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Posts Made By: Alex McConahay

August 16, 2008 01:56 PM Forum: Equipment Talk

Great Optics?

Posted By Alex McConahay

Sure,

I think one of the big things about the premium optics is that they have to pass a more rigorous selection procedure before they go out the door. There is more variation in mass market products, though. So, while you will always get a very good product from a premium marketer, only a smaller percentage of mass marketer products will hit that mark. But yes, it is possible to get "Great Optics" form anybody--just highly unlikely.

Alex

August 20, 2008 09:18 PM Forum: Digital SLR AstroPhotography

how to attach DSLR to CG-5 with ball-head?

Posted By Alex McConahay

You have several choices here. CG-5's come with a dovetail that will probably do the job. You just have to find an appropriate screw to hold the ball head on.

If your mount does not contain such, you could probably just call Anacortes, and they could get you one.

It looks like the kind of thing one of the supporters here sells--

http://www.desertskyastro.com/

so, contact them and ask.

And, you really can make a mount yourself with a small drill and a file, and a piece of aluminum stock about four inches long. It is relatively easy--I have made a few myself.

And, why do you want a ball mount under the camera? you could attach the camera directly to the dovetail plate.......And the CG-5 mount can point wherever you want.

Alex

August 24, 2008 01:43 AM Forum: Equipment Talk

Help request, setting up autoguiding

Posted By Alex McConahay

Paul,

What are you using to guide? An ST4 or something else?

Is the input of your mount electronics a telephone type snap connector? (RJ 11??RJ22? style?)

Alex

September 1, 2008 12:06 PM Forum: Digital SLR AstroPhotography

Got me a GPDX!

Posted By Alex McConahay

Assuming you have a "dovetail" plate for the mount, it should have one hole in it that will accept a 1/4"--20 thread screw of the appropriate length to stick into the bottom of your 20 D. Get a rubber (or cork) washer to stick between the camera and the dovetail, screw the camera onto the dovetail, mount the dovetail onto your mount.

Polar align the mount and start it tracking.

Point it to Saggitarius or Scorpio, and use the 70-200 mm zoom. Put the camera on Manual exposure at 30 seconds. Set the aperture to one stop slower than full aperture. ISO to 800. Large/Fine jpg's for quality. Set the camera to use the self timer. Set the custom functions to "Flash does not Fire." Focus and frame as well as you can looking through the viewfinder. Push the shutter release. Do that three or four times on the same subject.

If you have a remote release, you can change the part about using 30 seconds and the self timer to use whatever exposure you want.

You are started.

It does get more difficult that that, I should say, though.

Alex

September 9, 2008 05:07 AM Forum: CCD Imaging and Processing/Deep Sky

Made a new Dovetail for the MN66

Posted By Alex McConahay

Agree with that do it yourself 100%.

Alex

September 20, 2008 12:00 PM Forum: ASTRONOMY

what to do need some advice

Posted By Alex McConahay

Why should looking at the stars be a tricky subject? Just tell them what they are looking at and let them enjoy it.

Alex

September 21, 2008 06:58 PM Forum: AstroMart FAQ

Question: disappearing classified

Posted By Alex McConahay

Check the options in your settings about how long you will go back to display an ad.

Alex

September 30, 2008 02:17 PM Forum: Eyepieces

Ethos 17mm $750.00 ! ! !

Posted By Alex McConahay

We were able to use the whole line of Ethos eyepieces, including the new ones out at Goat Mountain last week in a couple of 12.5 inchers and the 22 inch Dob.

They are nice.

And "worth it" is in the eye of the beholder.

Alex

October 9, 2008 11:31 PM Forum: Beginning Astronomy?

What would you buy?

Posted By Alex McConahay

Slow way down, Ted.

What kind of pier are you putting in? Why are you putting in a pier at all?

Just what do you plan to do with this observatory?

We cannot offer any intelligent advice unless we know what your plans and goals are.

(And, by the way--I find it hard to believe that $2800 will buy whatever you want to put in that observatory eventually.)

Alex

November 3, 2008 02:27 PM Forum: Solar System Observing

Observing with Normal Telescope

Posted By Alex McConahay

Judson,

You sound like you are asking for advice as to how to get started in solar viewing. At the risk of covering stuff you already know:

There are basically two types of solar viewing for us commoners.

One is "White Light" and the other is Hydrogen Alpha.

White light is cutting down the amount of light that is coming into your telescope in the first place. You get to see the whole spectrum of light, but the dangerous rays and the intensity is cut off by a specialized solar filter or projection techniques. The two most common types of solar filters are film or glass. Film is much less expensive. A piece of Astro-Baader solar filter, available through many suppliers on Astromart, and I am sure at Anacortes (although I have not checked) would cost about $30. You can make a holder for it and attach it to the front of your scope (relatively easy to do--but be careful that you do it right....there are directions on the web). Glass filters are also available in various sizes, with one for your scope running in the hundred dollar and more range. (Again, I have not checked.) The Baader film is reputed to be a bit sharper. The color of the sun is a bluish gray. The glass filters usually offer a yellow/orange view that I find more pleasing. (It looks like the sun!!!).

You can also see white light through projection techniques. TO do so, you aim your telescope at the sun, and let the light flow through it, through an eyepiece, and onto a white board of some type (or through a projection screen, or in a variety of other ways). The white board can be attached to your telescope with a "holder" or on a separate easel, wall, or something. One does not see this projection technique too much in the solar viewing world, but it does have its place.....Be very careful of this technique. It can be hard on equipment, and dangerous in a in a public setting because somebody is gonna want to look through the telescope. A person can look through an unfiltered telescope directed at the sun only twice--once with each eye.

Oh, and there is another type of "white Light" solar filter--it is a piece of darkened glass that you put in your focuser--behind an eyepiece. DO NOT USE ONE OF THESE--especially with your large scope! There is a great danger of it heating up and breaking--catastrophically.

The other generally available technique is to use Hydrogen Alpha filters. These come in basically two general types, one using specially built filters involving some kind of electronics and special filters, and the other using "etalon" type of filters. THe etalon variety is what you find in the Coronado (like the PST) and Lunt products, and this is the type that brought Ha viewing to the masses. They function by allowing only a very specific wavelength of light into the eyepiece. They are generally a "system" of an "energy rejection" filter (which gets rid of a lot of the light) and the "etalon system"--which selects for an extrememly narrow band of light. You can buy them as a "solar telescope" which includes the telescope optics, the energy rejection filter, the etalon, and the appropriate diagonal. Or you can buy just the filter and the diagonal to add to an existing telescope. These systems can range into the thousands of dollars and more for larger scopes. The more expensive systems are "double stacked" to allow an even narrower band of light through, and enhance detail.

White light filters will show sunspots, but that is generally it. (And for the last ever so long, there have been none of them!!!) They show a bluish gray to orange color, depending on the brand, model, and so forth. Ha filters show things in a deep red because that is the only color they are allowing through. However, that red is the color of glowing Ha, and that is the stuff that is involved in so many of the interesting solar prominences and such. You should also be able to see detail on the surface of the sun, a granularity to it or the activity on the limb--prominences and so forth--depending on how you tune the etalon.

THere are other etalon based scopes (like those for viewing Calcium, and such), but they are relatively rare, and more expensive.

Old man advice--Go buy a piece of Baader solar filter and stick it on the front of your scope. Then save up for a PST or more advanced (larger) Ha scope. While you are saving up, consider how deeply you want to go into this solar viewing thing. Look thorugh other people's scopes to see the difference in the views, and decide what you want to do with solar viewing.

Alex