hil26
journeyman
Reged: 07/11/2007
Posts: 79
Loc: North Wales
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Have now tried 3 times to do this, first two times, the info at 1/60s was way out - then realised that I was shooting raw files and the raw editor was adjusting - aaggghhhhhh - note self - put brain in gear.
The third set taken as jpegs came a lot closer to the expected results except the true black which I assume will be the image taken at 1/1000s, I am getting readings that show some detail is apparent that is 7 7 7 top right hand corner, 8 8 8 in the middle and 6 6 4 bottom left.
Am I right in assuming that these should be 0 0 0 across the image - i.e true black. If so I must be getting some trace light onto the card that I was not aware of.
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2079
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Hi, even using Raw format the files shouldn't be 'adjusted' to make significant changes to the exposure that you made. The whole point of Raw is that you are in charge.
With the correct prevailing light levels you should be able to get somewhere near a good mid-tone reproduced from a grey card while using a 1/60sec exposure and an appropriate aperture. If the camera is correctly adjusted it should, a far as is possible, reproduce the tones as they appear in a scene, in this case a grey card, correctly - otherwise there is not a lot of point to an exposure meter!
If the camera gives a correct exposure at 1/60sec by the time you are shooting at 1/1000sec the grey card will be four stops under exposed but there will, as you have found, still be residual exposure and some noise etc - that accounts for the figures you are getting. Unless you are a scientist involved in camera development I wouldn't fret about that.
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hil26
journeyman
Reged: 07/11/2007
Posts: 79
Loc: North Wales
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Thanks Gary
am going to repeat as although results were nearer to expected a few were a little off in the "correct exposure" that is the figures in the blue channel were lower than the red and green
I have 131 132 and 116 at 1/60s, these changed
at middle to 131 130 110
at lower left to 125 124 and 103
which makes me believe that the light across the card was not uniform.
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FatherPie
journeyman
Reged: 18/04/2008
Posts: 91
Loc: West Yorkshire
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Quote:
Have now tried 3 times to do this...
Like you I have now carried out the test multiple times (4 if I'm honest). My experience is similar to yours with slightly different readings at different points of the picture. I have four different sets of results but in none of the tests has the "correct" exposure produced a reading of 128 (plus or minus 15). I have found through changing the setting on the camera in 1/3rd of a stop increments the nearest I can get to 128 is at an exposure between 1/3rd and 2/3rd over the metered reading.
Am I being completely clueless or does this ring true for some others?
Cheers
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Dave
www.whenham.net
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FatherPie
journeyman
Reged: 18/04/2008
Posts: 91
Loc: West Yorkshire
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Quote:
... that is the figures in the blue channel were lower than the red and green
Hi, my results are also lower in the blue channel whilst red and green very close to each other. Looking at the many shots I've taken today the blue is on average 8 lower than red or green. The values for red and green were invariably the same or within +/-1.
I have just taken 18 frames at 1/60th in under a minute and 12 were exactly the same reading (102/102/94) and all 18 were within 1 or 2 of these values.
Once again however (see previous post) an exposure at 1/40th, 2/3rd of a stop over the "correct" reading, produced closest results (134/134/124).
Goodness knows what the neighbours think as I run in and out of the house with camera and tripod to take another set of pictures of a grey card... LOL!
An interesting yet frustrating exercise!
Regards
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Dave
www.whenham.net
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hil26
journeyman
Reged: 07/11/2007
Posts: 79
Loc: North Wales
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it certainly is an interesting exercise, I am having to wait to repeat my exercise at the moment.
Glad to see my results appear to be no different to others.
Have a good long bank holiday weekend
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saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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Quote:
Quote:
Have now tried 3 times to do this...
Like you I have now carried out the test multiple times (4 if I'm honest). My experience is similar to yours with slightly different readings at different points of the picture. I have four different sets of results but in none of the tests has the "correct" exposure produced a reading of 128 (plus or minus 15). I have found through changing the setting on the camera in 1/3rd of a stop increments the nearest I can get to 128 is at an exposure between 1/3rd and 2/3rd over the metered reading.
Am I being completely clueless or does this ring true for some others?
Cheers
See my original post which started this thread and Garry's and Angela's replies- they may be of some help/comfort to you. Your experience was very similart mine.
You will see from Garry's reply that whilst your readings may vary from the base line, you are not necessarily going to be marked down provided your submission shows you have understood the purpose and parameters of the exercise and you interpret your results accordingly.
Hope this helps.
Peter 
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FatherPie
journeyman
Reged: 18/04/2008
Posts: 91
Loc: West Yorkshire
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Quote:
Hope this helps.
Peter
Cheers Peter, that's useful thanks - appreciate your help.
Regards
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Dave
www.whenham.net
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hil26
journeyman
Reged: 07/11/2007
Posts: 79
Loc: North Wales
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At last comp;eted the grey card bit, now have to get out and photograph a landscape
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FatherPie
journeyman
Reged: 18/04/2008
Posts: 91
Loc: West Yorkshire
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Quote:
At last comp;eted the grey card bit, now have to get out and photograph a landscape
Fingers crossed weather holds for weekend for you!
