Ghostless filter tackle's a problem called ghosting, but you see, ghosting can mean alot of things like when u take a pic with slow shutter speeds and ur portrait of your pretty subject goes all blurry... However, sadly, this filter can't help you fix that, instead it tackles a problem that only happens when you have a bright spot of light in your frame.
This kind of ghosting appears as another spot of bright light when there was no bright spot of light in that place in the first place! haha... For example, if there is a bright spot of light at the top left hand corner, then it will form another spot at the bottom right hand corner. And if you love physics, you'd love the diagram on the right..lols..
So how does the filter help? They just simply made the filter lens convex instead of a flat piece of glass! lols.. its cool nonetheless..
Well then, since its so great why no one is using it? Thats cos its a expensive solution to a rare problem. How often do you actually have this kind of ghosting problem? haha.. Besides, most modern lenses have tons of good coatings on them that solves the problem. Did i mention that its a very old solution?
In any case, I got mine second-hand off this old camera shop for $20..so its quite worth it for such a rare filter with a rather unique quality... besides its HMC :P Maybe one day I'll try and force this ghosting on a modern lens and see if the filter really works.. haha
Today I might have only talked about 1 filter, but there are tons of other filters out there which does all sort of whacky effects.. if I got the time, I might dedicate a post about filters... damn... i sure promise lots of stuff like my diary entry and my post on people dynamics... haha... ohh well...
Anyway... for those of you who guess the filter is purple, good try, it is purple, but not close enuf...:P the answer i was looking for is... Skylight 1B hahaha... its a light pinkish purple.. there is 1A and 1B, with 1B being a darker shade, thats why its more obvious, the purple in the photo:P
We used to have a Skylight 1B filter on a sigma 70-200, but i dunno why, every time someone drops a lens, it has to be that lens, so i bet by now, it has changed filters quite a few times, but if your bored in the clubroom, you can go open the drybox and look through all the filters and if you do find a skylight filter, place it on a white A4 paper, you can see the purple cast.. In case you were curious, Skylight filters do not filter the skylight!! haha, they just reduce the amount of blue from the sky and makes the overall picture warmer..
