Nikon 800mm lens calibration
Here at Cameracal we tend to specialise in the calibration of longer telephoto lenses , we recently had the opportunity to carry out a Nikon 800m lens calibration. To say these lenses are rare is an understatement. The retail price of this lens is currently £15,000 and are built to order with a currently lead time from Nikon Japan of two months. A 1. 2 x extender is produced specifically with this lens, again we calibrate this combination with both a Nikon D5 and D500. These lenses are used by sports and wildlife photographers and in this case the photographer John Gubbins intended using the lens for bird and wildlife photography.
The first hurdle to overcome with regards calibration was the required camera / lens to target distance which is 20 metres. The interior of our calibration studio is large enough to undertake calibration of a 600mm, for the 800mm and converter it was necessary to undertake this outdoors. Thanks heavens for a fine day! The calibration process itself was straight forward with the D5 body requiring a focus adjustment of -1, the D500 however required an adjustment of -5 which at a focal length of 800mm would have made a considerable difference to the sharpness of images produced.
The converter surprisingly made little difference. From experience converters are normally the main reason for front and back focus issues. When used with the D5 the converter required an adjustment of only +2.5.
After undertaking the calibration, we also performed a lens optimisation test. This process involves taking shots at every aperture to ascertain the optimum (sweet spot) and point of diffraction.[caption id="attachment_1335" align="alignnone" width="2600"] Lens Sharpness Test images of the 800mm[/caption]
With the vast majority of lenses the test results illustrate that the widest aperture tend to return the softest results with the sweet spot appearing mid-range. It was surprising to see that both the 800mm with and without the converter returned results that indicated the sharpest results (sweet spot) were wide open, not only this but results were equally impressive at apertures from 5.8 to 7.1.[caption id="attachment_1336" align="alignnone" width="2600"] Lens Sharpness Test images of the 800mm with the converter[/caption]
A true testimonial of the quality of the lens.
If you'd like to see what an Nikon 800mm and D5 can produce take a look at some of the John's images at johngubbins.zenfolio.com