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Forum: Pentax SLR Lens Discussion
02-13-2020, 07:35 AM
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I own the pentax DA15 which is cool because its compact and light and has nice color; it does have pretty bad field curvature which means stop down to F/8; but objects at F/4 on the edges that are closer to the lens are also in focus which can be used to the photographer's advantage once you understand it! The DA10-17mm fisheye is the other ultrawide I own; its a compact lightweight special purpose lens, but it can be really useful in some cases. The The PF can be removed in post processing....
If I were to buy a rectalinear ultrawide; the Sigma 10-20mm F/3.5 seems to be the best choice (I don't own it) available new for ~$330 or so. There isn't much used supply so prices are inflated for used Pentax ultrawides; the 12-24mm Pentax is overpriced. Pentax doesn't have a light weight rectilinear consumer grade UWA analogous to the Nikon 10-20mm F/4.5-F/5.6 There's also the Rokinon 10mm F/2.8 but its a little bit more expensive then the Sigma; ~$360 new.
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Forum: Pentax SLR Lens Discussion
02-05-2020, 10:05 AM
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Yeah, DA15mm + Pentax 10-17mm fisheye seems like an UWA winner since I already own both. I'm experimenting with defishing more; I discovered painshoppro gets rid of PF/CA pretty well which is the primary weakness of the 10-17mm fisheye.
Pentax mount 2nd hand copies of the Rokinon/Sigma10-20mm are rare and over priced and this is just a hobby for me and I have a bias towards more compact lenses. I have the same conclusion as tokyoscape; and the UWA showdown conclusion!
 Quote: Rokinon 8mm vs. 10mm vs. Sigma 8-16mm vs. Pentax 10-17mm Ultra-wide Showdown Review
It's hard to pick an overall "winner," and even going by the numbers we have an apparent tie. At the end of the day, if you could only afford one (and you aren't an overly demanding and professional pixel peeper), our choice lies in the Pentax 10-17mm fisheye zoom. Aside from the Rokinon 10mm, our reviewer has personally owned the rest of the lenses for over three years each, and yet all he has left is the Pentax after streamlining his kit... |
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Forum: Pentax DSLR Discussion
02-05-2020, 09:48 AM
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I own paintshoppro, and it actually does a pretty darn good job of removing the PF/CA; which means the 10-17mm fisheye is back to being my favorite UWA. I was thinking about getting a 10mm Rokinon or a Sigma 10-20mm, but 2nd hand pentax mount copies are usually over priced and somewhat rare, and I don't do real estate photography so I'm not adding anything else to my lens collection just yet.
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Forum: Pentax SLR Lens Discussion
02-03-2020, 08:48 AM
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what about the Tamron 10-24mm?
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Forum: Pentax SLR Lens Discussion
01-31-2020, 04:35 PM
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Forum: Pentax SLR Lens Discussion
01-30-2020, 02:55 AM
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Great pictures! Do you think 10mm rectilinear APS-C is so wide that it is rarely useful? I didn't realize the Rokinon 10mm was also heavier than the Pentax 12-24mm. I do like the compact DA15, but you have to be aware of its curved focus field which makes it harder to get the corners in focus. And I already have the 10-17mm fisheye. I wish I could rent/borrow an ultrawide rectalinear and get it out of my system.
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Forum: Pentax SLR Lens Discussion
01-29-2020, 09:46 AM
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I was thinking of getting an ultrawide rectilinear lens.
What are folks opinions of the Pentax 12-24mm F/4? Are 2nd hand copies usually pretty good?
The other lens I was looking at was the Rokinon/Samyang 10mm F/2.8, but it is harder to find used.
Then there is the Sigma 10-20mm; Sigma 8-16mm; Tamron 10-24mm; I've heard the Tamron 10-24mm doesn't have great image quality and the Sigma 8-16mm is pricey.
The widest rectilinear lens I have is the Pentax DA15mm. I own the Pentax 10-17mm fisheye, which I use a lot.
