Re: 50 or 100 mm

[Pentxuser]

If you are going to use a bellows, the 50 is more useable. If you want a 
straight macro to use without bellows, the 100 mm gives you more distance which is 
very valuable for all sorts of reasons, including room to use reflectors, 
flashes etc. With a 50mm you're in so close that the shadow from either you 
looking into the camera or the camera itself can cause problems...
Vic