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StephenFrink

Member Since 11 Dec 2002
Offline Last Active May 20 2014 10:11 PM
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Canon lens test - Trying to help a friend

23 January 2014 - 08:24 AM

I have a friend and Seacam client in Norway shooting orcas at the moment.  It is a challenging shoot because there is very little daylight, forcing him to shoot nearly wide open at high ISO to be able to stop the action.  It is impossible for him to do a pool test so I thought to do a semi-controlled test of 2 possible lenses he might use.  We already have good data on the 16-35II and recommend a 57.5mm port extension and Superdome for that one, but it was worthwhile to try to dial in the new 24-70mm II F-4 L IS and the 14mm II F-2.8.  I wouldn't use either lens at F-4 normally, preferring instead to get to F-8 or smaller, but as this is the world he is forced into at the moment the challenge became to get the best we can out of corner performance at F-4.  Canon 5D3, Seacam housing, swivel 45 viewfinder (no reason to get all the way wet on this cold morning), Superdome, Wideport, and either a +2 or +4 diopters were tested (only the 24-70mm II F-4 L IS would accept diopters of course)

 

Attached File  pooltest2.JPG   293.24KB   88 downloads

 

The results came out looking like this:

 

Attached File  Screen Shot 2014-01-23 at 11.19.32 AM.JPG   145.56KB   105 downloads

 

But, I guess the final analysis is with enlarged views of the corners.


Pool test D800 and 17-35 with Seacam superdome

19 May 2013 - 12:06 PM

Two of my friends were complaining about inability to get sharp focus on the same 17-35mm Nikkor zoom, and wondering if it was faulty glass.  As we dug through variables we discovered the issue was more about being set to continuous AF when they should have been on single servo, and the fact that the camera acquired focus more quickly than they were used to and was often catching detritus in the water rather than the intended subject.  But, while we were at it, we did some pool tests to determine which port extension was best with Seacam supedome, test PVL (port extension, in mm) 20, 25, 30, 35, 40, 45, 50, 55, and 60.  We also tested for sideways motion and forward motion, and how efficiently it acquired focus in single servo.

 

Both motion tests looked great, as they dealt only with performance in the center of the frame.

 

Scenarios looked like this:

 

Attached File  Motion_17.jpg   196.21KB   106 downloads

 

Attached File  Motion_30.jpg   223.82KB   104 downloads

 

100% views:

 

Attached File  forward_motion.JPG   184.23KB   98 downloads

Motion forward

 

Attached File  sideways_motion.JPG   161.77KB   97 downloads

Motion sideways