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Archive 2013 · Canon drop-in CPL performance
  
 
PetKal
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p.1 #1 · p.1 #1 · Canon drop-in CPL performance


Has anyone evaluated the effect on lens sharpness/contrast by Canon drop-in CPL ?
(Sorry folks, I am not looking for forumography answers, nor front-end/screw-on CPL experiences. )



Apr 29, 2013 at 11:52 AM
John Caldwell
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p.1 #2 · p.1 #2 · Canon drop-in CPL performance


A reasonable question to ask, but to know what the drop-in polarizer does to sharpness and contrast you have to compare it to some other standard. Polarizers do, in general effect contrast in particular, I believe. So a comparison to "no polarizer" isn't relevant perhaps.

I bring it up because the drop-in has affected images on our 200mm, and I have wondered if I'd lost more than I'd have expected with a front-mount polarizer. In retrospect, I think I'd chosen unwisely to use a polarizer for the scene at hand.

If you don't use a drop-in for your large format lenses, what other alternative might you use? I genuinely don't know what we have as a substitute that's practical in the field, so I ask quite sincerely.

John Caldwell




Apr 29, 2013 at 02:13 PM
darknite
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p.1 #3 · p.1 #3 · Canon drop-in CPL performance


Don't know if this is just repeating an urban legend, but over the years here at FM, many knowledgable members have mentioned that Canon designed the great whites with the drop in filter as an integral part of the optical path. They are made to have a piece of optical glass dropped in there.

If this is wrong, someone please post an give the real deal. I've often wondered about this. I rarely use the drop in CPL with my 300 2.8, but there are the times that its just gotta be there, and nothing can be easily attached to the front that would give the quality of a fine glass filter.



Apr 29, 2013 at 04:21 PM
BluesWest
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p.1 #4 · p.1 #4 · Canon drop-in CPL performance


Don't know if this is just repeating an urban legend, but over the years here at FM, many knowledgable members have mentioned that Canon designed the great whites with the drop in filter as an integral part of the optical path. They are made to have a piece of optical glass dropped in there.

It's not a legend, urban or otherwise. It's stated right in the user manual for those lenses.

John



Apr 29, 2013 at 04:58 PM
dgdg
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p.1 #5 · p.1 #5 · Canon drop-in CPL performance


I use the drop in cpl instead of the clear filter on my 400 f4 if I have strong enough light that allows it and seems to make sense at the moment. I have not done a side by side experiment as it seemed unnecessary based on good results in the field. It seems to work well for me and I always carry it along. Great for reducing water reflections and some midday harsh glare. I used it once on a rainbow telephoto landscape. Haven't thought that much about it. I always have one or the other in the slot.


Apr 29, 2013 at 07:14 PM
Roland W
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p.1 #6 · p.1 #6 · Canon drop-in CPL performance


It would be difficult to generalize about a loss of lens sharpness or contrast when using the Canon Drop In Polarizer, because one of the things that any polarizer can do is enhance contrast. Cutting haze to significantly improve contrast is one of a polarizer's benefits, but reducing specular reflections on green foliage or rock is another, and the result often gives not only improved contrast of those items, but also the appearance of improved sharpness. So any comparison with and without a polarizer will be highly dependent on the subject and lighting and the adjustment of the polarizer.

There have been past discussions about replacing the glass of the drop in polarizer with a better quality one. Most of what I remember has been trying to get an improvement in the amount of light lost, and not specifically to improve image quality. Singh-Ray has in the past offered a modification of the Canon Drop In Polarizer to upgrade to one of their polarizer glass elements, but I am not sure if they still do that. I have never upgraded my polarizer, and am very happy with the Canon version.



Apr 29, 2013 at 11:06 PM
John Caldwell
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p.1 #7 · p.1 #7 · Canon drop-in CPL performance



It's not a legend, urban or otherwise. It's stated right in the user manual for those lenses.

John


Does anyone here use a drop-in "blank" optical glass as a routine?



Apr 29, 2013 at 11:24 PM
 

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EB-1
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p.1 #8 · p.1 #8 · Canon drop-in CPL performance


PetKal wrote:
Has anyone evaluated the effect on lens sharpness/contrast by Canon drop-in CPL ?
(Sorry folks, I am not looking for forumography answers, nor front-end/screw-on CPL experiences. )


It is not noticeable compared to the improvement when a polarizer is warranted. Obviously, in lighting conditions where a polarizer is not desirable, e.g., into the sun, it is not the best for flare/ghosting/contrast.

But seriously, you have a pile of lenses so why not test some yourself

EBH



Apr 29, 2013 at 11:45 PM
blitzn
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p.1 #9 · p.1 #9 · Canon drop-in CPL performance


Does anyone here use a drop-in "blank" optical glass as a routine?

Great question. I have a 300 and a 500. I always leave the "clear" glass in place. But always wondered if I'd gain anything by removing it. These lenses outperform me, so I haven't found the reason to do it yet.

So to repeat the great question from above, Who keeps the blank in and who has removed the glass and what did you gain? (does the glass provide any sealing benefit internally, dust??)



Apr 30, 2013 at 06:43 PM
PV Hiker
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p.1 #10 · p.1 #10 · Canon drop-in CPL performance


PetKal we have both versions of the drop in CPL, 1 and II. We have not looked at what improvements there are for the version II over the I.

Do you think that with the current versions of II lenses, Version III extenders and 1DX there would be a sharpness, quicker focus, and IQ with the CPL II over the I version?

I know the benifits of using a CPL for the reasons others have posted, but how often do we really put it in? I should more than I do! Maybe I should cut a slot out in the LensCoat to make it easy.

Patrick



May 01, 2013 at 05:33 PM
arbitrage
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p.1 #11 · p.1 #11 · Canon drop-in CPL performance


blitzn wrote:
Does anyone here use a drop-in "blank" optical glass as a routine?

Great question. I have a 300 and a 500. I always leave the "clear" glass in place. But always wondered if I'd gain anything by removing it. These lenses outperform me, so I haven't found the reason to do it yet.

So to repeat the great question from above, Who keeps the blank in and who has removed the glass and what did you gain? (does the glass provide any sealing benefit internally, dust??)


My understanding is that the "blank" that comes with these lenses is meant to be left in unless replaced by another filter. I don't think you are supposed to use the lens without something in the slot. The manual clearly states that the optics are designed to have the glass filter in there at all times.



May 01, 2013 at 05:38 PM
Lasse Eriksson
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p.1 #12 · p.1 #12 · Canon drop-in CPL performance


John Caldwell wrote:
Does anyone here use a drop-in "blank" optical glass as a routine?


Everyone with the supertele lenses use a drop-in "blank" glass



May 01, 2013 at 06:06 PM
Lasse Eriksson
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p.1 #13 · p.1 #13 · Canon drop-in CPL performance


arbitrage wrote:
My understanding is that the "blank" that comes with these lenses is meant to be left in unless replaced by another filter. I don't think you are supposed to use the lens without something in the slot. The manual clearly states that the optics are designed to have the glass filter in there at all times.


+1
yes there should always be a glass in the slot.



May 01, 2013 at 06:08 PM





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