Tips on lighting/camera settings

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Tips on lighting/camera settings

Postby o3h1p » 09 Jan 2011, 22:00

Hello,

I have a very basic setup--think cardboard box, leaning tripods and a 2x4 with small mounted lights. Things come out halfway decent with a B&W text because scantailor does a good job at making things look black and white, but with a color text I have to try and preserve portions of the text. You can see my results here:

Image

I currently am using 3 small under-cabinet style lights, but my guess is that these are not cutting it. The other possibility is that I don't have the right camera settings. I am currently just using 'auto' for my shots.

Can someone offer tips as to what I can do to improve the color of the pages? Anyone have any recommendations of lighting? And what are the best settings I should use?

Thanks,
jack
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Re: Tips on lighting/camera settings

Postby steve1066d » 09 Jan 2011, 22:48

Change the white balance to "Tungsten." You'll also probably want to increase the exposure. (Since you are using automatic.. play with your exposure compensation.)

Though you should consider going to all manual... that way you'll get more consistent results from page to page.

Steve
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Re: Tips on lighting/camera settings

Postby daniel_reetz » 09 Jan 2011, 22:49

Can you please post one "original" (un-Scan Tailored) image, ideally from a non-copyrighted book?

If your JPGs are kind of brownish like that out of the camera, you will need to work a bit on your camera settings. You can definitely do this. It's not that hard.

First off, is your lighting fluorescent or incandescent/halogen? The color issue is caused by your white balance setting being incorrect. Check your camera's manual (which are you using? A590is?) and try different white balance settings until the page looks closer to white. If you're using a Canon, you can get to the white balance settings by pressing the "func" button in any mode other than Auto. (use P or M mode to set your manual settings).

Second, your exposures are too short, meaning not enough light is getting to the sensor. Exposure is fractional, so 1/100th of a second is shorter than 1/30th of a second. Try setting your exposure to a slower value, like 1/30th. That will brighten up your image. You can do that in M mode, too.

If you end up having to make your shutter speed much longer than 1/30th of a second, you need more light.

Please try adjusting these things and then give us some feedback in the form of images so we can help you get going.

(on preview: steve1066d is right on)
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Re: Tips on lighting/camera settings

Postby o3h1p » 09 Jan 2011, 23:05

Thank you both for your quick replies. I looked at the tungsten setting and the settings under manual and I bet that was the problem. I don't have time to try it out again, but I'll probably post in a few days when I try again.

Is there anyway to get the ideal settings? I saw a script that went through the different settings, but I couldn't get that script to work.

FYI here's my current lighting:

http://tinyurl.com/2dxrebs

It doesn't say but I assume it is incandescent.

jack
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Re: Tips on lighting/camera settings

Postby daniel_reetz » 09 Jan 2011, 23:10

Those are halogens, the incandescent setting (looks like a little light bulb) will be close.

In your case, the ideal settings are just something you'll have to test and see. Honestly, there are only three parameters so you can figure it out fast. Shutter speed, aperture, white balance. That's it... figuring out how to change them is the most time consuming part of all of it.
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Re: Tips on lighting/camera settings

Postby ibr4him » 11 Jan 2011, 06:19

Get an '18% Grey Card' to calibrate white balance?
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Re: Tips on lighting/camera settings

Postby spamsickle » 11 Jan 2011, 09:41

o3h1p wrote:Is there anyway to get the ideal settings?

If your camera offers a custom white balance setting, you can use it with a white card to match your camera to your lights. If it doesn't, and you're using halogen lights, choose the tungsten setting.

Set up your scanner, camera, and lights with the book you're scanning. Put the camera in "manual" mode. If your camera has an f-stop that actually stops down instead of using neutral density filters, you may improve sharpness a bit by stopping down (using a larger f-stop number). If your camera uses neutral density filters, you should use the largest setting (smallest number, brightest image).

Set the zoom level of your cameras to frame the book at the same magnification in each one.

Focus the cameras. I recommend always using manual focus. On my camera, there is a manual focus button on the lens. I pick a page filled with text, press the shutter halfway to let auto focus focus the text (gives me a "green box" when it's happy), and push the manual focus button to lock in the setting.

Make sure your lights are evenly illuminating the book -- no obvious hot spots, no detectable gradient from dark to light. This will be more obvious to the camera than it is to you, so you may want to do this through the viewfinders. If you have external monitors attached to your cameras, all the better.

Now, with the f-stop you have chosen, vary the shutter speed until the text is clear and the page is as white as possible without washing out the text. If you like, you can take a few test shots -- five should be plenty -- bracketing the exposure. Run them all through Scan Tailor to see how the final product looks, and pick the best one. You may also want to verify how even your lighting is -- the more even it is, the better Scan Tailor will work. If your lights need to be adjusted, do that and repeat this paragraph until you're happy.

At this point, if your camera has the option, I like to "save settings". My camera has a "custom" mode in addition to "manual", and saving the settings means the zoom level, aperture, and shutter speed are now my new custom setting. If I need to take a break and turn the cameras off in the middle of a scan, everything comes back automatically when I turn them back on. If you don't have this, it's no big deal, you can either leave the cameras on when you take a break or take your breaks between books.

If your lighting and camera setup doesn't change, the only things you'll need to fiddle with from one book to the next is the zoom level and focus -- white balance, aperture, and shutter speed should be the same every time.
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Re: Tips on lighting/camera settings

Postby o3h1p » 20 Jan 2011, 22:34

Ok trial 2 is a bit better. I'm not using a color book at the moment, but using my A590IS I'm using:

* Tungsten
* f-stop: 8.0
* shutter speed: 1/30
* iso: 1600
* focus: manual tuned with zoom box

I've attached one of the pages and the result after scantailor has done it's job. As you can see, it may be readable when you zoom out, but it's not as good as some of the results I've seen around here.

I do have a custom white balance setting for my camera so I'm going to try that next, but if you have any ideas please let me know.

Thanks,
jack
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Re: Tips on lighting/camera settings

Postby steve1066d » 20 Jan 2011, 23:42

An ISO of 1600 is too high.. You get a lot more noise in the pictures. The noise is especially noticable on darker pages. I also think its over-exposed a bit.

Maybe try an ISO of 200, f-stop of 4, and a shutter speed of 1/15 or 1/30.
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Re: Tips on lighting/camera settings

Postby daniel_reetz » 21 Jan 2011, 03:47

I'm not sure it's overexposed - though it might be - but the fact that you need ISO1600 means that you need more light. Can you move your lights closer to the page, and use a lower ISO?

Think of it this way- ISO is like a guitar amplifier. If you turn it way up, you can hear all kinds of hiss(noise), but things are very loud(bright). Each increment of the knob increases noise. But if your input signal is loud(bright light on the page) you can keep the volume knob down, and the sound will be both clean and loud (bright and clean images).

Boy, I hope that's as clear as it sounds in my head...
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