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Showing posts from August, 2012

Hate how airplanes wreck your star-trail images?

Hate how airplanes wreck your star-trail images?

Me too, here is how to clean them up without the trouble of cloning or healing.
For those in my #astromentorship  group and those who already know how to stack star-trails, the below image should explain it all.

With the 4 images below, the top two are already stacked, the bottom two are the same frame that was used to stack the image above it.

As you notice, the stacked image on the left, has the trails from the airplanes, the image below it shows one of the frames containing the airplane trails.

In the lower right you see the single unstacked image where the airplane trail has been erased.  Using the paintbrush and black paint works the same.  Above that image is the stacked image where all of the plane trails were done in this manner.  If you notice, you can't see any trace of where the planes were.  This is due to using the blending method "lighten" when stacking.  This method of blending takes all the lightest information …

The "Top Secret" "Rule of 600"

Ok, it's not secret at all, but is sure is asked about a ton!

One of the most important things when it comes to good looking landscape astrophotography shots is crisp round stars.  This is achieved by knowing how long you can keep your shutter open without having the stars move (trail) in the image.
I recently posted an image on G+ and a question was asked in the replies.  The question was regarding something called the “600 Rule” or the “Rule of 600”.

It isn’t some secret code among astrophotographers….. Oh wait…. Forget what I’ve said until now, there is no rule of 600, it doesn’t exist, enter the Men in Black…….

Seriously, there isn’t some great secret, there is however a bit of math, which some may find as scary as a visit from the “Men in Black”.

Ok, here is the meat and potatoes of the 600 rule.

600 / Real Focal Length = Maximum exposure before trailing occurs.
Confused yet?  I thought so……

Lets use a real world example.  I shoot with a Nikon D7000 which uses a 1.5 crop sen…