____________________________________________________________________________________________________________________________________

VOL XVII, NO 4                                                   APRIL 2002                                               Scott Petersen, Editor
____________________________________________________________________________________________________________________________________

©2002 BMAA, Inc

BMAA will be celebrating Astronomy Day on Saturday, April 20 starting at 10:00a at the Churchville Nature Center Earth Day Festival. We will have an info table and telescopes on display and we will feature our stand on light pollution. That evening starting at 8:00p, we will host a public StarWatch at Goodnoe's Restaurant in Newtown. We need club members to help at these exhibits, so volunteer for a day with the club.

After last month's publication of a list of Stella Della Valley door prize donors, Ed Radomski dug up a few more that had not been listed. My personal apologies for this oversight. They are as follows:

Clear skies,

Alan Pasicznyk

/

bmaa@ixc.net

Submission deadline for articles is the 15th of the month prior to publication.

SCOTT PETERSEN
CONSTELLATION EDITOR
WYCOMBE PA 18980-0333
TEL: 215/598-8447
FAX: 215/598-8446

 ___________________________________________________________________________________________________________

 2002 Calendar of Events

StarWatch Chairman: Antoine Pharamond, 215/412-9291 apharamond@comcast.net

President - Ed Murray, 215/493-2843 edward12@erols.com

Vice President - Antoine Pharamond, 215/412-9291 apharamond@comcast.net

Treasurer - Ed Radomski, 215/822-8312 ejrado@prodigy.net

Secretary - Ken Wieland, 215/362-7228 wieland7@netreach.net

Ach recently bought a miniature video camera from Intellicam, listed as a 'spy camera', with a very low light sensitivity of 0.03 lux. I have no real idea what a lux is, it may be the light of a standard candle at 10 feet. If anyone, knows for sure please pass it on as I am much too lazy to look it up.

These spy cams are truly tiny, this one measuring just an inch square and about 1/2 inch deep, with a removable mounting bracket making it about 1 1/4 inch. The lens (a true lens, not a pinhole) is focusable from about an inch, which gives a low power microscope view, to infinity. The lens is fairly sharp, but is badly afflicted with distortion. With an aperture of 1/32 inch and a field of 90 degrees, this is not surprising. Note: distortion is an aberration which causes a line, although straight if crossing the center of the field, to bend either inward or outward as it is moved toward the edge; many binoculars and low power scopes, like finders, show this, as do many wide field eyepieces.

These mini-cams come with an AC power pack, or can be used with a 12 volt battery. Using a battery would require an additional cable, not supplied.

The output is black and white 'video' via RCA plug, and can be input to a VCR to record, and to a TV equipped with a 'video in' jack. The resolution is 430 scan lines to the screen, but I am not sure if its interlaced or not. Unfortunately, there is no adjustment for gain, contrast or gamma as in more expensive models.

I had hoped to see real time video of the moon and planets. Well, if you were at the March meeting, you would have seen the little gadget is a surprising success.

The camera was used with my 4.5" refractor of 64" focal length input to a 13" TV via a VCR. At the focal plane with the camera lens removed the image of Jupiter is about 2" across and with a Barlow is enlarged accordingly. The image of Jupiter is so bright I found it necessary to use a density filter to knock down the intensity, and even tried a UHC filter which worked fine. It also sharpened the image by eliminating some of the out of focus infrared to which these cameras are very sensitive. The image of Saturn is fainter, and is usable without the Barlow.

Although the night when the video tape was made was anything but good, Jupiter showed some detail in the bands, along with the dark spot in the North Equatorial Belt which is currently on the other side of the planet from the Red Spot. On another occasion I had seen the Red Spot clearly. Saturn's Cassini division was easy, as was the crepe ring and a band or two. Fiddling with the contrast and brightness controls of the TV helped the visibility of the detail .

The moon at the focal plane is much too bright and requires a density filter, again the UHC doing the trick. I was amazed at the detail and contrast. Although not as sharp as naked eye, perhaps it would approach what could be seen with a larger scope and more magnification.

If a capture card were used the frames could be stacked and processed and would certainly then be near the limit with the scope used visually.

I have since made a few lenses to fit the camera, the most usable astronomically being a 50 mm focus lens of 0.75 inch aperture, which with I found the camera will apparently exceed naked eye limit. The belt stars of Orion were easy, and the nebula was visible, though not very bright, even though the night in question was hazy. I have not tried any further experimenting since, but am eager to see what it will do. For stars focusing is extremely critical, as the camera automatically tries to set it's intensity level. If there is a bright star in the field and the camera is out of focus, the fainter stars will be lost. The same goes for Jupiter's moons.

In a test on double stars, the components of Castor are clearly shown separated, again in poor seeing. The current separation of these is about 4 seconds. This was done at the focal plane with no Barlow. I am very eager to try the camera on a good night when the seeing is stable. I am guessing that with a Barlow of about 3X the detail on the planets will be pretty close to what can be seen through the scope with the eye.

Eyepiece projection (afocal) has just been tried for short time, and may be better for enlarging or reducing the image size, but alignment is very critical due to the small aperture of the lens. Perhaps the 50mm lens will help in this, but has not yet been tried. Some night when I feel like fiddling will come along.

Plans are to bring the gadget to the April meeting and hook it up to a C8 or similar, which won't have the uncorrected color of a doublet refractor. The planets should look pretty good. The drive on these scopes will also keep the target centered much better than my homemade drive, admittedly crude and geared incorrectly.

The camera lists for $59 complete through Intellicam (dot com, in Cincinnati) but I got it on Ebay for $39 plus shipping when they had it listed.

I have no experience with color versions of this type of camera, but I do know the resolution is somewhat lower and the light level sensitivity is about 0.5 lux. Perhaps this will improve soon. Even at that, a color model would be sensitive enough for the brighter objects in the sky.

A camera like this would be terrific at public star parties, as it shows a number of people a view at the same time and is part of the modern information age.

- BMAA member Bernie Kosher provides 'Observing' articles regularly. He can be reached at bkhere@optonline.net. [ -ed]

______________________________________________________________________________________________