Samyang / Rokinon 7.5mm behind a 4.33 Nauticam Dome

Hi All,

I am contemplating on getting a Fisheye lens for my E-M5 setup. I mainly shoot available light and always while FreeDiving. Most of the time I shoot either Whales and other large marine life or other freedivers.

I know the Panasonic 8mm is a great lens but the Samyang received great reviews in terms of image quality and sharpness. Will the fact that the lens is manual focus limit me too much? (Providing I can use the Zoom mechanism of the housing to Focus the lens). I can preset the aperture to F5.6-8 and only play with speed and iso...

Will the lens be sharp behind the 4.33 dome? I know it was designed for the Panasonic but the two lenses are very similar in terms or size (Pana is 61X52 and the Rokinon is 60X48.3).

Is the fact that the Pana has AF enough to justify the cost? Samyang- 260$, Panasonic-750$

Thank you very much,

Erez

I own a Samyang 8mm for Canon APS-C camera, but I have never used it underwater.

If I can borrow a fisheye port, I will try it some day.

It is common in landscape photography to work with the hyperfocal distance. Maybe this

is what you think about when you write "working at f/5.6 or f/8".

hyperfocal distance is a distance beyond which all objects can be brought into an "acceptable" focus.

http://en.wikipedia.org/wiki/Hyperfocal_distance

For example, this distance on an 8mm at f/5.6 on an APS-C sensor is :

H = 8*8/(1000*5.6*0.033) = 35 cm

So theoretically if I set my focus ring to 35cm or above, all should be in focus.

I do not know about Micro 4/3, but it should be similar. I think it is worth trying

to work with a manual focus fisheye lens if it matches the dome.

I have the 8mm for the NEX 7 and there is slight vignetting with the 4.33in dome. See my post in this thread: http://wetpixel.com/forums/index.php?showtopic=48094&hl=%2Bsony+%2Bnex+%2Bjmauricio regarding how it works behind the dome itself. don't worry about the purple fringe, this was a nex 7 specific problem and has since been corrected with a recent firmware upgrade.

obviously with the EM5 may or may not vignette but you can get a sense for sharpness.

Hi Waterboy,

I am also looking for a wide angle option for my Nauticam EM5 setup.

Have you been able to try the Samyang 7.5mm with NA-EM5 ? If so, can you tell us how it performed ? If you could use the zoom mehanism to control focus ? Which port have you used ? etc.

Thanks

I did get my hand on a port. Here are pictures of Samyang 8mm (+ APS-C) underwater with focus

set at 0.7m for the wreck and 0.5m for the other set. Aperture was f/5.6 for the record.

Wreck :

Small French harbor (and 4 macros) :

Hey.

I have ended up getting the panasonic 8mm.

I have used it behind the 3.5inch port for a while and am now using it behind the 4.33inch port.

I love this combo! Mainly using it for FREEDIVING shots but have just returned from tonga and found that when the whales were close enough the combo performed extremely well.

My other combo- oly 9-18 behind the 4inch wide port did not perform as nicely and I have found that I needed to stop down to f10 for good sharpness across the frame. This makes me boost ISO to over 640 which in turn degrades quality...

With the 8mm I can shoot at f7.1 and get awesome sharpness.

I will upload some samples next week.

Cheers,

Erez