I use a Sony TRV-900 3-CCD camcorder afocally
coupled to an ITE 4" f/10 Astro-Rubinar Mak-Cass scope through a U.O. 32mm
Konig e.p. straight out of the visual back, with camcorder and scope bolted
to an aluminum rail center-mounted on my Polaris GEM for all but three
of the images here, and a new 6" f/10 Intes-Micro Alter-M603 with
the Sony for those. Because of the Sony's ability to integrate exposures
down to 1/4 sec., you can work at a greatly expanded image scale with these
smaller scopes: compared to the video standard 1/60 sec., 1/4 sec. is 15X
or about 3 magnitudes greater in image brightness. The little 4"
easily images mag. 9 (Polaris' companion), while the 6" goes to at least
10.4 (Saturn's Dione). And I can see much more lunar and planetary
detail on the Sony's flip-out screen at high magnification than I can at
300X through the
eyepiece of either scope.
I initially developed this rig for recording
the June 21, '01 African solar eclipse - it was the only way I could
figure to get both overall and detailed shots with the same instrument
in those three and an half minutes of utter wonder and panic! By
putting the Sony in manual mode with aperture priority (wide open), and
pressing the "Exposure" button, you get thumbwheel shutter speed selection
of 1/4000-1/60 sec, and by further turning the wheel when 1/60 sec. is
reached, gain is increased in 3db steps from -3 to +18db, for an enormous
dynamic range of exposure, along with the 12x range of image scale with
the zoom - at the tips of two fingers! Those incredible Zambian kids
hooted and hollered along with me when that magnificant detached flare
bloomed on the 3.5 inch screen! But I made the mistake of not taking
a substantial mount with slow motions, as the med. weight tripod with pan
head was almost impossible to accurately locate at full zoom - it was bump,
nudge and hope the area of interest drifts into view when the shaking stops!
The overall eclipse pictures are taken at a little above mimimum zoom (which
is about 1200mm EFL), while the shots of the chromosphere and prominences
are near max. 12X optical zoom (EFL of about 14,400mm). Exposure times
varied from 1/60 sec with 0db gain for the corona (actually merged intermediate
and full coronal images), to 1/4000 sec, -3db gain, and the internal ND
filter on for Bailey's Beads.
A practical advantage in of the rig in high EFL
imaging of planets, etc., is the ability to locate the object at min. zoom
using a simple red dot pointer; then just keep it centered on the screen
as you zoom in to "stupid high powers" for capture. My ancient Polaris
GEM with fixed RA drive works fine, though a stepper drive with controller
would be nice. For super-critical focusing you can get into digital
zoom expansion: focus, then back out. The lunar and planetary shots
are taken with a 2:1 Barlow at max optical zoom with EFL's of near
28,000mm (no Barlow and EFL about 20,000mm for the 6") and exposures of
1/4-1/30 sec., with gain usually 6db or lower. Progressive scan mode
is automatic at speeds below 1/60 sec and selectable at higher speeds (used
for all images here). During frame-by frame review, images were captured
to the Sony's removable memory card in VGA format, mildly compressed to
a JPG file size of about 160kb. You are limited to this format for
internal capture, but I've compared these images to those captured through
the Firewire output in BMP format with 900kb file size and can't see any
difference. All images here are single except the view of Saturn,
which is a stack of seven - I've tried a little stacking of Jovian and
lunar images but find as much detail in single highly selected frames.
But I could just be lazy!
For those interested in taking a look at the
LZOS Astro Rubinar 4", I've not seen it offered stateside by anyone recently
but ITE (burnettweb.com/ite). There's an optical review by Mike Palermiti
- it's really as good as he says it is, and I've had mine about two years
now. It was originally designed as a 1000mm f/10 tele lens - and
for this it is spectacular, with full 35mm frame illumination and tack
sharp to the corners even when close-coupled. ITE modifies it for
astronomical use by removing the infinity focus stop giving very generous
back-focus, and certifies it to be of at least 1/4 wave quality.
It throws up a beautiful color-free image - edge-to-edge pinpricks on black
velvet and all that. At about $455, including screw-in lens shade,
T-thread outlet 1 1/4" visual back, diagonal, and a forgettable 26mm ep,
this has got to be about the best bang for the buck I've seen. An
excellent T-thread Barlow is offered at $50. The scope is extraordinarily
compact, measuring only 7" sans shade and diagonal and weighs about 5 lbs.
Two drawbacks: first, the rotating collar  mount
is too "wambly" for serious astronomical work. I fixed this with
four shots of 5 min. epoxy spotted around the aft end of the collar, which
unfortunately prevents rotation but does make it rock solid. Second,
focusing is through barrel-rotation, which is fine for 35mm work, but at
high EFL's a little bit of rotation goes a long a way.
One other technical note: I found the U.O. 32mm
Konig ep has the same OD as the ID of an old 52 mm Nikon filter.
I broke out the glass and, voila!, pressed the ep into the ring for a tight
fit. It then screws into the Sony's lens ring for a solid connection.
A little epoxy around the ring cements the deal. I've tried a couple
of other ep's including a TV 40mm Plossl and an Orion 40mm Optilux trying
to get a more solar corona, but both vignette more than the U.O. does until
zoomed in a bit.
Martian image of 6/4/01, CM= 246, with those I
sent earlier tonite. This image, like all except that of Saturn,
is single, and it raises some questions in my mind. It appears to
me that very fine detail is being shown in Sinus Sebaeus, with and unusual
bifurcation in its proximal portion, as well as a break in the region of
the Edom Promontorium before Sinus Meridiani. Also, the two projections
out of Iapygia at the base of Syrtis Major are visible, as well as Mare
Serpentis and Hellespontis branching up from the base of Sinus Sebaeus.
And there Hellas above Iapygia and the South Polar Hood; Chryse with two
of its small dark spots. Real detail or a lot of artefact?
No unusual processing - just the usual contrast stretching, brightness
adjustment, mild unsharp masking and then a slight Gaussian blur routine.
Its just hard for me to believe that even the best 4" scope could show
this much real detail. The same goes for the Jovian images with the
4" - if you look closely at the NEB, and to a lesser extent in the SEB,
you will see many small red barges - not like anything I've seen on any
images before. And in the Jupiter 2 image, delicate blue serpentine
tracery in the region of  the
NNTeB and NPR, again something I haven't. Jupiter 1 shows some detail
within the GRS, darker in these Jan '01 images than this year.
I haven't really gotten the hang of working with
the Alter 603 yet, and the seeing has been pretty lousy since I got it.
One thing for sure, you've got to leave it out to cool for a couple of
hours before critical observations. I think the great internal baffling
array probably slows primary mirror cooldown by delaying heat transfer
through the tube. The little Astro Rubinar only needs a half hour
or so before its ready to go.
Aristarchus-Schroter's Valley was taken last year
with the Astro-Rubinar 4", with a 2X Barlow, full optical zoom and 1/4
sec exp. in the TRV-900. Those of Hippalus et al and rills and Messier
"A" & "B" were during the recent cycle, with the Alter M603, full zoom
and exposures of 1/15 sec.
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