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

June 22, 2005 05:00 AM Forum: Beginning Astronomy?

Mercury, Venus and Saturn this week

Posted By Jon Isaacs

Hi Folks...

Something to look for in the early evening this week (and next):

Saturn, Mercury and Venus are within 5 degrees of each other, low in the western sky, slightly north of due west. They set around 9:30 PM in San Diego, but are visable in a small telescope or binoculars in the twilight. Venus is clearly visable to the naked eye and once spotted should guide you to the Mercury and Saturn.

Mercury and Venus are will be passing Saturn, on the 24th, they will all be within 2 degrees of each other.

On the 26th, (Sunday), Mercury and Venus will be very close, less than 1/6th of a degree apart.

Mercury is quite a treat in that it is something few people have ever seen, a particularly nice target for first timers.

Jon Isaacs

June 24, 2005 04:51 PM Forum: Equipment Talk

Re: most knowledgeable

Posted By Jon Isaacs

>>>>Hi all, I am wondering who everyone would pick, to be the most knowledgeable builder of telescopes.Or a great person to talk too about telescopes, with down to earth facts about scopes of all kinds,whether it be about the scopes they build, or other scopes.Without saying there scopes are the best and putting other scopes down, would that person be Markus L., Roland C., Vic M., Thomas B.
Mike P.,Bill B. Al N. I am curious you would win the battle and why.Or is there others. (It could be called the master crafter build off)

I am an old like Charles P. and have been reading Roland Christen's comments for quite some time. Looking at the names you have listed, it seems to me that there is no one else who is involved to such a degree with every step of the process, from the optical and mechanical design to the final figuring of the objective or mirror.


September 1, 2005 03:32 PM Forum: Telescope Making

Sonotube for 12.5 inch DOB

Posted By Jon Isaacs


I am considering replacing the rather beat up Sonotube on my 12.5 inch Discovery DOB. The current Sonotube seems to have a wall thickness of about 0.40" while the new stuff I see listed is about 0.20". Certainly the 10 lbs. saved by the thinner walled tube would be welcome but I am concerned that it would not be stiff enough to provide adequate support for the mirror cell, spider, bearings and focuser.

What do you think??


October 7, 2005 04:23 PM Forum: A Day in the Life of the Administrator

Will you stand for this

Posted By Jon Isaacs

An ad included the following...

""Remember to support Herb. He is getting old and feeble and needs the money (sorry Herb, hope the plea helps) Thanks for looking.""



October 13, 2005 06:58 AM Forum: Telescope Making

Re: Good Mirror Cell

Posted By Jon Isaacs


I have used the older University Optics cell. It "worked" but it is pretty flaky IMHO, definitely not for a thin mirror. I have heard the new one is superior.

I replaced the older UP with a Novak cell which is nicely made heavy duty cell. It's definitely a keeper.

If you are replacing an existing cell, you need to pay attention to cell height.


October 14, 2005 07:03 PM Forum: Eyepieces

Re: Glass magic?

Posted By Jon Isaacs


Consider this proposition:

The weak link in the chain is always the telescope. In comparison to any telescope, any semi-decent eyepiece is perfect.

So, differences in eyepieces are just not that important.

Put a TMB Mono or a Nagler or whatever else you want to, put that in a Baytronix 150/1400, the Ebay special short tube NEwt and no matter what you do the views will be awful.

Take the "Plossls" that came with the Baytronix and stick them in an 8 inch Astro-Physics APO and the views will be pretty amazing.


October 29, 2005 02:00 PM Forum: Equipment Talk

Is a SNT an APO??

Posted By Jon Isaacs

Check out this ad...

Seems pretty questionable to me.


November 4, 2005 07:53 PM Forum: Beginning Astronomy?

Re: Meade ETX-70 V Orion Starblaster 4.5EQ

Posted By Jon Isaacs

Hi Robert..

I owned an early ETX70, the GOTO worked nicely but the Optics were poor. I have never heard any great reports about the ETX-70 Optics, a 70mm F5 Achromat can offer widefield views but not much more.

I have heard many great things about the Starblaster though I have never even looked through one. People I trust such as Rod Mollise, Mr SCT have been very enthusiastic about the Starblast, it seems to work nicely even at high magnifications.

At this price point I think an ST-80 might be something to consider. For camping it also makes a decent terrestia/bird watching scope.


November 10, 2005 03:29 AM Forum: Eyepieces

Re: Safety undercuts

Posted By Jon Isaacs

I tend to dislike the "safety undercuts" but it does depend on the focuser/diagonal in use. In a TV Everbright with a set screw, they seem to work nicely.

One problem I haven't seen mentioned is that in a focuser/diagonal with that uses a non-captured screw, I find that I sometimes end up backing the screw out too far and dropping it. With a smooth sided eyepiece, it only takes a small twist and the eyepiece is can be removed, with the undercut eyepiece, it takes several turns and can result in the losing the screw.


November 23, 2005 04:08 AM Forum: A Day in the Life of the Administrator

Agent for Buyer/Scam warning

Posted By Jon Isaacs

The post appeared on the beginners forum this morning. The poster is a newbie trying to sell a scope and it looks to me like this response is a typical internet scam, the agent is in Oklahoma/Mississippi for a buyer in Benin... They are asking for the seller to reply to a Yahoo account...

Here is the text:

""This is an e-mail I received. How can I check this to make sure this is for real?

Date: 11/23/05 04:43:03
Subject: ASTROMART - Response to ad #390789

The following message has been sent to you in response to your Astromart classified ad #390789 - 'Celestron Celestar 8 Extras (lowered price)'.
This email was sent by registered Astromart user lyion gulter - (tulsa, ok) via Astromart's email ad response system. Should you choose to reply to this email message, your response will be sent directly to the recipient and will not pass through or be associated with Astromart in any way. Astromart does not condone or tolerate spam (i.e., unsolicited commercial email) and is taking steps to protect members from this abuse.

Hello Seller.
I'm Lyion an agent and i reside in Magee Mississippi.Okay?This is a purchase request notification for your item placed on on bahalf of my client, infact my client his satisfy with the detailed informations posted with the item.
This item will be ship to my client son in Metropolitan University Republic of Benin 22901.Okay?We 've shipping company who will take care of the shipment.Okay?

{1} Did you accept Money Order as the mode of your payment?
{2} Will you be able to wire an excess fund to the shipping company?

In order to schedule a pick up of this item from your location.
The reason is that,my client said he can only issue a money order for the sales of your item,the shipping cost,Insurance,Vat and Custom duties all in a money order.Okay?

If you can truely do this, Kindly email me the total final asking price with your Fullname,contact address and phone for immediate payment.Okay?
Hope to hear from you soon. Pls send your reply to:

Cheers!. ""