poor focus with polar filter and 100-300 zoom
Discussion
Hello All, i'm new to using filters so there is probably a simple answer to this and to be honest i feel stupid even asking it but i need to know your experience with the problem.
i got a CPL polar filter for xmas to go with my Canon 300d, it works well on my 18-55mm lense but if i try it on the 100-300zoom i cannot focus on anything, it screws on ok as both my lenses have 58mm threads.
any ideas?
is it that they don't work on large telephoto lenses?
Paul
i got a CPL polar filter for xmas to go with my Canon 300d, it works well on my 18-55mm lense but if i try it on the 100-300zoom i cannot focus on anything, it screws on ok as both my lenses have 58mm threads.
any ideas?
is it that they don't work on large telephoto lenses?
Paul
It will simply be a case of the filter blocking too much light and preventing the AF from functioning correctly.
If you try to use the same combination in brighter light you will find the level at which sufficient light is entering the camera for the AF to achieve a lock. A standard CPL filter will generally lose you 2 stops of light.
As an example, a lens which has a max aperture of f/5.6 at 300mm, will be reduced to f/11 with the CPL, unfortunately most AF systems like to work with a minimum of f/5.6 to be able to 'see' the contrast of the subject.
If you try to use the same combination in brighter light you will find the level at which sufficient light is entering the camera for the AF to achieve a lock. A standard CPL filter will generally lose you 2 stops of light.
As an example, a lens which has a max aperture of f/5.6 at 300mm, will be reduced to f/11 with the CPL, unfortunately most AF systems like to work with a minimum of f/5.6 to be able to 'see' the contrast of the subject.
I take it the lens (100-300) can focus ok on its own?
What brand is the filter, and has it acquired finger prints when being transferred to the larger lens? (Including on the back of the filter)
If the filter works on the 18-55, then it should work on the 100-300 provided it has enough light. Can you try the combination under some bright lighting and see if the results improve?
ETA - I'm off to a meeting, but someone else should pick this up with you
What brand is the filter, and has it acquired finger prints when being transferred to the larger lens? (Including on the back of the filter)
If the filter works on the 18-55, then it should work on the 100-300 provided it has enough light. Can you try the combination under some bright lighting and see if the results improve?
ETA - I'm off to a meeting, but someone else should pick this up with you
Edited by Ledaig on Wednesday 30th January 17:26
First off, Paul, let me say I have no first hand experience of Camlink products, so I might be talking complete bollox, but it's my experience that you get what you pay for. I paid £205 for mine from Lee Filters.
If the camera is hunting it's because it cannot find enough contrast in the frame to "Lock On " to, and this "could" be caused by less than perfect optics in your CPol. I'm guessing that it works on the smaller lens because it is a bit faster, let's in more light, and therefor sees a higher contrast image. I'm also guessing, and hopeing, that bright sunshine will sort the problem out. (And give it a good clean with a lens cloth too, just in case)
Martin.
If the camera is hunting it's because it cannot find enough contrast in the frame to "Lock On " to, and this "could" be caused by less than perfect optics in your CPol. I'm guessing that it works on the smaller lens because it is a bit faster, let's in more light, and therefor sees a higher contrast image. I'm also guessing, and hopeing, that bright sunshine will sort the problem out. (And give it a good clean with a lens cloth too, just in case
)Martin.
Edited by V6GTO on Wednesday 30th January 18:40
£205.....for a filter!!! FFFFFFFFFFFF......THUMP (sound of me falling off my chair)
i never knew they we're that price, although my other hobby is astroimaging/astronomy and i know how expensive the eye pieces can be.
it was a nice sunny day today and i was trying to capture the Cathedral in Lincoln, i also tried to manually focus but couldn't so i think i'll be leaving this cheap polar filter for the 18-55mm lense
Thanks
Paul
i never knew they we're that price, although my other hobby is astroimaging/astronomy and i know how expensive the eye pieces can be.
it was a nice sunny day today and i was trying to capture the Cathedral in Lincoln, i also tried to manually focus but couldn't so i think i'll be leaving this cheap polar filter for the 18-55mm lense
Thanks
Paul
Fwiw, for a more well known filter manufacturer like Hoya -
'Hoya Filter 58mm Super HMC PRO-1 Circular Pola' - £67.20
or
'Hoya 58mm Pro 1-D Filter WB PL-CIR' - £81.50
...on warehouseexpress.com
Cheers.
'Hoya Filter 58mm Super HMC PRO-1 Circular Pola' - £67.20
or
'Hoya 58mm Pro 1-D Filter WB PL-CIR' - £81.50
...on warehouseexpress.com
Cheers.
Paul, the night shot should be good with the floodlighting on both the Cathedral and Castle.
Didn't think we had enough sunshine today to be able to use the CPL
Ray
PS. Martin (V6GTO) raises a very valid point with regards to the quality of filters. There have been a number of very experienced togs who rightly comment about having a lens costing hundreds of pounds (thousands in some instances) and spoiling it with filter costing a few pounds. I use a Nikon CPL on my 17-55 knowing that it was not necessarily the best I could afford such as Lee etc.
Didn't think we had enough sunshine today to be able to use the CPL
Ray
PS. Martin (V6GTO) raises a very valid point with regards to the quality of filters. There have been a number of very experienced togs who rightly comment about having a lens costing hundreds of pounds (thousands in some instances) and spoiling it with filter costing a few pounds. I use a Nikon CPL on my 17-55 knowing that it was not necessarily the best I could afford such as Lee etc.
Gassing Station | Photography & Video | Top of Page | What's New | My Stuff