Image of the day

Captured by
Mark Killion

The Iris Nebula

My Account

New to Astromart?

Register an account...

Need Help?

Posts Made By: Jon Isaacs

October 23, 2003 07:00 AM Forum: A Day in the Life of the Administrator

Astromart ForSale Question

Posted By Jon Isaacs

Herb:

A question for you.

A fellow advertised a 3 inch refractor and 16 inch Dobsonian in the San Diego Union-Tribune. I talked to him and went to look at the DOB. Well it turned out to be a blue 13.1 inch Coulter. He wants $450 for it. I am not interested as I have a 12.5 inch Discovery.

The obvious place for this scope is Astromart but the fellow is not internet or even computer savvy and does not have access to a computer. The fellow is clearly a very solid man, older, has been living in the same place since 1971 with his family.

So, what do you think about my posting undermy name for guy with the situation stated clearly?? My thinking is that anyone interested would respond to me and then I would give them the contact information. The buyer would have to pickup the scope, shipping is not an option, the seller just wants to move the scope and it seems like a good chance for someone wanting some cheap aperture.

Thanks

Jon

November 12, 2003 10:50 AM Forum: A Day in the Life of the Administrator

High Power Green Lasers

Posted By Jon Isaacs

Herb,

Just wondering if you know that Z-bolt seems to be advertising on Astromart lasers for use as pointers that are Class IIIB ie greater than 5mw. According to Laser Safety Protocal, such a laser can cause eye damage and should not be used without adequate protection.

jon


November 17, 2003 07:15 AM Forum: Equipment Talk

Central Obstruction, A Doable Test

Posted By Jon Isaacs

Again and again the effects of a central obstruction on planetary viewing are debated with much information, analysis, experience, opinion, vague recollections etc. When comparing two scopes it is really not possible to determine the cause of any observed differences, subjective or objective, there are just two many variables.

The simplest way to eliminate these variables is to just use one unobstructed scope or two identical obstructed scopes.

If one wants to compare an 6 inch scope with 33% obstruction to a 4 inch unobstructed scope then simple masks allow one to do this easily. A 2 inch disk in the center of the objective and an ring with a 4 inch hole will make a 6 inch unobstructed scope into either of these. This eliminates all the other variables and reduces the problem to how a central obstruction affects the view. One can also investigate how adding a central obstruction affects the image for a given aperture.

Some further comments:

1. The best way to do this is a "blind test." When looking to see the effect of central obstruction for a constant aperture, this is quite doable and quite important. An assistant should change the size of the central obstruction and the observer should make every effort not to cheat. A quick defocus would suffice to see the size of the CO. Doing a comparison between apertures, the first test, the brightness difference should be obvious so a blind test would be difficult.

2. The outer ring used to reduce the aperture is easy to do, it just fits inside the dew shield. Attaching the inner ring is a bit of a challenge. One suggestion is to simply glue the ring to the objective. (NOT!!)

Actually fine wires could be used or possibly sticking a piece of plastic to the objective using a bit of water. Not quite sure how this is best done.


4. Unfortunately, this requires an APO or off axis Newt because color correction of an Achromat is affected by a mask. Adding a central obstruction will increase the false color and adding a ring that masks the aperture will reduce the false color.

5. Maybe someone else has already suggested these, I have not read all the posts on this topic, they are overwhelming.

Think about it.

Damon Rinard, well known for testing various aspects of bicycles had this statement on his website:

"One measurement is worth 50 expert opinions."

jon isaacs


November 19, 2003 05:36 PM Forum: Equipment Talk

Re: Brand new Meade 14" LX200 GPS for 2200.00

Posted By Jon Isaacs

As others have pointed out, these are scams. If you want to send someone $2200, please send it to me. I don't have any scope for sale but at least I am honest about it.

Your attitude towards the cost of Meade and Celestron scopes makes you a prime target for sucker deals like this one. You are exactly who these crooks are looking for. A Meade 14 inch GPS for under 5 grand is a hell of a deal as it stands.

jon isaacs

November 23, 2003 06:29 AM Forum: Equipment Talk

Re: Used Stellarvue AT-1010's, value?

Posted By Jon Isaacs

I see one going on Astromart right now for $290. I don't know a great deal about the various versions of the AT1010 but that seems like about the right price, especially if it has some accessories like rings and a diagonal.

$200 is what a new ST-80 costs with some stuff. Certainly not the scope the AT1010 is but it is new and ready to go. So you should get more than that.

And at $400-$429 for the AT-1010 and ED80s, clearly one has to be significantly lower than that.

I think the ED80 is going to make it tough on the AT1010. It is clearly the choice for anyone wanting a good quality 80mm refractor at a reasonable price. That "APO" objective is hard to compete with.

jon

December 15, 2003 06:39 AM Forum: Equipment Talk

Re: "Appliance" Operators?

Posted By Jon Isaacs

An interesting perspective, certainly good astrophotography requires good equipment. Compared to many other hobbies, well, $5000 for a scope and $5000 for a mount is a small investment, cars, boats, you name it. Heck, I have a neighobor who told me on a normal weekend his $50,000 boat will burn $400-$500 dollars worth of fuel.... A Nalger a weekend...

Another interesting fact to consider: the ultimate Astrophotography ATM, my vote... Roland Christen

In the 70s an amateur astronomer dissatisfied with the current state of equipment, he starts a company to build stuff so that he himself can have the equipment to take the pictures that he wants to take.

Go to the TeleVue website, the Celestron Website, the Meade Website, how many of those have photos taken by the owner, CEO etc?

Look at the AP website, lots of photos by RC.

Personally I am thrifty (read that cheap), but what I see is that because of people like RC the equipment to take those high quality photos does exist and while it does cost a pretty penny, it will essentially last forever and is not expensive when compared to other pursuits.

Jon Isaacs


January 23, 2004 11:48 AM Forum: Chinese Optics Imports

Anybody gotten a 102F6 yet?

Posted By Jon Isaacs

Just wondering....

jon

January 23, 2004 11:54 AM Forum: Chinese Optics Imports

Anybody gotten a 102F6 yet?

Posted By Jon Isaacs

Just wondering....

jon

February 3, 2004 01:40 AM Forum: Equipment Talk

Re: Oberwerk 22x100 likes and dislikes

Posted By Jon Isaacs

>I would recomend it over buying a $400 telescope.

This must depend on which $400 telescope.... For that $400 you can buy an 8 inch DOB which will be much more flexible than the binoculars, not only doing the DSOs in detail but providing some pretty amazing planetary views as well.

Jon

February 5, 2004 05:15 PM Forum: Chinese Optics Imports

For anyone still waiting for their 102F6

Posted By Jon Isaacs

Just a heads up here:

I had not received notification that my 102F6 was ready for shipment, or in fact any info from BO. I sent an Email to Tammy earlier today and received a reply this afternoon that all they needed was my credit card expiration date to ship it.

I had called them in December when the information about the 3 choices was posted here.

Apparently they did send me the Email but I missed it or something went wrong.

So, if you are still waiting, the scopes are ready to ship, give em a call or Email em.

Best wishes

jon