Forgot Password
Pentax Camera Forums Home
 

Showing results 1 to 25 of 151 Search:
Forum: Post Your Photos! 04-21-2014, 12:54 PM  
Night Share your "Blood Moon" photos here!
Posted By sheld
Replies: 93
Views: 12,205
amazing very sharp shot. The Pentax GPS unit must have worked well (13 sec).
Forum: Photographic Technique 04-20-2014, 06:20 AM  
Astrophotography. Astrotracer worth it?
Posted By sheld
Replies: 111
Views: 33,263
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.
Forum: Post Your Photos! 04-16-2014, 01:21 AM  
Night Share your "Blood Moon" photos here!
Posted By sheld
Replies: 93
Views: 12,205
My attempt, Bigma 150-500mm at F/6.3, 1/5th of a second, ISO3200.
Forum: Pentax Price Watch 04-04-2014, 02:27 PM  
35mm DA F2.4 - $140, through Amazon
Posted By sheld
Replies: 27
Views: 2,602
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.
Forum: Pentax SLR Lens Discussion 04-04-2014, 08:38 AM  
OFFICIAL: Sigma 8-16mm no longer available for Pentax Mount
Posted By sheld
Replies: 51
Views: 6,791
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.
Forum: Pentax SLR Lens Discussion 04-01-2014, 08:14 AM  
OFFICIAL: Sigma 8-16mm no longer available for Pentax Mount
Posted By sheld
Replies: 51
Views: 6,791
hmmm, maybe I'm maybe better off with the Sigma 10-20mm F/4-F/5.6? The Pentax 12-24mm is too expensive.
Forum: Pentax SLR Lens Discussion 03-31-2014, 12:41 PM  
OFFICIAL: Sigma 8-16mm no longer available for Pentax Mount
Posted By sheld
Replies: 51
Views: 6,791
Anybody ever heard of AkibaExpress? They have the 8-16mm Pentax version in stock; ships from overseas.
http://www.amazon.com/Sigma-8-16mm-4-5-5-6-Pentax-Digital/dp/B003G2A71G/ref=...=pentax+8-16mm

Also, same question for JAPAN ONLINE US STORE/365 days worldwide Shipping, which also has the lens in stock on Amazon.
- Sheldon
Forum: Digital Processing, Software, and Printing 03-23-2014, 08:57 AM  
K30, how big to print for optimal sharpness?
Posted By sheld
Replies: 14
Views: 1,216
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.
Forum: Digital Processing, Software, and Printing 03-22-2014, 02:44 AM  
K30, how big to print for optimal sharpness?
Posted By sheld
Replies: 14
Views: 1,216
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.
Forum: Digital Processing, Software, and Printing 03-21-2014, 02:34 PM  
K30, how big to print for optimal sharpness?
Posted By sheld
Replies: 14
Views: 1,216
Brooke Meyer,
Do you interpolate to 300ppi before printing (using genuine fractals or equivalent)? I haven't ever tried that.
- Sheldon
Forum: Digital Processing, Software, and Printing 03-21-2014, 12:42 PM  
K30, how big to print for optimal sharpness?
Posted By sheld
Replies: 14
Views: 1,216
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
Forum: Digital Processing, Software, and Printing 03-21-2014, 07:07 AM  
K30, how big to print for optimal sharpness?
Posted By sheld
Replies: 14
Views: 1,216
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
Forum: Pentax SLR Lens Discussion 02-26-2014, 04:17 PM  
OFFICIAL: Sigma 8-16mm no longer available for Pentax Mount
Posted By sheld
Replies: 51
Views: 6,791
Does anyone know if Sigma is going to make more of these Pentax mount 8-16mm lenses, for availability in the North America?
Forum: Troubleshooting and Beginner Help 02-17-2014, 01:04 PM  
Eneloops and charger?
Posted By sheld
Replies: 37
Views: 4,175
The best Sanyo Eneloops for cameras are probably the ones labelled "1800x", which can be recharged 1800 times. They're 1900mha, but they have a very long shelf life and they have an optimal battery output voltage for the entire battery life. I recently bought two 4-packs from ebay. You can use any nimh charger with eneloops.
2 Units of Sanyo Eneloop 4pk AA New Generation Recharges 1800X 8 AA Batt | eBay
Forum: Lens Sample Photo Archive 02-14-2014, 01:38 PM  
Pentax DA 55-300mm f/4-5.8 ED samples
Posted By sheld
Replies: 142
Views: 48,507
Looking at the print more and it actually isn't quite as noticeable in print, 12"x18", as I originally thought; just irritating that it could be perfect.
Forum: Lens Sample Photo Archive 02-13-2014, 01:41 PM  
Pentax DA 55-300mm f/4-5.8 ED samples
Posted By sheld
Replies: 142
Views: 48,507
How do you work around field curvature for the DA55-300mm, for landscape photos? Here is a shot at 170mm, F/8, which looks pretty good for the web, but the 12"x18" print has soft corners; the center is sharp.