- Sheldon
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Forum: Lens Clubs
01-23-2020, 09:56 AM
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I wish it had a little bit less PF; because there is no other compact UWA zoom lens for APS-C other than the DA10-17mm fisheye. The only other compact APS-C UWA is the DA15mm F/4; which isn't always wide enough. If there was a little less PF, I would also use the DA10-17mm at 12mm and defish to 10mm equivalent.
Still love the DA10-17mm fisheye though, just because it is such a compact masterpiece for when you really want to get it all in.
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Forum: Pentax DSLR Discussion
01-07-2020, 07:04 AM
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I guess the fisheye PF is too complicated -- I ran the RAW file w/out chromatic lens correction, and I could see that the original JPG with default settings was better with less PF, but sometimes there's a lot of PF still in the image that the lens profile didn't remove. The PF is the biggest flaw in the otherwise remarkable 10-17mm fisheye.
- Sheldon
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Forum: Pentax DSLR Discussion
01-06-2020, 07:36 AM
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What lens does the K-70 support in camera chromatic distortion correction for? Does this include the 10-17mm fisheye? How good is the PF correction?
- Sheldon
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Forum: Pentax K-1 & K-1 II
12-25-2019, 05:35 PM
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If I have the .PEF file for a multiple exposure; can I recover the two individual images by somehow reprocessing the PEF->JPG for each image separately? I just got my k-70 and I had the newbie multi-exposure setting problem.
I just tried "RAW" development in the camera and there wasn't any applicable option to fix a double exposure ...
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Forum: Pentax K-70 & KF
12-11-2019, 08:07 AM
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Can I turn off shake reduction in a user programmed mode in the K-70?
I have a 150-500mm Sigma lens with built in SR, and I wouldn't mind having a "user defined setting" which would be a 2nd aperture priority setting with in body SR turned off.
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Forum: Post Your Photos!
04-21-2014, 12:54 PM
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amazing very sharp shot. The Pentax GPS unit must have worked well (13 sec).
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Forum: Photographic Technique
04-20-2014, 06:20 AM
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Which is better for an astro-photography beginner, the iOptron SkyTracker Camera Mount, or the Pentax astro-tracer? My primary lens would be the Pentax 55-300mm, as well as 70mm/2.4 and a fixed focus 135mm/2.8. I also have a 150-500mm Bigma.
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Forum: Post Your Photos!
04-16-2014, 01:21 AM
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My attempt, Bigma 150-500mm at F/6.3, 1/5th of a second, ISO3200.
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Forum: Pentax Price Watch
04-04-2014, 02:27 PM
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sold me :) I view the DA35/2.4 as a lighter/smaller normal than the Sigma30/1.4 that I usually use. I might be able to fit the DA15+DA21+DA35+DA70 in the bag all at once.
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Forum: Pentax SLR Lens Discussion
04-04-2014, 08:38 AM
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its listed as in stock at 47th street photo, Sigma 8-16mm f/4.5-5.6 DC HSM Lens for Pentax SLR 8-16
But I'm nervous about getting a decentered lens. Plus, I looked at the photos in the 8-16mm lens thread, and they're not nearly as compelling as the DA15mm photos, so probably I'll stick with the DA15. I also have the DA10-17mm fisheye.
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Forum: Pentax SLR Lens Discussion
04-01-2014, 08:14 AM
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hmmm, maybe I'm maybe better off with the Sigma 10-20mm F/4-F/5.6? The Pentax 12-24mm is too expensive.
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Forum: Pentax SLR Lens Discussion
03-31-2014, 12:41 PM
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Forum: Digital Processing, Software, and Printing
03-23-2014, 08:57 AM
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I found a dpreview thread addressing my exact question. The poster concludes a pixel sharp 200dpi image is indistinguishable from sharp 300dpi image. This also matches my results in the experiment I did after posting this question.
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Forum: Digital Processing, Software, and Printing
03-22-2014, 02:44 AM
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I did that testprint at Costco. From an ideally sharpened source, I couldn't tell 204ppi from 272ppi, even staring with a closeup lens. And 163ppi was very very good, much better than I thought..
