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Discussion in 'Medium Format Cameras and Accessories' started by Darkroom317, Jun 12, 2009.
I need help with which polarizer to buy that won't vingette. Any suggestions?
Not sure if I can help since I use the Pentax 67. I use the Lee Holder with a Heliopan 105mm polarizer attached to the holder by means of a 105mm accesory ring. Moreover, the Lee Holder is mounted to my 45mm lens with the Lee Wide Angle Adaptor ring, which enables the Lee Holder to get closer to the lens front element in order to avoid vignette. I can use this setup in combination with ND grad in the Lee Holder without vignetting. My Pentax 55mm lens, on the other hand, does not vignette with a Heliopan 77mm slim polarizer which I screw directly onto the lens.
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Or start a Cokin 'P' system. 4" filters in a modular holder.
I use a standard Hoya MC Polorizer without vignetting, shooting Provia and Velvia.
I am assuming that is with the protection filter off if you are using one.
Probably. If one starts stacking filters with wide-angles, vignetting can't be far behind.
Yes NEVER stack filters. There is just no need to do that.
I have never seen a polarizer on my RB camera lenses vignette in the corners. 50MM, 65MM, whatever.
& Never, never stack filters. Got it? Really!
If you really get into a bind, what you can do is get a step up ring and put a larger polarizer on that. Granted, started from 77mm, you don't have too many (affordable) polarizers to step up to, but as a last resort... I do this sometimes with the 50mm lens on my mamiya 6, for obvious reasons.
A last ditch thing you can do with this and some other larger-size lenses (e.g. the fisheye) is mount the filter on the rear element. Obviously this is a pain because you have to take the lens off to adjust. But some filters are just too darn expensive for 77mm and beyond and it's worth the extra 30 seconds to make the adjustments and slip the lens back on. Also, my religion is that you can probably get by with uncoated filters on the the rear element. If you do mount on the rear, do take care to ensure that the mirror swings clear. You can do that by taking off the ground glass and inspecting it directly.
But, all said... I don't recall having any vignetting with a b+w linear polarizer on my 50. I don't remember testing it systematically at infinity focus and wide open though.
Not wanting to appear picky, me ol' fruit, but... Cokin P series filters are 3.25" square. Maybe you were thinking of the Lee filters ?
Not really. A filter adds two reflecting surfaces, no matter where they are.
The biggest filter you may ever need approach does work (financially too), if you get a big one that - with cheap adapters - can be used on all of your lenses.
In the end cheaper than getting a filter for each filter size your lenses need.
Unless, of course, if your (other) lenses all share one and the same size.
A problem with a big filter and step up rings is that it is unlikely that you will be able to attach a good shade.
A 77mm hoya or whatever polarizer won't vignette on on a 50mm. I sometimes use a 77mm glass polarizer then a Lee wide angle adaptor with a 100mm ND grad on the front of that and it still doesn't vignette on the 50mm.
While it's (trivially) true that a filter always adds two reflecting surfaces, it is incorrect to imply that the situation is as bad for an internal or back filter as for a front filter. By the time the light comes through the aperture it is quite well collimated. Moreover, if you just think about the total amount of direct and stray light reaching the filter, it is clearly far less an issue for internal and back filters. My own evidence is that even inexpensive, uncoated filters work dandily on the back. People do need to find their own evidence of course.
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I don't know ...
A glass surface reflects light. All that it needs is light hitting it.
If the last surface, it will reflect light back to the surfaces in front of it, which reflect it again to ... It just gets worse, no matter where the filter is.
The light may be collimated (it isn't) but that doesn't matter much. Just consider that all the surfaces that are in front of it, all the surfaces the light it reflects is bounced off again, are curved.
It will bounce around in all directions imaginable.
The light reaching the last glass element in a lens is very strong, compared to the light that reaches the film. In fact, it's just about at the same level, right?
So i don't see anything to convince me that it would be less a problem if the filter is behind the lens. The position matters very little, if at all.
That's not just trivially true.
Apertures collimate. That's what they do. Moreover, the lens barrel and hood in front of an interior or back filter also greatly reduces the solid angle of (stray) light reaching the filter. This is why sensible people use hoods, especially when they use a front filter.
So, filter position most certainly does affect the likelihood of artifacts. Whether you can see that or not really doesn't affect my conclusions because I have done my own experiments... as everyone should.
This discussion is also off topic and I will not entertain it further.
And the glass in front of it and behind it bend the light.
But i guess you're right in that this is going nowhere.