Adjustable back adapters (max. 3/10 mm, adjustable in single steps right down to 1/100 mm) with reuseable shims of various thickness are exclusive to ALPA. We have introduced these adapters some years ago even though our own components were and are manufactured to the highest degree of precision. The reason? With this we could, and still can, remove some problems:
Possible areas of problems:

1. digital back out of tolerance (and customer does not realises this)
   
2. adjustable ALPA adapter got altered by customer
   
3. lens misaligned
   
4. other components out of tolerance
   

1. Often the customer does not realises that the digital back is not sacrosanct. We often face customer problems when they upgrade their back or have a loaner. Everything else stays the same but results are different and the customer often does not question the back or the new filter glass et al.

2. Instead of taking pictures first they try to fiddle around where they shouldn't and do not know what originally was installed. We have to admit that due to mistaken measures by back manufacturers as well as also Peter Seitz once our adjustable adapters have turned out to be live savers.

3. Possible but not in this case. Nevertheless, due to the speciality of the 24 and 35 XL the lenses get adjusted with the center slightly beyond infinity. Therefore the scale on the helical of the 35 XL (standard Schneider helical) is a little bit offset. A fact we cannot change.

4. It is always best if one can countercheck with other hardware (other digi back etc.).In such situations the flexibility of the ALPA back adapters provides a sort of insurance policy. We must, however, ask our customers not to rush into changing the adjustments of their ALPA back adapters (for example, to check the workings of the adjusting function) without consulting with ALPA first.

In such situations the flexibility of the ALPA back adapters provides a sort of insurance policy. We must, however, ask our customers not to rush into changing the adjustments of their ALPA back adapters (for example, to check the workings of the adjusting function) without consulting with ALPA first.