saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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Having taken so long over Mod 1 I was keen to get on with getting Mod 2 ready whilst waiting for Mod 1 comments. I have run the grey card test a dozen or so times over last two days (yesterday in shade, today overcast) with similar results. The "correct" (i.e at 1/60 sec) exposure, instead of measuring 128/128/128, repeatedly came out at around 158 or so. I tried different ISO and White Balance settings with similar results. I therefore tried building in exposure compensation of -1/3 and -2/3 stop and found I was able to get readings in the 128 range for the 1/60 sec exposure. I am using a new Nikon D300 and had thought my pics were a little overexposed occasionally so I do not know whether it is my ineptitude or a feature of the camera settings in certain circumstances. I am now concerned with what to submit for Mod 2 . Any comments anyone or any view Garry? 
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2063
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Hi, first make sure the grey card is in even light - with no shadows or highlights or overly reflecting areas. Make sure you are completely filling the frame with the grey card - and I mean completely - anything else can really mess this set up.
Set the camera to manual mode, select 1/60sec and using the meter display adjust the aperture until the indicator indicates a correct exposure.
Before you do that make sure that any exposure compensation is cancelled - I had a module two last week where the student was unaware they had the exposure compensation set to plus 1 stop, so that is one place to look first if you are getting over exposed pictures. Seeing as how you are adjusting that at times to get a correct exposure it seems unlikely (but do make sure you have cancelled it after using it.)
If they card is measuring the same 158 in all channels then it's not a white balance problem. The ISO shouldn't have any effect on whether or not the camera gives a correct exposure - it will only change the shutter or aperture setting to suit the sensitivity selected.
If you are doing everything above and your card is still coming out consistently too light with no other camera control set to over expose then the camera is at fault and you should get Nikon to look at its calibration.
I Hope somewhere in there is a solution.
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saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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Garry,
Many thanks. I am completely filling the grey card so your comment about calibration of the camera may be right. Before I went outdoors to do the test properly I tried it indoors in natural but rather poor light for practice, and to get a correct exposure had to shove the ISO up to its limit. Strangely, readings on that one occasion were within 128 range. Is it acceptable to submit Module 2 with an adjustment to underexpose slightly as I have done to get the correct readings pending any corrections or otherwise Nikon may or may not do? I notice from a Nikon discussion site several people commented about possible slight overexposure with this camera. It is a manageable "problem" so I am not sure whether it is worthwhile taking it up with Nikon- everything else is so great. 
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2063
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If you explain that in your self assesment you certainly won't lose any marks as it demonstrates that you are completing the task very thouroughly indeed.
Yes indoors you would have to increase the ISO speed unless you have a fast (f1.4-f2.8 lens). Nothing wrong there but as I said a camera should give a correct exposure regardless of the ISO setting.
Personally I wouldn't be happy with a camera that routinely over exposes - any camera repair company could tell you if the camera's metering system is working correctly as will Nikon. You certainly shouldn't have to use exposure compensation to acheive a correct exposure to a grey card. My 50 year old Weston meter will acheive this so a new camera should! I'd get it checked out.
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saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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Garry,
Many thanks. Your advice is very much appreciated and will be acted upon.
Peter W
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ColinL
newbie
Reged: 10/01/2008
Posts: 5
Loc: UK
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I've also got a query regarding Module 2.
Having sorted the first part with the grey card, I'm a little confused with what is required for Part 2.
A. "An image with the exposure setting biased towards achieving maximum detail in the shadow areas" Am I correct in taking this to mean "maximum detail in the shadow areas without 'burning out' the highlights"? Or just maximum detail full stop?
And similarly for B. does this mean " maximum detail in highlight areas without 'blocking out' the shadow areas" or maximum detail full stop?
Any thoughts gratefully received. I can porduce images for either interpretation, but don't want to lose marks by not interpreting the question correctly. ColinL
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apdlc
newbie
Reged: 13/01/2008
Posts: 16
Loc: Jersey UK
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Rightly or wrongly I have biased the exposure for maximum detail in the shadow areas at the cost of the highlights, meaning some are burnt out. the opposite was applied to the highlight detail, maximising to the point where some of the shadow detail is lost . Im not sure if this is correct, but I will soon find out I am sure.
regards
Andy
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ColinL
newbie
Reged: 10/01/2008
Posts: 5
Loc: UK
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Thanks Andy, anyone else out there got an opinion?
