tsttm's build

[you1]

Thanks for your response spamsickle;
I had to look at my camera to better understand your comment.

Hitting +/- allows me to select between Eposure Value (i.e. F4.0) and I guess the duration for the shutter speed (1/125).

Am I right to say that you are suggesting to experiment with Exposure Value (EV) and the shutter speed until we reach a desired value.
Will do...
But that's lot of permutations to find the ideal setting. Is there a rule of thumb (i.e. if you raise EV then decrease shutter speed, and vice versa)? Or is trial and error the best method...

tnx

[spamsickle]

The EV adjustment is usually that +/- button. It only applies if you're using an automatic exposure setting.

On my camera, and I'm sure on yours too, there are three automatic exposure settings:

P, or "program mode" is fully automatic. The camera's software will choose a shutter speed (such as 1/125 second), and an aperture (such as f4.0) for you.

Av, or "aperture priority mode" allows you to set the aperture (f-stop, the size of the hole that lets light into your camera), and then the camera automatically chooses a shutter speed for you.

Sv, or "shutter priority mode" allows you to choose the shutter speed, and the camera will set the aperture.

For each of these settings, the EV adjustment will change how the camera chooses the value it chooses. A positive adjustment (+1, for instance) will cause the camera to choose a slower shutter speed (for example, 1/60 second instead of 1/125) or a larger aperture (for instance, f2.8 instead of f4.0 -- smaller numbers mean a larger aperture).. This lets more light in, and results in a brighter picture.

I'm suggesting that you don't use any of these automatic modes, and thus don't use the EV adjustment either, but rather use the M or manual mode, which requires you to set both the shutter speed and the aperture.

You're right that this would leave you with lots of potential combinations to check. I'd suggest that you start by setting your shutter speed to 1/125 second, and shoot with various apertures to find one that works. 1/125 second should be fast enough to get a sharp picture even if the book moves a bit while you're shooting it (the camera shouldn't move, because it's on a fixed mount). If you find a good combination, use it. If all of your pictures are still too dark, try setting the shutter speed to 1/60 and repeat the exercise. I'd be reluctant personally to go with a shutter speed any slower than 1/30 second. At that point, I'd look into adding more lights, but that shouldn't be necessary. I feel confident that if you're using two halogens, you'll be able to shoot at 1/125 second with an f-stop (aperture) that's smaller than the largest one available.

The reason smaller numbers mean larger apertures is because the aperture or f-stop is actually a ratio of the focal length of the lens to the size of the opening. You can think of it as the denominator of a fraction, so just as 1/60 second is "larger" than 1/125 second, f2.8 is "larger" than f4.0. Don't let it confuse you.

[you1]

Great info...
thank you.

[tsttm]

thanks for all the info. i'll play with various settings to see what works out best.

A couple things- having discussed all those settings, is it safe to say that it is less crucial finding the best looking settings if i plan to OCR all my scans? I'm just thinking that as long as things are in focus & the OCR is relatively good, it should be sufficient..right? Just curious, i'm new to OCR, so i don't know how good it is.

Also, what is the advantage of going with manual focus? Is it speed? Or is it to avoid focus problems with certain pages? because if it's speed, i'm wondering how much time you really save vs the risk of having a series of pages just slightly out of focus...My initial feeling is i'd rather trust the camera's autofocus.

Last thing- off topic, but i might as well ask: At the end of my project, i have a usb plug stump & an LED lightbulb leftover from my flashlight handle...can i create a usb powered light simply by soldering the +ve & -ve wires of usb to the lightbulb? (now that i've learned to solder...although i need a better iron...i want to see what else i can solder)

thanks!

[spamsickle]

If you plan to OCR all of your scans, a bit of grey in your pages shouldn't matter. The OCR output will still be black and white. If there's too much grey, though, the OCR software may interpret some of it as a picture rather than text, so it could potentially slow down your OCR processing.

I don't think I'll be OCR'ing many of my books any time soon. I still have hundreds of books to scan, and even the books which are "all text" take several hours for me to go through an OCR step. I just went through a very frustrating time with ABBYY on an old collection of Ralph Waldo Emerson essays. I had to go through and manually adjust the text blocks on several pages, and even after that was done, the fonts came out inconsistent. On some pages, several words were incorrectly recognized as BOLD type, and several whole pages were bolded. I started going through page by page and unbolding those that needed it, but after a couple of hours of that I decided I'd just leave it as is until and unless I can get a PDF editor like Foxit and unbold the whole document at once.

OCR does save a lot of disk space, but for me, time is much more valuable than disk space right now. Perhaps after I get everything scanned, I can go in and OCR them as I read them, but for now, image PDF files (up to a gigabyte per book) are readable and lightweight.

The advantage of manual focus is that it's always IN FOCUS. With autofocus, pages at the end of chapters, and title pages without much text, may not be in focus at all. Most times, autofocus needs something contrasty in the middle of the picture to work. But live and learn.

[tsttm]

Thanks for sharing. Can i ask you if you were using the pro version of abbyy? i heard really good things about abbyy, recognizing obscure technical stuff...but i haven't researched this myself, just reading from other experiences.

The main reason i'd like to OCR is to make the text searchable. I don't know how time consuming it'll be...i also don't want to spend too much time correcting it.

regarding manual focus, i guess it makes sense with the vst sliding & if the platen lowers at the same spot each time. i'll have to test it out myself to see, but it makes sense.

[spamsickle]

Yes, I'm using the pro version of Abbyy 9. It does a fine job of converting the text (not such a fine job on page numbers, but who cares, right?). And, to be fair, I'm a novice at Abbyy, so there may be ways of avoiding the problems I'm encountering. I'd originally thought searchable text would be a big deal too, and it is nice to have sometimes, but outside of history books I find I don't use it that much. In technical books (which is mostly what I have), the index is usually about as good as fully searchable text, at least for the kinds of things I've found myself seeking..

[you1]

In regards to speed, you may be able to save about half a second per page; which means about 8 minutes time savings for 1000 page book. Nice to have, not need to have.

ReFocus at the chapter ends (due to a lot of white-space) are a headache, that you can do with out.

... My initial feeling is i'd rather trust the camera's autofocus.

I don't know much about photography; thus, I also shared the same reservations regarding manual focus.
Which means, both of our gut feeling is wrong

I did an experiment and confirmed that manual focus is the way to go...
See my experiment here: http://www.diybookscanner.org/forum/viewtopic.php?f=1&t=55. See if you can tell if one page is out-of-focus compare to another one?

[adampadsadam]

tsttm that is a rad piece of equipment bro... well done!

[tsttm]

Well, i've given up on the camera arms. Not enough fine tune control & drifting was an issue. Plus the lack of side to side motion in the vertical plane was annoying.

I've switched to using a joby gorillapod i have (propped on a stool) with a 2nd joby i had planned to use as a gift (oh well). So far less frustrating in fine tuning...the only issue is i don't have much up & down options. I think ideally, two full size tripods would be nice (costly though).