在屯門海濱長廊影的日偏食

mca

食甚時黑子被月球遮蓋，食甚後黑子再現，不過這時行不開影相了。

Alan

daniel

good job!

jojomamani

Thx! Alan,

It's a decent documentary of this partial eclipse, simply but essential!

I saw the sun spot on the 12th evening  for a test run as well!
but I didn't record the sunspot that detail! I'm using the etx-90
as well! Just wondered what I was missing.

Will it be the sun was too low to the horizon to faint out the details?
or your sunspot one was do it at a respectively high attitude?

mca

Hi jojomamani,

The sunspot was cropped from the same frame of my solar image, when the Sun was 38 degrees high. Focusing must be very precise if you wish to capture any sunspot details. I did this by trials & errors, then selected the best focused frame to process with Photoshop. Here is the original frame from Canon 350D (frame size 3456 x 2304 pixels or 22.2 x 14.8 mm)




Note that the focal length of ETX90 is not fixed (a feature of all back mirror-focusing Maksutov/Schimdt-Cassegrain telescopes). If you measures the solar disk diameter in the image, it is 93 % frame height = 13.8 mm in true size. The angular diameter of the Sun at the eclipse day is 0.542 deg. So the focal length of ETX90 is 13.8 mm / sin 0.542 deg = 1460 mm. This is obviously longer than the 1250 mm focal length quoted by Meade. Such long focal length is approaching the full frame size of 350D. I needed careful positioning of the Sun’s image in the 350D’s eye-window; otherwise the Sun’s disk will be off the frame !

Alan

jojomamani

Thank you very much Alan, I just found out today. Might be I was using the eyepiece adaptor that capture the image via the internal mirror. I did a lot of try & error in the focusing process. the image is not as sharp as the one took directly from the rear port. I'll try to use the rear port more instead the easy working eyepiece adaptor way.

Thx for sharing!