ColinL 
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saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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I am in the process of doing this and would agree with Andy's assessment of the requirement. Certainly that is how I read it. If exposing for maximum detail in the shadow areas, I expect it is reasonable to expect to lose some detail in the the highlight areas and vice versa although how much may depend on the range.
Peter
Edited by saffron (23/03/2008 10:37)
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2063
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Let's see. You should by this point know how much over and over exposure your sensor can tolerate and with that information you can make two exposures to a scene while hopefully still getting a decent looking image without blown highlights or gross under exposure.
Obviously if you expose a black subject to appear grey you will get good detail in the darkest areas and if you expose to make your brightest highlight grey you will have lenty of detail in that. But that’s not the goal as you’ll have a poor quality picture either way.
The idea then is the subtly distribute the tones so that you biased the result towards shadows or highlights without too much compromise at the other end. In ‘the old days' we might bracket by half a stop to ensure a transparency that had the bias we wanted without any of the three shots actually being ‘wrong’ or useless - better to have three usable shots than one correct and two useless.
It's quite a subtle distinction but you should be able to assess which is which and why one is best and for what reason – the real point of the exercise.
A scene with snow might work!
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Angela Nicholson
AP Technical Editor
Reged: 07/02/2006
Posts: 139
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Quote:
Having taken so long over Mod 1 I was keen to get on with getting Mod 2 ready whilst waiting for Mod 1 comments. I have run the grey card test a dozen or so times over last two days (yesterday in shade, today overcast) with similar results. The "correct" (i.e at 1/60 sec) exposure, instead of measuring 128/128/128, repeatedly came out at around 158 or so. I tried different ISO and White Balance settings with similar results. I therefore tried building in exposure compensation of -1/3 and -2/3 stop and found I was able to get readings in the 128 range for the 1/60 sec exposure. I am using a new Nikon D300 and had thought my pics were a little overexposed occasionally so I do not know whether it is my ineptitude or a feature of the camera settings in certain circumstances. I am now concerned with what to submit for Mod 2 . Any comments anyone or any view Garry?
We have found that manufacturers regularly calibrate their cameras so that a mid tone is recorded with a brightness value of something other than 128. It doesn't mean your camera is faulty, it is how it is set-up. Making mid tones darker than they should be by underexposure, for example, will help retain highlight detail.
Angela
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saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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Angela,
Many thanks. That is a much clearer answer than I got from Nikon, bless them.
Peter
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Heart_Shaped_Bruises
newbie
Reged: 16/02/2008
Posts: 23
Loc: Coventry, West Midlands, UK
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Hi all,
Im having a bit of a nightmare with module 2!
After re-taking the grey card images several times, I finally got them just right and the "correct exposure" image finally measures at around 128/128/128 in each channel of the info palette. However, in the questions about finding the last images with highlight and with shadow detail, I have measured these with the info palette, and have found both for R10/G10/B10 and for R245/G245/B245 but these images do not actually have much, if any, detail in them. Im not sure if this would be acceptable or not, so I could use a bit of help!
Also, the questions after that, about "stops", I am not 100% sure on what is meant by "stops"...maybe Im having a stupid moment and its something obvious but Id appreciate it a lot if somebody could point me in the right direction.
Many Thanks,
Tina
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~I Noticed You...You Stood Out Like A Sore Thumb...The Most Beautiful Sore Thumb I'd Ever Seen~
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2063
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Hiya, the fact that they are 10 and 245 confirms there is something there - if you were to print them for instance the 245 should show the faintest of tones against pure white paper. You might want to check your monitor to confirm that the brightness and contrast are not set too high - here's an example of 245 and pure white- you should be able to see a clear difference -
As for stops - it's a bit of an antiquated term but is still used all the time. A whole 'stop' refers to a doubling or halving of exposure - depending on which direction you make the adjustment. Most cameras also offer you the option to adjust exposure by a third and a half of a stop. It can be achieved with the shutter or the aperture control.
