Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-03-2012, 03:40 AM   #16
Loyal Site Supporter
baro-nite's Avatar

Join Date: Aug 2011
Location: North Carolina, USA
Photos: Gallery | Albums
Posts: 4,298
QuoteOriginally posted by stevedh Quote
apart from when its too bright are there any other times that it is useful to go above f11 ?
When you really need to maximize depth of field, as with a wide angle shot with foreground elements very close to the camera. Keep in mind that DOF refers to the area that is reasonably sharp under normal viewing conditions. At the size you've posted it here, the full image is indeed reasonably sharp across the frame. Reproducing the full image at the same scale as the 100% crop you show would be about a meter across on a typical monitor, hardly normal viewing conditions. If you want shaprness at that scale you should use every trick in the book -- tripod, remote release, fast shutter, optimum aperture, and a lens with better edge performance than the 18-55 @ 18.

Your example doesn't look like camera shake; it's just uniformly soft. As BigDave says, is any part of the image sharper than this? At any rate, I think this degree of softness can indeed be caused by diffraction effects @ f/22. Of course it's also possible that the lens isn't focused correctly (this is why some Pentax camera models include per-lens AF adjustment) or that you simply has a poor copy of the lens, but lacking other data I'd put this down to diffraction.

09-03-2012, 04:49 AM   #17
Pentaxian
aurele's Avatar

Join Date: Jan 2011
Location: Paris, France
Photos: Albums
Posts: 2,906
Short version :

- The 18-55 @18mm gives its best around f8.
09-03-2012, 05:34 AM   #18
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,314
QuoteOriginally posted by Anvh Quote
1/30 is not so slow considering it's at 18mm
It is slow when enlarging beyond the equivalent of a 8x10 print.

Remember the rule of thumb is 1/fl/crop factor is for 8x10 prints. The bigger you print the faster the shutter to eliminate shake
09-03-2012, 06:02 AM - 1 Like   #19
Site Supporter
Sandy Hancock's Avatar

Join Date: Feb 2012
Location: Adelaide Hills, South Australia
Photos: Gallery | Albums
Posts: 5,249
It's an extreme crop of a hand held shot with a consumer class lens. I'd say there's nothing much wrong with it.

09-03-2012, 09:20 AM   #20
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by Lowell Goudge Quote
It is slow when enlarging beyond the equivalent of a 8x10 print.

Remember the rule of thumb is 1/fl/crop factor is for 8x10 prints. The bigger you print the faster the shutter to eliminate shake
Nope it won't because your typical viewing distance will be larger with such a large print as well
09-04-2012, 05:11 PM   #21
Veteran Member
mysticcowboy's Avatar

Join Date: Apr 2009
Location: port townsend, wa
Photos: Albums
Posts: 968
Most of this discussion is conjecture. Testing the lens is easy. Use a tripod or set the lens down and use the self-timer to insure no movement. Take a few shots at different apertures and ISOs. If it's the lens, that will quickly become apparent. There is no substitute for testing your camera/lens to find its limits.

My conjecture is that the softness is mostly from diffraction. The kit lens seems pretty bad to me at f/22. And, while I often shoot handheld at 1/30 with good results, it's also true that the faster the shutter speed, the better the chance of getting a sharp image, although the best handheld shot won't be as sharp as one taken on a tripod. And with the K-5's excellent high ISO performance, I typically use 200 as my base ISO for handheld, or 400 on overcast days, unless the sun is very bright. I save ISO 80 for tripod work.
09-05-2012, 01:27 AM   #22
Pentaxian
kh1234567890's Avatar

Join Date: Sep 2010
Location: Manchester, UK
Photos: Gallery
Posts: 2,327
There is some softness at f/22 but it is not that bad - this is how mine behaves. The OP shot could do with a bit of post-processing sharpening, CA correction and contrast/exposure tweaking. All in all it wasn't the best of days to shoot London landscapes
09-05-2012, 04:04 AM   #23
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,314
QuoteOriginally posted by Anvh Quote
Nope it won't because your typical viewing distance will be larger with such a large print as well
Not when looking at it on a computer screen.

09-05-2012, 09:55 AM   #24
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by Lowell Goudge Quote
Not when looking at it on a computer screen.
Indeed not then but you said print
09-05-2012, 10:09 AM   #25
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,314
QuoteOriginally posted by Anvh Quote
Indeed not then but you said print
maybe i should rephrase it as display a full frame in 8 x 10 format.
09-05-2012, 10:29 AM   #26
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
Mhmm but even with your rule of thumb 1/fl/crop factor you come at 1/27 for 18mm so 1/30th is alright.

