Here it is a quick change filter holder using a cheap lens hood a piece of 5mm thick black foamex and a little black electrical tape and a piece of welding glass for a big stopper (a real filter is optional)
It is very light proof thanks to using the bayonet mount fitting for the Hood
Well the lens hoods for the 70-200 and EOS-m have arrived today from Hong Kong and I must say the 70-200 one looks as good as the original and flock lined inside to boot and together cost about a fiver delivered.
The EOS-M hood was £1.89 delivered crazy cheap
I also have received my 2 pieces of welding glass for big stoppers £1.20 each delivered
Now all I need to do is a bit of hacking and glueing and I am set.
Here is how it was done and all for less than £4.00
Measure from the back of the hood mount location on the lens to the furthest thing you need to avoid in this case the screw in filter.
mount and check you got it correct
should look like this when cut out
lightly press down so the front edge of the hood and plate are flush
put some tape on the ends of the filter
Thats it made now I just need to see how many stops that welding glass is and mark it on the glass for future use
The particular glass I have is rated as #8 in welding terms but worked out nicely at 10 stops.
It is important that you work out by test exposure what the light transmission of the glass is as it can vary a lot as its designed to protect the eyes from an electric arc not for photographic work I have had glass with 5 stops difference with the same rated welding number.