Quote:
Originally Posted by bojan
Jethro,
Regardless of sensor size, you will be getting drift after couple of seconds of exposure with this particular focal length.
It is simply the consequence of Earth rotation, 15° per hour (or 15 arcsec per second), at celestial equator.
That means, with 100mm FL lens, (and M42 is close to equator) you will have drift ~4.85um per second (which is close to your pixel sze, 3.88um).
With longer lens, that drift will be proportionally longer, and it's value does not depend on the sensor size, it depends only on FL of the lens.
With 2.5 sec exposure, you have drift of 12 arcsec, or ~3.12 pixels on your photo (see below),
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So, really from that, is there "optimal drift" until I get the tracker going?
I think I have been wrongly trying to "eliminate it" when really, I will always have it given the current Setup. I have been seeing drift and thinking "exposure time too long".
Switching to a 35mm lens again would allow longer exposure but less resolution, what would be better for dss stacking / final quality?