Something moved during my night sky shot

[Bigshot]

Hello,

I recently want to learn night photography of the sky. I had my first experience but the results were disappointing. I have a Canon 5D Mark IV with 24-105mm 4L Canon lens. Here are the settings for my photo. Manual mode, exposure 25 s, aperture F4.0, ISO Auto. When I examine my photo (below), I found that something was moving during this long exposure but I have no clue where to look and correct. Can someone help me out? Thanks in advance.

[kvbarkley]

The earth was moving. 8^)

If you want to use long exposures without getting star trails, you need a tracking mount.

[Bigshot]

Thanks for your comment. However, I do not thinkthe problem is due to earth moving since in that case, I would get a uniform streak. My photo shows 3 dots indicating the movement is not uniform. I was suspecting that it was caused by pressing the shutter botton. I tried to use self timer. Same results.

[kvbarkley]

Your camera has a mirror lockup custom function for this sort of thing, too.

This is my shot of orion. It was 15 seconds at 150mm focal length. I did all the right things, on a good tripod with mirror lockup and an external shutter release.

[Bigshot · Accepted solution]

Thanks for the insight. Your image shows uniform streak for the stars but mine is not. Could this due to that your focal length is 150mm and relatively speaking, 15 s is way too long as compared to my 24 mm adn 30 s exposure (using the 500 rule)? As a result, I see dots but you see uniform streak? What was your ISO settimg?

[Waddizzle · Accepted solution]

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@Bigshot wrote:

Thanks for the insight. Your image shows uniform streak for the stars but mine is not. Could this due to that your focal length is 150mm and relatively speaking, 15 s is way too long as compared to my 24 mm adn 30 s exposure (using the 500 rule)? As a result, I see dots but you see uniform streak? What was your ISO settimg?

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According to the "500 Rule", you should have used a 20 second exposure, not 30 seconds.

You are looking at star streaks.  That is why you stars have trails, and the star trails are uniform.

[Johnw1]

An equatorial mount will keep the subject centered with no star trails.
You exposure is too long too.

[PhotoGerry]

My latest attempt with comet NEOWISE.  You can see some star tracking.  Either that or I bumped the tripod swatting mosquitoes during the 20 second exposure.  A satellite is visible tracking in the upper right.

A 20 second exposure, ISO 2500, f/4.  5D MkIII with a 24-105 3.5-5.6 IS STM.  This was my first attempt of astrophotography.  I'm interested in hearing about other's experiences.

[Johnw1]

Excellent work!

[ebiggs1]

Here is last night at Hillsdale Lake in Kansas.

EOS 1DX, 24mm, f4, 20 sec., ISO 1600.  You can just begin to see some star trailing at 20 seconds. This is probably the last time for me to get any good shots as the Moon is rising and storms are predicted.. The comet is diming, too.

The red streaks are cars on the causeway. I am using my Canon EF 24-70mm f/2.8L II USM Lens which is an amazing lens.