I Finally Landed A Fish

So a couple months ago I was lamenting not having a full frame fisheye. I also stated that I was in a quandary over just how "wide" the Sigma 15mm Fish is since it states that it has a 180 degree horizontal view, but photos on the web just didn't seem to suss that out - at least not consistently. The best I got was the trusted opinion of my brother who used one at PhotoPlus and confirmed that it was, in fact, 180 on the diagonals.

Today I got my usual daily reminder email from Amazon that there were things I looked at on their site and yet for some reason I had not spent my hard earned money on them, so they need to dangle them yet again, including the 15mm. This caused me to start digging again. I decided to go to Flickr and put Sigma 15mm in the search box, and this is one of the photos I got...




Risking being over punny, it brought everything into focus. At first glance it told me I didn't want it because it was essentially only a tad wider than my 16-35mm at 16mm. But then I noticed the "defished" text and realized that many of the images I was likely finding with this lens had the same treatment in post. The image in the bottom right is what I was looking for, and the look I could apparently get with this lens. Huzzah!!

On top of that what surprised me was the inset of the bear and the comparison to the edge sharpness of the Nikon 14-24mm "Holy Trinity" lens. That's pretty darned impressive for a lens that is less than 1/3 the cost (I've linked the full resolution image from Flickr so right-click and open in a separate tab/window to see the details).

Now I just need to wait for the right Holiday Sales Special instead of justifying that I need it this weekend and hitting up B&H. LOL

I'll be looking forward to seeing your results when you get this Jake. I'd like something wider than 18, but not at the prices of the Nikon offerings.

Wouldn't you know it, B&H dollars popped into my inbox tern minutes after I posted this. I believe the photo gods are telling me something. It'll be here tomorrow.

Congrats on the new lens Jake. I have a full frame fisheye for my Olympus bodies but haven't picked one up for the Nikons yet. One thing that you mentioned on your original post that sometimes gets overlooked is that there are two types of fisheye lenses, full frame and circular. A full frame has a 180 diagonal field of view (not 180 horizontal or vertical) and produces an image that covers the sensor. A circular fisheye has a 180 field of view in all directions and produces a circular image on the sensor.

Note: "full frame" in this post refers to a type of fisheye lens not to a type of camera body. The 8mm Olympus lens is a full frame fisheye lens when used on a Four Thirds (or micro Four Thirds) body.

Be aware that 'defishing' an image isn't all it's cracked up to be. In order to defish a digital image, pixels must be enlarged.

And not only does this enlarging cause sharpness issues, the further from the center of the image you get, the less sharp the IQ was to begin with.

So you end up enlarging the softest part of the image.

480sparky said:

Be aware that 'defishing' an image isn't all it's cracked up to be. In order to defish a digital image, pixels must be enlarged.

And not only does this enlarging cause sharpness issues, the further from the center of the image you get, the less sharp the IQ was to begin with.

So you end up enlarging the softest part of the image.

Click to expand...

I'm definitely not into "defishing", which is why I was put off by so many of the images I was seeing out there from this lens. I've got the 16-35mm to get me that look. I just thought the IQ compared to the 14-24 was noteworthy, even if it's in a cropped composite.

Steve B said:

Congrats on the new lens Jake. I have a full frame fisheye for my Olympus bodies but haven't picked one up for the Nikons yet. One thing that you mentioned on your original post that sometimes gets overlooked is that there are two types of fisheye lenses, full frame and circular. A full frame has a 180 diagonal field of view (not 180 horizontal or vertical) and produces an image that covers the sensor. A circular fisheye has a 180 field of view in all directions and produces a circular image on the sensor.

Note: "full frame" in this post refers to a type of fisheye lens not to a type of camera body. The 8mm Olympus lens is a full frame fisheye lens when used on a Four Thirds (or micro Four Thirds) body.

Click to expand...

Actually in this post it refers to both. I have a full frame, DX fisheye that I have used on my FX cameras, either in cropped mode or full frame and cropped later. What I mean here is a full frame/non-circular fisheye for a full frame sensor. But yeah, it's important to know the distinction. I've never been a fan of the circulars.

