Sigma 15mm FE vs. Canon 10-22mm

I bought the 15mm FE as part of my original underwater package, and just recently purchased the 10-22mm although I've not had it in the water yet. I'm wondering whether I really have a need for the 15mm anymore. Thoughts or advice?

I have a Nikon D70 and I have similar lenses i.e. the Nikon 12-24 and the Sigma 15 mm fish eye. Of the two I prefer the 15 mm because it focuses closer and because it's easier to manage i.e. no need to zoom.

However, I don't have TTL yet and this means that I am stuck with manual control of power. My expectation is that when I get TTL, which will be soon, I will find the 12-24 more manageable.

For sample pics taken with my 15 mm see the following two links.

http://www.splashdowndivers.com/photo_gall...ry_q/index.html

http://www.splashdowndivers.com/photo_gall...2005/index.html

Thanks for the feedback. A friend of mine wanted to buy the 15mm, but I think I'll hang onto it for now. I was also wondering if there were any particular advantages of this lens for over/under shots as well.

I don't think there are any particular advantages of this lens vs the Canon 10-22 for over/unders. They both focus close. They will produce a different effect though so its up to the user to decide which is best for which situation.

There will be a difference in barrel distortion though. The 15mm is a fisheye so it will render straight lines as curved while the 10-22 tries to make them straight. Sometimes the fisheye look is appealing in the frame sometimes not. On digital its not a true full-frame fisheye so the barrel distortion is less than on film and underwater almost undetectible except on straight lines like wrecks.

The 15mm is also wider than the 10mm end of the 10-22. So this is the lens to use for panoramas.

I have both the 15mm and the 12-24mm on Nikon. I like having both. I think the Canon decision is a bit harder because the 10-22 is a bit wider than the 12-24mm narrowing the FOV gap and the 10-22mm focuses so close which is not the case for the 12-24mm Nikkor.

The 15mm is also wider than the 10mm end of the 10-22. So this is the lens to use for panoramas.

No, it's not wider.

15mm FE @ 15mm * 1.6x crop factor = 24mm equivalent

10-22mm @ 10mm * 1.6x crop factor = 16mm equivalent

~Matt Segal

No, it's not wider.

 

15mm FE @ 15mm * 1.6x crop factor = 24mm equivalent

 

10-22mm @ 10mm * 1.6x crop factor = 16mm equivalent

 

~Matt Segal

<{POST_SNAPBACK}>

Yes, it is wider.

If both lenses were rectilinear, you would be correct. However, they are not and can't be compared this way. In this case you have to use angle of view rather than focal length as the factor in the comparison. The Sigma 15mm here is a fisheye, not a rectilinear lens like the 10-22mm, and as such it covers 180 degrees on a full-frame camera. That means that on a 1.6x crop-sensor camera it covers 180/1.6 or 112.5º. I checked Canon's site and the specifications for the 10-22 show that at 10mm the camera covers 107.5º. So, the 15mm fisheye is actually a few degrees wider. However, as was pointed out, you do get some of the barrel distortion you would expect from a fisheye lens, though not the full effect becuase you're only using the middle section of its projected image. In order that I may partly disagree with everyone I'll say that in my opinion, this makes it worse for panoramas because you have to correct for the barrel distortion to get the images to line up when stitching and the extra 5º probably isn't worth that hassle. I have the Sigma and like it. I can't use the 10-22 because my camera (EOS 10D) can't take it. I may look at the Sigma 10-20mm later in the summer when it is finally released. There is alos a Tokina 11-18 out now that has gotten positive press . . .

Mike

10-22 FOV's (Angle of View's) on 20D

Horizontal - 97.25°

Vertical - 74.11°

Diagonal - 107.47°

15mm FOV's (Angle of View's) on 20D

(Equisoidal FE)

Horizontal - 88.92°

Vertical - 58.30°

Diagonal - 108.09°

Not quite as large as was thought.

~Matt Segal

OK, so we were both wrong. The 15mm fisheye is not a 24mm equivalent like you first said and, the simple calculation I did comparing the diagonal fields of view doesn't work in the other directions (horizontal and vertical) because of the projection (equisolid) used to develop the fisheye lens' image. That is why the fisheye has a wider angle of coverage in the diagonal but not on the horzontal and vertical. The good news is that your last post does have the correct numbers in each direction according to the manufacturers' specs . . .

