- This topic is empty.
Dodgy meetering with Circular Polarizor
-
Here’s a question that someone may be able to help me on. I have a problem on my 40D where occaisionally it meters incorrectly and seriously underexposes, to the point of ‘black photo’s’. This tends to happen under certain ‘filter’ conditions.
Generally this happens when I use my Lee circular polarizor, (and possibly sigma 10-20mm) but incocsistently. I assume this is based on positioning of the filter and certain lighting conditions. (However I should add that this happens under normal daylight conditions)
At this stage I workaround these issues by dropping into manual mode with a set aperture and trial and error on the exposure time. Generally this is fine as my photography rarely depends upon split second timing.
So the question which I guess is more for curiosity than anything else. Does this happen to anyone else either with the 40D or with any other camera? I guess there is a tipping point when using filters where metering starts to become inaccurate, but I am surprised that a single polarizor in daylight can trigger this.
Cheers
Gary
Hi Gary. Never had that problem myself. Could it be that your meter is faulty? What metering settings are you using? A polariser shouldn’t cause much of a difference in the metering on its own, are you using other filters at the same time? I have used two polarisers together to deliberately cause the light to be blocked to almost black in cross polarisation effects, but I wouldn’t imagine other filters causing the same effect.
The only other case I can think of is, if your polariser is a linear one and not circular (not the shape of the filter itself)Thanks miki g.. I did think of the linear polarizer issue myself but it is definately a circular polarizer. My conclusion is also a faulty metering system, which seems to be intermitent. Additional filters (ND grads) don’t help the issue, but the polarizer seems to be the key element in all this. As I say I’m not too bothered as I can rectify the situation when it does occur by using manual exposure settings .. just wondered if anyone else was having similar issues.
Mr. H. I have exactly the same issue with my 40D. I have a Hoya Pro polarizer on my 70-200mm F4 and it constantly underexposes! Getting quite sick of it to be honest. I have heard that a polarizer will drop the exposure by about 1/3 of a stop, but with it on the camera it can be as much as 1 or 2 stops.
Regardless of metering mode the same things happens over and over again. Last time I was shooting a track day, and had to switch to manual exposure which is a pain, because as the clouds shift it was sunny and then overcast the next minute. Plus also I need the polarizer to reduce the glare from glass.
interesting Dave… so probably a fault with the 40D metering, although your problem sounds a bit more continuous, whereas mine tends to be more random. Are you able to dial in a 2 stop exposure compensation and then shoot as per normal?
Gary
I know how to solve the problem………..BUY A NIKON….. :lol: :lol: :lol: :lol:
Sean.
sean1098 wrote:
I know how to solve the problem………..BUY A NIKON….. :lol: :lol: :lol: :lol:
Sean.
:lol: :lol: :lol:
Mr.H wrote:
interesting Dave… so probably a fault with the 40D metering, although your problem sounds a bit more continuous, whereas mine tends to be more random. Are you able to dial in a 2 stop exposure compensation and then shoot as per normal?
Gary
I generally up shooting in manual mode, I do alot of panning shots so I do like the control, as frustrating as it can be…
I’ll post up some metering shots later…
Funnily enough I wouldn’t be averse to a switch the the other side… although my credit card would be.
Have any of you contacted Canon about this problem? Are both of you using the same brand of polariser? There could possibly be a firmware update which could solve it. Just a thought
Hi Dave and Gary…I use a 40D as well and often use ND Grads but do’nt have a problem
with these and metering…Dave…a polarizer which I use as well will definately lose you more
than 1/3 stop of light, depending on the strength of them they will make you lose up to 2 stops
of light but the meter should compensate for this on the end result. They can be fooled and
if using a circular polarizer the metering will change as you turn it around to get the effect you
want.Noel Browne.
You must be logged in to reply to this topic.
