoviewing helps, too.
OK, that's enough for now.