Posts Made By: Alex McConahay

I would recommend against welding. You may want to move to another declination someday (or the tripod may not be exactly the same level as it was when you set the welding---and besides, welding it in a set position overcomes problems only in the attachments that allow adjustments.

SO, unless you are welding a whole new structure, you are not doing anything.

Alex

Jay,

If you do things carefully, I do not believe you have anything to fear. We make a big deal about solar filter safety because it is important---but not because it is difficult.

I would strongly suggest you go with the Bader Solar filter and mount it yourself on a cardboard especially cut to fit your mount. On a C-8, I would consider making an off-axis arrangement. That is, you cut a piece of opaque cardboard (and I think it is called pasteboard, not corrugated cardboard) so that it fits snugly just inside your tube in front of the corrector plate. Then put velcro in the right places so that it cannot move from that position. Tilt your scope upside down and shake a couple of times. Give the cardboard a tug. If it stays on, and it is truly covering the whole inside of the tube and not any light can go down its sides to get to the corrector plate, it is safe. The only critical things here is to make sure the cardboard covers the whole aperture plus the surrounding ring, snug up to the inside diameter of the tube.

Then cut a three or four inch hole (the distance from the center of your secondary assembly and the edge of the corrector--or maybe half an inch shorter-- is the diameter of this hole) off center through the cardboard. That is, there is now a hole in your cardboard three or so inches round off center so that the hole clears both the secondary assembly and the corrector plate.

Now, cover this hole (the whole hole--past the edges of the hole) with Baader solar filter material. Tape the edges of the material in place.

Put the whole assembly on the front of the scope. And view.

The points to watch for is that the cardboard in fact stays right in place even if you happen to turn the scope funny, or some child wants to poke his or her finger at it.

Second, make sure you inspect before each use to be sure there are no holes in the solar film.

If you do this, you will be as safe as can be.....

Alex

Several things to think about, here, Jay.

If you want to spend big bucks, you want hydrogen alpha as in Coronado or soon to be Lunt or Daystar, etc. I shall leave these alone.

If you want "white light" remember that there is not much to see in white light right now. It has been boring!

But, back to white light choices. It is reputed (and I agree) that the Baader Solar Filter material is a little sharper than glass filters. It is also generally less expensive. It's kinda weird to look at, being just a piece of shiny saran-wrap like plastic---but it works great.

But it is a bluish white color. I happen to like my sun yellow. So, for solar star parties with the kids and such, I prefer my THousand Oaks glass filter. The only article I have ever read comparing the different solar filters says it is the best choice for those wanting a yellow sun. (Actually orangish) Or at least that is the way I remembered it.

Then you have to ask the question, full aperture or not? Eight inches is a good size scope, and you do not really need that much aperture.

At any rate, If I were you, I would build myself a solar filter from Baader solar film. It is by far the least expensive alternative for a beginner.

Alex

I agree with Roland that the C9.25 is best for galaxies. However, not necessarily best for you!

As a new guy to astrophotography, you will probably get quicker results with mounting the camera on the refractor, and trying moon shots. When you get that down--should be less than an evening on that--you should try 30 seconds at iso 800 or 1600 with some bright objects like M42, Pleiades, etc. Unguided.

Then, I have to ask--can the GPDX handle the 9.25 and the ed 80 at the same time--If so, mount the two, and use the 9.25 to guide while snapping one to three minute exposures of the same bright things. If the two cannot be on the mount at the same time, then pick up a cheap refractor from somewhere (Even an old Tasco), and mount the two of them on the GPDX. Use the ED80 to image, and the cheap refractor to guide.

You will need an illuminated reticle eyepiece and remote that allows bulb exposure to pull this last thing off.

Alex

Yeah, yesterday, I spent two hours cutting grass, including that around my observatory.

Alex

>>>>>If a Barlow effectively doubles a telescope's FL, why does one need a longer telescope?

Well, one does not. Especially with a very high quality Barlow. (Unless of course one wants even MORE focal length.) However, most people prefer as little glass as possible in their systems. Unless you get the best of optical quality, and virtually no internal reflections (and subsequent light loss), with a very expensive Barlow/Powermate, etc.....you will get less of a view from a Barlowed scope than from a telescope designed from the start with the longer focal length. Also, it is easier to design a telescope of longer focal length for any given aperture. So, it may be that for many objects, a longer focal length telescope appears sharper and more contrasty.


I'll let those who know the Barcon answer the next question.

ANd as for the last--we may have some difference of opinion in this. Remember, some telescopes are already designed with built in Barlows. And many eyepieces are also built with internal Barlows.....so, it is not that simple.

Alex

It can be done, but it gets a whole lot more complicated than most of us would want to do. Even me, and I am cheap and pretty cocky about fixing things. It takes special tools, and knowing when to push a piece of glass or not, and stuff like that.

Alex

Crazy--foolish

Sometimes I find it hard to choose. Could you be both?

Alex

The 9.25 makes slightly different assumptions in its design (than most SCT's) and has had a reputation for years as one of the high points in the lineup.

However, the move from an 8 to a 9.25 will not be as big an improvement as to an 11.

You got the mount? Can the DM-6 handle the larger scope comfortably?

Alex

Tryt to get at least CS1.

Earlier editions will work, but the features in CS1 are useful for our work.

Alex