With concerts i often shoot at around 1/fl without much problems


This one is at 1/13th 50mm handhold...
http://fc07.deviantart.net/fs70/f/2011/282/c/b/loonse__en_drunense_duinen_3_...vh-d4ca88p.jpg

1 second 18mm handhold, 2 other failed though... is an IR photo so only 2.5mp photo
http://fc00.deviantart.net/fs40/f/2009/053/a/d/A_Differend_View_by_Anvh.jpg

Last edited by Anvh; 09-05-2012 at 10:38 AM.
09-10-2012, 03:55 AM   #27
Pentaxian
Paleo Pete's Avatar

Join Date: Jun 2010
Location: Texas
Photos: Gallery | Albums
Posts: 2,872
QuoteQuote:
Testing the lens is easy. Use a tripod or set the lens down and use the self-timer to insure no movement. Take a few shots at different apertures and ISOs. If it's the lens, that will quickly become apparent. There is no substitute for testing your camera/lens to find its limits.
Me too. Take some shots under controlled circumstances. Tripod, set it on something, at least brace against a post, and try different apertures, and preferably faster than 1/30. I rarely try slower than 1/45 even with my 28mm lens, although 1/30 should work...theoretically...According to what I got with my kit lens, yours should do better than this. Anyway get some shots and see what the focus does in general, this shot may have simply missed the focus a bit. wihtout a few other shots to compare to, it's hard to form a solid opinion. Looks to me a lot like out of focus though, not motion blur.
09-23-2012, 05:34 PM - 1 Like   #28
Inactive Account




Join Date: Dec 2008
Location: Ames, Iowa, USA
Photos: Albums
Posts: 2,965
Your K-5's specifications are 4928 x 3264 (16.3 MP) with a 23.4 x 15.6 mm CMOS sensor. That's 4.7 microns pixel spacing. The diffraction spot diameter for f:22 is:

d=2.44*N*(.55 microns)= 2.44*22*0.55=30 microns!

That means when you shot the photo, each infinitesimal spot of light was spread over a disk more than 5 pixels in diameter. When displayed at 100%, each point of light in the original scene is spread over 5 pixels on the display (almost 1mm). No wonder it looks fuzzy!

To prevent strong diffraction effects at 100% display, your f-number should be such that the diffraction spot radius is about the same as the pixel spacing. In your case,

N ~ 4.7(microns)/1.22*0.55(microns) ~ 8

Or, avoid high enlargements at high f-numbers.

Dave in Iowa
09-23-2012, 08:58 PM   #29
Site Supporter




Join Date: Apr 2011
Photos: Albums
Posts: 2,882
QuoteOriginally posted by newarts Quote
Your K-5's specifications are 4928 x 3264 (16.3 MP) with a 23.4 x 15.6 mm CMOS sensor. That's 4.7 microns pixel spacing. The diffraction spot diameter for f:22 is:

d=2.44*N*(.55 microns)= 2.44*22*0.55=30 microns!

That means when you shot the photo, each infinitesimal spot of light was spread over a disk more than 5 pixels in diameter. When displayed at 100%, each point of light in the original scene is spread over 5 pixels on the display (almost 1mm). No wonder it looks fuzzy!



Dave in Iowa
Thanks for the formula. Very useful information, but I had not known where to look for it before.
09-23-2012, 09:12 PM   #30
Loyal Site Supporter
paulh's Avatar

Join Date: Sep 2010
Location: DFW Texas
Photos: Gallery | Albums
Posts: 12,466
QuoteOriginally posted by Sandy Hancock Quote
It's an extreme crop of a hand held shot with a consumer class lens. I'd say there's nothing much wrong with it.
I'm not an expert, but these are my feelings as well. The shot could definitely benefit from a little PP also.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, pentax help, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sharpness, Fine Sharpness, Extra Sharpness Taviali Pentax K-5 8 03-31-2012 12:56 PM
Nature need help - sharpness citrus sky Photo Critique 16 02-02-2011 05:51 PM
Sharpness VS Fine-Sharpness in k20d wasim_altaf Pentax DSLR Discussion 8 10-12-2009 11:41 AM
Sharpness vs Fine Sharpness on K20D morfic Pentax DSLR Discussion 2 11-02-2008 10:13 AM
Fine sharpness and sharpness move together on K20D 1.01 morfic Pentax DSLR Discussion 2 07-11-2008 09:18 PM



All times are GMT -7. The time now is 10:28 PM. | See also: NikonForums.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