Samyang 20mm f/1.8 vs. Pentax 15-30 for astrophotography - samples please !

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Dan Paris Regular Member • Posts: 485
Samyang 20mm f/1.8 vs. Pentax 15-30 for astrophotography - samples please !

Hi,

I have just received a Samyang 20mm f/1.8 for my K-1 II that I plan to use for astro work.

My copy is well centered but initial tests are not so encouraging.

At f/1.8 it is quite bad.  At f/2.2 it becomes decent, here is the corner performance :

Samyang 20mm f/1.8 - full resolution corner with K-1 II at f/2.2

At f/2.8 it improves only marginally

Samyang 20mm f/1.8 - full resolution corner with K-1 II at f/2.8

So it seems that there's lot of astigmatism in particular.

I chose this one over the Pentax 15-30 for several reasons : bulk, price, speed, and also because I am not that interested by shooting at 15mm

Do you have full resolution shots with the 15-30m, wide open at f/2.8 and focal length 20mm to share ?

If it is really better I'll probably return the Samyang and take the Pentax instead

thanks !

Dan

 Dan Paris's gear list:Dan Paris's gear list
Sigma DP1 Merrill Sigma DP2 Merrill Ricoh GR II Pentax K-1 II Pentax smc FA 31mm F1.8 AL Limited +7 more
Pentax K-1
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