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11-16-2011, 07:39 AM   #1
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Using the gray card

I have a long history of using pentax cameras, but it was alway by the seat of my pants and using lots of film. When I got my k200d a few years ago, I continued to take pictures the same way. Anyway I decided to take a class and the professor wants us to use a gray card to determine exposure.

As you might guess the prof is totally ignorant about pentax cameras and the way he was demonstrating on the Nikon doesn't match anything on my camera. He pointed the camera at a gray card, hold the shutter half way and the view finder shows him a +/- scale that he spins the wheel until it is neutral. I can't seem to find that scale. The only one I see is for the AV setting but not on manual. I scoured the threads and manuals but there is no step my step instructions on how to maually determine exposure with a gray card and he wants us to use manual only. I understand ISO and f-stops, but the determining shutter speed has got me stumped. Can someone point the way to understanding this? Thanks!

11-16-2011, 07:59 AM   #2
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If I understand what your professor wants--using the camera's meter to set exposure while using a gray card--I would just drop it into M mode, point at the card, and hit the green button. You can change the settings, but with a stock camera I would expect that to set the exposure according to the Program line.

If your professor wants you to get practice setting exposure to the card because he wants you to be familiar with manually adjusting aperture and shutter... Hopefully someone else here knows how to do that with a single wheel camera. My guess is that you hold a button while using the rear wheel.
11-16-2011, 09:20 AM   #3
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What you need to do is set a custom white balance. See page 152 in the k200d manual for how to do this. Your target is the grey card. It's actually very easy to do.
11-16-2011, 09:54 AM   #4
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Your professor isn't as dumb as he seems

Your camera can easily be fooled by light and dark backgrounds, backlit subjects, and highly reflective surfaces. A gray card is a great way to get perfect exposure. Since the camera has a reflected meter that is looking to average out the scene to an 18% gray, the gray card just makes it's work easy. It represents the happy medium the camera is trying to find. See if you can average the following set of numbers quickly in your head: 18, 18, 18, 18, 18, 18, 18, 18, 18, 18, 18, 18, 18 18, 18, 18, 18. That's what a gray card does.

If you have the camera in Av or Tv mode, point it at the gray card, fill the entire frame, and hit the AE lock button. If you are in M mode, again fill the fame with the gray card, you should see a similar scale to the one shown on the Nikon. Turn your thumb wheel until the indicator is in the center, then hit AE lock. Once you've done this you can adjust either the shutter speed or the aperture up or down and the other setting (the one you are not adjusting) will move in the correct direction to maintain perfect exposure.

Edit: I think on the K20d, I had to turn on the "display sensitivity" setting in the custom menu to get the little scale to show up. Unfortunately you have to chose between this and the number of shots remaining.


Last edited by maxfield_photo; 11-16-2011 at 10:05 AM.
11-16-2011, 10:01 AM   #5
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If you are in M mode, again fill the fame with the gray card, you should see a similar scale to the one shown on the Nikon. Turn your thumb wheel until the indicator is in the center

Therein lies the rub. I just do not see that indicator. Can you tell me where I can see it at or if there is a setting I need to set to see it. I am flying blind here it seems
11-16-2011, 10:05 AM   #6
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Wouldn't it be the EV indicator? No scale, but you would set it to 0?
11-16-2011, 10:09 AM   #7
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QuoteOriginally posted by blackcloudbrew Quote
What you need to do is set a custom white balance. See page 152 in the k200d manual for how to do this. Your target is the grey card. It's actually very easy to do.
Ok, it seems that my education is lacking. I am unsure in which way white balance and exposure are related. I had always thought that WB was for color saturation.
11-16-2011, 10:14 AM   #8
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QuoteOriginally posted by markdesmarais Quote
Wouldn't it be the EV indicator? No scale, but you would set it to 0?
Thats what I thought at first but mine is always at 0, no matter how much I spin the wheel. Thats why I am wondering if there is a setting that I need to change or if there is a button I need to press.

I am a visual person. Reading the manual just confuses me, but once I see it then I remember it. I guess thats why I love photograpy so much, but the terminology confuses me

11-16-2011, 10:23 AM   #9
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Gray cards can also be used to set custom white balances, but that's not what your professor is after, he's trying to teach you how to set proper exposure every time.

