Posts Made By: Paul Hyndman

Hi All,

I just churned my M19 images once again and am reasonably happy with the results (especially since this was a low elevation muddy fuzz-ball to begin with).

One goal was to keep the stars as bright as possible while shaving off some of the fuzz, but not so severely as to substantially diminish the diffuse nature of the outer core.

The star bands crossing the central core should be more noticeable while retaining their subtle coloration.

Reducing background noise without losing fainter stars was another challenge.

Perhaps most important was my desire to keep the image from "looking" processed... keeping a gentle touch with the changes.

I'm still learning the Images Plus ropes but am loving it!

Paul

Very nice shot Robert!

Ummmm... Can you elaborate on the nature of the "defect"?

Are you referring to a visible flaw on the mirror's surface (spot, smudge, etc.) or something present only in the viewed images?

Maybe a stupid question on my part, but if it is the latter problem, have you checked collimation?

Paul

Nice shots!

Nice shot!

Paul

Hi Mike,

I don't want this to come off as sounding condescending, but there is a very good reason why you don't see any dielectric diagonals for sale.... they're fantastic and they stay that way forever, subsequently they don't often get resold!

Consider their high reflectivity, lower scatter, and precise surface which (most importantly) will withstand a lifetime of use and cleaning without degradation (the two "biggies" use identically sourced mirrors that have 52 layers of dielectric coating applied). The views will be as pleasing in 20 years as they were when freshly delivered! The best of the best non-dielectrics cannot make that claim, gradually losing performance within only a few years... perhaps not even noticeable to many viewers unless directly compared with a pristine unit, and then the "Oh my Gawd" realization hits you!

As I step out of the pulpit, permit me these parting thoughts: if you plan on no longer needing a diagonal in a few years, replacing it every few years, or simply ignoring the loss in performance, then don't spend the money on a dielectric. If however you value squeezing the most oomph from your equipment consistently, then the additional cost of a dielectric is well justified. I have NEVER heard an owner of one say he regretted purchasing it, indeed most wish they had done so earlier! Will something better come along? Possibly, but it will more likely be a moot point if you've already got the best!

My 2¢,

Paul

A few suggestions, if I may:

Prior to making any scope adjustments, rotate your laser collimator in the focuser while observing that the beam does not paint an excursion (it should continuously point to the same spot). It's not unusual for a collimator itself to need collimation and a vee block is less accurate than using the focuser for this check.

Do your final tweaks using a point source (star)

Paul

--- http://www.astro-nut.com/ ---

Ahha... So you want to control nocturnal emissions, huh? )

While I prefer neutral density filters for the finest lunar (visual) work, a pair of individual polarizing filters gives good results and is much friendlier to use, as the intensity may be varied through a wide range by rotating the eyepiece.

Depending on the type of scope and EP diameters you will be using, you'll need two or three individual polarizers (which are much easier to use than those already co-joined as one unit). My current scopes (Mak-Newt and refractors) and a penchant for 2" EPs required me to get three... two 48mm (for the 2" EPs) and one for the 1 1/4" EPs. I thread one of the 48's into the end of a short (2" x 1") extender for the Mak-Newt or into a diagonal for refractor use, and one into the field-lens end of the EP barrel (either 2" or 1 1/4" as needed).

Some nights I run the gamut from eyeball-frying low powers to much dimmer high powers, yet these allow me to find a comfortable viewing level by simply rotating the eyepiece to change the intensity. The only time I rotate both filters is when I'm trying to reduce daytime scatter and control intensity simultaneously. (The January 2000 issue of Sky & Telescope has an interesting article on pp 136-137, touting the use of polarizing filters for daytime viewing.) Otherwise, you don't need to dicker with the inner filter, as turning the outer one will do the trick.

... or for an even easier view of the moon:

http://www.astro-nut.com/gibbousmoon.jpg

Cheers,

Paul

--- http://www.astro-nut.com/ ---

Nice shot, Andrew!

This was a fantastic sunspot grouping to watch (and photogenic to boot)!

Paul

--- http://www.astro-nut.com ---

Please excuse my kibitzing, but if you already have a Rigel and love it (as do I mine) why not simply put the spare base-plate mount on the ST80 and pop the Rigel off/on as needed between the two? (Rigels come with two bases for that reason, and additional ones available)

Re-alignment takes only seconds (I remove mine after each session), and you can't get much lower profile than the base-plate sans-finder.

Do you want it to be lower than this!?!: