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Posts Made By: Jon Isaacs

February 27, 2005 02:25 AM Forum: Equipment Talk

Re: I need help!!!!

Posted By Jon Isaacs

You can't beat aperture, especially when the focal lengths of the two scopes are nearly identical.

Having owned an ETX-125, I would definitely suggest the 8 incher, it gathers 2.5 times the light of the 125 and so will do a good job on DSOs as well as planets. Plus you can add a focuser/corrector which will bring the focal ratio down to F6.3 and allow for a wider field of view in the bargin.

Thats what I would do...

jon

March 11, 2005 03:27 AM Forum: Beginning Astronomy?

Re: Filter Question

Posted By Jon Isaacs

Gary:

If I were in your position I would consider returning the filters to the seller. Without markings and such vague information, I would not be confident that these were indeed the filters that he believes them to be.

Jon

March 27, 2005 08:19 PM Forum: Chinese Optics Imports

Re: BO 102 f/6

Posted By Jon Isaacs

>>At least Bill told us that the 40:1 fine focus knob was not included and Bill was also very honest about the rear baffle allowing only 92mm of aperture.
====

I believe that the actual effective aperture was somewhere closer to 80mm, at least that is what myself and some other folks got.

jon

March 30, 2005 05:11 AM Forum: Beginning Astronomy?

Re: my first

Posted By Jon Isaacs

Hi:

Welcome to Astromart, this is a great site with lots of experienced folks interested in helping others get a good start. Smart move on your part to ask some questions.

Anyway, my thoughts and recommendations:

1. The previous poster recommended that you forget astrophotography for the moment and I agree. Doing astrophotography "right" is a tedious and time consuming passion and requires top notch equipment. The demands on the mount are of a different order of magnitude those of visual observing. Visually the only requirement it that the object of interest stay in field of view for a while. Photographically, the requirement is that the star does not move at all over a period of several minutes. THere are no mounts (no telescope, just the mount) that are available for $500 that adequate for photography.

Add to that, trying to buy a scope that has some photographic capabilities will end up costing you visually because the scope itself will be smaller.

Anyway, that said, there are lots of options that will provide great views for your $500, the question is which scope do you want.

For smaller children, electronics and GOTO is probably a mistake. Getting them setup properly and aligned can be difficult for knowledgeable adults.

A couple of thoughts:

1. THe Orion Starblast. This is a small scope with good optics that allows for a wide field of view as well as some nice view at high magnifications. It's under $200 so it probably allow for you to get something larger at a later date. Definitely kid friendly.

2. 6-8-10 inch DOB. These are serious scopes, simple but serious. The 6 and 8 incher are reasonably sized and will show a lot, are simple to ues the 10 incher is more of a handful to move about but is quite amazing. These scopes would require some adult supervision IMHO.

Photos of the moon are quite easy with a DOB, photos of the planets possible, Deep Sky, no. I have attached a photo I took of the moon with a 10 inch DOB, camera to the eyepiece. I have reduced the size by a factor of 3 to to keep the size down.

3. Refractor of some sort. A small refractor is a nice general purpose instrument, robust and requires no alignment (collimation). They are more expensive than a small newtonian but can provide nice widefield views. Affordable refractors are all Achromats which means they will show "false color" at high magnification, the amount depends on the size of the objective and focal ratio, 120mm F5 with have lots of false color, 80mm F11, not too much..

So, that is what I can offer, look around, listen to what everyone has to say, try to get yourself to a club outing or star party and have some fun.

Best wishes,

jon

April 2, 2005 02:54 PM Forum: Pictures of Me and My Telescope and........

My New OLD scope

Posted By Jon Isaacs

I found this scope on a local for sale website and even though its a ladder scope, it was too pretty to pass up... So far so good.

jon

May 4, 2005 10:30 AM Forum: Eyepieces

Criterion AR eyepieces

Posted By Jon Isaacs

I recently acquired a Criterion RV-6, it came with 2 eyepieces, an AR-9 mm and an AR-18mm. Measuring the field stops, the AFOV should be 38 and 35 degrees.

I am curious if anyone knows much about these eyepieces, what type they might be. They seem quite simple but provide pretty decent planetary detail without ghosting or reflection, at least that was my first impression.

jon

May 8, 2005 07:39 AM Forum: After Dark

Burion 100F6

Posted By Jon Isaacs

Hello folks, last night was a happy night for me.

The Saga of my Burgess Optical 102F6 has finally come to a satisfying conclusion. In the beginning, all I wanted was an achromat with Synta quality optics and better mechanical components. But that dream , for me and others, was not to be and finally when BO shelved the "Semi-APO" objective it was clear that some had been left high and dry, some who had waited scopeless for a year only to get a scope that couldn't split Castor.

I had put the scope in the closet, figuring on parting it out. Fortunately some kind soul pointed to a Orion 100F6 Objective that was available at a well known auction site. I won the auction and true to form, it took over a month after it closed for the objective to arrive. This scope just did not want to be born...

