What lens?

[desperoadie]

Hello everybody,
I am considering upgrading from a Canon S1IS with the canon housing to a 20D with an Ikelite housing. I am not sure which lens to use, as this will determine the dome port. I now have a 17-40f4 and a 28-70F2.8. I understood that it is best to have a fast lens. I also see some people using a 16-35f2.8. I am not into macro and am looking for a 'general' lens for the usual reef fishes. Unfortunately, I don't see a lot of the biggy ones (like sharks) so I guess I don't really need a wide-angle lens?
And since I usually don't dive that deep (say 20m or 60ft max) I guess I'm OK with one strobe?
thanks for your input and Merry Christmas.

 

[String]

If you're not into macro then the 17-40 would seem more sensible (although its a little narrow even then)

 

[M_Bipartitus]

If I recall, the 28-70 is almost too wide to fit in Ikeltite ports. It may be that you will loose the ability to zoom or manual focus if it does fit. I personally use the 17-40 it doesn't go as wide as I'd like on the 1.6x crop sensors, but I will be going full frame as soon as my 5D mrkII gear comes in. My choice was simple as I already had the lens and I didn't want to buy more lenses (it was hard enough to convince the better half that I should spend $$$ to get all the gear for a dSLR.)
As for other lenses, the EFS 10-22 zoom is a great lens for 1.6x bodies if you aren't into macro since it can go so wide. I know a 5D user who always used the 16-35 underwater, but he has money to burn. Once again this one wouldn't go quite as wide as you may want. Remember that, even with a strobe, the best photos underwater generally are those close to your subject. The farther you go through water, the more contrast and color you will loose.

As a final note, consider the following website for ideas on how to get the most compelling photos out of such a wide lens

How to Use Ultra-Wide Lenses

 

[newmanl]

Hi desperoadie,

On one hand, upgrading to the 20D in an Ikelite housing will give you a lot more options with respect to lenses, but on the other hand it will give you a lot more options with respect to lenses! Most u/w photographers start out with gear they think they'll want/need and end up fine-tuning their kit once they have some experience - I know - that's where I am! At the moment I shoot with a 30D in an Ikelite housing and started with a 28/1.8 (because it was fast - bright in the VF) behind a 6" dome. It works great and I continue to use that combination (lens and port) - here's a photo I took in Maui recently.

Hawaiian Dascyllus Canon 30D, 28/1.8 and single DS-160

On the same trip I tried my 17-40/4 as well, behind a 6" dome. It did not work very well despite the crop factor as the corners were very soft. The problem is that rectinlinear lenes (like the 17-40) are designed to focus on a flat field while a dome port makes a curved virtual image on which the lens must focus. I thought about trying an 8" dome (larger radius usually helps with corner sharpness) and possible a dioptre (is also supposed to help with corner sharpness), but have not yet tried it. While I didn't like the corners, it was/is a good focal-length for fishes if you can get close enough. Here's a shot with the 17-40:

Big Scale Soldierfish, Maui. Canon 30D, 17-40/4 and single DS-160

Lastly, a lot of u/w photography is about wide angle or macro - not that you have to conform to that at all, but consider wide angle as the equivilent of terrestrial landscape photography (with slightly different rules). I opted to go for a Sigma 15mm fisheye lens that works very well behind the same 6" dome as my 28/1.8 - here's a shot:

Kona, Canon 30D and Sigma 15mm FE in available light (Magic Filter)

If you opt to use your 17-40 underwater, I'd suggest you either find someone with that same setup and ask to see some of their photos with it, or be prepared to experiment with other lens/port combinations.

Hope this helps. Best of luck with the DSLR and housing!

Lee

 

[montychandler]

With the 17-40 F4 lens, I feel you'd want to use the 8" dome port instead of the 6". I shoot with a 20D body - 16-35 2.8L lens using the 8" dome port without issue. I don't generally use a strobe with this lens, but if you reduce the amount of water between you and the subject as well as position the strobe(s) appropriately, you should be able to manage back-scatter.

Have a great time!!

Cheers,


Monty