Archive for March, 2009

Bahtinov grabber for any camera

Sunday, March 22nd, 2009

This simple application just grabs an area of your windows screen and finds the focussing accuracy:

download: Bahtinov grabber (13314)

Cloudy Nights Thread on this tool


It updates 10x per second, so you can also track a live viewing window, or a youtube movie:


An the latest additions:

- the error now has a sign (positive or negative)

- a red ball clearly indicates the direction of the error, indicating in which direction to adjust focus

- the average error of the last 5 seconds is shown, helpful in poor seeing conditions

Bahtinov mask from 3D printer

Sunday, March 22nd, 2009

Works fine for the tele lense. Note that the spacing of the grid is just 1 mm!


M81, M82 and NGC3077

Saturday, March 21st, 2009

Through light pollution and fog, still well visible. Not optimally focussed.

Nikon D90, 200mm F/2.8, 13x 30s, ISO200, 100% crop:


First Saturn of 2009

Friday, March 20th, 2009

The rings are much more closed than last year.


Comet Lulin next to M44 (Beehive cluster)

Saturday, March 7th, 2009

Much harder to image than I expected. Though a nearly full moon (77%) and  a lot of light polution should have been an indication that it would not be easy: 30s exposures, ISO200, 200mm F/2.8 on Kenko Skymemo

around March 6 2009, 2000h UT, when Lulin was closely passing a magnitude 9.7 star (GSC 1383.160)