The results implies that with sharp lenses, and proper technique, that the K30 at 16"x24" is very close to ideal, at 204ppi. And at 20"x30", at 163ppi, it should look really darn good. The limiting reagent seems to be getting sharp corners, for landscapes, due to field curvature. All of my prime lenses, with appropriate USM have ideal sharpness in the center, at F/8 and F/5.6, and probably F/4.
Even 136ppi for a 24"x36" print would not be a problem, because 136ppi can still look surprisingly good, and because with farther viewing distances, it probably doesn't matter. So, perhaps no need to try stitching.... or 24 megapixels or 4x5 view cameras. I've only printed one 20x30 so far, and that was from my K-x, and honestly, it was already sharp enough for everybody except me. This is my 20"x30" print, from my K-x, DA15, from Austin Texas; sold a couple of them. It has lots of fine sharp detail in the print, but obviously, the detail is limited by 142ppi.
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Forum: Digital Processing, Software, and Printing
03-21-2014, 02:34 PM
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Brooke Meyer,
Do you interpolate to 300ppi before printing (using genuine fractals or equivalent)? I haven't ever tried that.
- Sheldon
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Forum: Digital Processing, Software, and Printing
03-21-2014, 12:42 PM
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What is the ICC profile? I use .jpg, although I do mess with the raw image for better contrast. I sharpen using USM (1.3-1.7 pixels, 50-90%). I do not resize before printing; is it helpful? I avoid overly heavy duty processing that smacks of HDR.
I'll have to try printing a 16x24 on a 20x30 print. It seems like 20x30 is pushing it just a bit with the K30; but I printed a 20x30 from my K-x, and it was good enough that it sold, even though I always pixel peep, and see that the photo needs just a tiny bit more resolution, but nobody else seems to notice. One women who loved the photo is a big Ansel Adams fan, and used to shoot 6x7 weddings as a side career in college, and she really loved the print. Nobody (but me), seemed to notice the photo would look all that much more incredible with a little bit more resolution....
So, anyway, I'm just trying to start shooting more and displaying more photos with the local art club, and I'm experimenting with what the limits of my equipment are. I know from prints I've done that the K30 is more than good enough for really nice 16x20" prints (== 16x24). Also dreaming about K-3 and Nikon D800, but probably not necessary.
- Sheldon
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Forum: Digital Processing, Software, and Printing
03-21-2014, 07:07 AM
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Lets say I take a K30 photo with a prime lens at F/8. Maybe its a DA15 or DA21 or DA70, which I happen to own. Properly focused, all of these lenses are tack sharp at a pixel level (ignoring field curvature issues on the corners). How big can I print it before the print starts to look visibly less sharp then optimal?
Here is another version of the same question.
print an 8x12" from the 4928x3264 native K30 file at 408 ppi.
print an 8x12" from a 3264x2176 file, after downsizing and sharpening, that's 272ppi, which is the K30 at 12x18"
print an 8x12" from a 2448x1632 file, after downsizing and sharpening, that's 204ppi, which is the K30 at 16x24"
print an 8x12" from a 1956x1304 file, after downsizing and sharpening, that's 163ppi, which is the K30 at 20x30"
print an 8x12" from a 1632x1088 file, after downsizing and sharpening, that's 136ppi, which is the K30 at 24x36"
print an 8x12" from a 1224x816 file, after downsizing and sharpening, that's 102ppi, which is the K30 at 32x48"
Where does the 8"x12" print start to be visibly different than the native K30 print? Where does the print fall apart? I was thinking about doing this experiment.... but maybe someone else already has....
I use Costco for 16x20" and 20x30" prints.
- thanks, Sheldon
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Forum: Pentax SLR Lens Discussion
02-26-2014, 04:17 PM
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Does anyone know if Sigma is going to make more of these Pentax mount 8-16mm lenses, for availability in the North America?
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