Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_30_second_exp_2_winners.thumb.jpg.b5430b40547c40d344fd4493776ab99f.jpg

Dyptorden

Maximum exposure time for untracked mounts

Recommended Posts

Math is not my strongest point but i think the error is in the pixel size, you're using megapixel not pixel size in micron

Share this post


Link to post
Share on other sites

Your formula sharkmelley :

star_trail_length_in_pixels = focal_length_in_millimetres * exposure_time_in_seconds / pixel_size_in_microns / 15

Is the same with :

exposure_time_in_seconds = star_trail_length_in_pixels * pixel_size_in_microns * 15 / focal_length_in_millimetres

My Nikon D40 has a 23.7mm x 15.6 mm sensor size and 6MPixel

According to the formula : Pixel_size = 1000 * sqrt (sensor length * sensor width / number of pixels) , it results that my camera has a 7850 pixel size.

The telescope has a 1200mm FL

So the exposure_time_in_seconds in order to get a 1 pixel star_trail_length_in_pixels :

exposure_time_in_seconds = 1 * 7850 * 15 / 1200 = 98.125 seconds?

I can't really believe it.... where's the mistake?

Did some search and the D40 is 7.78microns, with that formula it gave 0.097 seconds.

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.