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

Reply
 
Thread Tools Search this Thread
Old Dec 10, 2009, 7:53 AM   #11
Moderator
 
Join Date: Aug 2004
Posts: 8,529
Default

I agree with Mark - for a 75mm lens there is absolutely no need for a monopod. Even for a 70-200 2.8 I don't recommeend it - precisedly for the reason Mark pointed out - it's a hindrance. Imagine standing on the baseline tracking a player on the left side of the key and he passes to a player at the top of the key - that's a pretty decent angle change. Using a monopod would make switching players very clumsy.

Again, a big part of it is simply taking shots from too far away and then cropping. People are under a misconception that megapixels allow you to crop for distance in sports shooting - it doesn't. Because you don't get the accurate focus. All the extra megapixels do is drive home the fact the focus wasn't accurate. The action needs to be framed tighter to begin with. Additionally, the focus speed limitations of the Tamron come into play. Camera shake is not a problem in these shots in my opinion.
JohnG is offline   Reply With Quote
Old Dec 14, 2009, 9:15 AM   #12
Senior Member
 
Join Date: Jul 2006
Location: Tumbleweed, Arizona
Posts: 1,381
Default

I believe that there is one additional contributing factor to the softness and that is depth of field. At 75mm and f2.8 the DOF is just ~2.5 feet at 20 feet. So if your slightly out of focus, DOF is not sufficiently large enough to help you out.

http://www.dofmaster.com/dofjs.html
interested_observer is offline   Reply With Quote
Old Dec 14, 2009, 9:27 AM   #13
Super Moderator
 
Mark1616's Avatar
 
Join Date: Oct 2005
Posts: 7,452
Default

Quote:
Originally Posted by interested_observer View Post
I believe that there is one additional contributing factor to the softness and that is depth of field. At 75mm and f2.8 the DOF is just ~2.5 feet at 20 feet. So if your slightly out of focus, DOF is not sufficiently large enough to help you out.

http://www.dofmaster.com/dofjs.html
I don't agree with this. If it were the case the something would be shape and 2.5 ft is quite a lot to play with. When shooting volleyball with an 85mm f1.8 lens you often have less than half a foot fully sharp but the results still work as you are not going out past the max distance of the lens.

I would say these are out past 20 foot when 75mm is used and even if it were 20 foot that is still right on the limit.
Mark1616 is offline   Reply With Quote
Old Dec 14, 2009, 9:41 AM   #14
Moderator
 
Join Date: Aug 2004
Posts: 8,529
Default

Also - shallow DOF is your friend and an integral part of sports photography. Which is why focus accuracy is so critical to sports shooting. From what I've seen so far, the K-7 should be up to the task. But you need a lens that's up to the task and the Tamron isn't it. AND you need to stay within it's limitations. With a faster focusing lens and working within the limits of the lens I'm confident the OP will see better results.
JohnG is offline   Reply With Quote
Old Dec 15, 2009, 7:27 AM   #15
Junior Member
 
Join Date: Jul 2007
Posts: 19
Default FocusMagic can help

The softness can be corrected a bit using Focus Magic, which actually refocuses the image by a mathematical method. Here's the result:

It is a good tool to have available.

Dave
dmartin@newarts.com is offline   Reply With Quote
Old Dec 16, 2009, 8:08 AM   #16
Senior Member
 
jnanpentaxfan's Avatar
 
Join Date: May 2009
Location: Fort Worth, TX area
Posts: 136
Default

Nice, Dave.
jnanpentaxfan 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 3:40 PM.