The Tamron 17-28mm F/2.8 Di III RXD is without doubt one of the best options for wide angle underwater photography.

As I wrote in a previous article this lens has several strengths

1. Close minimum focus distance (19 cm wide – 26 cm tele)
2. Lens does not extend when zooming
3. Reasonably compact (99 mm and 420 grams)
4. Good sharpness at the edges from f/4 onwards
5. Low cost compared to other Sony lenses.

The lens will cost you $799 vs $2,299 of the Sony 16-35 GMII which is the best lens in this class however the price difference will convince most people especially those only using the lens underwater that the Tamron is the way to go.

Parts for Nauticam Housings

The Nauticam 18809 wide angle dome port is not a classic dome but has design without a flat base. The port has 11cm radius of curvature and is 85mm deep 180mm wide this means the entrance pupil needs to be 25mm behind the extension.

Nauticam recommended extension is 40mm when combined with the 35.5mm N120 to N120 port adapter. Due to the shape of the lens this cannot be used with the N100 port as the zoom is close to the front of the lens.

Underwater housing manufactures unfortunately do not apply any science to the selection of domes and extension for a lens but out of pure coincidence the 40mm extension ring is what this lens requires.

With the 40mm extension the glass port will be exactly 11 cm from the entrance pupil and focus right on the surface.

The Nauticam parts will set you at $2,284 for the gear, extension and wide angle port.

Pool Session

I had already shot the Tamron in the murky waters of my local pool so I went to Luton that has a better filtration system and started with my usual shots.

I took shots from f/2.8 to f/22 obviously f/2.8 and f/4 are purely academic but decent results are obtained from f/5.6.

At F/2.8 most of the area outside centre is blurred.

By f/4 we have a substantial improvement.

At f/5.6 the lens is better than most already considering the very close shooting distance. Unfortunately at this stage I picked up a bit of debris on the dome and did not realise…

f/8 is very good and this is your default for shots that are not close when edges are not important.

f/11 is probably the best overall compromise between edges and centre.

By f/16 depth of field keeps everything in focus however the lens has dropped in the centre.

f/22 gives you a consistent frame but with evident resolution loss.

All the shots above have distortion correction deactivated.

I then went and shoot a tile wall to see how straight is the lens here lens correction is applied.

At f/5.6 shooting from 1.8 meters performance is excellent.

f/8 is even better across the frame and is your default if depth if field is not essential.

f/11 is great

f/16 and f/22 give consistent sharpness as expected again those apertures are normally not necessary.

Shooting people with the Tamron

One of the things you do with a rectilinear lens is to shoot straight lines and correct proportion people and wreck interiors for example. The inside of the pool lends itself well to this.

With subject not close the lens has a great pop and rendering at f/8

Even closer subject with not far background look great.

If you need the background to be sharper you can stop down.

Again considering that even WWL-1 and WACPs really need f/11 this looks terrific.

A final example shows that f/14 is enough to give you the depth of field you need when the subject is not too close.

Conclusion

There is no doubt that if you are in the market for a rectilinear wide angle and you are budget conscious this is the lens to get full stop!