Garry
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Heart_Shaped_Bruises
newbie
Reged: 16/02/2008
Posts: 23
Loc: Coventry, West Midlands, UK
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Hi Gary.
Thanks for the advice, I see what you mean now about there being slight detail. However, the last image with shadow detail I have is the image set at a shutter speed of 1/1000 second. I would have thought this would have no detail whatsoever as the image just appears black.
With regards to the stops, I am still a little confused. The way I am reading it, is it for example, if I set the shutter speed to 1/60 and then adjust this by 2 stops, the new shutter speed would be 1/100??
Thanks
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~I Noticed You...You Stood Out Like A Sore Thumb...The Most Beautiful Sore Thumb I'd Ever Seen~
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saffron
newbie
Reged: 30/11/2007
Posts: 29
Loc: Saffron Walden
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Quote:
Hi Gary.
Thanks for the advice, I see what you mean now about there being slight detail. However, the last image with shadow detail I have is the image set at a shutter speed of 1/1000 second. I would have thought this would have no detail whatsoever as the image just appears black.
With regards to the stops, I am still a little confused. The way I am reading it, is it for example, if I set the shutter speed to 1/60 and then adjust this by 2 stops, the new shutter speed would be 1/100??
Thanks
Hi,
On page 17 of the Module Book for Part 1 you are given a series of shuttter speeds either side of 1/60th sec. Each change is one stop up or down i.e 1/15th second is 2 stops slower and 1/250 is 2 stops faster shutter speed.
Hope this helps.
Found this a very interesting and informative exercise and, after the frustration mentioned at the beginning of this thread, a great deal of fun. Good luck.
Peter
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Garry McNamara
Snr Tutor/Bongo Banjo
Reged: 16/08/2006
Posts: 2063
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Hi, here's another of those silly pictures that proves even 10 is quite different from 0 -
As for the stops business - if you double 1/60 you get 1/30 and if you halve it you get 1/120 (but to keep things neat they round it up to 1/125 so the next one can be 1/250sec.) What's important to understand is these figures are fractions - put a 1 and a slash in front of the number and it all starts to make sense - eventually (says he with not even a CSE in maths!)
Apertures are a little less obvious but the normal sequence (halfing the amount of light entering the lens each time in this sequence)is 1.4,2,2.8,4,5.6,8,11,16,22, anything appearing between those figures is a third or a half of a whole stop,
Garry
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Heart_Shaped_Bruises
newbie
Reged: 16/02/2008
Posts: 23
Loc: Coventry, West Midlands, UK
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Hi Peter,
Thanks a lot for pointing that out, I had a feeling that was what it was but I wasnt 100%.
Thanks for putting me straight, much appreciated!
Tina 
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~I Noticed You...You Stood Out Like A Sore Thumb...The Most Beautiful Sore Thumb I'd Ever Seen~
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Heart_Shaped_Bruises
newbie
Reged: 16/02/2008
Posts: 23
Loc: Coventry, West Midlands, UK
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Hi Gary,
Thanks again for taking the time to explain. As I said to Peter, I had a feeling that was the way it worked, but I wasnt 100%, so thanks for pointing me in the right direction! The whole module seems a lot easier now, so phew!
Many thanks,
Tina
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~I Noticed You...You Stood Out Like A Sore Thumb...The Most Beautiful Sore Thumb I'd Ever Seen~
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hil26
journeyman
Reged: 07/11/2007
Posts: 76
Loc: North Wales
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Quote:
Hi, here's another of those silly pictures that proves even 10 is quite different from 0 -
Garry
Hmmm, its either my eyes or my monitor, as I can see no difference in black rectangle - I know you are saying there is a difference - so should see a line bewteen two rectangles, just not there for me.
I can however see the difference in the earlier white image.
I have calibrated my monitor using both Syder and agaion with the graphic card software (nvideo) and can see a difference at the black end using both.
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