Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-09-2013, 10:25 PM   #406
New Member




Join Date: Mar 2013
Posts: 16
Great pics in here. I've had this lens for a few weeks now using it with my only slightly older K-01 (which I love). I can get some pretty decently sharp images which are SUPER wide. But I seem to be having some issues with the distortion.. I usually don't correct for distortion but I never have shot with anything this wide

Here's an example I posted on the K-01 board:



I know the camera has issues with the EXIF data at 8-9mm. I'm using Lightroom to process my images. I'm wondering if this may be part of my problem!

Also I had distortion correction in camera set- but I'm pretty sure it shouldn't effect this lens but I wonder if that may be doing something.

Any thoughts?

04-10-2013, 06:21 AM   #407
DAZ
Loyal Site Supporter
Loyal Site Supporter
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 744
QuoteOriginally posted by brettgaddy Quote
Great pics in here. I've had this lens for a few weeks now using it with my only slightly older K-01 (which I love). I can get some pretty decently sharp images which are SUPER wide. But I seem to be having some issues with the distortion.. I usually don't correct for distortion but I never have shot with anything this wide

Here's an example I posted on the K-01 board:



I know the camera has issues with the EXIF data at 8-9mm. I'm using Lightroom to process my images. I'm wondering if this may be part of my problem!

Also I had distortion correction in camera set- but I'm pretty sure it shouldn't effect this lens but I wonder if that may be doing something.

Any thoughts?
In camera distortion correction will only work for a lens (Pentax) that the camera knows. It also will not do anything for perspective (keystone) distortion. You can use third party software to change the EXIF if you like or need too.

DAZ
04-10-2013, 06:37 AM   #408
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 40,442
Shoot the same scene with a 10-17 fisheye and you'll see some distortion.... my Aperture software calls all 8mm shots 0mm, but it gets the higher ones right, so I don't bother with it.
04-10-2013, 04:31 PM   #409
New Member




Join Date: Mar 2013
Posts: 16
QuoteOriginally posted by DAZ Quote
You can use third party software to change the EXIF if you like or need too.
I just tried that but it didn't seem to make a difference between the files (except it says 8mm in the data of course)

QuoteOriginally posted by normhead Quote
Shoot the same scene with a 10-17 fisheye and you'll see some distortion.... my Aperture software calls all 8mm shots 0mm, but it gets the higher ones right, so I don't bother with it.
I guess I was hoping to avoid those curved lines (like on the building on the right) like you would get with a fisheye.

I'm wondering if this is a technical issue I'm having or just something with this lens I need to work around.

04-11-2013, 06:28 AM   #410
DAZ
Loyal Site Supporter
Loyal Site Supporter
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 744
There is some lens distortion (curves) but most of what I see in that photo is perspective distortion. This kind of perspective distortion is usually called keystone distortion. Keystone can be for the most part is correctable PP but is usually not being corrected automatically but only with some input to the program. Keystone is not in the lens but is from not having the plain of the film/sensor perpendicular to the sides of the buildings. As this distortion is not in the lens the PP program is not correcting it so the number in the EXIF is not going to make much difference.

DAZ
04-11-2013, 07:56 AM   #411
Forum Member
wolffy's Avatar

Join Date: Mar 2012
Location: Saint Paul, MN USA
Photos: Gallery | Albums
Posts: 63
image with vertical perspective tweaked

I did this with PS Elements but the same thing is in Lightroom its under develop -- lens correction -- manual -- use the vertical slider. the only downside is you will need to crop the image afterwords, I left my example uncropped so you could see the effects

04-11-2013, 10:09 AM   #412
Site Supporter
Site Supporter
newmikey's Avatar

Join Date: May 2007
Photos: Gallery
Posts: 2,280
Haven't visited this thread for a while so 2 recent ones:







04-11-2013, 09:54 PM - 1 Like   #413
New Member




Join Date: Mar 2013
Posts: 16
QuoteOriginally posted by DAZ Quote
There is some lens distortion (curves) but most of what I see in that photo is perspective distortion. This kind of perspective distortion is usually called keystone distortion. Keystone can be for the most part is correctable PP but is usually not being corrected automatically but only with some input to the program. Keystone is not in the lens but is from not having the plain of the film/sensor perpendicular to the sides of the buildings. As this distortion is not in the lens the PP program is not correcting it so the number in the EXIF is not going to make much difference.

DAZ
Ahh, that makes sense. Thanks for the info.

QuoteOriginally posted by wolffy Quote
I did this with PS Elements but the same thing is in Lightroom its under develop -- lens correction -- manual -- use the vertical slider. the only downside is you will need to crop the image afterwords, I left my example uncropped so you could see the effects
I was actually trying this earlier and I did kind of get it the way I wanted. But yeah, quite a bit of cropping had to be done.

