18 replies to this topic

[DeepDiscovery]

Thought I would attempt to open a discussion about the value of zoom lenses versus fixed focal length lenses on a housed digital SLR. I am considering the Canon 10D camera and am now trying to figure out lenses for it. Obviously zooms have pratical application on land but what about underwater? If so, which ones? Thought this might make for some interesting discussion. Here goes...

How practical is a zoom lens, vice a fixed focal length lens, in underwater photography. If you like zooms, which ones and why? If you prefer fixed focal length lenses, which ones and why?

What do you think?

[craig]

Zooms don't work well behind a dome over a wide zoom range, so you either accept longer focal lengths or restricted zoom ranges. Usually you want close focus with longer lenses, so most longer zooms are ruled out. The wide angle zooms like the 16-35 can be used, but they won't that wide with the 10D. Still, it might be a lens you like.

Zooms work great with video especially when the optics are wide enough and still offer full zoom-through. Video camera lenses are much easier to build, though, since they don't need to the resolving power still cameras do. I'm sure if we had a still lens that offered superior quality, wide zoom range, good magnification, and a wide short end we'd all love it. That's more or less what videographers enjoy.

For the cropped dSLR's, I think most people here like a wide lens like a 14mm or full-frame fisheye, a short zoom like a 16-35 or 17-35, and the shorter macros lenses with a flat port. Some people are also using the 100mm and 105mm macros. I use a zoom macro lens which is wonderful, but it's not a lens many people can even house and it's not for Canon.

[james]

Let's assume for a sec that everything you take photos of is at 2 1/2 feet from your camera. You get good lighting at that distance.

If you use a wideangle zoom lens like the 16-35(canon) or the 17-35(Nikkor) then you can take pix of anything from the size of a car (or a whole diver) to the size of a snapper and get a great shot. With a fixed focal length lens it's one of the other, but not both on the same dive...

Nikon is releasing a 12-24DX zoom lens this week which will have the field of view of an 18-35 on a film camera body... this should be the "ultimate" underwater zoom lens if Nikon gets it right. And from all reports from beta testers, they did...

Cheers
James

[davephdv]

The Nikon 17-35 works great in a dome Under Water.

[donauw]

An additional advantage the zoom is to be able to "tighten"up your shot. This minimizes the need to crop and allows you to make the most of your resolution. i.e. compare a D100 file at 9 meg vs a scanned slide at 24+ meg... You have more leeway in cropping the slide...

I find the Nikon 17 - 35 AFS to be a great lens behind a dome. I'm anxiously awaiting the 12 - 24!

Examples of the 17 - 35 behind a Subal dome can be found at:

http://www.dwave.net...cao/page_01.htm

Regards,

[Alex_Mustard]

I find the 17-35mm great for 35mm underwater but not really wide enough for my small chip D100 underwater. The 12-24mm will fix this but I am not sure I can justify buying one for just the digicam.

I have been using the 17-35 on this trip on the D100 and it works fine but is not really wide enough for scenics. Today it is on the F100 (35mm) while the 16mm is on the digital.

I like my sigma 28-70mm (f2.8) on both (I use it behind a Subal 105mm flat port). Very happy with the results.

You can see results from both lenses here

Alex

[james]

Alex,

I love this shot!!!



Cheers
James

[Alex_Mustard]

Thanks James. I am a big fan of top down views of creatures. Peppermint gobies are v common out here - this shot is a bit more interesting than the standard because of the whitening of the coral and the curl of the tail of the fishy. It is interesting that you pick this one out because I wouldn't have. It is always interesting to hear what people think of your shots - because invariably they prefer different ones to your own favourites.

The reason I am posting is to say that depite saying I don't like the 17-35mm on Digital I used it yesterday on a 3 dip dive at the East End. Doing 2 rolls of film and about 10 minutes of digital on tarpon. Actually it is a great lens! Just a very different lens from what it is on 35mm!

Running totals for the trip over 1000 digital shots downloaded and 30 rolls of slide exposed so far. The end is insight. Thanks again for all the help and encouragement from the wetpixel crowd.

Alex

[tshepherd]

Actually it is a great lens! Just a very different lens from what it is on 35mm!

This is a great point Alex, and isn't necessarily limited to the D100, but to any dSLR without a full frame sensor. This is especially true with the 10D / D60 / D30, as the 1.6x factor makes the lenses behave that much more differently.

If you've got a film SLR and any lenses, the change to a dSLR can certainly be difficult for a time, since you might find yourself thinking "damn, if only the lense was as wide as it is on my XYZ". I can say from my limited personal experience that over time, you just adjust to it. It's been quite a while since I shot a role of film, long enough that I don't remember what it's like to have the lenses I have behave the way they were originally designed to.

Back to the original topic, I find that having a zoom is very valuable, even underwater. I like having the ability to alter the composition without moving too much, since the more you move, the more likely the subject is to disappear on you (ok, maybe not coral, but...). Having a zoom also allows you to get just a *little* bit closer sometimes, and to do so without the damaging the reef, or spooking your subject.