Focal length x crop factor, field of view x crop factor ….. creative maths for fisheyes going on here

equidistant projections are handled different (projected image point distance = reciprocal value of focal length x zenith angle)

As a hysterical dome nerd I have to have a small chart for Canon cameras from my earlier search for a proper setup:

Note that these values are based on manufacture data which usually have been rounded up or down (focal length, etc.). And I might have screwed up some sensor dimensions in this chart as well

I don't think there are any particular advantages of this lens vs the Canon 10-22 for over/unders.

Yeah, there is even a quiet huge difference in terms of DOF for split shots.

Regards,

Julian

Googled to get a better explanation of this than the charts allow:

http://www.photo.net/learn/fov/

Nothing like starting with a valid argument and then immediately ignoring one of the original assumptions .

Mike

Interesting posts guys.

Anyone have equivalent information for D70 and 12-24/15 FE?

Anthony....I don't do scientific.....just logical

I have both lens and before my last trip, I put the 12-24 at 12mm on the camera and aligned the right side with an object in the room and noted the location on the left side

I then put the 15mm on and put the right side on the same object and observed that the left side was practically on the same location as the 12mm

In other words, they are almost identical.....how's that for scientific?

Karl

Works for me Karl - don't think I'll bother with the 15 mm. Might get the 10.5 though....

Anthony, I didn't mean to imply that the 15 isn't a lens to consider just because its' FOV is so similar to the 12-24.....it will focus closer than the 12-24 and it has very sharp corners

If I'm on a dive just for WA, I'll probably use the 15 over the 12-24.....the 10.5 is even wider, but you have to be all over your subject....I'll still use the 12-24 on WA dives that need a little zoom control....ie: sharks

Karl

Thanks Karl,

Maybe I'll consider the 15 for the sharper corners - might get away without buying the 8" dome that way...

At this stage I'm having a ball with the 12-24 topside - great lens, but would prefer the sharper option UW.

Not quite as large as was thought.

Thanks I'm learning something here.

I had it that it was simply 180*1.5=120 degrees. Reinforcing how valuable this resource is.

Yeah, there is even a quiet huge difference in terms of DOF for split shots.

Is there a difference in the DOF calculation for fisheye vs rectilinear lenses or is the DOF difference simply due to the difference in focal length? Do the DOF equations like the one here:

Photo.net

still hold for fisheyes?

I originally bought the 15mm FE because conventional wisdom on wetpixel had it that the 12-24mm would need diopters in Ike dome. This would make it unusable for split-levels. Now that seems not to be the case.

The 15mm is still wider than the 12mm of the 12-24mm but not much. Its also faster and sharper and it takes gel filters. So I think it still has a place in my kit but I don't think its an easy question.

Mike:

You may want to check out the Tokina 12-24 for Canon mount DSLR's. It's not an EF-S lens so will work on the 10D:

http://www.bhphotovideo.com/bnh/controller...u=360349&is=REG

It's reported to be an excellent lens and you can't go wrong at $499

It will work on the 1DmkII from something like 16mm up which might be handy.

Cheers

James

Wow! Lots of great info here. Thanks for all of the explanations. Think I'm going to hang onto the fisheye for now and make a final decision on whether to keep it once I have more experience with the two lenses.

@UWphotoNewbie

Yes, 10mm delivers more DOF (being a function of the focal length) than 15mm fish.

I have also thought of the possibility that fisheye lenses might differ in the DOF calculation. But I’ve never found some information in that direction and in real life tryout my Sigma 12-24@12mm delivers a lot more DOF than my Sigma 15mm fisheye (@same aperture). I guess that fisheye DOF might increase to the corners as reproduction ratio changes in comparison to a common wideangle. But I don't know and from experience the normal wideangle formula works here as well.

Biggest DOF - I’ve experienced with the 8mm fisheye being the shortest focal length I've tried.

Different to topside I like those cropped sensors a lot underwater. Same FOV – more DOF, good for wideangle and macro as well.

Julian

I'll still use the 12-24 on WA dives that need a little zoom control....ie: sharks

 

Karl

<{POST_SNAPBACK}>

Aha! So maybe I should try out the Tokina 12-24 next month at Tiger Beach! I can get that one now, which will give me time to fabricate a zoom ring, or modify an existing one . . . Sigma still isn't giving very firm answers on their lens and, though I'd like to have 10mm vice 12mm on the wide end, a bird in the hand and all that . . .

Mike