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Sculptor Galaxy (NGC 253)

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Posts Made By: Alex McConahay

August 25, 2005 12:40 AM Forum: Solar System Observing

Need info

Posted By Alex McConahay
Go to one of those websites that make a model of the solar system, and spread it out on the local playground.

Take a basketball, and put it on home plate and say "This is the sun, see how big it is" (and talk about it for a while). Then walk the few feet to a piece of raisin seed and say "This is Mercury." And talk about it. Then another few feet to an orange seed, and say "See Venus....It is really hot." By the time you are at first base (Another orange seed for the earth) you turn around and say--"look how small the sun has gotten." And it just goes on from there for a few more planets.

Alex

August 25, 2005 02:08 PM Forum: Beginning Astronomy?

Digital Indexing for Dobson Mounts

Posted By Alex McConahay
I have not seen reference to the term Digital Indexing.

Could it be that you are talking about Digital Setting Circles? The idea is that you have an electronic counter on each axis of rotation (altitude and azimuth). The readout of these sensors is sent to a computer (or handset). After you initialize the computer, it keeps track of where the scope is actually pointing. You can then use the computer by telling it what M or NGC (or whatever) object you want to find, then you push your dob, and the computer will tell you when you are pointing at the object of your search.

Is this what you are talking about?

Alex

August 28, 2005 03:32 AM Forum: Equipment Talk

Laser pointers? Good or bad?

Posted By Alex McConahay
There's a new forum just for laser pointers--you may want to post there also.

Alex

August 29, 2005 02:56 PM Forum: Equipment Talk

Add-on motorized focuser

Posted By Alex McConahay
I just made a motorized focuser from an old Losmandy (Hurst) motor and some electronics described by a fellow named Anat. Go to the DSLR Focus Yahoo site, and see the information for "Anat's Low Cost Focuser."

http://groups.yahoo.com/group/dslrfocus/

Of course, a few months ago, I used an old JMI Motofocus, and made a motorized focuser by basically taking the knob off, and affixing the shaft of the Motofocus to the shaft of the focuser, and then riveting together some brackets to hold the Motofocus in place.


Or you could go Robofocus for a few hundred dollars.

Alex


August 31, 2005 03:02 PM Forum: Politics

Hurricane Katrina photo op

Posted By Alex McConahay
Donald,

Like it or not, a job is a job. The president should visit a disaster area. You cannot hold that against him.

Don't let cynicism take over.

ALex

September 2, 2005 03:39 AM Forum: Equipment Talk

G-11 Tracking Problem

Posted By Alex McConahay
Well, I found another motor. I had to solder the leads back to the connectors, but it worked. Had the same problem as the others, though.

I also swapped the RA and DEC worms. Same results. (I also swapped the rest of the worm hardware-bearings, little nylon transmission connector)

So far I have tried three motors, three RA Worms, two sets of electronics. I've taken the Digital Setting Circle Encoders off.

The results look visually the same.

If I manage to go out to the club site this weekend, I will try a couple of motors that I know were working fine when my friend swapped them out to upgrade to Gemini. If that does not do it, it has to be in the ring gear, or shaft, or bearings, or where?

ALex

September 2, 2005 02:42 PM Forum: Equipment Talk

Help with Sticktation

Posted By Alex McConahay
Mark,

You said: I don't care for the car wax/armoral idea so I was going to start with sanding the Teflon

Could you explain why you don't like the idea of waxing, and why you think sanding would help?

Alex

September 4, 2005 08:29 PM Forum: Digital SLR AstroPhotography

Arriving late to the revolution...

Posted By Alex McConahay
My recommendation for deep sky work is to skip straight to the Canon. Forget the Meade.

Getting decent photos with a DSLR is easier than with the Meade products. For one thing, the sensor is much larger. Therefore, whatever you get will not need to be enlarged as much.

Alex

September 7, 2005 02:06 PM Forum: Film Astrophotography - Imaging and Processing

Parafocal or not...

Posted By Alex McConahay
What you are running into is common. There is no reason for an eyepiece completely inserted into an OAG to focus at exactly the same place as the main imager. You have to pull the eyepiece out (don't insert it all the way in) to get it to focus, or, if it is already too far out, you have to shorten the tube on the OAG.

Alex

September 9, 2005 03:18 PM Forum: Equipment Talk

dew shields, when to use them?

Posted By Alex McConahay
Jim,

I think the usual name for the process you are using is "stopping" down. I don't know that "collimating down" is ever used to describe this.

I cannot see how removing your dew shield can make your aperture larger. And if it not doing that, I don't see how you could be getting more light to the eyepiece. (Unless the dew shield is supposed to be acting like a field stop, and cutting off the edges of your objective--and the designer would do that only if he or she felt the edges were bad.)

However, it could well be that things will appear brighter in the eyepeice because you are getting extraneous light coming in from the sides, and hitting the front element of your scope. This light is generally, though, unwanted. It reduces contrast.

In short, I don't see how removing a dew shield would increase brightness of the desired target object. (It would increase extraneous light, however).

Alex

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