Experts: What is going on?

I received my kenko 2:1 teleconverter from Ryan and Co. yesterday and am experimenting with it on land. The Kenko that Reef Photo reccommended dowes allow autofocus with my Af-105-VR and was much cheaper than the Nikon, Thanks guys.

Ok, I understand that I will lose two stops with a 2:1 teleconverter and, sure enough, my 2.8 lens will now only open up to 5.6. On the other hand it seems I get a F/64 stop from my Nikon D-300 and I appear to have a reasonable depth-of-field.

So what is going on? My understanding is that maximum sharpness (actually resolving power) is usually two stops above the smallest F/stop. Is this two stops up from 2.8 (the actual lens) or 5.6 (apparantly lens + TC)? And more importent when does the image "appear" the sharpest, (the mixture between resolution power and depth-of-field that appears the sharpest to the human eye)?

It is my nderstanding that the sweet spot of the AF-105-VR was about f/22 for 1:1 macro and about f/11 for a shot 18"-24" away. Is that true? And what are the sweet spots for the lens teleconverter combination.

In short what f/stop should I shoot the combination at minimum focus distance and what f/stop should I shoot the combination at maximum lighting distance?

Regards,

For those foolish enough to attempt this high-tech idiocy, I will post my impressions of the Af-105-VR and Kenko Pro 300 DG 2x.

Here is my preliminary impressions and testing of this combination: (everything is on land)

First, sometimes the camer gets confused and won't auto-focus. I am not sure why but it seems to lock a minimum focus. However, if you move to minimum focus distance and get a view of the subject the autofocus will work. The focus is not necessaryly perfect, however. Hou must rock back and forth to get a true focus. I shoot in focus priority mode which means the shutter won't release until the camera has a focus. Any shaking or movement will prevent a focus and a shutter release. I would like to manual focus if a focus gear is available for my rig.

I found with the Sub See +10 that getting to the minimum focusing distance and a 2:1 super macro means that the camera will have difficulty focusing and ANY movement will prevent a good picture. The 2:1 TC acted the same but with a longer minimum focus distance. However, my goal was not necessarly to get better than 2:1. Rather I wanted good magnification at a working distance of a foot or more so I could capturs small, skittish critters like a jawfish with eggs or a blenny out of his hole.

#5391 is my test of a less than 1" fish from a working distance greater that 1'. At that range focus is rather easy

#5374 is gaining magnification with a 50% crop from a 1' or so working distance. I was testing the flexibility of this rig in taking a standard shot abet at a somewhat longer working distance

Thanks for posting these Tom. Is the f22 what is showing in the viewfinder, or the "actual" f22, or are they one and the same on the Nikon?

The image quality of the shot of the lightbulb sure looks low compared to the flower shot.

Cheers

James

Note the lightbulb shot needed two stops of increased exposure in Camera Raw. I think what really happens is that the iso is increased 2 stops. The F/stop is what appears in the EXIF data. That data shows the lens as 210mm.