Canon EF 8-15mm Fisheye Zoom
Posted by Matti Ovaska 2011-07-26 02:32
Canon recently released a new lens which has got a lot of people interested in Underwater photography interested in possibilities of the unique capabilities of this lens. As a result of this I bit the proverbial bullet and purchased one for myself. Again the main purpose for this lens is for underwater photography but I can also see opportunities on land as well but it won't be the be all end all of lenses just another way of communicating with a unique perspective.The first challenge was to see how I could house this lens and make maximum use of its extreme zoom range.
So I had a quick play with the lens and also sorted out some port options and zoom gear with stuff I already
had (a small collection of bits). I used the 8inch port from which I had removed the port shade.
Housing set-up:Aquatica 5D MKII Housinghad (a small collection of bits). I used the 8inch port from which I had removed the port shade.
8inch dome
port with no shade,
Extension
part number 18453, with this extension ring the lens protrudes ~2-3mm above the
inner flat face of the port.
Extension
part number 18463, with this extension ring the lens protrudes about the same
as the Canon 15mm does with just the 8inch port on the housing.
Zoom gear
part number (z) 18708, this is the same is what is used for the EF 16-35mm MKII
lens.
Putting lens on was a bit of a pain, so
what I did was I removed the lens removal button lever (within the housing) and
I could then insert the camera with the lens (with lens cap on just
in case) from the rear.
The fitment of the 18708 zoom gear on the EF16-35mm MKII is
definitely more snug than on the EF8-15mm. On the EF16-35mm the zoom will just
work without using the grub screw to firmly fix it place where as on the
EF8-15mm the clearance between the gear and the zoom ring is greater and you do
have tighten grub screws to get the zoom gear to work. In looking at the Focus
gear for the EF15mm fisheye the clearance on this combination of gear and lens
would be about the same as the clearance with the 18708 gear on the EF8-15mm.
Examining the 18708 gear
and the EF8-15mm within the housing that the leading edge of the gear (as far
as the gear can be put forward on the lens from the camera body) is about ~4mm
back from the leading edge of the housing gear (ie the housing gear is mounted
further forward: away from the camera body). This means that the zoom gear will
always engage the housing gear even with the gear made thinner to allow for the
lens release lever fitment. As mentioned previously the distance from the rear
edge of the zoom gear on the EF8-15mm to the lens release button is
approximately 11mm and the same distance on the EF16-35mm is ~18mm. So the new
gear for the EF8-15mm would have nominally the same bore as the 18708 but would
be nominally 6mm thinner to give a similar clearance for the zoom release
lever. Refer to the following photos for Lens and zoom gear fitment and clearances.
Canon Ef 8-15mm with 18708 Zoom Gear.
Canon EF16-35mm with 18708 Zoom Gear.Trial Photographs taken at Julian Rocks Byron Bay, Australia.
Canon EF8-15mm with 18463 Extension and 8" port.
Canon EF8-15mm with 18463 Extension and 8" port.
Canon EF8-15mm with 18463 Extension and 8" port.
Canon EF8-15mm with 18453 Extension and 8" port.
Canon EF8-15mm with 18453 Extension and 8" port.
Canon EF8-15mm with 18453 Extension and 8" port.It seemed to me that the shorter 18463 port extension with 8inch dome worked better with the same blue chroma effect right on then edge frame where as the longer 18453 port extension this was only evident on one side and it seemed to catch a slight reflection on the right hand side where the dome port interfactes with the port backing plate. More testing is in order as this was just a quick real world shooting test with one dive per port extension.
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