How to choose a lens to create a virtual tour?

Now that you know how many photos you want to shoot for what final quality, you only have to choose your ideal lens. Here are a few elements of choice...

When we start talking about the choice of lens, we think firstly and right away about its optical quality. It is of course very important, but it's also clear that other points need to be taken into account.
Some of them, like the quality and the "beauty" of the beams are completely subjective but others, like the quality and the stitching quality, a lot more "objective". However, not all objectives are equal on this criterion. The 8 and 7.5 mm Fisheye Samyang, 8-15 mm Fisheye or 10-17 mm Pentax and 8-15 mm Canon Fisheye are the best on these last criteria. And contrary to popular belief, the 14 mm Canon and Nikkor are much more complicated to Stitch properly... As for the Ricoh Theta S and its 0.75 mm F2.0, you have to take it as a whole and accept its quality as it stands because it is obviously part of the concept ...

Lens quality, optical distortions, etc...

One very surprising fact is that the panoramic photographer tries to stitch together the worst parts of the images: their edges! It is the basic principle of panorama by stitching, but it's indeed where all the defects of a lens are gathered:

• Vignetting, sometimes a big defect;
• Chromaticism;
• Loss of sharpness in comparison with the center of the photo and above all...
• Distortions, more complicated and even, in certain cases, impossible to fix, in addition to the fisheye distortion.

In addition to the shape of the beams created when you're shooting a light source directly ... which does not fail to happen when we photograph on 360°!

Optical quality

Almost all lenses on the market are at least good nowadays except that of Ricoh Theta SC, only medium. Some, of course, are excellent, and it's very important in panoramic photography. Regarding virtual tour creation, I wouldn't be so sure. A good lens is enough. The case of Ricoh Theta SC is a little different because it is mainly a concept all in one very easy to use. The quality is not at the rendezvous but can however largely enough in certain cases where one needs to make very many panoramas very quickly. Google recommends it for example to its photographers for the Google Streetview program. It is true that its quality is not so far from its cars ... Most of the time, you'll work with a very closed diaphragm to have a maximum depth of field and you'll then see appear diffraction effects, meaning a slight loss of sharpness. (It's not that bad because it can be fixed with an over-accentuation). Even the Samyang, once over-accentuated, is full of surprises but you need to accentuate it more than a Canon or Nikkor, it's true.

Here is the result of my tests in a recapitulative table...

Recapitulative table of fisheye lenses   Lenses Quality Price   Nikkor 10.5 mm FE $650   Nikkor 8-15 mm FE $1,250   Pentax 10-17 mm FE $400   Canon 8-15 mm FE $1,300   Sigma 4.5 mm FE $900     Sigma 8 mm FE $900     Sigma 15 mm FE $600     Samyang 7.5 mm FE $250     Samyang 8 mm FE $250     Ricoh Theta SC $250

Optical distortions

Almost all images distort the images. Except in architecture photography, it is seldom a problem. However, when you're stitching photos together, it can quickly become annoying because the stitching is not perfect then, as you can see in the example here. This defect of the lens materializes by an imperfect alignment of the two photos. Even if you might be tempted to blame it on the setting of the nodal point, it is in fact often due to another defect, viciously hidden in the lens formula: distortions. It is so important in panorama by stitching that I dedicated an entire page to it.
When the lens has lots of optical distortions, it often happens to see straight lines stitchings, especially, imperfect with most panorama software. Straight lines don't overlap perfectly. It is then necessary to perform edits in Photoshop after stitching. It is maybe even more essential in virtual tour creation because you're stitching photos taken in all directions. The less residual distortions your lens has (well-hidden behind the big distortion due to the optical formula of the fisheye lens!), the more perfect your stitching will be on first try, with no need for further edits.
You can imagine that all lenses aren't equal when it comes to distortions and there are lenses of all kinds! From very sharp and very distorted to very sharp and not so distorted, and even pretty good and not too distorted, etc.

My recommendation: I prefer a little bit less sharp lens but without distortions because I know that the stitching will be good on first try!

I thus think that the nature of the distortions of a lens is the key point to watch when you want to make lors of panoramas by stitching. It is true that it becomes less of a problem from version of old Autopano Giga 4.4. Indeed, not all photographers realize that it's the main cause of failure when stitching a panorama, unlike the nodal point, which in the case of no foreground, won't really matter. If your stitchings are not perfect, look into your lenses rather than the settings of your panoramic head!

Beams on light sources

When shooting indoors, a detail often draws my attention: beams! That's what gives a starry aspect to our punctual light sources. Their shape depends on the number of blades into the diaphragm, of their thickness and their position in the lens. They're thus more or less numerous and aesthetic, according to me.

Here are a few examples gathered during my training sessions...

All these photos have been shot with the same diaphragm, F11.0.

In the next page, we'll detail my favorites fisheye lenses...

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