Originally posted by hnikesch That zoom looks interesting I will keep a lookout for your posts with it.
Hans
Hi - this is some cross posted samples from two C-mount zoom lenses [1,6/4-10 mm] & [1,6/2,8-12mm]:
All PP in camera - just downscaled to 1024x. Both lenses cover the Q sensor at full wide setting. Significant barrel distortion on both at full wide setting.
To be honest I haven't really used these lenses at longer settings than full wide. I tried them [Click!], checked them [Yes, there is a picture!],
then I fastened the zoom at full wide. Cheap Chinese C-mount zoom lenses are a pain (read: impossible) to use the same way as for instance
you would the 02 or 06 or any other "normal" zoom... Everytime you change focal length you will also have to refocus...
no more zooming to tele to set focus, then back out to take pic.
Sometimes even changing the aperture makes me have to refocus (yes, the same focus point as before changing f-stop, not a bokeh issue).
So I'll just leave them at the wide setting.
The lenses look like this [2.8-12mm: weight 140 grammes / 4-10mm: weight 85 grammes]:
Re above see the following quote (thanks to Nater for this clarification!): Originally posted by nater A lens that changes focus point when zooming is called a varifocal lens (there are even some K-mount zoom lenses that are varifocal, though it is not that common). Most manual focus DSLR zoom lenses are parfocal, i.e. they retain the focus point while zooming. There is extra optical design work needed to make a lens parfocal, which is why it's less common with CCTV lenses (and some AF lenses, since it's not as important to think about retaining focus point while zooming in an AF lens).
Focus point changing when adjusting F-stop is known as focus shift, and is something that happens with lenses that let in lots of light (this is common in full-frame DSLR lenses that are f/1.4 and especially f/1.2).
Colour rendition of these lenses: Acceptable. You can't compare lenses like this ($40-50 including shipping) with, for instance, my Samyang 8 mm for K-mount, but on the other hand it's really really difficult to fit a K100D with a fish eye in the pocket like I can with Q....
[
Afterthought: I've never tried the Samyang 8 mm on the Q. Might be a cool replacement for the 01.
https://www.pentaxforums.com/forums/pentax-q/206350-did-you-buy-2nd-q-post224...ml#post2242588
and the marking is Fish Eye CS - didn't notice the "CS" before
]
4 mm Circuit Board - 1/40th sec at (probably) close to full aperture and [Bold Monochrome] on front dial at ISO400 under a lightbulb in the kitchen:
2.8 mm Circuit Board 1/30th sec at (probably) close to full aperture and ISO400 under a lightbulb in the kitchen (adjustment of WB when I developed the RAW):
Pentax Q with zoom C-mount lens f1,6/2,8-12 mm set at appx. 3 mm 1/30th sec and f2,8-4 (?) at ISO400
Pentax Q with zoom C-mount lens f1,6/2,8-12 mm set at appx. 3 mm 1/25th sec and f2,8-4 (?) at ISO400
Thanks/Erik