I am looking to buy the GRD IV pretty soon and I was curious if anyone has tried to use the GRD IV with the GT-1. Will the lens fit onto the adapter? How is the performance?
So it can be made to work but the vignetting is something you'd have to deal with, however the IV may behave even differently so you could be in new ground.
There were comments that this lens flared easily but was a very good optical performer.
You may want to try digital zoom if you do buy the GRD IV - it has an optional feature called auto resize which effectively performs an in camera crop and saves the result at the approprite number of mega pixels. If you read the comments on Pavel's test linked above, one way of avoiding the vignetting using the GT-1 is to crop out the corners effectively giving you a reduced MP picture...well you can do the same with digital zoom without all the expense and bother. I did some basic comparisons here between the GT-1 on a GRD and digital zoom on a GRD IV: http://ricohforum.com/viewtopic.php?f=66&t=8550
Before I tried this I belonged to the 'never use digital zoom' brigade but I now have the rocker switch set to digital zoom and use one press (more or less '35 mm') quite a lot and two press ('40 mm') a bit too and the results printed at A4 are fine.
Richard, that sounds like the best solution for a camera which has the virtue of being discrete and pocketable. I will try a GT1 on the A12 28 unit which is hopefully coming my way though. A large area of glass in front of them is what the bigwigs I take portraits of at work seem to expect.