Here's the disappointing soft lower/left corner at 1:1. I'm not sure if this happens at all focal lengths, or if it depends on the focus distance, or if it effects all copies of the lens. I'm just slightly disappointed with my enlargement.
Forum: Pentax K-30 & K-50 02-13-2014, 12:18 PM  
Diffraction on K30?
Posted By sheld
Replies: 7
Views: 1,115
I think with the live-view autofocus, one can focus the edges, or even the corners, and that might work really well, but I haven't tried it on the DA55-300. I originally thought the Curved Focal plane thing was only a problem for wide angles, like the D15/DA21.
Forum: Pentax K-30 & K-50 02-13-2014, 09:56 AM  
Diffraction on K30?
Posted By sheld
Replies: 7
Views: 1,115
I usually shoot at F/8, where there is little to no diffraction, but I haven't tried any landscapes at F/16, or even F/11, so I don't know what aperture it is best to use for enlargements.
Forum: Pentax K-30 & K-50 02-13-2014, 08:05 AM  
Diffraction on K30?
Posted By sheld
Replies: 7
Views: 1,115
I seem to have trouble getting consistently getting sharp landscape photos. How far can you stop down on the K30 before diffraction is a real limiter? This question would be for landscape photos enlarged to 30"x20",

I usually stick with F/8, for landscapes using my DA15, and DA21, making sure to focus on the background, preferably near the edge of the image.

I recently made an 18"x12" enlargements from the DA55-300, and I was unhappy with the soft corners at 170mm, F/8, but I didn't try focusing on the edge, instead of the center. Could I have gotten better results stopped down to F/11 or F/16 (with tripod)?

I have learned that with the DA15 and the DA21, I can get sharp corners at F/8 but that it really helps to focus on the edge of the picture instead of the center due to field curvature, or alternatively, to just know where infinity for the corners is on the lens. I have some DA15 pictures that had soft corners at F/8, and other that were very good. But I haven't experimented with F/11 or F/16.

Here's the DA55-300mm photo at 170mm F/8, which has soft corners when enlarged; although I have another at 150mm F/8, the Los Angeles skyline from the Griffith observatory, that looks pretty good (sharpened a bit).


Here's the disappointing soft lower/left corner at 1:1

- Sheldon
Forum: Pentax SLR Lens Discussion 02-10-2014, 07:45 PM  
Sigma 30mm f/1.4 thoughts and examples
Posted By sheld
Replies: 395
Views: 97,968
In the cave with my K30, ISO3200, 1/8th of a second F/1.8.


and another one at 1/15th of a second, ISO3200, F/1.8
Forum: Pentax News and Rumors 02-10-2014, 08:53 AM  
Sigma 30mm F1.4 DC HSM for K-mount
Posted By sheld
Replies: 71
Views: 14,520
I'm glad to see that Sigma is supporting the Pentax mount. I have the old Sigma 30mm/1.4, and it is one of my favorite lenses. I usually use it at F/1.8 for a normal focal length high speed lens in low light. The 30mm Sigma has a curved focus plane, but the center is very sharp. The edges are reasonably good, provided one takes into account that the critical focus point is closer than in the center. Caving yesterday, at F/1.8 and 1/8th of a second, ISO3200.
Forum: Lens Clubs 02-09-2014, 05:24 PM  
The 300mm plus lens Club discuss your long lenses.
Posted By sheld
Replies: 29,982
Views: 2,654,723
Bewick's Wren, (I think), Sigma 150-500mm @500mm, 2:1 crop. From this morning's bird walk in Austin. The Sigma/K30 combo works really well.
Forum: Pentax K-30 & K-50 02-08-2014, 01:58 AM  
Kx to K-30 upgrade
Posted By sheld
Replies: 22
Views: 2,643
I upgraded my Kx in Nov. The bigger/brighter viewfinder and bigger LCD alone makes it worth it. Plus autofocus and liveview improvements, 1/2 stop noise ISO improvement, and higher resolution. I recommend the AA battery pack and Eneloops.
Forum: Lens Clubs 02-07-2014, 07:17 AM  
The 15mm Limited controls my mind - club
Posted By sheld
Replies: 11,103
Views: 1,786,939
nice shot!
Forum: Pentax SLR Lens Discussion 02-06-2014, 06:20 AM  
Why do mm count more at the wide end?
Posted By sheld
Replies: 21
Views: 1,571
Especially if you show area too.
Search took 0.01 seconds | Showing results 1 to 25 of 151

 
Forum Jump


All times are GMT -7. The time now is 07:08 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top