Look in your custom menu, there should be an option called "display sensitivity". When you set it to 'on' you'll see the little scale, when you set it to 'off' you'll see the number of shots left on your SD card.

Last edited by maxfield_photo; 11-16-2011 at 11:53 AM.
11-16-2011, 10:26 AM   #10
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Ok, it's really simple no dials to spin to set a custom white balance. You go to the function menu, shift the WB to manual, you then point the camera at the grey card, and take a picture of it, then the camera will say either no good or OK, if Ok you it the ok button. Presto you've set a custom WB for that light.

What WB does (essentially) is tell the camera what white is and then it figures the rest of the colors from there. No dials to turn.

Edit: Apparently in reviewing this thread, I may be off base here from the OP's original question. If so, sorry about that. It looked like a custom WB issue but I'm suspecting that the point was in utilizing Ev.

Last edited by blackcloudbrew; 11-16-2011 at 10:50 AM.
11-16-2011, 11:28 AM   #11
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QuoteOriginally posted by Ccat Quote
Ok, it seems that my education is lacking. I am unsure in which way white balance and exposure are related. I had always thought that WB was for color saturation.

Yes, they are not related and the answer was for a different question :-)

WB is not really for "saturation" - that has it's own setting. WB corrects the general color cast created by say, the late-day sun (yellowish), open shade (bluish) or odd lighting. Note that in many cases you do expect to see a color shift, like in golden hour, so making it neutral could look goofy.
11-16-2011, 11:54 AM   #12
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QuoteOriginally posted by SpecialK Quote
Yes, they are not related and the answer was for a different question :-)

WB is not really for "saturation" - that has it's own setting. WB corrects the general color cast created by say, the late-day sun (yellowish), open shade (bluish) or odd lighting. Note that in many cases you do expect to see a color shift, like in golden hour, so making it neutral could look goofy.
Golden hour would be the time to have a set of WB cards like the movie industry uses a company by the name of Warm Cards actually makes a big range of cards. small for in your bag or big studio/film set versions (could warm up non golden hour as well)

WarmCards - White Balance Reference System
11-16-2011, 01:45 PM   #13
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Are you asking about White balance (I don't think you are) or Exposure? If Exposure, using a gray card to center the exposure, try page 94 (manual mode). It appears it shows as a number only. 0 is a centered meter. In semi-auto, none of my cameras show an active meter but unless you have set an exposure compensation for other than 0, it will center the meter and pick your shutter speed or aperture (depending on the mode), see page 100 for EV Comp.

11-16-2011, 07:27 PM   #14
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In manual mode on my DS the meter is a numeric display in the bottom right hand corner of the viewfinder. 0 means the meter is centered, and it will read up to 3 stops over or under exposed by displaying values like 1 or -1. If you are off by more than 3 stops then the 3 or -3 flashes. To adjust the aperture while metering a grey card I would press the AV button and spin the rear dial, while shutter speed is the default setting of the rear dial when no other buttons are pressed. Half pressing the shutter button turns the light meter on, after which you would adjust shutter and aperture setting while metering off of the card until the meter reads 0. Shutter and aperture are probably controlled in the same manner on your K200d by default.

My K10d has a meter that is more intuitive to read at a glance. It displays exposure on a horizontal bar in manual mode. When the indicator is in the middle the scene is properly exposed, and a bar extends to the right to show over exposure or to the left to show under exposure of up to 2 stops. The front dial on the camera controls shutter speed and the rear dial controls aperture by default.
11-21-2011, 03:26 PM   #15
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I wanted to thank you all for your replies and thoughtful comments. It gave me the start to identifiying my problem. Apparently you have to have lenses that have the m setting on the aperture ring and apparently mine are too old, they date back to my film days 30 years ago. I borrowed a friend's lens with the m setting and it worked like you all said.

I will have to figure out a way to determine exposure apart from from the gray card or buy newer lenses. I used to have an exposure meter long ago but it got wet and never worked again. Anybody use the sunny 16 rule?
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