Posts Made By: Bob Woish

I just got a new Orion Astroview 90 (f/10.1) and I am real pleased with the images. After reading reviews I wasn't expecting as much image quality as I got. I can see belt detail on Jupiter (NEB split into two components, showed irregularities, and GRS was in my face) and even at a measly 7.6" I can still see detail on Mars. Polar cap, surface detail (although small), etc. A nice view with nice shading on the planet. Saturn showed Cassini all the way around and up to 160X was razor sharp. I haven't pushed past 160X yet. I could also see (crisply) the shadow of the planet against the back of the rings, even this close to opposition when the shadow is smallest. The southern limb contrasted nicely against the rings and darkened toward the top. I looked again to make sure this was only a 90mm. Color error was not at all bad (had to look hard at 130X to see it around Saturn). The violet was more pronounced with Jupiter but I was so absorbed in checking for detail I forgot all about it until now. So it wasn't too obvious.

However, the star test showed spherical abberation. Out-of-focus patterns showed the outermost ring quite bright on one side of focus and quite dark on the other. I'm not that star-test literate so maybe I can get some help here.

Is this normal or could another Astroview 90 do better? I find that hard to believe based on planetary views.

I've had a Skyview 120 (sold), ETX-90 RA (sold), Celestron 8 inch SCT, homebuilt 6 inch Newtonian with Parks optics (whick kicks butt), and a 10-inch Dob (sold), also with Parks optics. I got the 90mm for quick outings with my daughter. She's used to a 60mm f/15 Monolux from the 60's, which is great for its size, not at all like the junk they make these days. I also tried a TAL OTA-100RS and was dissapointed. The 90 does better than the Tal especially on color. (The Tal unit I tried had some other problems as well.) It also outdoes the ETX-90 for detail.

This scope should get a lot of use considering what it's delivering. Views in the 6 and 8 are of course bigger and brighter and make detail easier to see, but not by as much as I thought. If I went broke and had to sell all else, this scope would keep me happy. 90mm? I shake my head.

The star test difference inside/outside of focus looks pretty pronounced. That bothers me. Any thoughts?

Thanks,
Bob

Anybody try the Orion MV? Is this the same as the Sirius MV? Any other brands? I wonder which is better...

Thanks,
Bob

Orion Astroview 90 vs. Homebuilt 6” f/8 Newtonian w/Parks Optics

OK, here’s the comparison I promised, right on schedule (the weatherman finally called it right days in advance!)

First of all, a few comments and report on seeing conditions. Thursday was a great night to do this test since both Saturn and Jupiter were well placed in the sky and seeing was excellent.

It would be unfair not to preface this with a comment on the optics in the reflector. Parks makes excellent production mirrors, better than most. If one is to make a decision between an Orion and similar 6 inch Dob and the AstroView, I don’t think the comparison would be quite the same. I wouldn’t expect the same quality from Orion that I expect from Parks. That being said…

To begin, I used a 12.5mm Ortho in the Newt and a 9mm Ortho in the AstroView and aimed at Saturn. This yielded powers of 98 and 101 respectively. Seeing was steadier in the AstroView, although both were above acceptable. There were LENGTHY periods of steady seeing in the smaller aperture scope, and this provided more opportunity to view detail. Not a surprise. Steady moments were rarer in the Newt, and the glare from sheer brightness washed out some detail.

The South Polar Region yielded more detail in the 90, it was just easier to see. A neutral density, colored, or polarizer filter would fix the obscuring brightness for larger apertures such as 6 inch but for this test I used no filters. Cassini was sharp and clear in the 90, and the same was true of the 6 but only during moments of steady seeing. The shadow of the globe on the back of the ring system was easier in the AstroView as well. But in those good moments, detail was a bit sharper in the 6. The South Equatorial Belt was obvious in both scopes. The view in the 6 was pretty bad in rare moments when the seeing acted up. The 90 had no such problems.

Then I switched the 9mm to the 6 incher, and put a 7mm Ortho in the AstroView, yielding 135x in the Newt and 130 in the 90mm. Now the Newtonian started to do its stuff due to the reduced brightness. Still, seeing was a factor but no problem for the AstroView. At this point it was a very close contest, in fact, pretty much strictly a matter of taste. The brighter image in the 6-inch was now at a more comfortable level than the AstroView, which was a bit dim. Still, no problem making out lots of detail in either. I’d say I preferred the brighter image in the 6 at higher powers, but preferred the steadiness of the image in the 90. I could see the same amount of detail in either, both provided excellent views.


continued...

I just got the Fringe Killer and tried it with my AstroView 90 Refractor. I know there's been a lot of questions about minus-violet filters so here's what I saw.

Seeing was not all that great, maybe 4/10. Because of this I held the power down. Saturn was 70 degrees high. There were occasional moments of steadiness.

At 100X without the filter I focused on Saturn and of course, it looked good, but with the trademark violet fringe. Not bad but it was there. I put the Fringe Killer in and yes, it did reduce the violet but not by as much as I would have liked, about half. The main benefit seems to be in sharpness, which is what Baader claims. Again, not a humungous difference but enough to make it worth it.

I had previously tried the Orion V-Block and it didn't do much. The Fringe Killer works better.

After a while I thought, since I had used a #12 yellow filter with minor success, probably mostly due to narrowing the spectral passband, I'd try stacking. That's when it got interesting. The violet dropped some more and the sharpness went up considerably. There was what I'd call a humungous difference. Contrast was excellent, the sky was quite dark, but from 15 miles from center city Philadelphia, you don't get black. But this was far better than I'm used to.

I don't know what Apo views look like, but I've owned a lot of scopes including several small refractors, and this is the best resolution and contrast I've ever had. Due to the seeing, my 8 in SCT could not keep up with the AstroView on this particular night. The colors were quite natural, I guess the violet cast and the yellowish tints came pretty close to correcting each other. Or maybe my eyes adjusted. But it looked great.

The rings showed nice detail - contrast was pronounced between the various sections of ring, with a thread-like quality toward the outside. Banding on the globe was more contrasty than even the SCT on a good night.

I'm a pretty happy camper.

Bob

I guess my astrophoto technique must be improving!

Celestron G8 / LXD55 Mount, 2X Barlow, Phillips ToUCam Pro.

I'm just a rookie so this is probably the best planet image I've done so far. And what good timing!

March 22, 2004, 9:13 PM EST, Celestron G8 on LXD-55 mount, Philips TuOCam Pro with Apogee 3X barlow. 562 frames processed in Registax and Paint Shop Pro 6.0.

Io / Europa transit tonight at 0120 UT. GRS is also in view, this should be a good photo op.

This is 1001 frames. Celestron G8 on LXD-55 mount; Philips ToUCam Pro at f/30. Seeing 6/10.

Here's what I saw tonight through a layer of cloud... check out how thin and blue the festoons look. Anybody else observe this?

Celestron G8 at f/30, seeing 8/10, 1000 frames.

I just got a 5mm Meade Plossl on Ebay, and it arrived in a box marked "for ETX-60AT and ETX-70AT telescopes." Is there some difference between this and other 1.25" Plossls? Meade says no, it's just because it's the 1.25" size. But geez why not put "For Meade ETX-90, Meade ETX-125, or even "Meade Reflector Telescopes?" Or any telescope? Why specifically ETX-60 and 70? Anybody have a clue in this?

Thanks,
Bob