Posts Made By: Ron Sowers

Wow, thanks for all the posts and help! :-} I should have given a few more details, see if this helps. It's a Discovery 6inch EQ F5. When I first received it, it had a bad zone on the primary, I sent it back and a couple months later I recieved a new mirror. This one is a sital mirror! It was promised to be figured and tested properly. It is truly zero expansion glass, so the only cool down issues are related to tube currents. So, I do let it cool for an hour anyway. I collimate first with laser, then with star test, gradually increasing power etc. The only problem I KNOW it has, Is inside of focus. There are no diffraction rings, more like a spikey blob. Outside of focus it has nice rings. I have made a new thin metal spider for it, also the tube interior is lined with one peice of black velvet. The weird thing is, is that Saturn has looked pretty good in it. Mars is aweful, even a couple summers ago. And Jupiter is just two featurless bands. I have BARELY detected the GRS and NEVER seen a moon transit or it's shadow. I live in Northern Idaho, maybe the seeing is always bad? I know in the winter the Jet Stream is coursing right over us and that can't be good haha. I have also collimated and checked the diffraction patterns on a false star I made. If anyone is really into optics, and has some spare time, I could even photo the diffraction pattern with my digital camera and send it. :} But any advice is just as welcome, Any other ideas? Thanks so very much to all! Ron S

OH wow, I was just poking around on google image search, this is EXACTLY I mean, EXACTLY what my star test looks like, even the way one side is "cleaner looking" has anyone else seen one like this? http://www.stellarproducts.com/about/observatory/10fmseries.jpg

Hey thanks for all the replies everyone! So looks like the Discovery wins over all? I remember in S&T they gave the edge to the Orion, any comments on that?
Here are individual comments to all :-)

Doug, Thanks, I am amazed that the Hardin has that good of Optics! Thanks!

Michael-Well, no cash, credit card LOL, hoping to have 500 or so free on it soon. :-)

Anthony-Thanks, our scope now is a Discovery, 6 inch F5 and I think the optics are good, maybe just the F5 part that is making the poor planetary images. That's why I'm thinking of the 8 inch F7 :-)

Michael- Oh man, yes If cash was no limit, the portaball would be cool!

Doug- Oh man, any of the 3? haha, now I'm back to where I started! LOL

Michael- Ha, yes all 3 AND a portaball AND a pig roast! Sounds great!

Anthony-OK, that's 2 votes for Discovery optics. :-)

Thanks and anymore input is more than welcome!

Take care all and clear skies to ya!
Ron

Thanks for the tip on hands on optics, guaranteed 1/8 wave!!
And 449 including shipping, 50mm finder, dang, that's awesome!!

http://www.handsonoptics.com/astronomy/sky_anteres/8xl/8xl.html

Ron

Just a little extra note here, last night I observed Jupiter again, I collimated the scope, then brought it out to cool, I looked at Jupiter and it was pretty good at 136, then I moved up to 272 and it was all smeared and mushed out. I re-checked the collimation and it was off a tad, I got it spot on, and then looked again at 272 and it was about 300% better. So it's definately true that with a fast F ratio, exact collimation (or as close as possible) really does make a big difference

Take care!
Ron S

BTW the new scope was shipped yesterday and I just ordered Suiters book :-)

They both work good, I personally use a laser, but I've heard a cheshire works great too. A cheshire is great for aligning the secondary with the focuser. The laser (if accurate) is easier when adjusting the angle of the secondary to line up with the center dot on the primary.

I just started using the "barlowed laser" method for the final primary alignment, you can find a description of that on maybe page 4,5 or 6 of this forum, it works really nicely.

Are you familiar with the general procedure of collimation?

Take care!
Ron

Hey Bill,

The dumbell might be too bright in the 10 inch I did there, but the others look real close to my eyeballs. It looks pretty good in our 6, but in the 10 there's so much there it kinda washes out the dumbell shape a bit.

Thats right, you have that 8000 watt, burn your face bright monitor haha

This comparison though was meant more to show the difference between, not be accurate to actual brightness. It's hard since I used CCD images and edited them, CCD's capture things different the brain/eye combo. does, but I tried to be as accurate as I could :-)

Take care!
Ron

Wow, this is a huge thread!

I wish I had time to read everyone's responses, but I'll just put my 2 cents and hope I'm not repeating anyone

I read your review there Ron, it was actually a good review!
I personally can totally relate to what your saying, I think it's alot of what we get used to. We started with a 6 inch Newt, and with that size, usually the stars look pretty good but at high power are a little like **. But then we got a 90mm ETX, and the star test is perfect in it, now false color, the stars are dots like a refractor, but my complaints were that everything is so DIM! Our 10 inch, stars are more like asterixes, but man, globs and nubulas show so MUCH more! I think your lucky though, now you have the best of both worlds! Hope you learn to like collimation though, I actually have fun with doing it! I have it down to about a 45 second deal and maybe a couple minutes for fine collimation on a star. :-)

If your dob moves stiff and it's hard to track, in case no one mentioned this, make a couple washers from a milk jug and put them around the center bolt, I did that and now I have to troubles moving it fine amounts even at almost 300X!

Take care!
Ron S

Great comparison again Ron, sounds like your findings support the idea that "WHEN seeing permits, larger aperture will show more detail" of course, that's assuming the optics are good too.
One trick for you with the dob, as your looking through the eyepeice, get a feel for the speed and angle of the object in your FOV, then when you need a new pencil, move the scope ahead of the planet, by the time you find your pencil it will just be coming back into veiw. I also take a peek every few second to make sure it hasn't crossed and left the other side. :-)

Take care,
Ron S. (cool sketches too BTW) :-)