Originally posted by cheekygeek A lens that is fine enough to do astro images AND close focusing/macro images and for under $100 is a no-brainer! The "slowness" of the lens is less of an issue with the high-ISO performance of today's Pentax also! (My 54B will be here in a couple of days. I found it for $79/shipped!)
Congratulations cheekygeek,
True, I have been using this lens a lot for Lunar and Solar photography (together with a 2X Tamron SP teleconverter to which the Model 54B responds very well) - but not so much for starfields and deep-sky, because my favourite 300'is lens here is my Tamron catadioptric 350mm f/5.6 Model 06B - it is a hazzle to focus focus properly, but it is just sooo wonderfully free of any abberations.
In fact, I had to go back to 2012 to find some test images just after I received my O-GPS1. I have now done some stacking (never came to it back then) and found, that the Model 54B may indeed have its place in my future arsenal for certain deep-sky photography too. A few samples:
Orions Sword. 5 Images stacked in DSS: 15 sec. at f/5.6 and ISO 1600.
M13 in Hercules. 19 images stacked in DSS: 25sec. at f/5.6 and ISO 1600
Pleiades. 35 images stacked in DSS: 20 sec. at f/f.56 and ISO 3200
All images taken with my Pentax K-5.
The lens does produce some fringing, typical for many photographic lenses, around the brighter stars, but this is easily manageable in post-processing.
Enjoy you Model 54B when it arrives cheekygeek!