I have a couple of GX680 II bodies and the 65, 125, 180 and 300mm lenses. I used this for many years with my P25 and a Kapture Group One Shot solution for wake-up and sync. This system rocked and was my go-to platform for my food and still life work.
When my batteries for the camera died and I discovered I could not buy new ones, I simply cut the base off one of the batteries, took the top off a Nikon charger, glued the two together and Viola! I now have a battery adapter that takes Nikon batteries (pinched from the D700 gathering dust in my cupboard).
Once I replaced my P25 with a P65+, and now the IQ180, I no longer need the Kapture Group One Shot solution. Using the backs in zero latency mode works fine. As I have also moved from V mount to M645 mount, I bought one of the Chinese adapters available on eBay and this works fine.
The 300 suffers from vibration issues due to the massive mirror, even when mounted on my massive Foba head and large camera stand. The other lenses are superb and have large image circles too. This is one of the most versatile systems around, but you have to get your head around the sheer bulk. I bought my system new in 1995 and it served in a high-volume studio environment for 7 years without missing a beat. For sheer ease and speed of use when using shifts, it's hard to beat. Full frontal movements with reflex viewing - what's not to love about that?
I pretty much do what Bryan does, I use the 65, 125 and 210 lenses and a chinese adapter that allows me to use the same MFDB as on my Contax 645 system. I just want to add the following:
1. I do have 100% success (not one shot missed) in microstep 16x with my GX680 and Imacon 528c back, thus producing a 508MB, 88mpx file in stills, that easily beats the file of an 80mpx modern back (I repeat IN STILLS). This I have succeeded by using a SUPERB tripod (the FATIF) and I don't only do stills, but also reproduction of paintings with it.
2. The best and cheapest way of redoing the batteries is to do what Bryan has done, but instead of using an EN-EL3, clean the inside of the cover and wire 6 rechargable Nicad AAs in series! They fit perfectly, you have 6x1.2=7.2Volts, it will rework with your charger, only cost 12Euros for the lot, can be replaced again whenever they die (just make sure you don't over-glue the top part of the battery when you put it back) and you can use 1500mA ones, that doubles the life of the original battery.
3. To tether the back you require a special cable that will connect the dedicated multi pin connection of it with the one at the camera were the dedicated remote release plugs AND another one that connects the PC socket of the camera to the back. The camera has to be on "multi" in its shooting mode dial and will be triggered by the dedicated program on your computer.
4. The lenses are super sharp and bear the most neutral color I've seen, but if you see the microstep 16x image out of it, It's good enough to ..."drop dead" ...You simply can't believe that such kind of quality exists in this world!!! Just imagine what will happen when I will be able to cover the whole 8x6 area, by stitching 2 microstep files together for 1GB total. Now where is that Kapture stitching adapter for the Contax.... if I won't find it and they don't remake it, I will have to convert one of their HassV ones or built one my shelf. Regards, Theodoros. www.fotometria.gr