I had no idea of how I was going to mate the Orion objective to the Burgess OTA. However when it arrived and had them side by side it was obviously it would be quite simple. Both scopes use collimatable cells that use 3 screws to attach the cell. They do not quite line up but are close enough that 3 minutes work with a file and undersized drill, pushing the holes in the cell slightly to the center, and the cell was mounted to the OTA.

Viola and the Burion 100F6 was born...

The BO lens shield did not fit but some creativity with some camping pad foam and a bit of Crazy Glue took care of that nicely.

When the scope was finished, I quickly removed my Pronto from it's mount (Bogen 3040 with 3047 head sidesaddle style) and took it outside for a look. Still early afternoon, the views were crisp and very promising, I was elated.

But it was cloudy with spots of blue, if this scope was going to see first light, it was going to be viewing through sucker holes..

First light:

The long awaited moment. With the original BO objective, this had been disappointing, a first low power view of the moon immediately pointed to problems, not sharp, not crisp but an softness that I had never seen at 25x in any scope. 100x on Castor showed a severe astigmatism even with the restrictor baffle in place.

But this was a new objective, one with Orion bloodlines, though I did wonder why it had been removed from the original scope...

Apprehensive, had I just thrown more money away?

A quick look at Castor told me I had a winner. 67x and it was split cleanly, 125x and it was beautiful, 250x and it was amazing with nice round diffraction rings. A jaunt over to Saturn showed the Cassini cleanly, IZar was beautiful at 125x, Jupiter, bathed in the purple glow of chromatic aberration still showed sharpness that revealed detail in the cloud bands. The double-double split cleanly even though it was 12 degrees above the horizon and barely out of the tree tops.

Early this morning, just before sunrise, a quick look at the summer milky way showed M6 and M7 to be glorious, nice sharp pin points, bright. Wandering around, there was m22, m16, the trifid and down to the lagoon, globulars to the west, oh there's the Wildduck, up to 100x and its nicely resolved, over to M27, nice and bright and there's m71...

Is that Mars low in the South east, sure enough...

======
WOW
======

This is the scope that the 102F6 should have been, a good achromat coupled with a good mechanicals, no magic here, this scope has obvious false color, it is unavoidable in a fast achromat. But the images are bright and sharp, it does as good a job as a fast achro can do and it is in a very nice package with a smooth focuser.

If the Burgess Optical 102F6 had arrived to us when promised with optics of this quality, things would be be quite different, Bill Burgess and Burgess Optical would have been the hit of the season. This is a good scope, no magic, just a good scope.

For those of you who own the Burgess Optical 102F6, I hope that Bill reconsiders his decision to shelve the 102F6 "Semi-APO" objective. In my view, there is no need for a "semi-APO" objective, just a good quality achromat is all that is necessary.

I have attached a photo of the Burion 100F6. The only noticeable difference is that dark gray ring, it's the Orion objective Cell, it's a bit bigger than the Burgess cell.

Best wishes and clear skies to all

Jon Isaacs


May 15, 2005 06:32 AM Forum: Equipment Talk

Re: OK! Be honest

Posted By Jon Isaacs

Just lost another good deal here on astromart. Ok! Be honest, why does some people don’t ship overseas? Is it the trouble with shipping fee, packing or something else? Please can someone explain this?

Thanks,
Lukman Mazneh
-------
Hi: I can only speak for myself...

For me, it's the added effort required and the added uncertainty. I have a hard enough time as it is shipping something inside the US. Overseas requires more care packaging. Also there are uncertainties about customs, both a declaration at the post office on this end as well as issues with customs on the buyers end. And then there is the issue of theft somewhere along the line.

I personally prefer to sell things locally so that I can meet up with the buyer and make sure he or she is getting exactly what they are expecting and is happy with the deal.

My suggestion to you, as an overseas buyer would be to offer to pay the seller something extra for the added efforts and uncertainly that shipping overseas entails. It would probably be worth it for you.

jon isaacs

May 30, 2005 05:11 PM Forum: Equipment Talk

AC for Old EQ mounts

Posted By Jon Isaacs

Looking for ideas/experiences on running old AC EQ mounts on inverters. The other night I hooked up the 110 volt drive on my RV-6 to a simple inverter hooked up to 12 volts. The normally silent drive was now loud enough to hear so I decided I wouldn't risk using it.

I guess the 110volt 60 cycle produced by the inverter is not a very good sine wave, maybe closer to a square wave.

Any solutions?

Jon

June 6, 2005 05:05 PM Forum: Equipment Talk

Re: A second set of bearings on a Dobsonian

Posted By Jon Isaacs

I would like to know if someone (besides me) ever thought of putting a second set of bearings on a Dobsonian (in a different spot around the tube) so as to have the focuser in a more comfortable position for veiwing certain parts of the night sky, or to accomodate the smaller persons wanting a view so as not to stand on a ladder or have to resort to a boxed cradle for rotation of the focuser.
------------------

One relatively common solution is just to build the scope using rings or better yet, rotating rings to mount the OTA in the bearings. If I am not mistaken, many of the very early DOBs were built this way.

Jon