There are times when shooting macro where you will need that extra bit of extension – for me that would be when doing extreme close-up UV-induced visible fluorescence (UVIVF).
Hence I have been building a kit to use with my Olympus EM-5 and the Coastal Optics 60mm F4 APO in Nikon F-mount, when my focusing helicoid will not get me close enough.
I chose the BPM bellows, which is no longer in production. It was manufactured in the UK by the Butterfield Photographic MFG Co., which were based in Sussex. The reason I chose this was because it had a few useful features, and seems to pop up on eBay every now and then.
It has two adjustment screws up top for both camera and lens mount adapters. There is a lock nut to tighten the extension adjustment screw.
Bellows fully retracted: 28.2mm (excluding adapters), 41.8mm (including Micro 4/3rds and Nikon F adapters) Bellows extension: supposedly 15cm, although mine only reaches 12cm – the bellows was very tight so I didn’t push it any further
The fact there are 2 points where you can mount to the tripod is very useful. I mount my Arca release plate to the front 1/4″ female thread, as that means the lens stays the same distance from the subject with any focus adjustment done by moving the camera towards or away from the lens. So no chance of the lens actually touching the subject or encroaching on the lighting to the subject.
This is UVIVF shot at maximum magnification with my focusing helicoid (stacked images):
This shot was done with the bellows system and stacked with Helicon focus:
Equipment used: Olympus EM-5, Coastal Optics 60mm F4, Baader UV-IR cut filter, Nightsearcher UV torches, BPM Bellows