Posts Made By: Tom Masterson

Linton:

I haven't seen or heard of any stories of quality problems with the Meade Coronado scopes or filters. I had a chance a couple years ago to look through several at the Meade Hands on the Sun conference and they performed very well. I have to say the current sale prices are very, very attractive.

There's no question it would be quite a step up from your PST.

I too am very curious about the new Lunt filters/scopes. I have a 50mm filter on order, and in the next few weeks should be able to see first hand how they perform. Of course that doesn't help you much considering the sale deadline on the Meade/Coronado unit.

That said, if the Lunt system has good performance you can get a .5a scope at pre-production prices for less than the sale price of the .7a Meade/Coronado scope. People who go .5a never go back to viewing at .7a! You'd ust have to wait a while for the scope to come to market. Not a bad thing in the long run if you can wait. I pre-ordered mine in February and am ok with waiting however long it takes. Hope this helps some.

I saw them too!. Captured some images in both h-alpha and CaK but have recently changed internet providers so I can't post them quite yet. They were AWESOME! The Sun has been so bland recently it was a nice to see such beautiful proms.

Alex:

My vote is for atmospheric, and my reasoning is the violet on one side and yellow on the other. Depending on the altitude of the Moon and Jupiter this is pretty classic atmospheric dispersion.

Another possibility is a very very very slight fog or haze forming or even ice crystals up high in the atmosphere. I've observed from my garden observatory a few times recently where I didn't notice the fog just barely starting to form, until I looked horizontally accross at some very distant lights. It doesn't take much to refract the light coming from a distant bright object.

Because your eye is a fast singlet it produces lots of chromatic abberation which the brain proccesses out. If you were able to see it it should be uniform around the image. I have a pretty good case of astimatism and enjoy looking at bright point sources whe getting my eyes dialated for testing. I don't recall seeing differing colors on opposite edges of an object, just an oval spikey haze that shimmers with just a little bit of color all the way around the edges.

PST CaK:

Sent to Meade for another common problem - focuser prism shift/misalignment which showed as astigmatism in the image. Prior to the repair the astigmatism was quite severe. Only about 1/4 of the solar disk was sharp and any given focus point. After the repair it focused perfectly across the entire disk. Performance was MUCH, MUCH better than before the repairs.

Alex:

Then other answers are right on the money. The blocking filter is a nesessary part of the filter system, without it, the filter won't function and I doubt it would even be safe.

To answer your questions one by one;

"What does the diagonal do on a Lunt system?"
The diagonal contains a blocking filter and I believe an additional IR/UV block filter.

"I know it says Blocking filter, but is it blocking energy (heat, etc.) or a certain wavelength, or what?"
The blocking filter rejects unwanted out of band harmonics that the etalon produces. Without it, there'd be other wavelengths mixed in with the h-alpha light and the image would look much like a white light image showing NO h-alpha features - BUT it would be VERY, VERY, VERY, bright since the etalon is passing much more light than a regular white light filter passes. The second IR/UV is in part a back-up to remove any IR/UV that makes it through the system. I don't know if Lunt uses a separate IR/UV filter in the diagonal or if its part of the blocking filter itself. End results are the same though.

"What happens if you look through the scope using a regular diagonal?"
See above - BRIGHT BRIGHT BRIGHT!

What happens if you image without the diagonal?
Same as above.

In a nutshell, an etalon without a blocking filter is useless for imaging or visual use.

Great questions though.

David:

I wouldn't worry about it. Shouldn't effect the image at all. Certainly not the ability to effect image sharpness. Technically, the scratches might scatter some light when viewing something bright like the moon but I doubt it would be noticable at the eyepiece.

Those scratches are going to bother you a lot more than they will the image. Kinda like dust on a mirror.

Beautiful work Jeff!

You've done an outstanding job of capturing the intricate and delicate details seen in the eyepiece, that are soooooooooo difficult to capture in an image.

Thanks for sharing

Scott:

Spare parts for these scopes are rare as hen's teeth. I'd post a wanted ad in the classified section. Not too long ago I saw a whole fork mount for sale. This is another option. From what I understand the 8, 10, and 12" scopes all used the same guts. You just need to be sure the hardware version is the same as yours. The very old units used a different motherboard and aren't compatible with later versions.

Its been two years since I found a spare set of electronics advertised and I almost missed the deal. I was only looking for a spare handbox and motors but the guy was selling all the internals plus a handbox. It was more than I planned on spending, but I realized I better jump on it or I'd regret it later. I was lucky he had requests to buy individual parts but I offered to buy the whole lot. Since this was his preference in the ad I got the sale. I haven't needed anything yet, but at least I know I'll have spares should a failure occur.

Good luck with your search.

Red Spot Jr?

Tom

Phil,

To answer the last question first - YES, the drive bases are all the same for the 8, 10, and 12". Just the forks are different.

Now the first question.

If you've miss aligned the encoder masks here's a link with the instuctions on making the repair. Hope this helps you.

http://www.mapug-astronomy.net/ccdastro/decfix_8.htm

Good Luck!