Wide angle lens for full frame Nikon mirrorless camera

[EGN]

Hi everyone,

I am interested in purchasing a new lens for my Nikon Z6ii for architectural photogrammetric applications (mostly monumets) and think both the zoom 14-30mm/F4 and the prime 20mm/F1.8.
Which one do you suggest?
I worry about the distortion in the 14-30 lens.
Can Metashape handle with that properly?
Has someone any of these lenses to share some comments?

Thank you!

[Bzuco]

You can always calibrate lens with checkerboard or let metashape deal with distortion automatically, but..
..from my perspective there is no need use wide angle lens for architecture/buildings/monuments because you can make photos of object from oblique angles with 24/28/35mm lenses(where is less distortion).
I am using 15mm lens(24mm after 1.6 crop factor) and I had never problems with distortion(in terms of bad alignment). Mostly doing photogrammetry of houses in exterior for garden projects.
So grab some prime 20+mm or use that zoom 14-30 lens at 25-30mm focal length.

[EGN]

Thanks Bzuco!
A zoom lens is far more versatile than a prime (e.g for traveling) so I am more interested in such lens.  If Metashape has no issues to correct distortion with focal lengths around 20mm, I could shot at >20mm even with the 14-30/F4, just to avoid extreme distortion.
I have never used ultra wide lens before, that's why I am asking, before buying one (costs about 900€).

[ManyPixels]

When using lenses with noticeable distortion, it is interesting to launch a project or part of the project to be processed, to make a good alignment and then to export the calibration. You can then import it back into the final project and fix all the parameters. This greatly helps in getting good matches.


You can of course release the parameters once the alignment is finished and run an optimization to improve the result.

[EGN]

Thanks ManyPixels!

Never done this procedure before (export calibration), but I hope it will work.
This meas that, ultra wide lenses  (even a GoPro cam) can also be used in Metashape without issue.

[ManyPixels]

Not sure if works well with a GoPro, it depends of the kind of project you're working on. Generally, higher resolution sensors mean more matches and the overall result is better (so it's better to have 100 50Mpx images than 400 12.5 Mpx images for the same area and resolution). I made some tests using the import video features, but even with a good camera you'll never get better images than shooting RAW. Distorsion on wide angle lenses is really not a problem. You even get better results with a low end wide angle than using a pricey telephoto lens in photogrammetry. The only application where you could use a focal higher than 100mm is for panoramic views.

[EGN]

Thank you ManyPixels!

Have ou ever tried working with a wide-angle lens with manual focus only (no metadata)? Does Metashape can handle well that?

[Kiesel]

Generally I prefer prime lenses over zoom lenses in photogrammetry. Zoom lenses are allways a bigger optical compromise by their construction, which results often in lower resolution, and lower optical stability (more moving optical elements), more instable focal length, edge softness and so on than prime lenses. If you want to use zoom lenses it is good to tape them to a specific focal length.

Yes you can use manual prime lenses in Metashape. In 'Tools/Camera Calibration... you can input a focal length as starting point, you can even use film cameras with fiducial marks. You should use the lens as its aperture where the lens performs best, its 'sweet spot', so something between 5,6 to 11, depending on the lens.

Not for photogrammetry but photography you get some insides here: https://www.cambridgeincolour.com/tutorials/lens-quality-mtf-resolution.htm

Best regards

Kiesel

[EGN]

Thank you Kiesel.

Any additional links for photogrammetry are welcome!

One question: Does sensor resolution (e.g. 44MP vs 24MP) matter a lot for architectural photogrammetry or lens quality is more crucial?

[Bzuco]

If 44MP doesn not have significantly more noise, you can take less photos. For achieving same details with 24MP you need to get closer to objects and take more photos.
Bad lens can always decrease alignment quality, good or perfect increase.
But big sensor and perfect lense are not necessary for photogrammetry. The proof is that even with mobile we can achive good results.

[cbnewham]

Thank you Kiesel.

Any additional links for photogrammetry are welcome!

One question: Does sensor resolution (e.g. 44MP vs 24MP) matter a lot for architectural photogrammetry or lens quality is more crucial?

Oddly (or perhaps not so oddly) I have sometimes had better results resampling the original images at a lower resolution (60% to 40% and stripping the metadata) and performing the photogrammetry with those. In my experience (confined to sculpture), higher resolution is no guarantee of good results. It comes down more to how many pictures there are and how much overlap there is. The number of pictures is quite crucial.

[Kiesel]

Hallo EGN,

to my experience behind 24 Mpix lens quality matters a lot. You need very good lenses for 44 Mpix cameras. If you have that, you need less photos for same SD (sampling distance)
Besides that, as allways, you need good stereo cases to get good quality out of stereo photogrammetry.


Kiesel

[3create]

Just on a note concerning the 20mm 1.8 Nikkor (I use it): it is great for photogrammetry, distortion is no issue in Metashape and it has very low chromatic abberation (someting which shouldn't be neglected for photogrammetry).
Wide angle lenses are generally benifitial for architectural reconstructions, as every image has more information on surfaces parallel to the viewing direction (i.e. pillars sticking out of the facade), less images are needed (increasing the likelyhood of more consistent lighting outdoors) etc.
However, there is the issue of GSD and texture detail (i.e. walls with little texture variation for alignment and reconstruction) with 24 MP.

Concerning GoPros: this is a completely different topic (the distortion is close to fish-eye, not mentioning quality of lens, sensor size, trigger delay...)
If I get around to it, I can hopefully post more details on GoPros soon, as they also have their use cases.

Guy

[EGN]

Just on a note concerning the 20mm 1.8 Nikkor (I use it): it is great for photogrammetry, distortion is no issue in Metashape and it has very low chromatic abberation (someting which shouldn't be  neglected for photogrammetry).

However, there is the issue of GSD and texture detail (i.e. walls with little texture variation for alignment and reconstruction) with 24 MP.

I am waiting for my 20mm f1.8 to arrive within the next days. It's good to hear that you are satisfied using it.
Regarding the 24MP sensors, I have not tested my Z6ii for photogrammetry yet, but it seems that I should have bought a Z7ii with the 44MP sensor.



Thank you all for your answers!