multi-coated filter on a single-coated lens?

[Notendo]

I've got my eye on a CV 40mm nokton, the single-coated version because I shoot black and white. But I was wondering, if I use a multi-coated yellow filter on there then would that negate the shadow-detail qualities of the single-coated lens? Thanks!

 

[former member]

No- the shadow detail of the lens is still there, and you lesson any reflections that might come off of the flat filter if you go with a multi-coated filter.

Multi-coated filter does not have any downsides in this capacity. I use them on my Uncoated 5cm F1.5 Sonnars.

 

[Notendo]

Ok, good to know. I'm still curious why using a multi-coated filter wouldn't be like having a multi-coated lens.

Why couldn't you 'multi-coat' a really old lens by just sticking a multi-coated filter in front of it. Wouldn't that work?

 

[Tim Gray]

Because multi-coated lenses have coatings on most if not all air-surfaces of every element. Not just the front one.

 

[xwhatsit]

Ok, good to know. I'm still curious why using a multi-coated filter wouldn't be like having a multi-coated lens.

Why couldn't you 'multi-coat' a really old lens by just sticking a multi-coated filter in front of it. Wouldn't that work?

Because you're not "adding a coating", you're really adding another reflective surface.

When you put a filter on, you're adding another reflective surface. If you have the best multicoated optics in the world, and add a crappy single coated (or uncoated) filter on the front, you're adding flare that wasn't there before.

So filters get coated, multicoated even better, to reduce the effect of yet another reflective surface.

If you had the most perfect multicoated flare-free filter on the front of your old uncoated lens, then best case scenario, you'd have no differences (other than the filtering) between the lens with filter and the lens without.

 

[f16sunshine]

Internal reflections are the big enemy of contrast ( or friend depending on how you look at it). Putting a MC filter in the front will not slow down air-glass Surface reflections between internal elements.

 

[Notendo]

Oh I understand. Makes sense.