Heidecke's Monster

Started Sep 30, 2022 | Discussions thread
OP Bosun Higgs Regular Member • Posts: 425
Re: Heidecke's Monster
1

Rod McD wrote:

Hi,

Thanks - an interesting project.

Can I ask what you used for the interior coatings please. My interest is for the inside of adapters and lens hoods. I'm horrified by just how much light cheap anodized black coatings reflect at acute angles of incidence. I've tried many things over the years including off-the-shelf mat blacks, blackboard paint and paint with chalk dust added, etc. The latter is better than some off the shelf blacks, but the more chalk you add the more fragile (brittler) the coating becomes becomes - hopeless for a surface that may be contacted or cleaned. You referred to a Black 3.0 coating - what's that?

Many thanks, Rod

Sorry for the long delay in replying - I finally managed to catch Covid so I've been out of it for a while.

The Black 3.0 (B 3.0) is a water-based black paint made by Stuart Semple at Culturehussle.com, it costs £24 for 150ml. They also sell the earlier Black 2.0 for £5 less, I have used both and the B 3.0 is definitely less reflective.

I have yet to find a surface the paint will not stick to as long as you degrease, bare aluminium is no problem. The paint is pretty thick as it comes, but you can easily thin it with water. The dried paint is durable enough inside lens hoods and tubes, but will rub off on any surface prone to abrasion. On the rear of many projection lenses the shiny edges of the bright anodised/plated lens tube face backwards, so I paint these with B 3.0 to stop sensor reflections, but if these edges are not protected by mounts or helicoids, the paint soon wears off with handling.

As my main lens group is projection optics I use a lot of the Chinese metal lens hoods, and as you mention, the anodised inner surface on these is quite reflective. Nowadays I routinely repaint the interiors with B 3.0.

Another common source of reflection is the interior of M42 extension tubes, I use these a lot to optimise the lens back focus distance to the helicoid I'm using, they too now routinely get the B 3.0 treatment.

Many projection lenses have less than optimal internal blackening, I've come across several that were actually painted gloss black! That said, I have some very early lenses by Taylor Hobson and Dallmeyer that have internal blacking that is easily as good as B 3.0, so repainting is not always necessary.

An alternative to paint is telescope flocking, this is a self-adhesive sheet of "velvet-like" material. This is roughly equivalent to B 3.0, but may actually be less reflective at low incidence angles. It can be useful inside lens assemblies where the elements or irises cannot be removed and paint is not usable. It is however very tricky to fit successfully inside small lens tubes and will not conform to sharply curved surfaces.

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