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Posts Made By: Jon Isaacs

March 18, 2006 10:37 AM Forum: Equipment Talk

Re: Jason 60mm

Posted By Jon Isaacs
Sandy:

Here is my thinking, having owned similar scopes...

1. Money has to be relevent, otherwise, you would just replace the mount, the eyepieces and the scope itself....

2. The mount has wooden legs, better IMHO than the modern extruded aluminum legs. Probably adequate for wide field views.

3. Normally the 60mm F11 objectives are pretty decent on these scopes.

4. The finder is pretty flaky. The cheap solution is to just remove the optics and use it as a sight tube. The expensive option is to replace the finder with either a red dot or a 6x30.

5. Eyepieces, a Hybrid diagonal will be allow the use of 1.25 inch eyepieces. Add a Hybrid diagonal and some eyepieces and the scope will be actually quite nice...

On the practical side, reality speaking...

If you do/did end up with the 4.5inch Short Tube Newtonian and if it is anywhere near as bad as the 6 inch I tested from the same source, then you will have an extra mount, a couple of decent eyepieces as well as a finder.

I think the mount would handle the Jason rather easily, though rings would need to be bought. The eyepieces are normally actually not so bad and the finder much better than the 5x24 that comes on the Jason....

So, my suggestion is wait and see what you get...

Jon

April 8, 2006 04:30 PM Forum: Beginning Astronomy?

Re: Latest News On Laser Eye Surgery??

Posted By Jon Isaacs
Herbert:

I am glad you brought this issue in this forum, most people are not aware of some of the past problems associated with laser eye surgery and how it affects their night time vision.

I have heard things are better now but personally, though I wear glasses for both reading and distance, my vision is too important to mess with, even a small chance of a problem is not worth the risk. And too, for many of us who are older, the problem is not the lens itself but rather a lack of focal range, the eye is stiffer. For us, changing the shape of the lens only changes the limits of our range. And at the scope, this has no value.

Thanks again...

Jon

April 14, 2006 01:56 PM Forum: Beginning Astronomy?

How old are you???

Posted By Jon Isaacs
Hi folks:

On another forum on Astromart some folks were lamenting the lack of young people interested in astronomy. While I agree the patience required and lack of blood curdling thrills makes it attractive to the more "mature" mind, I meet many astronomers who are in 20's and the 30's or even younger.

So... Just how old are you and are you just getting started or have you been around a while??

Myself, I just turned 58 this month and have been doing this for a while... I live in light polluted San Diego, pretty much spend every clear evening stargazing from my back yard and try to get up to the dark skies of the nearby mountains at least 2 times a month.

With our great weather here, I commute to work on a bicycle and often take the "long" way home, this week it looks like I will getting in about a 140 miles...

So, how old are you and tell me a bit about yourself...

Jon

April 16, 2006 01:37 PM Forum: Eyepieces

Antares 8.6mm W70 Uncovered...

Posted By Jon Isaacs
I know most of you guys are into Naglers and stuff so this might not be of interest. The other day I was looking at my 8.6mm W70 and comparing it to the Generic Synta 66 degree Widefield. In a telescope, these two eyepieces give identical views and outside of the fancier aluminum barrel, they appear to be identical mechanically.

With a bit of tugging and twisting I was able to get that fancy looking cover off and see what was underneath... The 8.6mm W70 is nothing more than the generic Synta with a cover glued over it...

(In the photo, the eyepiece on the left is a partially disassembled W70 showing the generic label, on the right is the generic synta 66 degree eyepiece with the printing worn off.)

jon

April 24, 2006 05:13 PM Forum: Beginning Astronomy?

What Do You Do Aside From Astronomy?

Posted By Jon Isaacs
Larry Thraxton proposed the following:

"What Do You Do Aside From Astronomy?" It would be interesting to see how we balance things out.

I say lets go for it....

Myself:

I have two other "hobbies/passions."

