FX & DX w 200-500 w / wo TC + P900
The purpose of this thread is to illustrate the comparative central resolving capability of the 200-500 lens @500mm, with and without a TC (Nikon TC-14E III), using crops of images of the same subject taken on the same day/ same time with 3 DSLRs of varying format/ pixel density, as well as a CoolPix P900 at its max 2000mm eFOV.
The fine print: All were shot at 100 ISO, in bright light, VR on with shutter speeds either side of 1/1000. Images were captured in RAW, converted to TIFF using Nikon Capture NX-D software at Standard Picture Control settings, AWB, sharpening set to a minimalist 2, NR OFF with no other processing. A number of shots were taken at various apertures with each permutation to determine if stopping down was beneficial: I determined, by comparing, that wide open was as good as any for all combinations except 24MP FX+TC & 24MP DX+TC which were marginally better at f/9 (stopped down 1/3). Stopping down further presented no observable gains. Shooting conditions were fairly good but not perfect (some wind, some dust: target is estimated to be about 100 feet away). JPEGs were produced with Photoshop using minimum compression and uploaded to my DPReview gallery.
The composite below is comprised of 200% enlargements to more clearly demonstrate differences in detail in the text. Left to right:
To put the crops into perspective, below is an FX w/o TC perspective (500mm focal length/ FOV) and the P900's 2000mm eFOV:
My conclusion related to images from the DSLR/200-500/TC combinations is that images resulting from higher pixel densities and/or greater focal lengths (magnification) never yield less information or exhibit lower resolving capability than images resulting from lower pixel densities or lower focal lengths (edit: ... and to be clear, the corollary, increased focal length or pixel density always results in greater resolving capability and more information). WRT central sharpness, stopping down had no benefit in most instances. (edit: in cases where there may be a modest contrast loss with the TC, any deficiency(ies) can be addressed in post for the most part)
I would summarize that where "reach" is concerned, TCs work and pIxel density matters (up to diffraction limits). As a result, images of small or distant subjects captured with the 200-500 may benefit from the use of a TC. As a side benefit, a TC also increases magnification at MFD. OTOH, atmospheric conditions, the need for increased ISO in lower light, handling changes among perhaps other things may impact the usefulness of a TC.
I have and use the TC-14E III: I have heard people with other TCs may not be as satisfied. I also have set AF-FT for each lens/ lens+TC combination: Contrary to Nikon's admonitions, I'm a believer in the testing of AF-FT-capable bodies and lenses wrt AF-FT and I do not hesitate to use AF-FT in those combinations where I find it beneficial (which is most). YMMV
The P900: for a small sensor camera in such a portable package, understanding its range goes from an eFOV of 24mm f/2.8 to 2000mm f/6.3, I'd say it performs remarkably well. While I prefer the handling of a DSLR for many tasks, the P900 is surprisingly capable -- I am often surprised just how capable! -- and did I mention its portability?
If you feel this illustration provides some basis for comparison, you are welcome to draw your own conclusion(s). If you feel this illustration does not provide any basis for comparison, there remain 149 opportunities in this thread to express your opinion. Fire away!