Hi Paul, sorry for delay, but here we go :
In early 2000s I made two versions - one from DDR Pentacon Meyer 50mm / f1,8 and another from soviet Helios 44.
I trashed everything out except front element which has meniscus shape. For full effect it must be reversed. In front goes black cardboard
diaphragm with about 18mm hole for f4. For BW I use Yellow Green filter which is very useful for woods / plants and sky and helps to focus too.
Extension rings are needed for correct infinity focus. For Helios you will need two - 15mm and 5 mm ( it is approx. if you want I will check exact size )
Both are about 85mm focal length with very short MFD which is perfect for closeups. For last 20 years I use these with 35mm BW film almost
exclusively. I have long distance and close up examples at my web. Hope this helps.
Best wishes.
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