480sparky said:

Be aware that 'defishing' an image isn't all it's cracked up to be. In order to defish a digital image, pixels must be enlarged.

And not only does this enlarging cause sharpness issues, the further from the center of the image you get, the less sharp the IQ was to begin with.

So you end up enlarging the softest part of the image.

Click to expand...

With a full frame fisheye (180 degrees diagonal FOV) this isn't completely true. The pixels along the vertical and horizontal axis out to the edge of the frame will not be modified by defishing the image. The pixels that have to be modified the most are the ones closest to the corners. Depending on the subject matter this may not be an issue. Interior shots are where it will show up the most if you are trying to straighten lines that are near the edge of the image. For a lot of landscape type of shots it is not much of a problem.
These two pictures were both taken with an 8mm fisheye on an Olympus E-5. First one had the horizon line centered, second one had the horizon line below the horizontal center.

BackdoorHippie said:

Actually in this post it refers to both. I have a full frame, DX fisheye that I have used on my FX cameras, either in cropped mode or full frame and cropped later. What I mean here is a full frame/non-circular fisheye for a full frame sensor. But yeah, it's important to know the distinction. I've never been a fan of the circulars.

Click to expand...

Sorry Jake, I just meant in my specific post not in your post.

Geeze Jake, stop it!!!

I'm going to have to stop looking at your posts because they leave me wanting more lenses!

So how does a rectilinear lens compare with a full frame fish eye? How do they differ?

My understanding is that a rectilinear lens attempts to correct the "fisheye distortion" with the optic design of the lens. In other words, it keeps straight lines straight.

hark said:

Geeze Jake, stop it!!!

I'm going to have to stop looking at your posts because they leave me wanting more lenses!

So how does a rectilinear lens compare with a full frame fish eye? How do they differ?

Click to expand...

Easiest way to understand it is that a rectilinear lens (for the most part) removes barrel distortion so that your vertical and horizontal lines remain straight. A fisheye is all about barrel distortion. If you look in the photo above, the "de-fisheyed" shot is roughly what a rectilinear 15mm shot would look like, where the one underneath has the fisheye elements and evidence of barrel distortion/pin-cushioning. In rectilinear lenses the perspective is often exaggerated in order to make corrections.

Here's a good example of the difference. The top is the curvilinear perspective you get from a fisheye, the bottom is with a rectilinear lens. Both show the same field of view and you can see how the edges become stretched in the rectilinear photo. You can also see how the corners are cut off, which is where you lose the 180 degree field of view in the non-fisheye.

My wife has a 10.5mm DX fisheye and I tried it on the D800 the other day. I can actually cut a circle out of the FX image in photoshop that's much bigger than a DX sensor. I'm away today or I would post the result.

I'm thinking of trying it on some night sky shots.

Jake, thanks for the explanation. I think it cleared up my muddied understanding of the differences between rectilinear, full frame, and circular fish eye lenses.

Steve B said:

With a full frame fisheye (180 degrees diagonal FOV) this isn't completely true. The pixels along the vertical and horizontal axis out to the edge of the frame will not be modified by defishing the image. The pixels that have to be modified the most are the ones closest to the corners

Click to expand...

Isn't that what I said?

Steve B said:

......... For a lot of landscape type of shots it is not much of a problem.
These two pictures were both taken with an 8mm fisheye on an Olympus E-5. First one had the horizon line centered, second one had the horizon line below the horizontal center.
View attachment 61494
View attachment 61495

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So what does taking two images with different views have to do with defishing?

Just curious, when moderators (@fotojack) edit a post is there any way they could PM the original poster and let them know why, or at least park the reason in parens at the bottom? I sort of hate the idea that something I posted was changed without being able to decipher precisely what it was.

BackdoorHippie said:

Just curious, when moderators (@fotojack) edit a post is there any way they could PM the original poster and let them know why, or at least park the reason in parens at the bottom? I sort of hate the idea that something I posted was changed without being able to decipher precisely what it was.

Click to expand...

I'd appreciate knowing why because I'm the one who asked for the info--was there anything pertinent to my question that was removed from BackdoorHippie's post? I came back to this thread to reread what Jake wrote and wondered if the info was changed in some way. Thanks for any information.