Long lenses with focal lengths beyond 800 mm offer fascinating photographic opportunities. The Nikon 800 PF compatible with both TCs pushes the limits of diffraction on the Z9/Z8 and the Z6 III quite differently. Join us on a photographic trip stretching from wildlife photography to the laws of physics.
Into: 00:00
Why so much focal length ? - looking for the very small: 00:25
On the Nikon Z6 III: 01:44
Why so much focal length ? - looking for the very far: 02:45
Birds in Flight with the 2.0 Tc: 04:27
Animal Portraits: 05:48
The Laws of Physics - Diffraction and Resolution: 06:12
Comparative Reference Photos & Conclusions: 08:36
References:
photographylife.com/reviews/nikon-z-400mm-f-2-8-tc-vr-s
photographylife.com/reviews/nikon-z-800mm-f-6-3-vr-s
Why so much focal length ? - looking for the very small:
Even though the 800 pf offers already a lot of reach extending with Tc's gives a special look due to a change in the field and depth of view. Even with the 2.0 Tc the video capabilities remain very strong ! The RED LUTs work very well ! Close-up photography of small birds - benefiting from image compression in a special way. The lens stays sharp with both TCs (morelater) and can be used handheld even at 1600 mm focal length. Motion blur is is probably most underestimated leading to both narrow apertures and the need to take pictures at sufficient shutter speeds. On subjects that are further away we observe a great bokeh and very good subject isolation.
On the Nikon Z6 III:
The bigger pixel of the Z6 III is more forgiving. It also copes with the higher ISO values very well yielding very strong results. However, there is a limited option to crop due to the lower pixel number and the 2.0 Tc compensates as it to a certain limit. The Tc helps subject detection in case of good light and is useful to deal with more busy backgrounds.
Why so much focal length ? - looking for the very far:
Since the short distance results were so positive I did go to one of my favorite birding spots. During winter the northern part of Germany is home to many birds from Scandinavia. The location features three hides with photographic distances from 15 to 500 m. Compared to 600 mm the 800 mm and its Tc variations offer compressed close ups of wildlife .... but even cropping delivers in 4K. Even at 1600 mm the video autofocus works great and allows to close in on interactions between different individuals...
Birds in Flight with the 2.0 Tc:
Birds in flight at 1600 mm handheld at medium to large distances. Sure there is a loss in IQ due to the long distances, but overall I like the results ! Depending on heat take up and a couple of other conditions heat haze is always a challenge ! Some results are still amazingly sharp ! Juvenile white tailed sea eagles roam along the tree lines generating frequent activities !!
Animal Portraits:
1600 mm is a great focal length to capture animal portraits !!
The Laws of Physics - Diffraction and Resolution:
The key components determining the effective system resolution are PIXEL SIZE, APERTURE, and the optical LENS RESOLUTION without diffraction. Shallow depth of field is one main reasons to photograph with the Z800 PF. However, both, cropping and using a TC will decrease the depth of field. Roughly a factor of 3-4 can be accomplished ensuring an excellent subject background separation. The Airy Disc size is a measure for diffraction. 0 % shows a complete fall of of its intensity yielding clean pixel-sharp information. Different sensor pixel sizes have different critical apertures. The 4.3 um pixel of the Z9 has a critical aperture of F/6.3. Not a surprise considering the 800 F/6.3, 600 F/6,3, etc. With a Tc we are increasing the F_Stop. Diffraction will decrease our resolution. But how much ? We can convolute all three factors and determine the bare optical resolution. Using linewidth per picture height, we can compare to the measurements from Photographylife. Fits to the data yield the green curves.... The optical resolution of the 400 Tc is better than