Posts Made By: Roland Christen

It's almost always lateral color in the eyepiece, especially if it's yellow on the limb at low power. Simplest thing to do is to leave the Moon right where it is in relation to your telescope, and physically move the eyepiece over sideways so that the edge of the Moon is now in the center of the eyepiece. Color will be gone. This tells you that the eyepiece introduces the lateral color. (so you can't move the eyepiece over sideways 'cause the 1.25" hole is round and not oval? well just remove the adapter and hold the eyepiece in your hand).

By the way, folks, this is the single most common problem that just about every beginner experiences when looking at the Moon for the first time at low powers with a wide field eyepiece. The other common problem is that stars look oblong or have flares coming out of them at low power (mysteriously this disappears at higher powers). Anyone like to guess what causes that? (how about the objective is out of collimation with a low power eyepiece and somehow senses that you placed a high power ocular into the focuser and rights itself magically so that the high power view is correct).

Rolando

Unfortunately, for astronomy it has a fatal flaw.

Rolando

>>So what is it....misscollimation? Too bad in that case as C80ED can`t be collimated as far as I know >>

It is a slight amount of miscollimation, but no amount of tilting of a lens cell would fix this. The problem is that the three spacers are not quite exactly the same thickness. The way to get it perfect would take a long time for a properly trained technician to do, and that would have cost more in labor costs than you would have wanted to pay.

Rolando

Excellent colors and nice detail.

Rolando

Here is a first report, posted on the AP user group, from another customer who has had a chance to test it on the night sky - testing for periodic error and guiding ability. Basically the accuracy is in the Paramount range, and I am quite pleased that they went together so well for us (after almost a year of 120% effort on all our craftsmen involved in its development).

Rolando

Here are the first test results for my new Mach1 GTO SN#18. First
the equipment and software:

AP155 EDFS at f/7
Mach1 GTO w/ flat plate adaptor + two 9lb CWTs (at very end of shaft)
Pier Tech II pier fastened into a 18" x 70" concrete footing
ST-10 XME w/ CFW-8
Pyxis Camera Rotator
Custom Auto Focuser

Software products are: PemPro, Sky, Maxim DL/CCD, FocusMax,
PoleAlign Max, PulseGuide.

I balance both axes (to with a few pounds on RA axis. I need a few
more pounds or an extended shaft for this combo).

I initilized with PulseGuide, then used FocusMax and PoleAlign Max
for accurate pole alignment (about 1 arcminute). The seeing was
about 3/5. I pointed at a star at 0 degree DEC near the meridan to
test the mount's periodic error.

Via PemPro, the periodic error was +1.6/-1.6 arcseconds right out of
the box using the AP155 at 1.27 arcseconds per pixel. With PemPro
and using 2 worm cycles of data and PEC on, analysis showed +.65/-
.65 arcseconds of error with an rms error of .55 arcseconds. I did
not add a second refinement curve.

Conclusion: Excellent product AP guys! Big 'scope festooned with
usual CCD gear on the mid-side mount did just fine.

I would suggest that you have a knowlegeable person test your scope. The descriptions that you gave leads me to think you are misinterpreting the star test. I believe you are getting confused by the different star patterns, some of which are due to eyepiece aberrations and some due to a person's eyes.

Rolando

Sometimes you will get 4 color crossings if the index data used in your calculations is only to 5 decimal places, however when you use 6 place data, there will be only 3 crossings. The number of crossings is not important, rather what you want to see is overall color error or the percentage defocus over a large wavelength spectrum. You could theoretically have a 2 color crossing lens that has better performance than a 3 or 4 color crossing lens.

Rolando

I like driving my new Pony car very much. It really is a sweet little performer. I will try to not crash it.

Rolando

Thaks all. The bulk of the work was done by Ray Gralack shooting near San Jose in less than pristine skies (fair amount of light pollution). Scope used was 160EDF operating at F5.7. The core was shot with my 10" Mak-Cass here under the Target/Builders's Square light dome nearby my observatory. It shows that you can still do meaningful astrophotography even if you do not live in the sticks.

By the way, the comet looked about as bright as M13 in my 15 x 70 binoculars. I could not see much tail because of my local light pollution.

Rolando

That is a gorgeous image! You are fast becoming an expert in narrow band. Your images all seem to have superb processing.

Rolando