Thinking about going wider then 11mm. Fisheye lens?

[Allan Jeffers]

My camera is a Canon 30D and right now, my widest lens is a 11-16mm f/2.8 tokina. I enjoy shooting cloud-scapes, Atmospheric Optics, like halos and even severe weather, but I mainly interested in the cloud formations of the severe weather, like shelf clouds, wall clouds and so on.

So I have started to think about going wider and this means a fisheye. The cheapest would be a 8 or 15mm fish be it a sigma or canon, but I wonder if that would be enough. Sigma also has a 4.5mm fish out but cost more then twice the amount of the 8mm.

I do realize that the FOV is probably going to be a bit more then the focal length of the lens, but I am wondering since I will likely be sticking with a crop camera if I should just go for 4.5mm at a whopping 1000 bucks. So off to do some research I go, starting with asking fellow photographers of the sky if you shoot with a fisheye, and if you do, can you share some shots, your camera and what fish you used?

 

[Kevin Cramer]

One thing to keep in mind with the extreme focal lengths, is that they will give you the circle crop (like this - from the 4.5mm). I've never shot with one so I can't comment on its use, but I personally will probably avoid the 4.5 because of the circle crop.

 

[Allan Jeffers]

I hit up flickr and did a search on the 4.5, it was like looking at a spear, so the 4.5 is probably out as I don't think that can be "de-fished" very good in favor or maybe the sigma 8mm.

I tried to do a panoramic with the 11-16mm in an attempt to get a cloud-scape, it did not work like I thought it would.

I suspect a fish would have been a better option for this

 

[Darren Addy]

I believe you are confusing "focal length" with "field of view". What you want is wider "field of view" and it is true that if you are comparing a rectilinear lens to a rectilinear lens a shorter focal length will give you a corresponding wider field of view. But when you compare a rectilinear with a fisheye you are now comparing apples to oranges, because (as you mentioned) the fisheye now needs to be "defished" to get a rectilinear image (which is what you want).

Therefore, taking an example from the Pentax lens world: the focal length on a 10-17 fisheye zoom is not equivalent to 10-17 on a rectillinear lens; the 17mm fisheye has similar angle of view as the 12mm end on the DA12-24 (a rectilinear).

Bottom line: Compare apples to apples and just looking at focal length of the lens does not do that for you.

Put another way: Yes you may get more field of view with a fisheye, but at the expense of image edges that are now circular. Once you defish and crop to get straight edges again, you will be CROPPING OFF the very field of view you gained (and you've had to spend time and energy defishing/cropping).

The only other thing to get wider you can do (sort of shooting panos) is change to a camera with a smaller focal length multiplier. For simplicity, lets use a Sigma 10-20mm for comparison. At the wide end, that 10mm will give you 16mm [35mm equivalent focal length] on a Canon (because Canon non-fullframe DSLRs have a 1.6 focal length multiplier*). That same lens would give you 15mm [35mm equivalent focal length] on a Nikon, Sony, or Pentax model that has a 1.5 focal length multiplier. This is one reason that 4/3 camera systems aren't great if you like to shoot wide. They have a 2.0x focal length multiplier, meaning that same lens on an Olympus would only be able to give you a 20mm [35mm equivalent focal length].

If you go to a fullframe digital camera (NO focal length multipler) you now have the option of finding a wide lens that's image circle can cover it. For example, the Sigma 12-24/4.5-5.6 lens has a lot of appeal since it has full frame coverage. Now instead of shooting 11mm and multiplying by 1.6 (17.6mm 35mm focal length equiv.) you are shooting a true 12mm wide. (However at the expense of speed. You are going from f2.8 wide open to f4.5 wide open).

It is always a series of tradeoffs, you just have to decide which attributes are the most important to you and which lens is the best at delivering those attributes and at what expense to the others.

If you tried this same shot with a fisheye (putting the horizon line that close to the bottom of the frame) it would NOT be straight. It would be moon shaped and the whole scene would scream "distorted" and "untrue". Defish it, to get a straighter horizon line and you are going to lose the upper corners, and thus have to crop in side-to-side to eliminate that problem (giving up the field of view you were seeking).

* Canon EOS 1D Mark II, Canon EOS 1D Mark IIN, Canon EOS 1D Mark III, Canon EOS 1D Mark IV, all have a 1.3x focal length multiplier. The Canon EOS IDS models and 5D models are 1.0x.

 

[Allan Jeffers]

Darren, you bring up a good point. But getting a used full frame camera brings up another issue. Most places want around 1500 for a used 5D, give or take. A camera that, while is an upgrade, at least for its sensor size, don't have alot of what I am after. Micro adjust, live view, video mode.

Do I need that stuff? Not really, but it kind of irks me that I can spend a couple hundred more for a new camera that has the features that I want. I guess the best solution is to go with both a cropper and a (used) full frame. If I had 3 grand I could get a 50DmkII

Kind of a catch 22 for me I guess