The reducer is a flattener as well but I could not justify a AU$450 reducer for an $800 scope, I bought the flattener for about AU$200. The flattener raises the F-stop to F6.2 (372mm, 45mm Image Circle), the reducer drops it to F4.4 (264mm, 44mm Image Circle). Focusing was very difficult, probably due to the weight I have hanging off the end.
[edit]
Taxman sent me
this page which shows backfocus for lots of tak flatteners/reducers. This one is
Quote:
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*****The 56mm back focus is measured from the rear of the threaded end of the reducer/flattener rather than from the shoulder.
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