Posts Made By: Gary Carter

Uh...er...Houston, we have a problem!

In addition to Rod's points, many who want to perform astrophotography find the AP gear unable to clear the fork mount. GEQs resolve this issue.

Ya beat me to it, Arnie!!! Me neither!

Since you mention the Skywatcher 120ED I would like to pass along my experience. I too wanted something a little larger than my Orion ED80 that I would still be able to use as a "grab-and-go" setup. I snapped up a SW 120ED that came up for sale here on AM.

Optically and mechanically speaking the 120ED is on par with the stock ED80 - everything I expected it might be with one disappointment - the focuser. I could not adjust the stock two-speed focuser such that it would hold focus with heavier eyepieces (31mm Nagler) - especially when pointing towards zenith. After performing all the standard mods to make the typical Synta Crayford work I still could not get the focuser to function properly. I finally replaced it with a Moonlite. This was a great upgrade and I'm now very pleased with the OTA setup.

I've used it with a Televue Telepod on a heavy-duty Bogen-Manfrotto tripod with great success, though I'd say this f/7.5 scope, as light as it is, is about at the limit of this particular mounting arrangement.

The 7mm Nagler originally came to us as a Type 1 "Smoothie" with a slip-on rubber eyeguard. Later came the 7mm Type 1 with the rubber grip and fixed rubber eyeguard. It also featured the grooved barrel. Most of the Nagler Type 1's received this treatment during thier lifecycle - the exception being the 11mm Nagler Type 1 that was out of production by the time the rubber grip, eyeguard and groove features were added. (The 12mm Type 2 was in production by this time.)

You'll find some old ads here on AM that mistakenly claim to be selling a 7mm or 9mm Type 2. Many folks mistakenly identify the later 7mm and 9mm Type 1 Nagler models with the rubber grip/eyeguard as being a Type 2 Nagler....there are no 7mm or 9mm Nagler "Type 2" optical designs. (ref. Myth #3 in the article http://www.cloudynights.com/documents/naglers.pdf)

The Nagler 7mm, 9mm, and 11mm focal length optical designs remained unchanged from introduction until they were issued again as re-designed members of the Nagler Type 6 family.

So was it Religion, Politics, or Global Warming that lost your attention? 8O

About a year ago I managed to snag an old original 11mm Nagler from a seller in Brooklyn while on a business trip to New York. I double bagged it in anti-static bubble-wrap with some dessicant to protect it on the trip home. I tossed it in my computer bag along with my cellphone, GPS, etc.

As I started to pass through security at the Newark Airport I recalled the legendary "hand-grenade" metaphor the early Naglers earned and thought to myself "This ought to be interesting...". Well you should have seen the look on the Xray operators face when that bag passed into view. (I think she was a trainee to boot!) She called for her Supervisor. Two of them looked at the screen together. I could then see the Supervisor prompt the trainee what she should do. The answer was a hand search, of course. They called one of the guards over to the screen. His eyes lit up too as he gazed at the contents and was assigned the hand-search task.

So the guard intercepts the bag as it exits X-ray. He asks me to confirm the bag is mine. I try to console him a bit offering that I know what may be causing concern - but he isn't interested. He directs me towards the search table - but instructs me to stand at a distance off to the side. He also instructs me not to move, keep my hands to my side, not to contact any of my belongings or advance towards the table in any way. He then proceeds to carefully opening the bag and removing everything. The GPS and cellphone were the first two items to be removed (probably added a bit to the drama.)

When he gets to the bubble wrapped eyepiece he asks me to confirm it to be the object of interest. He set it aside and returned everything else to the computer bag. He then placed the eyepiece (without unwrapping it) into one tote, and the computer bag in another. He then returned the two totes to the X-ray operator.

The trainee re-examines the eyepiece in every wavelength and viewing angle with the Supervisor looking over her shoulder. She obviously had no clue what she was looking at. I believe the Supervisor then asked her if she had any idea - the operator shook her head "No." To my surprise the Supervisor declared it to be "an Astronomical Eyepiece" and instructed the operator to pass it through....I was impressed to say the least...

