[RolandF]

It´s quite courageous to adress this Bf 109 as V4. The important features are not visible. At least it is one of the two earliest batches 6-1 to 6-3 (Dec 1936) and 6-4 to 6-16 (Feb 1937). Those planes wer prototypes and pre-series A-variants not ready for combat and otherwise to be tested. This testing happened under operational conditions but Messerschmitt and Junkers(engines) personnel contantly changed the equipment and appearance of those planes.
Overheating problems were overcome by cutting-out of ventilation slots into the engine hood,a feature which lasted to the final B-series, the C- and D-series until the E-series.
This A-series does NOT have those slots, so it is photographed in early-1937 imo. The spinner of the Schwarz prop does not fit good on ALL Bf 109s of this sereis (the so-called "Bf 109B-1s") because the wooden prop was a stop-gap solution until the Hamilton license-built metal prop was available and fitted to the A-series Messerschmitts (the so-called "Bf109B-2s"). The A-series was to have an engine cannon but the tests weren´t satisfactory which lead to the wing mounted additional guns until the engine cannon was thoroughly tested. Even 6-15 tested in the USSR features this gap between spinner and engine cover.
The markings are "early-style" before the "B-2" standard was applied in April 1937 together with a complete re-painting of the remaining A-series planes.
So this is one of 6-1 to 6-16, photographed between February and April 1937.

Regards

Roland