SLR lenses help plz!!

[parabolic]

What is the main difference in taking pictures UW between 12-24mm and 10.5mm?
what is better to invest in?

It's primarily just the width. The 10.5mm is a 180 degree fisheye and the 12-24mm is a rectilinearly corrected lens (angle of acceptance 91-66 degrees at 12mm and 24mm respectively), but that doesn't make much difference underwater where there are very few straight lines. Personally I don't think there is much value to a zoom lens underwater. I bought the RS 20-35mm zoom, thinking it would be a good lens for shooting big animals, particularly sharks. But after an initial love affair with it I found that I rarely used it. With sharks and other big animals I found the action was just too fast to use a zoom lens effectively. For me it was better to use a fixed focal length lens (28mm or 13mm) and just wait for the frame to develop. But that's just me. There may well be some good application for the zoom in more fixed wideangle shots like reef scenics that don't move. Also, IMHO, I love the 10.5mm, if it's a choice between the 10.5mm and 12-24mm underwater, go with the 10.5mm (I have both lenses and have used both underwater).

 

[Mariozi]

Also, IMHO, I love the 10.5mm, if it's a choice between the 10.5mm and 12-24mm underwater, go with the 10.5mm (I have both lenses and have used both underwater).

IMHO parabolic is perfect.
I used to have something like it in my film setup (16mm/2.8 fisheye, 20mm/2.8 and 24-85mm/2.4-4). UW the fisheye lens are just "magic visibility amplifier machines"!!!
If your model is 2-3m from you he'll appear to be at 6-8m!!! On the other hand, if you get close... WOW!!! You will get 6-9ft corals from small sprouts!!!
A friend of mine once described how he feels with a 20mm compared to a fisheye (wich is pretty much the same as a 12mm compared to a 10.5mm):
"Its like playing football (soccer in our case here) in bathroom!"
12 to 10.5 is not a big difference in numbers, but as parabolic said, the 12mm provides HALF of the field of view of the 10.5.
Not that it is not a good lens, but UW the 12mm is just what a 16mm is topside:
A great differential, but not the workhorse.

 

[Warren_L]

What is the main difference in taking pictures UW between 12-24mm and 10.5mm?
what is better to invest in?

Probably not a lot of difference. There will be a greater angle with the 10.5mm, and will have a wider aperature as well, but I think it depends greatly on the kind of pictures you want to take. I have the 12-24mm zoom and it stays pretty well wide out at 12mm 100% of the time while shooting wrecks (which is the diving I do when I am not travelling). However, I like the flexibility of the moderate zoom on the 12-24mm when diving in the tropics as I can get a touch closer for certain types of marine life. I've done a number of shark dives and I really like the ability to move up to 24mm if I want to.

For land, the 12-24mm is a great lens for doing landscapes and such, but if you're using onboard flash, you're going to be limited to about 20mm or higher due to the shadowing of the flash created by the lens barrell. The kit lens 18-70mm I really did not touch much to begin with I've re-discovered and have been using that a fair bit more on land these days. Pretty versatile. But for strictly underwater I use 3 lenses - 12-24mm wide zoom, 60mm macro and 105mm macro.

 

[Mariozi]

Warren, its about half the coverage...
while the 10.5mm gives you 180 degress the 12-24 at 12 gives little more than 90 degrees.
When it comes to area covered you will need 4 images taken with the 12 to make up one 10.5mm pics...

When I talk about coverage this is what you get at fisheye that you dont get anywhere else:

here the dome is less than a foot from the bow.

I am not saying that the 12-24 is a worse lens than the 10.5.
In fact I think they are exactly the opposite.
The 10.5 shines UW, and makes a good differential for your pics topside.
The 12-24 shines topside, and makes a good differential for your pics UW.
But considering the price tag and its use (UW) I always suggest the 10.5 for UW use.
I wish I had them both, as I did (I owned a 18-35 with film) before...

 

[Diver Dennis]

I have a Canon 10 - 22MM, I know this is a Nikon discussion, and I have found it's one of my favorite U/W lenses. I use a 100mm exclusively for macro.

 

[HowardE]

I have a Canon 10 - 22MM, I know this is a Nikon discussion, and I have found it's one of my favorite U/W lenses. I use a 100mm exclusively for macro.

That's ok - you REBEL

As to the zooming thing... I zoomed in when I was shooting macro (since usually those things don't move that fast) when I was drifting along, I would zoom out to 17mm just in case something big swam by.

 

[Jamdiver]

That's ok - you REBEL

Ba dum ching........
Thanks i'll be here all week .

 

[Diver Dennis]

.:d :d :d

I kind of like the fisheye look but I hate too many options U/W because we can only take one lens at a time and I can't afford two housings...

 

[aboalreem]

If I am buying a lense to use on the land to practice and build my skills for the SLR for 2 month before hitting the water, what lense should I buy? 105 10.5 or 60? or others?

 

[HowardE]

If I am buying a lense to use on the land to practice and build my skills for the SLR for 2 month before hitting the water, what lense should I buy? 105 10.5 or 60? or others?

For topside - get a good zoom lens, like the 18-200 or even a 300mm zoom.