Star Tracker and Manual Focus lens

sarge1776 · 05-05-2016, 10:10 PM

Does the k3 II star tracker feature work with manual focus lenses? I have a Rokinon 14mm that was recommended in an astrophotography forum...but serious star trails are showing up. Thank you for any info provided...

Adam · 05-05-2016, 10:15 PM

Originally posted by sarge1776

Does the k3 II star tracker feature work with manual focus lenses? I have a Rokinon 14mm that was recommended in an astrophotography forum...but serious star trails are showing up. Thank you for any info provided...

Yes it does, however with really wide lenses like that, distorted corners are to be expected due to the way that the stars move in the frame.

dakight · 05-06-2016, 05:23 AM

Manual lenses are no problem. Some star trailing can occur, primarily low on the horizon. The problem is that the sensor moves in a linear fashion when astrotracer is enabled but the stars in different parts of the sky move at different apparent speeds. Stars low on the horizon, particularly those to the south for people in the northern hemisphere, appear to move faster than those high in the sky. The actual center of rotation is the North Star and the further away from that you get the greater the discrepancy in apparent motion of the stars.

05-05-2016, 10:10 PM	#1
sarge1776 New Member Join Date: May 2016 Photos: Gallery Posts: 16	Star Tracker and Manual Focus lens Does the k3 II star tracker feature work with manual focus lenses? I have a Rokinon 14mm that was recommended in an astrophotography forum...but serious star trails are showing up. Thank you for any info provided...

05-05-2016, 10:15 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,597	Originally posted by sarge1776 Does the k3 II star tracker feature work with manual focus lenses? I have a Rokinon 14mm that was recommended in an astrophotography forum...but serious star trails are showing up. Thank you for any info provided... Yes it does, however with really wide lenses like that, distorted corners are to be expected due to the way that the stars move in the frame. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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05-06-2016, 05:23 AM	#3
dakight Veteran Member Join Date: Sep 2014 Location: Phoenix, AZ Photos: Albums Posts: 1,216	Manual lenses are no problem. Some star trailing can occur, primarily low on the horizon. The problem is that the sensor moves in a linear fashion when astrotracer is enabled but the stars in different parts of the sky move at different apparent speeds. Stars low on the horizon, particularly those to the south for people in the northern hemisphere, appear to move faster than those high in the sky. The actual center of rotation is the North Star and the further away from that you get the greater the discrepancy in apparent motion of the stars.