Graduated filter exposure with EOS

Can someone please point me in the way of an idiots guide to exposure when

using Cokin P graduated grey (0.9 - 3 stops) with a Kood � graduated light

tobacco�. Particularly landscapes, including sunrise and sunset.

 

I have done a search and found lots, but being a beginner I am not 100%

clear on the instructions posted.

 

My EOS 5 means I can use spot or centre weighted metering, or if using my

EOS 1000f instead I can use partial metering as well as the evaluative stuff.

 

I have a 35-80mm kit lens, 75-300mm kit lens and a Sigma 24mm f1.8, if it

makes any difference.

 

Jim Zuckermann�s book �perfect exposure� helped me big time finding middle

grey for spot readings etc., but his writings in this volume do not include

metering with graduated filters.

i was wandering through the pages at www.naturephotographers.net and found a little bit (one paragraph) of information.

 

here's the url

http://www.naturephotographers.net/dw0502-1.html

 

basically, they point you to meter both the light and dark "halfs" of the frame and take the difference in stops. subtract this difference by 1 and use the corresponding graduated filter while having the camera correctly expose the darker half.

haha... halves... sheesh... spelling...

I may be wrong, but I would assume that if you use evaluative or center weighted average metering, won't the camera take into account the filter(s) and compensate for correct exposure?

The meter will of course compensate, but that is not what Nicholas wants. Nicholas, why not do a simple test. Point the camera at the landscape and take a reading using whichever metering method you prefer. Now put on the filters and note the new reading. The meter may now perhaps show four stops more exposure from your first none filtered reading. You can now see that both graduated filters will fool the meter into wanting to overexpose by those four stops. All you need now do is consistently under expose from the meter reading by four stops, but so long as you always use the same metering method.

I assume you, Nicholas, would use a graduaded filter in order to:

- obtain a certain colouring effect

- reduce contrast range of motif in view

 

I would make a spot measuring of a zone which I feel as "medium tone" and use this aperture / time combination. Or spot on something "very light with detail" and add 2 stops. Or spot on something "light" (your palm if you are caucasian) and add 1 stop. Etc.. It depends on your mood and on what you want to express in that shot in selecting what is "medium tone" or "very light with detail". A bracketing would also help: it might happen that after processing the film you will find another bracketed combination to fit more your feelings. Anyhow, filter or no filter, it is the same as long as you use a SLR with TTL metering.

"Anyhow, filter or no filter, it is the same as long as you use a SLR with TTL metering."

 

I think some people may be missing a fundamental issue. The use of a graduated ND filter is to reduce the exposure level in say, the sky. If a 'normal' reading is taken with the ND on the front of the lens the meter will partially (partially because the ND part won't cover all the lens)compensate for the ND and bring you straight back to where you started! So what would be the point? Likewise if any part of the ND was over the spot metering area the same would happen. Some of you people need a lesson in photography.

Steve's right!<br><br>

 

I think you should just put the filters on to cover the lighter part (the part that would most likely come out overexposed) and probably use center-weighted metering (you know what to expect from it).

<br><br>

The half-ND filter diminishes the contrast between the parts and then the average metering will simply "tell you the average" (METERED WITH HORIZON IN THE MIDDLE!). You should also consider the dynamic range of your film (ca 10 EV on negative and ca 6 EV on slide) which is the difference between the darkest point and the highlight point in the scene.

<br><br>

Example1: with the spot metering you meter this: highlight=12EV, shadow=4EV => difference=8EV. <br>

Solution:<br>

- negative film => set exposure to 4EV+(8EV/2)=8EV<br>

- negative film + half ND filter => highlight=(12-3)=9EV, shadow=4EV => difference=5EV => set exposure to 4EV+(5EV/2)=6,5EV<br>

- slide film + half ND => the same as neg.<br><br>

 

Example2: if you are shooting a sunset: spot metering of highlight in the sky should be (6EV/2)=3EV above your exposure. <br>

Solution: (the spot meter says 250/f8, but you will shoot 125/f4) OR (set exposure compensation to +3EV and AE-Lock the spot metering of sky)<br><br>

 

Hope this helps.