I'm going to have to keep working on my technique with this lens and read up some more on keystone distortion. I really like this lens but it can be pretty tough to use

Here's another one I shot, maybe not be one the best photos I've taken but it's great that I had this lens and I could get the whole building in the shot!
Attached Images
View Picture EXIF
PENTAX K-01  Photo 
04-13-2013, 08:00 AM   #414
Senior Member




Join Date: Jul 2012
Location: Singapore
Posts: 208
04-13-2013, 01:56 PM - 2 Likes   #415
DAZ
Loyal Site Supporter
Loyal Site Supporter
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 744
QuoteOriginally posted by brettgaddy Quote
Ahh, that makes sense. Thanks for the info.



I was actually trying this earlier and I did kind of get it the way I wanted. But yeah, quite a bit of cropping had to be done.

I'm going to have to keep working on my technique with this lens and read up some more on keystone distortion. I really like this lens but it can be pretty tough to use

Here's another one I shot, maybe not be one the best photos I've taken but it's great that I had this lens and I could get the whole building in the shot!
There is a lot of misleading and outright wrong information out there on Perspective Distortion, so be careful. Perspective distortion is in all photos that don't have all elements in the photo on the same spherical plain. It is easier to perceive Perspective Distortion as the lens lengthens get very long or short so at 8mm it can really stand out. Here are some examples that can start to mess with your head.


https://farm9.staticflickr.com/8337/8253293835_96ff179a87_b.jpg


https://farm9.staticflickr.com/8070/8253294505_1beffbf08c_b.jpg


https://farm9.staticflickr.com/8354/8254379406_c669eff869_b.jpg


https://farm9.staticflickr.com/8070/8254380334_ba4483587d_b.jpg


https://farm9.staticflickr.com/8206/8253308793_185d45199e_b.jpg


https://farm4.staticflickr.com/3185/5772576576_bfc9d7fd66_b.jpg


One manifestation of Perspective Distortion is “keystone distortion”. This is one of the easiest distortions to get and get rid of either in camera or PP. In camera just hold the camera perpendicular to all objects to not have it and at an angle to make it. As it is a geometrical distortion it is something a computer can deal with in a straightforward way. Some PP programs (I use Paint Shop Pro) have a perspective correction tool. You can have more then one plain not perpendicular but the computer can correct for both plains at the same time. When you use the tool it will give you a box. Move the corners of the box to something that should have all of it's corners perpendicular like a building. For the photo in your first example it has so little distortion that little of the photo is lost and no cropping is needed.


DAZ
04-15-2013, 10:46 AM   #416
Pentaxian
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 40,442
From today's outing.... the outlet of Costello Lake. Shot at 12mm.

04-15-2013, 01:44 PM   #417
Site Supporter
Site Supporter
dadipentak's Avatar

Join Date: Jul 2008
Location: Baltimore, Maryland
Photos: Gallery
Posts: 11,590
Nice, Norm!
04-15-2013, 02:38 PM   #418
Forum Member




Join Date: Oct 2012
Posts: 50
Daz, your final picture of teh room, is a work of art!!!
What a great picture!!!

Zorza
04-20-2013, 08:31 PM   #419
Senior Member




Join Date: Jul 2012
Location: Singapore
Posts: 208
Singapore CBD Area with MBS Panorama Shot

04-21-2013, 11:28 AM   #420
DAZ
Loyal Site Supporter
Loyal Site Supporter
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 744
QuoteOriginally posted by zorza Quote
Daz, your final picture of teh room, is a work of art!!!
What a great picture!!!

Zorza
Thanks. Every now and then I get some wood on the ball.

DAZ
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!
8-16mm, 8mm, club, curvature, dog, f8, field, flickr, harrison, hdr, images, john, k-mount, lake, lens, love, madrid, merlion, pentax lens, photos, pm, post, shots, sigma, sigma 8-16mm, snow, thanks, time, twilight
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sigma 8-16mm Review viking79 Pentax SLR Lens Discussion 14 02-15-2018 04:56 AM
What about Sigma 8-16mm?? mikiresty Pentax SLR Lens Discussion 5 06-19-2010 04:00 AM
When does the 8-16mm sigma come out? WerTicus Pentax SLR Lens Discussion 1 05-16-2010 01:13 PM
Sigma 8-16mm Preorder Nerdold Nerdith Pentax SLR Lens Discussion 12 04-20-2010 05:54 AM
For Sale - Sold: Sigma 180mm f3.5 macro, Sigma 16mm f2.8 Filtermatic Fisheye, K20D, K100D Super jfirneno Sold Items 16 02-05-2010 06:46 AM



All times are GMT -7. The time now is 11:14 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