Posts Made By: Bret Akers

You might want to try this...

http://www.starcrwzr.com/focuser.htm

Hi Ron,

Since I probably know many of the guys who were at the "Stars in the Park star party that you went to (especially after listing which scopes were present), I thought I'd chime in and add to your thoughts.

To see the kind of planetary views that is appears you were hoping to see, you really need to look through a larger scope (10" +) on a night with rock-steady seeing. A couple of weeks ago, we had just such a night at SDAA's dark sky site. For about 3 hours, the seeing was about as close to a 10 out of 10 as you will see. Personally, in my 12.5" dob using a friend's 3.6mm Takahashi eyepiece (441x), we saw detail in Saturn that we hadn't seen in ages. You could "drive a truck" though the Cassini division. The Encke Minima was as easy to see as Cassini is in many smaller scopes. Spokes in Saturn's rings were fairly obvious and everything was *tack* sharp.

So what I'm getting at is that you need to find the right time and place to do scope comparisons. Balboa Park isn't it. I'll bet if you had a premium mid size dobsonian or catadioptric (10+ inches) set up next to your premium refractor in your dark-sky backyard, you'd be getting aperture fever in a hurry...

Thanks,
Bret

Hi Mike,

If you've got really good optics (meaning very well figured with a smooth microfinish), the sweet spot for observing planets typically falls between 10" and 14" at around 200x given acceptable seeing conditions. I've seen some great views of Mars in good 4" scopes (APOs), but the amont of detail just doesn't compare with a view from a good scope with more aperture.

So to answer your question on what the lower limit is...it depends on how much detail you *want* to see.

Bret

The best way to go might be to get a 2" SCT visual back adapter from Astro-Physics ($40) and then get their 2" Maxbright diagonal ($290). It's a much better diagonal than anything Meade offers and is built better than the Tele Vue Everbright. It's a bit pricy, but then you'll never have to worry about a diagonal bringing down your image quality...

16 Nagler Type 5. If you need lower power, you might want to try the new 20mm Pentax XW.

If cost is an issue, I'd go with the Meade 24.5 SWA. It's almost as good as the 24 Panoptic and over $100 cheaper...

-Bret

I have a Feathertouch in my Starmaster and I've used a DX1 quite a bit in a friend's Obsession. There's no contest. The Feathertouch performs that much better and it also feels much more substantial...Also, I don't like the way the fine focus spins in the opposite direction of the course focus on the JMI DX1. The additional cost of the Feathertouch is well worth it.

On a side note, I've seen a couple of Feathertouch focusers (my 2-inch and one of the new 3-something inch jobs that are on the new TEC APOs) that came from the factory feeling a bit "rough". If you get one and have any concers, calls the guys at Feathertouch and they'll take a look at it. In my case, some dirt worked its way into the pinion gear which caused it not the have the right Feathertouch feel...By the way, I would have never noticed the feel being off (the roughness) if I hadn't seen another one with the "correct" feel.

-Bret

Two weeks ago at a public star party someone walked up to m scope (12.5" Dob) with a Siebert binoviewer and asked if he could take a look at Mars with it. I'm not sure what eyepieces he had in there, but the resulting image was perhaps the best view of Mars I've ever seen.

-Bret

Hmmm...usually when I hear about airy discs being brighter on one one side then the other I'm thinking coma...but I wouldn't expect that in a f/8 refractrr unless the lens cell wasn't squared

Best planetary scopes I've seen without question are Zambuto-equipped Newtonians...

One of the main things to consider when viewing planets with medium to large aperture is the quality of the optics and the size of the obstruction. If you have superb optics with a small obstruction (less then 20%), the best planetary views I've seen are in scopes with 10 to 14 inches of aperture. If the optics in a scope are not extremely well figured or the micro finish is a bit rough or you have a scope with a larger obstruction, the detail on the planet can be a bit washed out for a myriad of reasons. In these conditions, observers may need to resort to an off-axis mask or filtration to see the detail.

The Orion scope will have decent optics, but I've never looked at planets through them. However, I'd get the 10" if I had the choice--regardless of light pollution.