I'm looking at getting the new Canon 17-40L as my primary wide-r lense. The other lense I am considering as an alternative is the Sigma 14mm, which many people with Canon's seem to like.

One thing to consider since you seem to be buying the body, lenses, and housing all at once. Make sure that whatever camera and lenses you decide on are supported by one of the major housing manufacturers. You might even want to consider what housing manufacturer you want to buy from and working backwards from there. I love my D60, and I really like my Sea and Sea housing, but there's lots more options for the D100, and if I were starting from scratch knowing what I know now, I would consider that. That being said, the 10D is a better camera than the D100 in my opinion, but I'm partial to Canon instead of Nikon so...

Just my $0.02
Tom

[craig]

Good advice, tom. Having the zoom is why I like the 70-180 for macro so much. I absolutely agree that considering body, housing, lens and ports is the best way to make a decision. I also feel that the choice of housing (and ports) should be the highest priority. This is equally true for video.

Have you considered a fisheye instead of the 14mm Sigma? Alex has some great examples using a fisheye.

[MikeO]

There was a post a while back about some software that turns fisheye images into rectilinear images. Anyone remember what it was?

Mike

[tshepherd]

I've considered the fisheye, but I've not got a normal wide angle yet for topside. With the Sea & Sea, there's a very limited set of zoom / focus gears supported as well, which is causing some difficulties in choosing a lense as well.

S&S supports the Sigma 14mm and Canon 15mm fisheye right now, and will soon support the 16-35L (pricey), but not much else in terms of really wide angle. I can probably live without a focus gear, or a zoom gear for some of the other lenses, and I could probably find a place to get one made if I had to.

The issue is that I'm going back to Truk Lagoon in May, and I want to have a solid setup before then. Tough decisions...

[craig]

There was a post a while back about some software that turns fisheye images into rectilinear images.  Anyone remember what it was?

Mike

The standard is called PanoTools. It can be difficult to use, though. An option is Grasshopper ImageAlign. Quite easy to use by comparison. I have both but use ImageAlign as a Photoshop plugin.

One thing to watch for. The standard advice you read for correcting a fisheye works but it destroys much if its wide angle benefit. The reason is that it maintains the original image dimensions but stretches the image to straighten it out. In order to get maximum wide angle, you need to increase the image size, correct the distortion, then crop the result. This is easier in ImageAlign. The resulting file will be wider that 3:2 but that's to be expected. Sometimes you don't mind the reduction in width and prefer to retain the 3:2 size.

I set up a tripod, shoot a grid, determine my PanoTools/ImageAlign parameters, then create a PS action to straighten the image. After that it's a one-click fix.

[ehanauer]

When I was shooting film, the 24-50 was the lens I'd use when I was uncertain about what I might encounter. It's good for everything except closeup. I had previously used a 28-85, but at the long end was reaching too far, shooting through too much water, and at the near end it wasn't wide enough. The 24-50 was a good big critter lens.

Now that I'm shooting digi, I'm using the 16mm full frame fisheye (20mm equivalent) for wide angle, 24mm (36mm equivalent) for big critters. The 16 has become an everyday tool instead of a specialty lens. I'm anxiously awaiting Nikon's 12-24 (18-36mm equivalent) as an all-around zoom lens to replace the 24-50.

BTW, on land my bread-and-butter lens is Nikon's 24-120.

Eric
www.ehanauer.com

[underwatercolours]

There was a post a while back about some software that turns fisheye images into rectilinear images.  Anyone remember what it was?

Mike

There are two Photoshop plug-ins that I'm aware of that can do this. Once of them is PanoTools that Craig as already mentioned, that you can read more about at this web site and another is called Defish. I couldn't find my original link for them, but you can find a download link from this page. Scroll down to about the middle.

Both of these programs work quite well to remove distortion, but they can also equally create it. Defish seems to work much better for serious distortion. Both also will degrade the image quality, so be careful.

Bonnie

Correction: Defish is not a Photoshop plug-in, its a standalone application

[wetpixel]

I set up a tripod, shoot a grid, determine my PanoTools/ImageAlign parameters, then create a PS action to straighten the image.  After that it's a one-click fix.

Yo, Craig -

Got params for us for various lenses? I have both as well.

[craig]

I have a Panotools set for the Nikon 16mm. I haven't done the Sigma 15mm.

[Ryan]

I could be wrong, and probably am, but I understood that the equivalence of the new 12-24 dx Nikkor Lens is 12-24mm. It is a true 12-24 equivalent, not an 18-36 equivalent, and the whole purpose of the dx-series lenses is to eliminate this equivalent bs.

[craig]

Here is a link of an announcement on the new lens. It's focal length range is 12-24 since cropped sensors don't change the focal length. It's field of view is equivalent to a 18-36 for full-frame. The confusion is understandable.