Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Pentax Lenses

Reply
 
Thread Tools Search this Thread
Old Mar 3, 2008, 11:34 PM   #11
Senior Member
 
Join Date: Jul 2006
Location: Tumbleweed, Arizona
Posts: 1,381
Default

... and here is another...
Attached Images
 
interested_observer is offline   Reply With Quote
Old Mar 4, 2008, 12:38 AM   #12
Junior Member
 
Join Date: Jan 2008
Posts: 26
Default

I have this picture taken with FA 80-320 @ 320mm. I'm a newbie in this photography world, but I think some how you can judge the lens a bitthrough this picture though. And BTW, please give mecomments and critiquesplease.
Attached Images
 
Ken T is offline   Reply With Quote
Old Mar 4, 2008, 9:22 AM   #13
Senior Member
 
bigdawg's Avatar
 
Join Date: Feb 2005
Location: Thach Alabama
Posts: 14,981
Default

GrahamM wrote:
Quote:
I want to get a nice big lense like that also Dawg, but gotta break the wifey in slowly :lol:.

My main purpose for this lense will be wildlife and ships out in the lake ( I live at the mouth of the St. Clair river ).

I am fairly new to this stuff, so what does CA mean?
CA means Chromatic Aberation. The green, blue or purple outlines caused by the light entering the lens at an angle and the lens acting like a prism and breaking the light up into different colors and outlining things with those before mentioned fringe colors. An example here from my Vivitar 300mm lens.
:?

You'll see the purple and green outlining the limbs here. I didn't mean for you to buy the Bigma but the photos were to show what the APO lens was capable of...The same APO technology is in the 70-300mm APO lens!

Dawg
Attached Images
 
bigdawg is offline   Reply With Quote
Old Mar 4, 2008, 9:28 AM   #14
Senior Member
 
jachol's Avatar
 
Join Date: Aug 2006
Location: NW. England
Posts: 1,201
Default

Quote:
I have no experience with the Sigma or the Pentax, but I do have the Tamron 70-300, and it does have a serious problem with CA, particularly when shooting up into trees for birds. I might just have a bad copy of it, but I've been disappointed on this score.

Hi Paul,

I've noticed the CA problem with my Tamron 70 - 300mmalso, so think it must just be a featiure of that lens.I've just had to brush up on PS techniqes to remove it, I'm disappointed too.

GrahamM ... CA is Chromatic aberation which is coloured fringing seen on branches etc. when shot against a bright background, caused by the lens having different refractive index for varying light wavelengths. Hope this helps. ... Jack

Edit ... Apologies I see Ed has already answered your question. I missed that. ... J

jachol is offline   Reply With Quote
Old Mar 4, 2008, 9:35 AM   #15
Senior Member
 
bigdawg's Avatar
 
Join Date: Feb 2005
Location: Thach Alabama
Posts: 14,981
Default

jachol wrote:
Quote:
Quote:
I have no experience with the Sigma or the Pentax, but I do have the Tamron 70-300, and it does have a serious problem with CA, particularly when shooting up into trees for birds. I might just have a bad copy of it, but I've been disappointed on this score.

Hi Paul,

I've noticed the CA problem with my Tamron 70 - 300mmalso, so think it must just be a featiure of that lens.I've just had to brush up on PS techniqes to remove it, I'm disappointed too.

GrahamM ... CA is Chromatic aberation which is coloured fringing seen on branches etc. when shot against a bright background, caused by the lens having different refractive index for varying light wavelengths. Hope this helps. ... Jack

Edit ... Apologies I see Ed has already answered your question. I missed that. ... J
No apologies needed Jack...Your explanation is probably better than mine!

Dawg
bigdawg is offline   Reply With Quote
Old Mar 4, 2008, 11:26 AM   #16
Senior Member
 
jachol's Avatar
 
Join Date: Aug 2006
Location: NW. England
Posts: 1,201
Default

There you go Ed !, ... Photoshop to the rescue, hope you don't mind me getting rid of the fringing. ... Jack.
Attached Images
 
jachol is offline   Reply With Quote
Old Mar 4, 2008, 1:50 PM   #17
Senior Member
 
bigdawg's Avatar
 
Join Date: Feb 2005
Location: Thach Alabama
Posts: 14,981
Default

Don't mind at all..Thank you Jack...For those that might want to know what did you do...In detail now!

Dawg
bigdawg is offline   Reply With Quote
Old Mar 4, 2008, 5:05 PM   #18
Member
 
Join Date: Nov 2007
Posts: 71
Default

Thanks for the help everyone.
GrahamM is offline   Reply With Quote
Old Mar 4, 2008, 6:14 PM   #19
Senior Member
 
bigdawg's Avatar
 
Join Date: Feb 2005
Location: Thach Alabama
Posts: 14,981
Default

You are welcome Graham...Have you decided?



Dawg
bigdawg is offline   Reply With Quote
Old Mar 4, 2008, 7:56 PM   #20
Member
 
Join Date: Nov 2007
Posts: 71
Default

I would say that I am leaning towards the Sigma. At $300.00 though I would'nt call it a budget lens though as posted above.
GrahamM is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 1:26 PM.