diopter with Nikon 17-55mm in Subal domeport?

I am going to Palau in April and am thinking of getting the 17-55mm for reefshark shots. Do you need any diopter to use with the 17-55mm with Subal 8 inch dome? Last year in Yap, I used the 12-24mm for reefshark shots but found that the lens was really too wide for most shots unless the reefshark came within arm reach (easier said than done) so I think the 17-55mm might be a better choice. What do you guys think?

Just as a reference point - my setup is different (Nexus D70 with custom 190 dia port) but I use a +4 diopter. Anything less gives soft edges.

Hey Boi -

I used the 17-55 for GW's in Guadalupe on my D2X and thought it was a great lens... Used +2 diopter with my Nexus setup.

M.

Hey Boi -

 

I used the 17-55 for GW's in Guadalupe on my D2X and thought it was a great lens... Used +2 diopter with my Nexus setup.

 

M.

Hi Boi, I bought the 17-55 last year and have been very impressed with it's performance. Luiz Rocha, who was already using the lens, recommended a 66mm extension ring and a +2 dioptre with my Subal housing and I found the results were excellent.

Don

I used a +1 with the FE Subal dome and 66mm extension; I really like this lens.

Thanks everybody for the information. I already have the 66mm extension for the 17-55mm. I will definitely try out both 1+ and 2+ diopter combination. Can't wait to get back into the water again

I use a +4 with a Subal 40mm extention and FE dome. I also tried a longer extention ring setup - but as that caused a leak at the end of 60 minute dive - I decided not to risk it again as I only have one camera...

Alex

I use a +4 with a Subal 40mm extention and FE dome. I also tried a longer extention ring setup - but as that caused a leak at the end of 60 minute dive - I decided not to risk it again as I only have one camera...

 

Alex

Alex, ouch, I hope that does not happen to mine

I have used the 66mm extension on several dives on my last 2 divetrips with a flat port for my 105mm VR so far with no problem. Hope it stays that way!

This brings up some questions for the 'Dome Theorists' out there. Reading some dome theory explanations, I do not find this clearly discussed.

1. When choosing a dome and / or extension, how critical is placement of the front element of the lens relative to the dome surface? I understand that if the extension is too long, then of course corners may be cropped; but how far forward towards the dome surface is acceptable or desirable for ideal quality?

2. My second question that follows is how does image quality then change with zooming and positional change of the front element of the lens, which is more appreciable with the 17-55 than the 12-24?

3. Finally does anyone know what the diameter of the Subal FE dome is, and does it have coatings etc. I cannot find any info on their site.

I found something here http://www.marinethemes.com/domespacer.html

that states that a lens should not extend more than 1cm into the dome.

Alex, with the 17-55 at it's wide end, the front lens element extends the closest to the dome and with anything shorter than the 6cm extension the front of the lens sits pretty close to the dome at 17mm. My understanding is that it is particularly at the wide end of the zoom, it is most important for the lens to sit as close as possible to the center of curvature of the dome for ideal image quality.

This brings up some questions for the 'Dome Theorists' out there. Reading some dome theory explanations, I do not find this clearly discussed.

1. When choosing a dome and / or extension, how critical is placement of the front element of the lens relative to the dome surface? I understand that if the extension is too long, then of course corners may be cropped; but how far forward towards the dome surface is acceptable or desirable for ideal quality?

2. My second question that follows is how does image quality then change with zooming and positional change of the front element of the lens, which is more appreciable with the 17-55 than the 12-24?

3. Finally does anyone know what the diameter of the Subal FE dome is, and does it have coatings etc. I cannot find any info on their site.

I found something here http://www.marinethemes.com/domespacer.html

that states that a lens should not extend more than 1cm into the dome.

Alex, with the 17-55 at it's wide end, the front lens element extends the closest to the dome and with anything shorter than the 6cm extension the front of the lens sits pretty close to the dome at 17mm. My understanding is that it is particularly at the wide end of the zoom, it is most important for the lens to sit as close as possible to the center of curvature of the dome for ideal image quality.

If I use an 8 inch Aquatica dome with the Nikon 12/24/4 or 17/55/2.8 will I really need a diopter? I ask this question because Aquatica has specific extension rings for these lenses which should place the lens nodal point close to the dome's nodal point. I suppose that this specific extension ring should optimize edge sharpness...but does anyone know from experience if a diopter is still necessary for proper focussing. I can't determine the true radius of this dome to do the calculation.

Thanks for your advice.

To answer the original question I use a +2 dioptor with the 66mm ext. It gives good results. One thing to think about is that you cannot get sharp pictures if you shoot through too much water. Meaning that if you can't get close enough to shoot the sharks through the long end of the 12-24, your not going to get a sharp shot with the 17-55. I find the 17-55 to be a good lens if you shooting a combination of small reef subjects and moderate wide angle subjects.

To answer the original question I use a +2 dioptor with the 66mm ext. It gives good results. One thing to think about is that you cannot get sharp pictures if you shoot through too much water. Meaning that if you can't get close enough to shoot the sharks through the long end of the 12-24, your not going to get a sharp shot with the 17-55. I find the 17-55 to be a good lens if you shooting a combination of small reef subjects and moderate wide angle subjects.

I assume that you are using an 8 inch Aquatica dome with the +2 diopter on the 17-55/2.8 because that is the lens that uses the 67mm extension ring/port...do you use any diopter on the 12-24/2.8 with the prescribed 34mm ring?

Thanks

I assume that you are using an 8 inch Aquatica dome with the +2 diopter on the 17-55/2.8 because that is the lens that uses the 67mm extension ring/port...do you use any diopter on the 12-24/2.8 with the prescribed 34mm ring?

 

Thanks

That would be hard to use on my Subal rig. I use the FE2 domeport which I believe is 9" not 8" as many have posted. I have used the 66 mm ext ring with this set up. I recently bought the 70 mm ext ring that Subal indicates should be used with this lens but have not used it yet.

I have used 66 mm ext rings and 120 mm ext rings without a leak problem.