Lens Aperture Optimisation
Lens Sharpness Test from Cameracal on Vimeo.
This is a popular service and one which often makes a real difference to the performance of a lens. Often lenses do not perform best at their largest aperture / wide open. Our calibration tests are performed at these apertures as front / back focusing problems are most prevalent at these apertures.
It is often presumed that the best aperture or “sweet spot” of a lens is mid-way through the aperture range of typically F8. Whereas this may be applicable to certain lenses and is a generalisation and as such it is by no way 100% accurate.
Ascertaining this optimum aperture can be both time consuming and difficult to perform. Here at Cameracal for a small additional cost we can undertake a specific “Lens Optimisation” test which is unique to the camera and lens combination, rather like a digital fingerprint.
This test conducts a series of tests / shots to determine the following:
- Best aperture (sweet spot)
- Point of diffraction (aperture at which the sharpness gets progressively worse). With ever increasing pixel counts the problem of diffraction becomes more apparent.
- Worst aperture (this is often wide open / the widest aperture i.e F1.8 on a 50mm F1.8)
- Acceptable range as in range of apertures that can be actively be used at in “real world” as opposed to “lab conditions”.
The results are plotted against a chart listing the aperture and the result in terms of Lines Per Millimetre.
The results can make for surprising reading and even the most expensive prime lenses including telephotos do not always resolve the highest quality when used wide open / at their widest apertures.
A calibration on its own is only one part of the solution. In order to ensure the best possible performance from your lens we strongly recommend a Lens Optimisation test
Please refer to the following video for a demonstration of the process.