A couple of quests IYDM

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CCDeye
Posts: 17
Joined: 20 Apr 2011, 12:28

A couple of quests IYDM

Post by CCDeye »

Hello,
Recently I fell into a situation that I needed to build a custom book scanner to scan a bunch of books. Unfortunately I first bought a camera and then found this site, CHDK and other useful information. So my camera is Canon PowerShot A490. Very nice camera for the money, but no CHDK support for it so far. As my explanation implies, I use only one camera. My books are rather small - both pages spread are under A4 in size. As a power source, I use a PC power supply to power the camera. It seems to work pretty well even on 5 Volts, despite of the fact that it accepts 3V. Actually it was quite picky to the power supply. It didn't like most of the cheap 3V wall warts, probably because of the low amperage or due to pulsations etc.
As you may already suspect I have a couple of questions.

0.Is it a really bad idea to power the camera wich needs 3V with 5V ? Should I use a voltage regulator like LM340, etc
1.I plan to automate most of the work needed to scan the books. Should I go with a different Canon model. A model that support CHDK, is cheap enough and could be found easily on stores. Wich model do you reccomend ?
2. I really need a very short shot-to-shot time. Right now, the slowest unit of the scanninjg process is the camera itself. I can turn pages and click the shot trigger button real fast, but the camera needs some time to focus, to take the picture, to code it and to write it on the memory card. Should I buy a DSLR camera in order to obtain much more shoot speed ?
Can I make my camera Canon A490 faster using some custom settings, smaller resolution, faster memory card, manual focus, etc ? Can CHDK custom settings provide more speed to a camera shooting times ?
3.Can I skip the memory card writes using CHDK and sending the images directly to the PC via USB, etc. Is it going to be slow ? Is a "Frewire 1394" interface unstead of USB goind to solve the speed issues with the data transfer to the PC in real time ?
4. I intend to automate most of the work, so I plan to implement some kind of page turning system. My platen is flat, I use one camera mounted above the book, someting like a standart copy machine with transparent cover to pressurize the book pages. I need a system, (mechanical, pneumatic, eletrostatic etc) to turn the next page when I lift the cover. Can you give me some Ideas ?
5. How many pictures a compact camera like Canon A4XX could take in a life time ? Is there internal moving parts that get wear out ? I can hear servo motors, shutter clicks etc. How about the memory card writes...

Thank you in advance.
spamsickle
Posts: 596
Joined: 06 Jun 2009, 23:57

Re: A couple of quests IYDM

Post by spamsickle »

2. You should avoid auto-focus. Use manual focus or focus-lock instead.
5. I don't know. I've worn out two shutters on my cameras; they cost $130 each to replace.
CCDeye
Posts: 17
Joined: 20 Apr 2011, 12:28

Re: A couple of quests IYDM

Post by CCDeye »

spamsickle wrote:2. You should avoid auto-focus. Use manual focus or focus-lock instead.
5. I don't know. I've worn out two shutters on my cameras; they cost $130 each to replace.
Thanks.
I don't think my Canon A490 has auto or focus lock unfortunately.
$130 for shutter replace seems too much to me, especially if we are talking about cheap compact camera like mine. What was your camera and how many pictures did you take with it to wear out the shutter ?

Thank you.
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Gerard
Posts: 154
Joined: 17 Oct 2010, 07:15
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Location: Berlin (Germany)

Re: A couple of quests IYDM

Post by Gerard »

CCDeye wrote: 0.Is it a really bad idea to power the camera wich needs 3V with 5V ? Should I use a voltage regulator like LM340, etc
i've bought some cheep power supplies, like the original ack800 from canon but one of it produce noise in the images, maybe a cheep circuit with LM340 would also produce noise
why do you don't use the 3.3V part of the atx power supply?
CCDeye wrote: 1.I plan to automate most of the work needed to scan the books. Should I go with a different Canon model. A model that support CHDK, is cheap enough and could be found easily on stores. Wich model do you reccomend ?
a495 :)
CCDeye wrote: 2. I really need a very short shot-to-shot time. Right now, the slowest unit of the scanninjg process is the camera itself. I can turn pages and click the shot trigger button real fast, but the camera needs some time to focus, to take the picture, to code it and to write it on the memory card. Should I buy a DSLR camera in order to obtain much more shoot speed ?
Can I make my camera Canon A490 faster using some custom settings, smaller resolution, faster memory card, manual focus, etc ? Can CHDK custom settings provide more speed to a camera shooting times ?
focus lock is possible with the a490 see the manual, this helps a lot but be aware of the distance change while you scan the book
you can also play with the settings (turn review off) and flash also