The whole experience left me wondering if the Supervisor was that well trained by the TSA, if she was an Astronomer herself, or if the Nagler family had personally carried enough of their eyepieces through the Newark airport over the years that she had seen them all at one time or another.

Just last week I took the family to Orlando for a Disneyworld vacation. I hand carried a set of Oberwerk 22x100 binos in a Pelican 1510 on rollers. (I checked the parallelogram/tripod). TSA at DFW inquired what was in the Pelican case as I placed it on the conveyor, but never opened it. TSA at Orlando never asked me anything. Unfortunately the weather didn't allow me to use them :S But then again I was pretty happy to hit that pillow after 10 hours of walking every day too 8)

I second Mark's opin on Oberwerk. They are very well built and have a long history of good reviews if you look around (Here on A.M., C.N., or simply through a Google search).

1089 is putting on a great show today here in Texas. 1089 is presently made up of two large spots with numerous smaller spots spanning the distance in-between. I setup a recently acquired TV-85 with the Baader Herschel Wedge equipped with a Solar Continuum filter. I looked at it with a number of E.P.s with the best view being a 3.5mm Nagler and a polarizer filter. The filiments reaching from the penumbra across the umbra are easily observed at 170x. The atmosphere was fairly steady.

Come take a peek!

The key difference is that Powermates are telecentric lenses. For Solar System imaging this is an important feature.

Televue excerpt:

Powermate™ vs. Barlow

To understand the Powermate, we must first understand the Barlow lens. Barlows amplify the power of a telescope. They can be considered “focal reducers” for eyepieces, or “focal extenders” for objectives. Terence Dickenson, in his Barlow test report in Sky and Telescope, July 1997, says: “Technology has erased the old objections. A modern Barlow will not degrade your telescope’s optics. Anyone telling you otherwise is using outdated information. Moreover, the highly regarded Nagler eyepieces and their clones have built-in Barlows, ample evidence that the lens is not some detrimental intruder.” Thanks, Terence, for laying the myth of the degrading Barlow to rest.

A high quality Barlow must be properly designed and manufactured in order to avoid compromising a telescope’s color and spherical aberration corrections. The “invisibility” of Televue’s 2-element Barlows has been noted in test reports in the astronomy magazines. However, by the nature of its negative power lens, a Barlow will do more than just increase magnification, regardless of the number of elements.

The diverging rays leaving the Barlow result in moving the exit pupil further out, thereby extending the eye relief. In short to medium focal length eyepieces the change is not noticeable. However, in the case of long focal length eyepieces, the increase can be significant and not without performance consequences.

Vignetting can occur due to the altered ray path, when the eyepiece’s lenses are not large enough in diameter to allow all the rays to make it through. Shorter Barlows, or ones with too much magnification, only exacerbate the problem because the ray path entering the eyepiece is steeper.

We had to go beyond the Barlow concept to achieve the goal of a compact, high power, fully corrected image amplifier. The Powermate™ consists of a negative doublet plus a positive “pupil-correcting” doublet. This 4-element system provides the magnifying function of a Barlow without its limitations by restoring the field rays back to their original direction, as if the Powermate™ were not there. The result is a pure magnification increase.

Unique Benefits and Applications for Powermates™

* Vignetting, edge field aberrations and pupil movement - all introduced when using Barlows with long focal length eyepieces, are minimized.

* Telecentric operation (field rays leave parallel to optical axis, unlike Barlow lenses which diverge rays). This is ideal for Hydrogen-alpha filter use such as with Daystar models.

* High performance for image amplification, CCD or film (some of the finest Earth-based planetary imaging is being done with Powermates™).

* Flexible for visual and imaging with all types of telescopes and eyepieces. Essentially Parfocal, and with nearly constant magnification regardless of image distance behind top surface (except 5x model which increases 1x for every 35mm of image distance increase).

* Higher magnifications are possible with high optical performance compared to “doubling up” Barlows.

* All will reach parfocal point in star diagonals, except for the 2”, 2x which comes very close.