The Tokina 11-20mm has arrived, I’ve had a couple of days to play around and I have to say my first impression is overwhelmingly positive! Little overview of my experience so far.
So first pleasant surprise: the box in which the lens came states that it’s an aspherical lens! Hadn’t read that in any of the reviews or online specs, but Wishgranter said that was the sort of lens I should look for so that’s great.
Secondly: ultra-wide really does mean ultra f*cking wide. I guess I theoretically “knew” that the angle was going to be very wide, but I didn’t really grasp just how wide until I took my first pictures. You can literally photograph another person standing at arms length and have their entire body in that single shot, with plenty of ground and sky left along the edges. My first tests were on a square with a church, and I could easily capture the entire opposite side of the square with a single picture, whereas with my regular 35mm ‘wide’ angle lens I’d need at least 8 pictures (4 along the width of the square + a second row of pictures above that to get all of the facades).
In terms of handling: the lens feels very sturdy, the zoom ring is quite “resistant to change”, so you don’t have to worry about it moving in our out without you actually meaning to do so, and the auto focus is fast and accurate.
Picture quality looks great (here’s a landscape shot I did, edited in DxO), the wide aperture allows for good shooting in low light and at F11 the images look sharp from corner to corner.
So my first photogrammetry tests were on a city square with a church: I first recorded a statue and the bottom of a tree there. I then decided to push my luck and record a tunnel by just aiming the camera in the same direction as the direction of the tunnel (not the walls of the tunnel) and hope that because the view angle is so wide the entire thing would align. Finally I made some shots of the church on the same square. The images were a mix of 11mm, 16mm and 20mm. Total number of images: 173.
Processing just the images of the statue in RC showed that everything aligned without a problem. Because of the large view angle lots of stuff besides the statue was also recorded, though it’s clear that towards the edge of the reconstruction the noise in the mesh increases. Same story with the pictures of the tree. I was really impressed that the images of the tunnel aligned without problem, considering that none of the surfaces (walls / ground / ceiling) of the tunnel were ever in the middle of the pictures but only at the edges.
Finally because so much of the background that I didn’t intend to record was also being reconstructed, I decided to have a go at aligning all images together, and was surprised to see that even that worked. I should remark that in the areas overlap at the ‘bottom left corner’ of the screenshot there are some misalignment issues, but that area was always just recorded in the corner of my camera and was never really the focus of the shoot, so I’m surprised that it managed to align to the rest of the model at all! The camera locations are shown on that screenshot for those interested.
So conclusion: I think the Tokina 11-20mm F2.8 AT-X PRO DX lens is a great price / quality purchase for photogrammetrists! The software didn’t have any problem aligning the images even when taken at the widest 11mm and the wide angle allows you to significantly reduce the amount of pictures needed to completely record large or cramped spaces.
The only downsides compared to my regular Nikon 35mm prime is that the Tokina is significantly heavier (you definitely can’t shoot from just the wrist, you need two hands; that’s all right for a couple of pictures but if you’re taking thousands of a pictures in a day I can imagine your arm getting tired). You also have to remind yourself that even though an area at the edge of the field of view might be reconstructed, you also have to take images of that surface with the camera oriented perpendicular to the surface (nadir) in order to avoid surface noise. Finally the Tokina captures a lot of the scene in a single shot, but those pixels still have to share the same sensor space (in my case 24MP), so you can’t expect the same mesh detail from 20 ultra-wide pictures as you’d be able to get with 160 less-wide closer up images of the same scene taken with another lens.
Hope this little “review” is helpful to someone!
