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StephenFrink

Member Since 11 Dec 2002
Offline Last Active Apr 15 2014 11:57 AM
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Posts I've Made

In Topic: Canon lens test - Trying to help a friend

23 January 2014 - 09:10 AM

Ok, so here is the final observation from this test, the optimal port extension for 24-70mm II F-4 L IS and also the +4 diopter, both on Superdome.  Note differences in corner performance and field of view:

 

Attached File  24-70II_PVL45_superdome_16.JPG   401.87KB   32 downloads

24-70_PVL45_superdome

 

Attached File  24-70II_PVL40_superdome_+4_10.JPG   418.19KB   26 downloads

24-70_PVL40_superdome_+4

 

If you need to work wide with this lens try it without a diopter, but still try to get F-8 or smaller for a working aperture to achieve reasonable corner performance.  For reef fish, accepting that you'll be tighter on the subjects, the +4 diopter is quite nice.


In Topic: Canon lens test - Trying to help a friend

23 January 2014 - 08:51 AM

Now the same with diopter, both Superdome and Wideport:

 

Attached File  24-70II_PVL40_superdome_+2.JPG   132.38KB   30 downloads

24-70II_PVL40_superdome_+2

 

 

Attached File  24-70II_PVL40_superdome_+4.JPG   148.46KB   27 downloads

24-70II_PVL40_superdome_+4

 

 

Attached File  24-70II_PVL40_wideport_+2.JPG   133.62KB   26 downloads

24-70II_PVL40_wideport_+2

 

 

Attached File  24-70II_PVL40_wideport_+4.JPG   142KB   32 downloads

24-70II_PVL40_wideport_+4

 

Note significant Field of View loss by using a diopter, and the greater the strength of the diopter the more the wide angle field of view is compromised.  This should be well known by now.  But, if we are strictly looking at corner performance the diopter does help, although at the expense of additional chromatic aberration.  Still, it seems the best corner performance is achieved with a +4 diopter, and the Superdome is still significantly better than the Wideport.

 

If you can stand the loss of field of view, accepting that software can correct for chromatic aberration, the Superdome and a +4 diopter would be a good solution.  But, if you need your 24mm to be 24mm, use the Superdome and PVL45 without a diopter.


In Topic: Canon lens test - Trying to help a friend

23 January 2014 - 08:42 AM

OK, now the 24-70mm II F-4 L IS.  This is a new lens to me so I have no data at all.  But, here's what the tests reveal:

 

Attached File  24-70II_PVL35_superdome.JPG   132.02KB   31 downloads

24-70_PVL35_superdome

 

Attached File  24-70II_PVL40_superdome.JPG   140.93KB   23 downloads

24-70_PVL40_superdome

 

 

Attached File  24-70II_PVL45_superdome.JPG   138.85KB   28 downloads

24-70_PVL45_superdome

 

 

Attached File  24-70II_PVL50_superdome.JPG   134.51KB   30 downloads

:24-70_PVL50_superdome

 

PVL 45 is the best with the Superdome


In Topic: Canon lens test - Trying to help a friend

23 January 2014 - 08:33 AM

Canon 14mm II @ F-4:

Attached File  14II_PVL20_superdome.JPG   131.62KB   36 downloads

14II_PVL20_superdome

 

 

Attached File  14II_PVL20_wideport.JPG   114.24KB   29 downloads

14II_PVL20_wideport

 

 

Attached File  14II_PVL30_superdome.JPG   112.93KB   28 downloads

14II_PVL30_superdome

 

Attached File  14II_PVL30_widport.JPG   100.57KB   31 downloads

14II_PVL30_wideport

 

Attached File  14II_PVL20Left_PVL30Right.JPG   141.86KB   28 downloads

comparison with PVL 20 on the left and PVL 30 on the right

 

All are very, very sharp in the center but do fall off in the corners.  No surprise about that at F4.  However, the PVL20 is better than the PVL30, and the 9" superdome is far better than the smaller wideport.  The only time I'd use the wideport with the 14mm II lens is when snrkeling with big animals and you have to lose water resistance, and are willing to sacrifice corner performance.  In any diving scenario, the 9" superdome is far superior.


In Topic: Canon 5D mark iii

20 October 2013 - 11:24 AM

I was kind of slow to embrace this camera, only because I was so happy with the combination of the Canon MKIV and 1DsMKIII that fit into my same SEACAM housing.  I liked the combination of full frame and 1.3 crop, and wasn't sure I wanted to go back to full frame only.  However, the image quality and color rendition and ergonomics of this camera are so good, I'm glad to have now nearly fully migrated.  If I need an ultra-fast motor drive I'll still go to the MKIV, or maybe use it for marine mammals or big sharks that work well with the 8-15 Canon fisheye zoom.  But, the 5DMKIII is a step up in both AF and IQ.  The IQ in the 1DsMKIII is still pretty remarkable for the age of the camera, but the speed of writing to buffer is another huge advantage to 5DMKIII.  I just came back from the Solomons shooting only the 5DMkIII UW, and was very pleased.