So what is the problem with the 102F6....

Started by Doug Peterson, 05/04/2004 09:06PM
Posted 05/04/2004 09:06PM Opening Post
For those of us who came late, I gather that some people are upset about late, or very late, extremely late, deliveries, but in addition, what actually are the technical problems with those delivered? Is the baffling stopping down a problem? What is that problem? Spherical abberation, chromatic abberation, astigmatism? Are there people also happy with their scopes?

"--Granted, that's a worse case scenario. The destruction might in fact be ... limited to our own galaxy."
Posted 05/04/2004 10:24PM #1
all the above.... (grin)

All were stopped down with baffling. The argument is anywhere from 76mm to 90mm depending on what calculations you use.
A few had astigmatism so bad it wasn't usable.
Others had bad yellow hallows and some not so bad..
Some had shipping damage to focusers etc..
The crosshairs on the finders turned out to be to dim to see and some objectives cells on the finder came unglued..

Most were able to be fixed by the do it yourselfers..( me being one)But some were unfixable and they are waiting for the new lense.

Then there are those like me who received a reasonable scope and am happy... I will be getting the upgrade when available.

I don't think I missed anything..

Other than the fact that Bill is "not" making any more of these... He is just trying to fill the semi-apo order at this point. The current 102f6 owners can upgrade to this lens..

Mark Visser
Posted 05/04/2004 10:25PM #2
Doug, These lenses are stopped because of a figuring problem with the outside edges of the lens (I believe). This problem was known before we opted to receive our scopes a.s.a.p.. We are all waiting for the replacement lenses when they are available.
In the meantime, I am fairly satisfied with the views through my 1026. I have since removed the rear baffle and replaced with a 87mm aperture stop over the dew shield. This works pretty well as I have taken this scope up to 250x with decent results. Low power is better though. This scope is better than my 80mm F/5 skywatcher. Much clearer and sharper and less color problems. The view through the skywatcher is milky looking in comparison. Therefore it has become my grabber scope. Looking forward to the improved lens however, as this will be a great scope then. Yes, for 150.00 I am satisfied. Charlie
Posted 05/04/2004 10:44PM #3
Hi Doug:

I have a Burgess 102F6 and will respond mainly from my experience with it.

The 102F6 OTA's come with the second baffle sized and placed to stop the 102F6 to a working aperture of approximately 70mm (F8.6). This goes back to September 2003 when Mr. Burgess noticed a yellow halo around the image of Mars while he was star-testing the first batch of 12 OTA's. After iterating with the factory to reduce or eliminate this problem, he announced (roughly last November) that he was going to replace the lens with semi-apo lens of a TMB design (current estimated color correction = 2.7 that of a normal achromat). They are supposed to be available within a couple of months. Meanwhile,if you didn't want to wait that long, you could buy a stopped down 102F6 for $150 ($200 with case). The lens were supposed to be stopped to 90mm but it's been shown that the lens are stopped to 70mm (I confirmed this for my 102F6 with the exit pupil test using a 40mm Plossl).

Since then, some people have left their scopes at 70mm and are OK with this. One gentleman has removed the stop (as I'll call it now and made a 88mm mask for his OTA). He is very happy with his observing sessions with this. I've simply have removed my stop and allow my OTA to work at full 102mm aperture and at F6. Basically, I'm fine with this while I wait for the semi-apo lens. Here's the lowdown on what I do and don't see with it.

Saturn (100X) - nice image with 3-D hint to it. I believe this is because I see the shadow the of the planet on the rings or vice-versa. Cassini's Division is more of a challenge but I do see it on good nights (like yesterday). There is is soft yellow halo but it doesn't get it the way of havving fun looking at Saturn.

Jupiter (100X) - nice image - always see 5 bands - usually see 7 bands. Have on good nights seen hints of swirls in the bands. Limitation: I've seen the beginning and end of moon transits but not quite the middle;, i.e., haven't seen the moon shadows on the planet. There is more aura but it's acceptable, I've learned to block it out.

Venus (100X) Let's just say I'm glad I'm not interested in Venus. The yellow halo at 100X is to me intrusive - makes the image look like a flower (disc in the middle).

Sirius - see Venus notes.

Castor: This is a double with 2.2" separation. Here's another limitation for me. I can get a Dawes' split but not a Raleigh split. It does fine with Mizar but that's 14".

Open Clusters - Wonderful: M44 and M45 at 15X, and 35-M38, M41 at 100X - can see roughly 100 stars apiece.

M42 - Nice at 100X. On good nights have seen 5 stars in the Trapezium.

(Summary in later note).

Mark Costello
Matthews, NC, USA

"I hear you're mechanically inclined. Did you ever do anything with perpetual motion?"

"Yeah, I nearly had it a couple of times."