CCDeye wrote: 3.Can I skip the memory card writes using CHDK and sending the images directly to the PC via USB, etc. Is it going to be slow ? Is a "Frewire 1394" interface unstead of USB goind to solve the speed issues with the data transfer to the PC in real time ?
you have to look for ptp remote capture, but i read that it is slow

CCDeye wrote: 4. I intend to automate most of the work, so I plan to implement some kind of page turning system. My platen is flat, I use one camera mounted above the book, someting like a standart copy machine with transparent cover to pressurize the book pages. I need a system, (mechanical, pneumatic, eletrostatic etc) to turn the next page when I lift the cover. Can you give me some Ideas ?
hire someone, a student or someone else (for page turning), it depends on the amount of books you wont to scan, but the money for the parts and the time you need to invest in developing (currently we have only small prof of concepts) and build the machine is a high investment

CCDeye wrote: 5. How many pictures a compact camera like Canon A4XX could take in a life time ? Is there internal moving parts that get wear out ? I can hear servo motors, shutter clicks etc. How about the memory card writes...
ask in the chdk board, they using the cheep a4XX for time laps
CCDeye
Posts: 17
Joined: 20 Apr 2011, 12:28

Re: A couple of quests IYDM

Post by CCDeye »

First of all, thank you for the reply
Gerard wrote: i've bought some cheep power supplies, like the original ack800 from canon but one of it produce noise in the images, maybe a cheep circuit with LM340 would also produce noise
why do you don't use the 3.3V part of the atx power supply?
OMG, I completely forgot about ATX providing 3.3V. I was using an old AT power supply and there is only 5V and 12V. Thank you.
Gerard wrote: a495 :)
Yep, since I bought the A490 recently from a local store, today I went and ask them if they are going to change it for a A495 or something more expensive. They said "probably", but first bring the camera and all the stuff in box and bring some extra money :) I'm afraid to tell them that I need a camera that supports CHDK and I intend to use it really extensively and take several thousands pictures per day. They may say - Oh noes mister, warranty won't cover that ! :mrgreen:
Gerard wrote: focus lock is possible with the a490 see the manual, this helps a lot but be aware of the distance change while you scan the book
you can also play with the settings (turn review off) and flash also
Thanks, I overlooked 'focus lock' option obviously. The review and flash are off.
gnosis

Re: A couple of quests IYDM

Post by gnosis »

I read somewhere from a post from Canon that CHDK does not void the warranty as it does not modify anything in the camera itself.
CCDeye
Posts: 17
Joined: 20 Apr 2011, 12:28

Re: A couple of quests IYDM

Post by CCDeye »

Well, if I made a product and want it to be popular, I will make it mode-able I guess.
I'm not implying that Canon stays behind the CHDK development, but it could be a nice conspiracy theory :)
Anyway, I got a A495 today, but forgot to buy a card reader. Canon makes it impossible(PTP ?) to use an USB cable to transfer files on the card via WinExplorer or even Canon's ZoomBrowser. so I can't test the CHDK yet and write some scripts. :)
pav
Posts: 25
Joined: 05 Mar 2011, 17:41

Re: A couple of quests IYDM

Post by pav »

Hi,
I wonder if anybody else could share their experience re: the number of pictures cameras can take before dying.
(The question has been asked before but not answered comprehensively ;-) )
[Spamsickle]
[...]I don't know. I've worn out two shutters on my cameras; they cost $130 each to replace.
[...]
Does wear of a shutter (or other parts) have implications in terms of running costs of a scanner?
e.g. is it not particularily wise to buy a second hand camera vs. a new one?
Does it depend on a type of a camera?

Any insight much appreciated (+ I love this forum)
pav
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