1. Bird watching... I like birding watching, both backyard as well as going on trips and walks. Got some feeders out year round, spend about $40/month on bird food..Broke my foot a few years ago chasing a cat out of the yard.

Over the last several years I have taken several thousand images "digiscoping." This is afocal photography with a digital camera, ie, taking a photo of through the eyepiece. Over the years I have gotten some good ones, this is my best...
http://members.aol.com/jonisaacs/bikephotos/poglidsk.jpg

2. Cycling: San Diego is a great place to ride a bicycle. I ride to and from work every day and sometimes ride on weekends. Most weeks I put in over 100 miles, last week was 160 miles. I am mostly a "roadie" but have a few MTBs as well. I like the older classic steel bikes from the 80's and early 90's and have a small collection of around 15 or so bicycles.

http://members.aol.com/jonisaacs/bikephotos/ttbeany.jpg


3. Golf: Not really... I used to drive a VW Rabbit Diesel, does that count?? 8)

Jon

April 28, 2006 10:14 AM Forum: Chinese Optics Imports

Larger Backpackers???

Posted By Jon Isaacs
Hello folks:

FWIW, here's a picture of a larger scope with the label "Backpacker".

Purportedly the scope is hidden away in a secret garage somewhere in California awaiting final tweaking. Rumour has it that it offers superior light grasp and resolution to the previously announced "BackPackers" as well as truly color free views at F6 (!!). There have been hints that it may need to go on diet before final production begins as a few more frail testers seem to have difficulty hiking with the scope.

Sources who have seen it say that it is a well proven design using well known glasses so finding a manufacturer should not be a issue.

Best to all...

Jon



May 5, 2006 10:15 AM Forum: Refractors

Re: Stripping Coatings

Posted By Jon Isaacs
http://www.astromart.com/forums/viewpost.asp?forum_post_id=429547&poll_id=&news_id=&page=

Jon

May 17, 2006 10:32 PM Forum: TeleVue

Re: FS on 24mm Widefield

Posted By Jon Isaacs
Does anyone have the fieldstop diameter on the TV 24mm Widefield? I went to the "Ask Al" page at Televue and found some stat's on this NLA eyepiece but not the fieldstop.
------------

I have a 24mm Widefield and have measured the field stop reasonably carefully. I believe the number I measured was 24.8mm. I do know that what I measured correspond to an "effective AFoV of between 59 and 60 degrees.

The formula I used was

Effective AFoV= 57.3 x (Field stop/focal length)

I have 3 Widefields, the 15mm, the 24mm and the 32mm. They all seem to have effective AFoV's of between 59 and 60 degrees.

I should add that mine has the smooth sided barrel with the rubber eye shield.



jon

May 25, 2006 02:23 PM Forum: Celestron

Re: C10 Newt F/4.7

Posted By Jon Isaacs
Can anyone tell me if W/O Binos will work in this scope and I can not get my 20Da to come to focuse in it, what can I do.

thanks, denjo
-----

Yes:

See the reflectors forum...

In general it is not considered good netiquette to post the same question in two different forums. It makes for a more scattered effort with people answering a question that has already been answered elsewhere.

I suggest deleting this post because you already have two responses in the reflectors forum.

Jon

May 27, 2006 04:13 PM Forum: Eyepieces

Filter Placement Question...

Posted By Jon Isaacs
Filters are normally threaded onto the front of the eyepiece in a position that places them near the focal plane of the eyepiece.

The other night as I was observing, I began to remove the eyepiece to put on a Minus-Violet filter when I wondered why bother, why not just place the filter on top of the eyepiece. It seemed to work just fine.

Obviously this requires eyepieces with sufficient eye relief and a design that keeps them in place but given those constraints, it seems that placing the filter in the exit pupil might have some advantages because it is filtering the already magnified image, thus this approach might be less sensitive to the optical quality of the filter...

Just thinking, wondering, comments appreciated...

jon

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