Hi John
If the lens is of a comparable resolution to a $1,500 AF macro
then $400 would be a very attractive price.
If the quality is low then it isn't money well spent
The AF 200/4 is better than MF 200/4 IF.
It's up to you if the IQ difference is worth 1000 $ or not.
1:1 would be great but 1:2 is acceptable. This would be primarily for closeups. I'm mostly photographing reptiles, amphibians and bugs.
For reptiles and amphibians 1:2 could be enough although sometimes I've photographed reptiles at 2:1 on DX! For small bugs 1:2 is not enough most of the times.
So from my comments above you see I'm looking for a high quality macro but am willing to buy an older MF lens if it provides good resolution
The AI(AIS) 105 f/4 is a good solution. High resolution, but WD at 1:2 is 27 cm (with the MF 200/4 IF, WD @ 1:2 is 48 cm); to get 1:1 PN-11 ext tube is required, and WD is 19 cm. Not so bad if compared to AF Sigma 150/2.8, whose WD at 1:1 is just 20 cm (due to the shortening of focal length at close distances).
However, the 105/4 has a drawback: it's "dark" (f/4 at infinity, f/5.6 at 1:2 and f/8 at 1:1). For the sake of comparison, the AF ED 200/4 is f/4 at infinity, f/4.8 at 1:2 and f/5.3 at 1:1. The MF 200 macro behaves similarly up to 1:2.
Is the AI Micro-Nikkor 200/4 IF as sharp as the AIS 105/2.8?
More or less. However, the 105/4 is better at close distances.
And how would you rate each of those with respect to the 200 AF?
The AF ED 200/4 is the winner. The AF Sigma 180/3.5 is not bad at all, and you can buy a used sample in Exc++ conditions at the same price as the MF 200/4 IF.
A defect of the MF 200/4 IF is the tendency to get the multicoating layer of the front group attacked by humidity and/or fungi. I've seen several samples with this problem. I would buy the lens only if I could scrutinize it.
Regards,
Riccardo