Home · Register · Search · View Winners · Software · Hosting · Software · Join Upload & Sell

Moderated by: Fred Miranda
Username   Password

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Canon Forum | Join Upload & Sell

1       2       3              6      
7
       end
  

Tamron 150-600mm gets DxOmarked!
  
 
krementz
Offline
• • •
Upload & Sell: Off
p.7 #1 · p.7 #1 · Tamron 150-600mm gets DxOmarked!


johnctharp wrote:
I read it as 'effective F-stops', where both the stated aperture and the efficiency of the glass is taken into account.



Therefore, does Tamron's 6.6 t-stop (noted above) mean that wide open at f/6.3, the sensor only receives as much light as a f/6.6 in a (non-existent) perfect lens? In comparison, the Sigma lens needs to be 0.1 stop more open for the same exposure?




Mar 13, 2014 at 07:12 PM
Imagemaster
Offline
• • • • • • •
Upload & Sell: On
p.7 #2 · p.7 #2 · Tamron 150-600mm gets DxOmarked!


stegosaurus wrote:
It would stall and quit trying to achieve focus on the 7D if I had focused on a near object, moved to focus on a far object and moved back to a nearer object. I took it back and tried 2 more copies of the lens but all had the same issue. That night after trying to solve it by carefully looking at the 7D setup, I realized that Custom Function III Option 4 was set to stop the lens drive if focus couldn't be achieved. I reset this to "1" and then went back to my camera dealer to
...Show more

No, if you read all the posts on the problem, you will see that it has nothing to do with "focus search".

On a 7D with the lens in the 500-600mm range, the lens will not change focus in AI Servo when focused on a far object and moved back to a nearer object.

It will not change focus, regardless of "focus search', focus-limiter, or a poor contrast subject. If yours does, you are lucky.



Mar 13, 2014 at 07:13 PM
johnctharp
Online
• • • •
Upload & Sell: Off
p.7 #3 · p.7 #3 · Tamron 150-600mm gets DxOmarked!


krementz wrote:
Therefore, does Tamron's 6.6 t-stop (noted above) mean that wide open at f/6.3, the sensor only receives as much light as a f/6.6 in a (non-existent) perfect lens? In comparison, the Sigma lens needs to be 0.1 stop more open for the same exposure?



That's the theory



Mar 13, 2014 at 07:42 PM
 

Search in Used Dept. 



krementz
Offline
• • •
Upload & Sell: Off
p.7 #4 · p.7 #4 · Tamron 150-600mm gets DxOmarked!


thanks


Mar 13, 2014 at 07:46 PM
Pixel Perfect
Online
• • • • • •
Upload & Sell: On
p.7 #5 · p.7 #5 · Tamron 150-600mm gets DxOmarked!


alundeb wrote:
So the lens metric scores totally hide that the Sigma is abysmal at longer focal length where the Tamron shines.


Indeed, this is why I rarely check out DxO, the comparison is a joke.



Mar 13, 2014 at 09:03 PM
johnctharp
Online
• • • •
Upload & Sell: Off
p.7 #6 · p.7 #6 · Tamron 150-600mm gets DxOmarked!


Pixel Perfect wrote:
Indeed, this is why I rarely check out DxO, the comparison is a joke.


I'd bet that the full comparison is spot on, but that their subjective method of reducing a set of results with a half-dozen or so dimensions to a single number probably doesn't fully represent the perspectives of everyone who has used the lens .

That, and they don't do stuff like test AF or IQ at different distances or rate micro-contrast or rendering and so on...



Mar 14, 2014 at 02:15 AM
1       2       3              6      
7
       end




FM Forums | Canon Forum | Join Upload & Sell

1       2       3              6      
7
       end
    
 

You are not logged in. Login or Register

Username   Password    Reset password