Camera and Lens Calibration - The Stig Test
Why You Should Get Your Photographic Equipment Tested - The Stig Test
If you are expecting this post to be filled with Top Gear references then you are going to be disappointed. However if you have ever bought new or second hand photographic equipment or spent a small fortune on a once in a lifetime photographic trip then read on. You could save yourself not only a considerable amount of disappointment and frustration but also cold hard cash.
The following are two recent examples, cautionary tales of why you should always treat you photographic equipment to a camera and lens calibration.
Calibration Example 1 – Camera problem
We recently had a pro wedding photographer visit us for a camera and lens calibration of their newly acquired Nikon 28mm F1.4 to their Nikon D750.
Apparently this combo had recently been purchased second hand from a leading used photographic dealer along with all the assurances that it had been thoroughly checked and tested. This combo was used for the first time on a wedding shoot. Unfortunately the captured images using this combo where far from perfect.
The camera and lens calibration process performed at our Studio resulted in a calculated value of -42 needing to be applied for this combination. A value which was outside of the range of adjustment within the camera, in fact it was over double! (Nikon’s AF Fine Tune allows for an adjustment of + or – 20 micro adjustment values).
In order to determine where the fault lay we then calibrated the same lens to a different body (as a matter of reference we chose to use our test Nikon D700 which has a correctly positioned AF sensor thus produces accurate results as in a “perfect” lens needing no adjustment).
The calibration results on this body recorded a value of -11 needing to be applied, just outside the “normal” Nikon tolerances of + or -10 micro values. From these tests we concluded that the error lay with the camera body with the difference between -11 and -42 being down to a badly misplaced camera AF sensor.
What could have caused this huge difference in required adjustment values?
From our experience this need for such a huge adjustment is down to the camera having sustained a significant impact which would have displaced the AF sensor. Again from experience we have found that Nikon bodies showing this need of adjustment often need a front body mount which can cost as much as £600-00 or more on a full frame body.
Where does this leave the customer?
Armed with the detailed reports and comparisons, the customer was able to go back to the dealer and demand a replacement. How about the wedding images though? These were unusable !!! Is this a case for claiming compensation from said dealer, that remains to be seen.
As a footnote and to add insult to injury, said camera was also covered by the Nikon D750 shutter recall,. Had this been checked by said used dealer this would have been undertaken FOC and would have also likely have corrected the AF sensor displacement problem as the camera would have been rebuilt and the sensor correctly realigned*
*The need for a new body mount would not have been covered under warranty due to impact.
We regularly see customers who bring their recently purchased, second hand equipment for camera and lens calibration and from experience we have found that although externally equipment may seem clean and tidy this is by no means a guarantee of proper mechanical operation.
Clearly the second hand market is the place for some to knowingly dump equipment be it faulty cameras / lenses or both that may have been knocked or dropped to the point of being out of alignment. EBay is often referred to by many photographers as the camera / lens grave yard.
Calibration Example 2 – Lens problem
A few days ago we were contacted by one of our regular customers who had just taken delivery of the new Nikon 500mm F5.6 PF ED VR lens. As some of you may know this is a very new lens and as such in very short supply. The sole purpose of this purchase was to couple it with his new Nikon D850 to take to India and photograph tigers. This combination was going to be his prime piece of kit. Having had his previous photographic equipment calibrated by Cameracal, he was acutely aware of the benefits of calibration and the vast improvements this can bring to his image success rate.
The Lens Calibration Process…
From experience we have found the new range Nikon PZ lenses to be incredibly consistent and well with the Nikon tolerances (+ or -10 micro adjustments). So much so, that in our exhaustive tests we have found the new Nikon 300m F4E PF ED VR to be one of Nikon’s most consistent lenses. However even the smallest calculated adjustment can make a significant difference especially when used wide open and on a camera as unforgiving as the D850. As this was the first Nikon 500mm F5.6 PF ED VR lens we had had the opportunity to calibrate we were excited to see how this matched up to the Nikon 300m F4E PF ED VR in terms of consistency.
So with anticipation, the lens calibration started but pretty soon we realised there was something not quite right. The first initial test resulted in a required adjustment value of -50 being required. In the 3 years we have been running our calibration services we have never seen such an adjustment as high as this needing to be applied on ANY lens.
Not only was the required adjustment value more than two and a half times the maximum value that can be applied in camera (Nikon’s AF Fine Tune facility allows for + or -20 micro adjustments to be applied) but the before image displayed by the Focal calibration test completely out of focus.
As with Example 1, just to make sure there wasn't a problem with the customer's camera body we calibrated the lens on our own benchmark Nikon D750 body , the results were similar.
There was a problem with the lens. A big problem!! Problematic enough to ruin any photographic opportunities sat in the jungles of India watching tigers. Enter the Stig Test.
The Stig Test
As part of our calibration process we also run an Astigmatism test which essentially generates a report on the alignment of all the glass elements within the lens. Generally speaking if the stig result reports an average score of below 10 the lens should be fine. If below 5 then exceptionally good. Above 11 and the lens glass elements are so out of alignment that the lens would be totally unreliable as far a focussing is concerned. Such misalignment is almost always due to the lens having being knocked or dropped. The stig test is basically an essential test to have conducted if you have recently bought a new or second hand lens. As with all online purchases you have 14 days to return the item. When you are splashing out hundreds, if not thousands of pounds on a new or used lens, then a stig test costing £49 to ensure your lens is not a lemon is well worth it. This will ensure you are not saddled with faulty lens. All our stig tests booked with us will come with a Stig Report that can, if needed be used to prove that the lens is faulty.
Stig Report on a Nikon 500mm PF
The report above shows a stig result of 18.1%. Essentially the lens is totally unusable. Focussing utterly unreliable. Our customer, who had waited in anticipation to receive the lens and who had the massive expense of a photographic expedition was about to get some very bad news. It was however, in one crucial way very good news. Whilst he would not be able to take the Nikon 500m PF lens with him at least he wouldn't be taking thousands of shots and over 95% of them be out of focus.
The test results thus allowed him time to source an alternative lens, to have it calibrated and sit in the jungle with confidence that when the moment came to start shooting he would be capturing the sharpest results possible as a result of having said lens perfectly matched to his camera.
So what as the outcome?
Armed with all the report documentation (including the stig results), our customer returned the lens to the retailer who admitted that the lens had previously been sold to another customer who had decided against keeping it and thus returned it. Retailers rarely have the resources let alone the expertise to test all returned stock. A superficial inspection is usually all that happens before the product is put back on the shelf and then resold. That's with new stock. Imagine the gamble with second hand items.
If you have recently bought a camera or lens and would like to make sure it is of the quality you expect then book a calibration or stig test before your return period finishes.
If you are going on a trip of a lifetime and want to be sure your photographic equipment is working to its maximum performance then book a calibration beforehand.
Please note that any calibrations booked with us will automatically come with a Stig test report.