Canon R + ?? to Underwater - What to choice?

Hello guys,

I own a Canon R + Liquideye + 6.5'' Dome and used a Canon RF 14-35 f4L before with weak results underwater to be honest, but I had to sell it and now need a new setup.

My options for next summer around ~$300 are:

• Canon RF 16 mm 2.8 (new)
• Canon EF 15 mm (2nd hand)
• Sigma EF 15 mm (2nd hand)

What would you do, or pick any lens that is not here?

Thanks and good shots!

I'm not really sure what you are asking, are you saying you want recommendations for a lens to use in a 6.5" dome with a Canon R? 

Using a full frame with a 6.5 " dome is going to have soft corners with any rectilinear lens, that's down to dome port optics.  Any rectilinear wide with similar field of view is going to have the same issues.

I assume the 15mm lenses you refer to are the EF 15mm fisheye and the sigma 15mm fisheye?  I would look at those two lenses as they will have much better corners in a small dome port.  I would also pick lenses that appear on the housing manufacturers port chart as they should have the right extensions for the lenses to work at their best.  I would think the sigma 15mm would be better as it focuses closer and should work better with small domes.  The EF fisheye is quite an old lens now.

I note that the liquideye housing is a surf housing and they say not suited for diving - a fisheye lens may not do what you want it to.  It would be easier to help if you told us what subjects you had in mind and described better why you thought the 14-35 produced weak results. 

Hello ChrisRoss, I just do some snorkeling with my surf housing and have the opportunity to shoot some mantas and trying to find a whale shark soon! Yes, my question is what lens to choise for this Canon R + Liquideye + 6.5'' Dome setup. 

My Canon 14-35 f4L had poor results probably because dome is too small, as you comment. Corners were totally out of detail. Maybe I should invest in a 8'' and RF 16 mm because I like the image to be rectilinear or use Sigma 15 mm and edit on Lightroom with corner distorcion?

Any other suggestion?

24 minutes ago, stillviking said:

Hello ChrisRoss, I just do some snorkeling with my surf housing and have the opportunity to shoot some mantas and trying to find a whale shark soon! Yes, my question is what lens to choise for this Canon R + Liquideye + 6.5'' Dome setup. 

My Canon 14-35 f4L had poor results probably because dome is too small, as you comment. Corners were totally out of detail. Maybe I should invest in a 8'' and RF 16 mm because I like the image to be rectilinear or use Sigma 15 mm and edit on Lightroom with corner distorcion?

Any other suggestion?

The 16mm would be no different to the 14-35 zoomed in to 16mm in the same dome, SO I think those are your two choices, fisheye with existing dome or something like the 16mm with a bigger dome.  Even with a 230mm dome corners will still be a little soft with a 16mm lens and people generally stop down to f11-13 for better corner performance.  It's a characteristic of dome ports unfortunately. 

The 15mm fisheye  will be quite sharp in your existing setup, a lot of people use fisheyes in UW work, they can be made to work as long as you don't place anything important in the corners and don't include straight lines in the composition, you do need to be very close though.  You can de-fish but there is no free lunch and the corners may still suffer a little in the de-fished image.

You will probably find the 16mm in a large dome works OK for many things where you don't have important detail in  the corners - like large pelagics like mantas with water in the corners.