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MarkD

Member Since 28 Sep 2006
Offline Last Active Sep 16 2017 01:08 PM
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Posts I've Made

In Topic: Nikon 8-15mm in the house!

13 September 2017 - 01:37 AM

"I was using it without the port shades and the lens hood, because I had a zoom gear on it"

 

 

It hadn't occurred to me to put the lens hood on the lens within the domes, so I tried that out today at home. On the Nauticam system, the lens hood will not pass through the N120 housing throat so has to be mounted from the front after the camera has been installed and before mounting the dome. That works fine with adequate clearance for the Nauticam 210mm dome and 20mm port extension. However there is insufficient radial clearance for use with the Zen DP-100 dome and the recommended 30mm port extension. There will probably be adequate clearance using larger Zen domes. The Nauticam zoom gear does not prevent mounting of the lens hood. It would be interesting to find out if using a lens hood within larger domes avoids the flare that is apparently sometimes an issue using full frame without external dome shades.

 

Mark


In Topic: Nikon 8-15mm in the house!

12 September 2017 - 09:21 AM

Alex. I have recently taken about 560 images underwater with the Nikkor 8-15 fisheye on the DX format D500, around 230 of which contained partial or full sunbursts or dappled light. Most were taken with a 210mm Nauticam acrylic dome but a few were with a Zen DP100 dome and a few again were taken in conjunction with a Kenko 1.4x TC. Focal lengths varied through the DX applicable zoom range and there are a mixture of horizontal and vertical format shots. None of the images show any hint of the flare seen in your and Adam’s shots. Many of the sunburst shots were taken fairly shallow – a few at 3m. or slightly shallower. Probably the relevant difference is that using DX, I didn’t need to remove the dome shade but I didn’t use the lens hood. 

 

Mark


In Topic: Knowing your in Rear syc Nauticam Housing

11 September 2017 - 02:46 AM

Press Info button to see Info screen on rear LCD. Flash mode shows at left, second row down (if pop-up flash is up, or a strobe is connected electronically via the hotshoe)?


In Topic: Nikon 8-15mm in the house!

16 August 2017 - 07:14 AM

Further land-based observations on the Nikkor 8-15 Fisheye used with and without a teleconverter on DX (D500):

  • A Nauticam zoom gear for this lens is now available - but there isn't currently one listed for the lens with teleconverter
  • Nauticam and Zen now have port extension recommendations. Of interest to Tokina fisheye upgraders, the relative differences from those recommended for the Tokina 10-17 vary with the specific dome. For instance Zen recommend a total of 30mm extension for the DP-100 compared with 15mm for the Tokina, while Nauticam recommend the same 20mm extension with their 210mm acrylic dome as for the Tokina. For those upgrading from a DP-100 with integrated 15mm extension, the best solution seems to be the removal of the integrated extension and reassembly of the dome assembly using shorter screws (easy), then using a Nauticam 30mm port extension.
  • My earlier experience using the Nikkor 8-15 with an elderly Kenko 1.4x Teleplus Pro 300 was possibly flawed as that particular TC became progressively dysfunctional in autofocus and aperture control and had to be replaced by a new Kenko 1.4x Teleplus Pro 300 DGX. The new TC has so far autofocussed impeccably on land with the Nikkor fisheye - scarcely different from using the lens alone.
  • Optically on land, the Nikkor performs significantly better than the Tokina across the zoom range with vastly less Chromatic Aberration and better sharpness both at the centre and edges. These comparisons have been limited to the f8 and f11 apertures I typically use behind domes.
  • With the Kenko 1.4x teleconverter the zoom range usefully becomes 11-21 with complete coverage of the DX sensor throughout the range. Fully zoomed out on DX, the angle of coverage is just slightly less that that of the lens on its own at maximum full coverage of the sensor (about 10mm zoom). Fully zoomed in to 21mm the angle of coverage (reach) is greater than that provided by the Tokina on its own but less than that provided  by the Tokina plus TC (24mm).
  • Comparing the 2 fisheye lenses optically on land in combination with the 1.4x TC, the Nikkor still performs substantially better than the Tokina across their zoom ranges for Chromatic Aberration, central and edge sharpness. At 11mm and f9.0, the Nikkor is very sharp centrally but the edges are soft. At 21mm and f9.0, sharpness is still very good centrally but is also good at the edges.
  • The focal length of 11mm can be achieved either by using the Nikkor alone at mid-zoom or by using the lens with 1.4x TC fully zoomed out. Both deliver excellent central sharpness but while with the lens alone edge sharpness is good, with the TC the edges are quite poor.

DX land-based Conclusions:

  • The Nikkor lens is a substantially better performer than the Tokina both with and without a teleconverter
  • The TC works much better optically with the Nikkor, at least peripherally, when it is zoomed in. Edge performance suffers when zoomed out. The same is probably true of the Tokina but performance is poorer with this lens throughout the zoom range and across the image.
  • It is a viable strategy to optimise the Nikkor's zoom range for DX cameras by using a Kenko 1.4x Teleplus Pro DGX teleconverter only as long as good edge performance when zoomed out can be sacrificed. Otherwise it may be better to reserve this combination for use only when fully zoomed in.

Caveat:

  • How these observations and conclusions translate to use behind domes with their curved and close virtual images remains to be explored.

Mark


In Topic: Nikon 8-15mm in the house!

13 July 2017 - 09:08 AM

After playing with the new lens on my D500 on land for a couple of hours this afternoon I can add the following:

  • Unlike on Adam's Seacam setup, with Nauticam, the 10-24 zoom gear is a few mm too long to get the teeth to mesh in the housing. Other gears in my collection don't appear to be easily adaptable either, so it looks like waiting for Nauticam to produce a definitive gear or making something custom.
  • As expected, the lens isn't physically compatible with Nikon's own 1.4x Mk III TC.
  • The lens will work with my fairly old version of the Kenko 1.4x Teleplus Pro 300 and as Walt suggests, this allows a full zoom range without any cut-off/vignetting on the DX sensor and presumably a maximum angle of coverage only marginally less than the Tokina 10-17 at its widest. However autofocus using this TC and D500 is subtly less good with the Nikon lens. AFS on back button appears to work well with both lenses. AFC works OK with the Tokina with just occasional and minor initial hunting. On the Nikon lens, AFC also works but with significantly more frequent and rapid hunting before the focus settles at least in indoor light. As far as I can tell at the moment, final focus accuracy is OK. I don't get the impression that this is a deal breaker for most circumstances when this combination is likely to be used, but it could be an issue if using the TC to extend reach for rapidly moving pelagics? I haven't so far compared optical quality.

Mark