Over the years I've messed around with almost everything in UW photo gear but I've never needed to learn about increasing optical zoom in a lens.

To be clear, in the past I've purchased and used (for example) a 105mm lens if I needed to "reach" a remote subject. I don't have that option now because I am using a Canon R50 in the Nauticam housing. I'm really happy with the rig, but it has it's limitations. As sold by Nauticam the ONLY internal lens option is the 18-45mm (effective 27-67mm) lens. To this you can add the WWL-1B for wide angle and CMC macro lenses and I have both. This, however, is not doing what I need.

I like to do fish portraits and, as an example, I recently tried to shoot a Jawfish with babies. As you might expect I had to stay back some and I just didn't have the optical reach I needed at the effective 67mm. If I had 100mm, or so, I would have done well. With what I had I tried digital zoom in post processing and the results were barely OK.

So I'm wondering about wet diopters and such. I'd like to add an optical zoom of about 2X, and I think that's what wet diopters do. Given that I've never used one I'm just not sure what I want, or if this is the right approach. Also, since close focus is not an issue for this case I don't care if things like this change. My subjects will be 12-24 inches away from the glass.

I'd appreciate any advice the community can give and, any wet lens products you might suggest.

Gary

If I read this right, Gary, you want to be able to stand further back from your subject? So getting the same distance from your subject as oyu did with the 105mm

If that's the case, you could perhaps add a 1.4 or 2.0 teleconverter (TC)? this would increase the magnification of your 18-45mm lens by either 1.4x or 2x. You'd lose a bit of sharpness but arguably not that much and a slight loss of light. You could increase the ISO a little to compensate or use a slightly slower shutter speed or open the aperture. So there are options. You'd also need an extension ring to house the width of the TC - 20mm for, say, the Kenko 1.4 TC which is popular underwater.

Generally a diopter allows closer focussing rather than necessarily magnfication

Yes, you're correct that I need to stand back. A Jawfish (especially one with babies) will not let you get very close. Even the "brave" ones would like you to stay a few feet away.

I really like the Nauticam R50 housing, but it comes with a non-removable / changeable flat front port. The fixed port includes a bayonet mounting and can also (with an accessory) accommodate screw mount wet lenses, but any such addition must be a wet lens because there is no way to add anything to the interior of the housing.

So it seems that a wet teleconverter is what I want. Does anybody have a wet optic that they would suggest?

Gary

Sorry, Gary. I didn’t know about the fixed port. Tricky. Yeah, it has to be a wet lens then.

Been looking and reading ... might the Kraken KRL-05S be what I want, or is the reduction in focusing range going to be a problem? Seems as though that would become the issue. All the wet lenses I see suppose that one is trying to magnify for macro purposes, where I am just looking to increase the effective lens magnification.

Gary

Wet lenses generally allow you to focus closer not to increase the focal length. I think this has been asked before and the only option was a Canon 50mm f1.8 prime lens as far as what would fit in the housing goes.

You might be able to add a Kenko 1.4x to the 50mm f1.8. I found a review of the 18-45 that said it was 77mm long at max extension The 50mm f1.8 is 46mm long and extends to 60mm long and the Kenko is about 20mm thick so it might just fit and the lens would just hit the port glass at minimum focus. Min focus would be about 200mm from port. You would be stuck at this focal length and just be shooting fish portraits the whole dive.

Any wet diopter works by allowing the lens to focus closer, it doesn't give more reach, the KRL-05S is no different to any other diopter.

10 hours ago, Proteus said:

Over the years I've messed around with almost everything in UW photo gear but I've never needed to learn about increasing optical zoom in a lens.

To be clear, in the past I've purchased and used (for example) a 105mm lens if I needed to "reach" a remote subject. I don't have that option now because I am using a Canon R50 in the Nauticam housing. I'm really happy with the rig, but it has it's limitations. As sold by Nauticam the ONLY internal lens option is the 18-45mm (effective 27-67mm) lens. To this you can add the WWL-1B for wide angle and CMC macro lenses and I have both. This, however, is not doing what I need.

I like to do fish portraits and, as an example, I recently tried to shoot a Jawfish with babies. As you might expect I had to stay back some and I just didn't have the optical reach I needed at the effective 67mm. If I had 100mm, or so, I would have done well. With what I had I tried digital zoom in post processing and the results were barely OK.

So I'm wondering about wet diopters and such. I'd like to add an optical zoom of about 2X, and I think that's what wet diopters do. Given that I've never used one I'm just not sure what I want, or if this is the right approach. Also, since close focus is not an issue for this case I don't care if things like this change. My subjects will be 12-24 inches away from the glass.

I'd appreciate any advice the community can give and, any wet lens products you might suggest.

Gary

The Nauticam setup sounds great for wide and the occasional macro photo. @dhaas quite likes it. But I think you're stuck not being able to access longer focal lengths. I might consider a Seafrogs housing and a macro lens if I were in the same situation.

seafrogs

R50

Thanks to Chris R. for the info about wet lens optics, I was afraid this was going to be the issue. If anybody has tried anything else and had it work I would appreciate your thoughts.

Also thanks to Chris H. for the Sea Frogs idea. I might have gone this route if I'd known from the beginning though, otherwise, I really like the Nauticam housing.

I might end up giving the 50mm/Kenko idea a try as I already have the Kenko and wouldn't mind having the 50mm lens. If it fits I guess it would no worse than jumping in with other fixed focal length rigs that I've owned. It is really nice, though, to be able to re-plan under water.

Does anyone know if the limitation on wet lenses is a physics thing, or just a matter of no one making such a thing? From an uneducated perspective it seems as though it's just that no one is asking.

Gary

6 minutes ago, Proteus said:

Does anyone know if the limitation on wet lenses is a physics thing, or just a matter of no one making such a thing? From an uneducated perspective it seems as though it's just that no one is asking.

Gary

Don't believe it is , a lot of compacts used to have accessory converters to increase the focal length that went on front - the only option as the lens was not detachable. Interchangeable lens cameras generally use a tele-converter between lens and body, probably because it a cheaper solution with smaller optics compared to a full diameter optic attached to the front of the lens. So one could probably be designed, but the market would be quite small I expect, mainly barbecue conventional 1.4x and 2x converters do such a good job at a reasonable price point.