Linear Polariser - seems to have no problem with D5100
It is said that technically a curcular polariser is required for Digital DSLR cameras as it is said that using a linear polariser would lead to exposure problems.
Well, I just dropped my Hoya HMC circular polariser accidentally down a cliff during yesterday's photo trip.. But I fortunately had my old original Pentax polariser on hand, which was bought in 1980 - which is a linear polariser. I used this for many frames. I could still get correct polarisation as well as correct exposures. This is on a Nikon D5100 with 50-200mm DX lens.
So was i really lucky or was it a fluke to get these correctly exposed shots even at full polarisation? To me it seems to behave the same as the circular polariser.
Please kindly explain (BTW I know very well about the technical differnces between the two - hence this question).
with best regards
#1. "RE: Linear Polariser - seems to have no problem with D5100" | In response to Reply # 0
blw Nikonian since 18th Jun 2004Tue 02-Oct-12 05:02 PM
Linear polarizers are really not as bad as the common wisdom. They only create problems when either AF or metering is diverted from the main light path by particular types of beam-splitting mechanisms. I still have my linear polarizers from the 1970s and 1980s, and none of my Nikon bodies (F100, various DSLRs) have malfunctioned with them - granted that after a while I don't keep trying as I have a fair idea that they will continue to work properly.
I've had to buy new polarizers in the past few years as I never had linear polarizers in common Nikon sizes (52, 62, 72, 77) - I've only got them in 49 and 58mm. So I've been buying circular ones, but I am pretty sure that linear is just fine with all majority Nikon SLRs.
I think the conventional wisdom is a shortening of the more general statement "get a circular polarizer if you want to be sure of never having trouble, regardless of the design of your camera."
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#2. "RE: Linear Polariser - seems to have no problem with D5100" | In response to Reply # 1
PRSS Registered since 10th Apr 2012Tue 02-Oct-12 05:26 PM
Thank you, my heart feels lighter now.
Another important thing i would like to mention. This Pentax Polariser has a very light grey color when compared to other makes - which are dark grey and steal 1-1/2 to 2 F stops. But his Pentax Polariser cuts down the light only by about 1/2 F stop even with full polarisation. I think it is a wonderful piece. It also gives very true colors without any color cast of its own.
Yes,it is a 49mm dia filter. My Nikon lenses are 52mm and I am using a step down ring. It does not affect my tele zoom but gives a slight vignetting on my 18-55mm lens at 18mm - if i push it to about 2o mm or so there is no vignetting. This is just to share my thoughts.
With best regards
#3. "RE: Linear Polariser - seems to have no problem with D5100" | In response to Reply # 1
Ned_L Charter MemberTue 02-Oct-12 08:41 PM
I did encounter problems with my old linear polarizer with older DSLRs, the D70, and the D200. In both cases I had exposure setting problems and with the D70 it caused the camera to have autofocus problems.
After having the problem with the D200 I finally got rid of the product and replaced it with a circular polarizer. Since then I've only purchased circular polarizers.
The problem relates to DSLRs and even some SLRs, particularly ones with autofocus capability which use partially reflecting mirrors. The reflected light goes to the viewfinder and metering systems, while the transmitted light goes on to the auto focus sensors. If a linear polarizer is used, the intensity of light sent to the metering system would depend on the intensity of the light, and problematically also on the polarization angle. When a photo is made, however, the exposure is only dependent on the intensity of the light, because the mirror is up. With regard to phase detection based autofocus the polarization from the filter can also be affected.
In my old D70, autofocus was noticeably slowed at times with the linear polarizer. It took me a while to realize that. It didn't take me long to realize the exposure meter could be off either way up to a full f/stop. With the D200, I didn't notice an autofocus problem, likely because the Nikon autofocus system was greatly improved compared to the D70. The D200 still had an exposure meter problem of +/- a full f/stop.
I have no experience since then as I moved to circular polarizers exclusively at that point.
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