A very quick report using the quick and dirty method only at this stage. So, take it with a bucket of salt for now.
Mongo tested 3 lenses using a modified Nikon 16A teleconverter on a D800.
Lenses: Nikkor 300mm f4 AFS (latest model)
Nikkor 300 f2.8 AI-s
Nikkor 400 F5.6 AI-s
The main reason for the test was to see how the 300 f4 performed with something more than the 14EII teleconverter. There are varying reports about how useful it is with a 17EII. Mongo hopes to test it with a 17 EII when he next runs into Sar or Lance. For the moment, Mongo will report on what he does have. In addition, this converter can auto focus manual nikkor lenses within a limited range and it is thus useful for Mongo to know how good it is for his other manual lenses.
Importantly, all shots where on a tripod , 400 ISO used, D800, RAW , full frame, shots converted to Tif in View NX2, No processing whatsoever was done to them except resizing for posting. This struck Mongo as the only real way to compare “apples with apples” results. AF was veery quick in all cases
Things you must allow for:
- The differing magnifications/size of images may give a different impression of sharpness;
- the shutter speed was considerably less for the “longer“ teleconverters and even more so for each extra stop down. This will also affect the impression of sharpness due to possible movement.
- you CANNOT have an AF lens and an AF converter with the AF turned on in both at the same time !! For this test and for practicable use in future, you must turn off the AF function of the 300 f4 AFS lens itself and just leave the AF on the camera body turned on. Mongo suspects you may damage your lens otherwise.
First, a clumsy combined chart of the 300 F4 AFS. Each of the 3 vertical rows from left to right shows, respectively,
left row: lens wide open, stopped down one stop, stopped down 2 stops
Middle row: lens with 14EII wide open, stopped down one stop, stopped down 2 stops
right row: lens with 16A wide open, stopped down one stop, stopped down 2 stops
you should be able to draw some conclusions from this. Mongo’s quick assessment is that the lens is reasonably good wide open without converters and increases in sharpness at f 5.6 and a little more by f8. The latter maybe due to some increase in contrast as well as a little sharpness.
With 14EII it is noticeably less sharp wide open. Again, sharpness increases at f5.6 and f8 but there is almost nothing between these two f stops except, again,a little more contrast at f8
with 16A , wide open it looks ever so marginally less sharp than the 14EII at the same setting. Importantly, (and this was the purpose for the tests), it is not much different to the 14EII stopped down 1 and 2 stops as the 14EII was at those stops. The results at one stop down seem to be its best and very comparable to the 14EII. Its too close to call , so, Mongo would be interested in your thoughts/assessment.
Secondly, a similarly clumsy combined chart of the 300 f2.8 AI-s which shows from top to bottom, bare lens at f4, lens with 14EII one stop down and then the 16A @ one and 2 stops down. Mongo did not see any point at trying this lens wide open as he shoots mainly at f4 and at times f5.6 without converters anyway.
The lens is extremely sharp at f4 on its own. With 14EII,even stopped down one stop, it is noticeably less sharp. Although in the field and over the past year, Mongo has noticed virtually no deterioration of IQ with the 14EII on this lens. The 16A is a little worse but by 2 stops down, it is sharper than the 14EII is at one stop down which should make it very usable.
Mongo has not prepared or posted the Nikkor 400mm f5.6 ED-IF results as he was too tired tonight. Plus, Mongo does not know of anyone else who has one of these !
More to report after the 17EII (and maybe a Kenko also) have been tried on this lens.