I ache, therefore I am
Quote:I think this is wrong views. Are you vendor?The merit of the forum is to make parallel between observations and OTA characteristics.
I want to do more then just look.
Quote:The visibility of the dusky markings of Venus atmosphere is a much debated question that can be traced, for example, through the JBAA reports. It is beyond doubt that they can be visible under favourable conditions even through small instruments, however the slightest ondulations of the atmosphere tend to obliterate these subtle features generating illusory details. Their observation and reporting requires considerable skill and experience and should always be considered with much caution. In some instances, however, more contrasty details can be easily seen, this occurred for example during the early spring of 2012 when the visible counterpart of some prominent UV bands could be traced through blue and even green filters.
Quote:After almost twenty years of observing and collecting Venus observations for the UAI, it is now my opinion that the visual observer should concentrate most on those details that can be seen with certainty at the eyepiece, that is the phase, the ashen light, the bright caps, the terminator shape etc. leaving the study of the dark bands to the CCD imagery which is more effective at the shortest wavelengths.
Quote:This is getting very close to saying that, in this age of advanced technology, visual observations no longer have a value.
Quote:Visual observation in daylight is not so effective as diffuse skylight reduces the already minimal contrast. In my experience, anyway
Quote:Hope I am clear enough.
David Cotterell Toronto, Ontario "If an observer actually sees an object, there is no point in referring to a formula to find out whether he ought to see it; and if he fails to detect it, no formula will ensure his success." - W.H. Steavenson 8" f/15.5 TEC Maksutov - 16" f/5 Teeter/Zambuto Dob - TEC 140 - AT 65EDQ APO Refractor - Astro-Physics Mach 1 GTO Mount - iOptron ZEQ25 mount - Discmount DM6 - Canon 60Da
Quote:Please have a look onhttp://alpo-j.asahikawa-med.ac.jp/kk13/v130706z.htmsince for the 1-4-5-6th last.S-J
Quote:I donot expect some issue with seeing effects.There is nothing to do under the conditions of use.See the linkhttp://alpo-j.asahikawa-med.ac.jp/kk13/v130620z.htmfor comparison with a short 120 achromat here better than the said semi-apo (120ED is not an apo).The lacks observed in B and R channels are, on same channels the 100mm achromat allows to see more (here a TAL100mm).Sothat my conclusion is that these apos are not suitable for use on planets except for getting pleasing views in IL that is.This is a little disapointing and with regards to the expense done for few (being the fifth apo tested from 100, 110 now 120ED).I will continue the comparison with the MN127mm Intes and the venerable 154mm newtonian, largely less expensive.Brian, don't know if spherochromatism can be the answer because when practicing the ronchi with color filter B and R (with a grid of 10lp/mm) spherical aberration is not appearing sensitively on the 120ED. But this is an explanation. I think the residual chromatic aberration in these channels are not negligeable in fact but don't know how to measure this effect with reliability. May be the roddier can bring something and investigate more this.Tests are continuing. Thanks for your posts.Stanislas-Jean