Martin the Mannequin - Our Focus Test Dummy
Welcoming our new staff member
Here at Cameracal we never like to rest on our laurels and always look at pushing the boundaries to provide the best possible service for our customers.Previously this has included the introduction of live chat, simplified calibration, and sensor cleaning reports (the focal reports are ideal reading for insomniacs !!) and recently a focus / sensor contamination /diagnostic facility via live chat.
As such, our latest introduction in our quest to push the boundaries further is an a recent addition to the team,Martin the Mannequin..
Martin is a (fairly) life-like mannequin (some say he looks a little too much like our MD Anthony !!)and is used in all our calibration reports.
Although the test target used for calibration is a necessary part of the testing process the fact that is two dimensional does not help demonstrate the difference between the uncalibrated(before) and calibrated (result)as in front and back focus issues.
As Martin is 3 dimensional, any front / back focus issues can clearly be seen and although this may be of greatest benefit to portrait photographers (as they can clearly see if the set up prior to calibration was focusing on the nose or ears as opposed to the eye) it also applicable to other photographic genres. It certainly beats using a stuffed bird..
So how does this work and how with Martin be used in the reports we provide you?
After the calibration process has been completed and the results determined (as in if your camera / lens combo was “front” or “back focusing) we take two test shots ensuring the point of focus is placed over the eye of Martin the Mannequin.
Two shots are taken, the first pre calibration as in no AFMA (Auto Focus Micro Adjustments) applied and at the widest aperture of the lens (images shot at the widest aperture will display more of the front / back focus.
The second is taken with the calculated AFMA values applied and at the concluded Lens Optimisation result as in the best aperture / sweet spot.
These two images are then loaded into either Canon’s DPP software (if the model is a Canon) or Nikon’s NX-D software if Nikon.
Both applications are able to display the chosen AF point and display the appropriate metadata including any AFMA value applied
So how effective is this in demonstrating the before and after result and that the calibration has made a REAL-WORLD difference.
We recently had a Nikon D750 + Sigma 35mm F1.4 Art series come in for calibration, with the customer who was a portrait photographer complaining that they were unable to capture images in which the eyes were sharp. After confirming the correct protocols had been adhered to as in the use of Single Point AF-S focus, focus point placed / moved manually to the eye etc we took a shot of Martin and then dropped the image into Nikon’s NX-D software and enlarged the image.
NIKON IMAGE OPENED IN NIKON NX-D –SEVERE FRONT FOCUS
From the image shown above it is obvious that there was a problem with focus as the selected point of focus was not sharp.
As the ear / are behind was not in focus either, it was deemed that the camera / lens combo was front focusing but by a considerable amount as even the nose was not in focus.
So onto the calibration test to determine if our diagnosis was correct and ultimately the amount of adjustment required to correct this.
The calibration results
From the screen shot above it was obvious that the combo was indeed front focusing (as it required a + value to push the point of focus back) but we surprised by how much, in this case +13.
Having applied the +13 calibration, we then took another shot of Martin, again focusing on the eye, this was again opened in Nikon’s NX-D.
In this instance the +13 to correct for FRONT FOCUS resulted in a pin sharp result as in on the eye.