Posts Made By: David Simons

Hi Bill,

Have you done a search on the old ads here on Astromart ? There should be plenty of listings for the scopes you mention.

Of course your friend should give you a slight discout : ) Also he will not have to ship anything either.

David Simons

Rick,

I did a search on the old ads, and found this one.

http://www.astromart.com/classifieds/details.asp?classified_id=274221

Looks pretty cheap. You may want to do further searches. I used "Starfinder"

David Simons

Celestron or Meade GOTO SCT OTA's that detach from their forks, so hoisting a 75lb fork and OTA assy. on top of a tripod could be avoided.

A ~3X 45 degree angle correct view Telrad type device with long eye relief and wide field. A zero power device sometimes just does not work in a star poor area, and a little magnification is needed to bring a few dimmer stars in.

A 2" Power Mate type of device that along with a 2" eyepiece gives a correct view from a newtonian, and does not require any back focus, and has a short stubby barrel.

A Telrad type of device that has some kind of built in readout that gives ALT/AZ or other info through the display as you move the scope. (Like Luke Skywalkers binoculars)

I could go on ..

David Simons

Hi Dave,

I usually agree with all the other comments already posted, but I just had an interesting experience in the Idaho mountains 2 weekends ago with my Sky90 and a 10" older Coulter dob. These sizes aren't exactly what you were looking for, but somewhat similar I think. I had both scopes side by side running about the same magnification of 40X. Sky with partial moon below the horizon was only giving about a mag 6.

The collimation on the dob was a little off, but at such a low power, stars were still reasonably sharp, and it was not noticeably bad. I looked at all the usual bright Sagittarius objects as well as the Ring, and Dumbell. When I did my side by side comparison, the 10" was of course always giving a brighter image, but the Sky90 was just so sharp that delicate wispy details seemed to show up in the Sky90 while the Dob would just be a brighter less detailed image. My family had all gone to bed, as well as my dad, but my mom came out around 11pm to see what I was up to. After looking at a few of the clusters and nebulas in the Teapot, she preferred the Sky90 as the stars were just small pinpoints and the finer (dimmer) nebulosity was more finely detailed.

It could be the dob's coatings were too old, although a quick look down the tube at the mirror showed no obvious problems. Collimation is always an issue with short F-ratio dobs, and this one could use a tweek. I was using an Ultima ep. on the Dob, which may not have been the best for such a short F-ratio. Also, some Coulter dobs were just not that good, this could be one of them, but at such a low power, I would not think a 1/4 wave mirror would harm the system that much at 40X . Lots of potential optical variables here.

The conclusion for me, was that a dob needs a certain amount of care and feeding such as collimation, and re-coating, while the APO is always at peak performance. Also with low end dobs, some optical quality issues can come up. Although most of the newer scopes seem to be fine in that regard.

At first it would seem the Dob would be the easy answer, but factoring in some of these issues can sometimes make the decision more interesting.

The 5” f12.1 Mak is a different scope than a f5.5 Sky90, so my recent comparison may be a little off topic, but some of the points may still apply.

David Simons

Hi Gary,

I very much feel for your loss.

Please post this list in the Stolen Equipment forums also, as this is a quick way for anyone to check on these items in the future if they think they may see them for sale.

Sincerely,

David Simons

Hi Dave,

Thanks for the latest. Now that the fires here are starting to die down, the sky is starting to clear up a bit.

We had "golden" afternoons for a couple of days, when the sunlight was trying to go through the burnt brush and old oak trees smoke. Everything was lit by a ruddy golden color sun. Actually somewhat pretty. The moon was an orange and golden color as well, very spectacular, and most of the stars were carbon stars !

Hopefully back to dark skies !

David Simons

Hi Scott,

Takahashi used to make a series of small Newtonian scopes of very high quality. They show up on astromart from time to time. I think one of them was around 130mm diameter. I have heard these scopes give excellent high power views.

http://www.astromart.com/classifieds/details.asp?classified_id=282710

Did you have a particular type of observing in mind ? Wide field, high power ?

I have the Meade 8" Schmidt Newt, and I like it a lot for wide field viewing, the 6" I have heard to be very good.

For a very portable setup, the 4.5" Orion Starblast has gotten good reviews, despite it's low price.

Let us know what you decide !



David Simons

Hi Larry,

I think a lot of that price is in the short focal length of the 180, and the fact that very few of the 180's were made at all, and even fewer were the shorter f7 ratio.

So there is a performance issue, and the more slippery collector/rarity factor.

I can't remember off hand if TMB makes a 180f7 focal ratio scope, f9 yes. My guess is no.

The 9" f9 lens would be killer on a lot of objects, but would not be quite the same scope for imaging purposes. Focal ratio is king in the imaging world.

If money were no object, then I would get a 200mm f6 APO built !

David Simons

Hi Daryl,

Did it look a little like this ... ?

http://www.astromart.com/forums/viewpost.asp?forum_post_id=221652&poll_id=&news_id=&page=

I was surprised how large it was, but very faint.

David Simons

Jeff,

Check out this thread.

Also do other searches on "bino collimation"

http://www.astromart.com/forums/viewpost.asp?forum_post_id=121228&poll_id=&news_id=&page=

David Simons