|
Forum: Pentax SLR Lens Discussion
09-11-2014, 03:51 PM
|
| |
Yes, manual focus can be tricky at night with this lens at the widest settings, and I join in the wish, that this lens had an infinity stop of some kind. But inspired by Tsuken's desire to use it for astro photography, I just made a simple test tonight under a rather hazy and light polluted sky:
Using a bright star, such as Vega in Lyra in the example below, it is possible to get critical infinity focus, using live view and 10X magnification:
.JPG)
K-3 and DA18-135mm astrophoto: Crop near centre of 6016 px wide image with Constallation Lyra and star Vega.
40 secound exposure at 18mm F.L., f/3.5 and ISO 400.
Click to see the non-resized crop (1280 px)
But what about coma then, as also mentioned by Tsuken? Surprise, surprise(for me at least):
.JPG)
Crop from upper right corner of the same original image as used above.
Click to see non-resized crop.
OK, there is a little distortion of the brighter stars, but to me, this is almost incredibly good - far better than I have seen with many (otherwise fine and expensive) primes. I must admit that I had not expected this kind of excellence form a (super)zoom like the DA 18-135.
One final word about the DA 18-135 for night/astro photography: In long exposures, the well known vignetting at 18mm and wide openings may become VERY pronounced: For astro photography, I would definitely recommend stacking including the use of flat frames.
|
|
Forum: Pentax SLR Lens Discussion
09-02-2014, 03:42 PM
|
| |
I just (also) love the DA 18-135 for its close focus capability.
DA 18-135 @ 135mm on Pentax K-3. 1/200s, f/5.6, ISO200:
Sharp enough for me to allow for some tight cropping:
 |
|
Forum: Pentax SLR Lens Discussion
03-26-2014, 02:52 AM
|
| |
.JPG)
Pentax K-3; DA18-135 @ 135mm; 1/800s; f/6.3; ISO 400 (: deliberately underexposed a bit to enhance the sun rays)
|
