Astromart

I've been using a Canon SX50 IS for a couple of years now, largely for bird photography. Lately I've been experimenting with lunar photography. When mounted on a tripod its 1200mm 35mm equivalent focal length optical zoom is quite adequate to produce nice shots of the Moon.

Here is one from last night. It was cropped and tweaked a little in Adobe Photoshop Elements.

March 18, 2017 08:15 PM Forum: Solar System Observing

Daytime Venus

Posted By Alan French

I've been having a lot of fun watching Venus for the past few weeks. I look from the deck on the east side of our house, safely set up in the house's shadow, when Venus is due south and highest. Today's 2.7% illuminated Venus was lovely.

I also catch it in the western sky just after sunset. The crescent is easy in 12x36 IS binoculars and visible in 8x32 binoculars if they are steadily held.

Clear skies, Alan

October 5, 2002 12:45 AM Forum: Birding Optics and Photos

Favorite Birding Binoculars

Posted By Alan French

I had a pair of the older Porro Fujinon 8x40 BFLs, which were nice, but I got the bug for something really nice. After three years of checking binoculars, I wound up with a pair of the Swarovski 7x42 SLCs. There were the right "fit" for me, but others will certainly have different favorites. Anyone searching for new binox should make sure to "try before you buy."

November 6, 2002 12:53 AM Forum: Zeiss

Zeiss 100 mm Huygens Eyepiece

Posted By Alan French

Hi Markus,

Interesting and somewhat puzzling. On a telescope of 2327mm focal length, this eyepiece would yield a field a bit over 3.3 degrees across at 23x. This implies an apparent field of about 76 degrees - awfully wide for a Huygens.

Was this eyepiece for some specialized purpose?

Clear skies, Alan

November 9, 2002 09:57 PM Forum: Telescope Making

Herschelian Relflecter?

Posted By Alan French

The Herschelian does not use a flat mirror - a flat mirror will not form an image. The Herschelian is simply a Newtonian design without a secondary, so the primary is tilted so that the image can be examined with an eyepiece without getting the observer's head into the path of incoming light. Since the primary is working off axis, the images suffer from coma and astigmatism. You can minimize this by using a very long focal length primary. Modern versions may use primary mirrors that are off axis sections of a parabaloid, or may use some type of corrector to control the aberrations.

November 27, 2002 04:35 PM Forum: Equipment Talk

Planetary scope specs

Posted By Alan French

The design is less important than making sure you get excellent optics. The advantage to the longer focal lengths, as others have mentioned, is the ability to get high powers more easily. In reality, though, there are modern eyepieces of very short focal lengths, so this is less of an issue than it used to be. I feel that tracking, whether it is an equatorial mount, a computer drived altazimuth, or a Dob on an equatorial platform, is highly desireable for serious planetary observing. I used a "hand driven" Dob for years - and I would not go back to that era. The driven scope is just so much better for prolonged viewing and attempts to see subtle details, IMHO.

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Posts Made By: Alan French

Supernova in M82

Eastern Kingbird

Nice Prominences Today (Sat, Nov 15)

Solar Prominence Fri, April 15

Lunar Photography: No Telescope Required

Daytime Venus

Favorite Birding Binoculars

Zeiss 100 mm Huygens Eyepiece

Herschelian Relflecter?

Planetary scope specs

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