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Dave
www.whenham.net
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cgryce
newbie
Reged: 24/12/2007
Posts: 7
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Have read the different posts and have taken my grey card shots with my Nikon D2X. They have not yet been transferred to my PC.
I noticed that when taking the grey card shots my auto-focus kept zooming in and out trying to focus, but unable to do so. I read in my Nikon instruction manual that some subjects which lack contrast can fool the most sophisticated auto-focus system-so I had to turn mine off and use manual focus. Anyone else had this problem?
Also on page 17 of the module handbook, you are advised to use spot metering of the shadow and highlight areas of your landscape pictures. What would happen to the readings if I used Matrix metering instead of spot metering? Am just curious!!!
Chris Gryce 
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hil26
journeyman
Reged: 07/11/2007
Posts: 79
Loc: North Wales
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Matrix metering would not give the results required for the module, as it would use its memory banks to find a setting that would suit the image being taken - a sort of average.
It would probably give a good image but not for the course.
Well that's how I understand it anyway
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4BIKER2
enthusiast
Reged: 01/02/2008
Posts: 267
Loc: West Midlands
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I agree with above, the matrix metering will try to balance the lighting.
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Nigel
http://www.flickr.com/photos/24057726@N02/
The learning curve is so steep I keep falling off.
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2079
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Yup!
The other point about auto-focus is why I don't bother with auto-focus - not that I only photograph grey cards but I tend to photograph a lot of odd things that confuse auto-focus -
- so I just find I can do it better than the camera. Sometimes the camera does it quite well but that means switching auto-focus on and off all the time and really can't be bothered.
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cgryce
newbie
Reged: 24/12/2007
Posts: 7
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Thank you all 3 of you, hil26, Nigel and Gary. Your comments were most helpful.
Chris Gryce
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George_Georgantidis
newbie
Reged: 01/03/2008
Posts: 6
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To Garry McNamara
Hi Garry and firs of all thanks for all your comments and advice tips on your reply back to me for the Module 1. I was getting ready to start my Module 2 when I found out that my camera (Nikon coolpix 5000) does not provide all the options required for full manual operation. I am planning to buy the new Nikon the D 300 by the end of this year but in the mean time should I proceed with Module 3?
Another option would be to by a cheaper model now (the Nikon D 80 or D 60 ) and try to achieve my best result in Module 2.
Please advice and one more many thanks for all your comments positive and negative.
George
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2079
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Hello George - which features doesn't it have? As far as I know the Coolpix 5000 has Program and Manual modes, Matrix, Spot and Centre Weighted metering options - that's all you need for module two.
Have a good look at the manual and you should be able to complete module two with the Coolpix,
Garry
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George_Georgantidis
newbie
Reged: 01/03/2008
Posts: 6
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Hi Garry
Many thanks for your advice. I have to admit that I rushed in posting questions to you. Sorry about that indeed. You are absolutely right. The P5000 can do all the settings in manual mode. I just though for a minute that only 5 pre-selected options are available but now after looking the manual I know one can do much more with this little camera.
I am going back to my Module 2 now.
Many thanks again
George
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cgryce
newbie
Reged: 24/12/2007
Posts: 7
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Like quite a few people on this forum, I'm struggling with my grey card shots. My first attempts with a D2x camera and a 5omm F1.4 lens(100ISO)were taken outside. Although for much of the time-it was overcast-the light did change quite a bit.
My "correct exposure" readings(using the info palette) for a shot taken at F8 @ 1/60th were as follows:
R88 G91 B98. I tried taking readings from different parts of the image and these varied slighly from those given. Anyway-these readings are nowhere close to the recommended 128 in each channel.
What else can I do? Am thinking of re-taken the shots indoors at night in my kitchen. No doubt, I'll have to change the White Balance to Fluorescent as I'll be shooting under these lightening conditions.
Any advice much appreciated.
ChrisG.
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2079
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Hi, that's really quite under exposed, not always a bad thing but a camera should produce a reasonably accurate representation of the subject is photographs and that isn't. Put another way if your computer screen or printer gave a darker version of everything you would find a way to fix it.
If it’s any help I had two perfect examples shot with Nikon D200s over the weekend so with attention to every variable it is possible. A catch light on the card will throw the results out so make sure it’s not reflecting a brighter light than the whole and is evenly lit.
Secondly you might get better results with more settled artificial light indoors - light can vary quite a bit for instance with changes in cloud density between shots. This is a precise, almost scientific, test so you do need to remove all variables and a cloud going across the sun or twenty seconds passing between your initial reading and the last of your shots can make the whole process meaningless.
If you are going to use a low energy bulb for instance I would turn it on about half an hour before I took the pictures as these get progressively lighter after a short period of use.
If you do in the end discover that your camera is under exposing by a half stop or so then you can apply exposure compensation in future – that’s what we’ve been doing with film for years – pro films even come with the ‘real’ ISO printed on the batch and a good photographer would never simply trust the manufacturer’s figures.
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