Musings
1) Quest for Higher Resolution
14/02/2019
Like many photographers, I’ve recently been captivated by the quest for increased resolution in my images. Some years ago I bought a D800, then moved on to a D810 in 2011 and then last year moved on to a D850. The increased resolution is discernable compared to my old D700. However, the increase resolution creates a big challenge. Jim Brandenberg said that the latest generation of high-resolution cameras will test both your skills and your lenses and find you wanting if you cannot ’up your game’. High resolution cameras magnify flaws. Among the many issues facing users of high resolution cameras are lens quality and focussing accuracy! This is why Nikon offers ‘AF fine tune’ on their top-end cameras produced since the D3. I have recently checked this out with Reikan’s FoCal software.
Reikan FoCal Software
Reikan (https://www.reikanfocal.com) produces FoCal software that checks and tunes how a camera body and lenses work together. This is a convenient way to use ‘AF Fine tune’ on Nikon cameras. Essentially this allows lens/body combinations to be calibrated to optimise optical performance. In doing so, the software generates a lot of quantitative information. One of the products is an index termed ‘Quality of Focus’. Using a black and white target, this seeks to maximise the contrast of the image obtained at different camera fine-tune focus settings. The stronger the contrast, the better the lens/body set up. This can be used to test how well lenses perform relative to one another as well as obtaining fine-tune focus settings for a lens and camera body. Here I show results from assessing performance of my different lenses used with my D850.
Optical performance of different lenses
Using Reikan’s Quality of Focus (QoF) index, I ranked my lenses from 5-star through to 2-star, as follows.
Nikon 5-star lenses: These lenses scored values of >2200 and are the very best performers. These are the 500mm f4, 400mm f2.8, 300mm f2.8 and 300mm f4 PF lenses. Among my zoom lenses, the 70-200mm f2.8 and the 70-200mm f4 also fall in this category.
Nikon 4-star lenses: Obtaining QoF values 2100 to 2200, Nikon’s 4 star lenses are for me my 10 year old 600mm f4, the 60mm f2.8 macro, the 80-400mm f4.5, the 24-70mm f2.8 and 24-85 f3.5 lenses.
Nikon 3-star lenses: With QoF values of 2000 to 2100, the only 3 star lens was my 105mm f1.4. I was surprised this scored so low after reading all the reviews of this lens.
Nikon 2-star lenses: With QoF values less than 2000, only my 105mm f2.8 macro lens fell in this group. I was surprised by this believing that macro lenses should offer high optical resolution.
Lessons learnt
1) In a way, there are few surprises here as it has been long recognised that Nikon’s big guns are simply superb. But it is very reassuring that an individual (well, for me at least) can test one’s lenses in an objective way.
2) I was surprised my old 600mm f4VR did not achieve 5-star level. It is possible that the newer 600mm FL lens would do so but first these results suggest it would be worth getting this lens serviced and optically checked by Nikon.
3) I was also surprised that my 105 mm f2.8 macro performed so poorly and the lesson here is that if I want optimal quality macro images, I should use my 60mm f2.8 lens. It also suggests that the 105mm f2.8 macro should go in for a service and optical check-up.
Next steps
My next step is to look at a) the reproducibility of the Reikan software and b) lens performance with Teleconverters. I will soon add this analysis as a new section here.
Reikan FoCal Software
Reikan (https://www.reikanfocal.com) produces FoCal software that checks and tunes how a camera body and lenses work together. This is a convenient way to use ‘AF Fine tune’ on Nikon cameras. Essentially this allows lens/body combinations to be calibrated to optimise optical performance. In doing so, the software generates a lot of quantitative information. One of the products is an index termed ‘Quality of Focus’. Using a black and white target, this seeks to maximise the contrast of the image obtained at different camera fine-tune focus settings. The stronger the contrast, the better the lens/body set up. This can be used to test how well lenses perform relative to one another as well as obtaining fine-tune focus settings for a lens and camera body. Here I show results from assessing performance of my different lenses used with my D850.
Optical performance of different lenses
Using Reikan’s Quality of Focus (QoF) index, I ranked my lenses from 5-star through to 2-star, as follows.
Nikon 5-star lenses: These lenses scored values of >2200 and are the very best performers. These are the 500mm f4, 400mm f2.8, 300mm f2.8 and 300mm f4 PF lenses. Among my zoom lenses, the 70-200mm f2.8 and the 70-200mm f4 also fall in this category.
Nikon 4-star lenses: Obtaining QoF values 2100 to 2200, Nikon’s 4 star lenses are for me my 10 year old 600mm f4, the 60mm f2.8 macro, the 80-400mm f4.5, the 24-70mm f2.8 and 24-85 f3.5 lenses.
Nikon 3-star lenses: With QoF values of 2000 to 2100, the only 3 star lens was my 105mm f1.4. I was surprised this scored so low after reading all the reviews of this lens.
Nikon 2-star lenses: With QoF values less than 2000, only my 105mm f2.8 macro lens fell in this group. I was surprised by this believing that macro lenses should offer high optical resolution.
Lessons learnt
1) In a way, there are few surprises here as it has been long recognised that Nikon’s big guns are simply superb. But it is very reassuring that an individual (well, for me at least) can test one’s lenses in an objective way.
2) I was surprised my old 600mm f4VR did not achieve 5-star level. It is possible that the newer 600mm FL lens would do so but first these results suggest it would be worth getting this lens serviced and optically checked by Nikon.
3) I was also surprised that my 105 mm f2.8 macro performed so poorly and the lesson here is that if I want optimal quality macro images, I should use my 60mm f2.8 lens. It also suggests that the 105mm f2.8 macro should go in for a service and optical check-up.
Next steps
My next step is to look at a) the reproducibility of the Reikan software and b) lens performance with Teleconverters. I will soon add this analysis as a new section here.