It seems to me that if people with existing P series backs have them fitting perfectly firmly on their Mamiya/Phase One 645AFD I/II/III/DF bodies, Alpas, Arcas, Cambo, etc, and then more than a few IQ backs seem variable on AFD & DF bodies, plus Alpa (and I expect Arca/Cambo too btw) then it doesn't take a rocket scientist to work out where the problem probably lies ...
If it were just Alpa fitting that was loose then it would be pretty obvious who needs to make a change. Since there are reports here of some being loose on Phase One cameras I think it's a bit damning on Phase One.
Btw, I have a similar issue with my Leaf back on my AFD II/DF being slightly loose yet my P40+ fits like a glove on all of my gear, including Alpa.
As some of you know, I run P65+ and Aptus 12 backs in my architectural photography business. The incredibly supportive Mrs.Siebel just added an IQ180 to my bag.
One of the significant reasons for shooting with Alpa in the first place is the ability to shim the mount adapter so the sensor sits precisely where it should, not "within tolerances". The shorter the focal-length, the shallower depth-of-focus (as apposed to depth of field) becomes. The fully manual focus system also is a small factor in this chain-of-focus.
Alpa, in recognising that backs from Phase and Leaf had slightly different measurements in the Mamiya645 mount, have for quite some time had 2 different adapter plates. The difference in dimension is such that it is impossible to fit my P65+ onto the Alpa ooo (Leaf M645) mount.
Lets be clear about this - the fit of a Leaf M645 back on an Alpa oo M645 Phase mount is so sloppy as to render shimming pointless - the back wobbles.
Enter the IQ180 - mounting it on my Alpa oo M645 adapter which works perfectly with my P65+ (fits without forcing, sits with no wobbles), leaves me with a back-to-adapter fit that is clearly loose. It wobbles.
What is interesting is that the same IQ180 back, when fitted to my ooo adapter, which I had to get when I bought the Aptus 12 (which wobbles on the oo adapter), fits as snug as can be.
The mount is a major component in the system that makes the Alpa the precision tool that it is.
Firstly, Alpa users upgrading to IQ backs need to be aware of this. Very, very few will have the luxury of multiple backs (and theresore mount adapters)I do.
Secondly, Phase need to confirm that the current IQ dimension will continue through the production life of this back and that this is not a "within manufacturing tolerances" issue. Given the precision required by the 5.2 micron generation sensors, this is doubly important. Also, we need to know that the IQ180 mount will be identical in dimension to the IQ160 and IQ140.
Alpa and Phase probably need to have a quiet chat about how the P+ series users upgrading to IQ backs are handled. There IS an issue and the "manufacturing tolerances" argument is a weak one.
Ultimately, the solution is a simple one - IQ180 backs need a ooo adapter from ALPA.
I, for one, am absolutely delighted with both my back and my camera, so I'm now going to do the fun stuff - take pictures.
Cheers.
