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Lens unit replacement

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Offline fabri22

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Lens unit replacement
« on: 30 / November / 2014, 06:53:29 »
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Not sure this is the right section for asking.
On next week i've planned to replace the broken lens unit in a ixus115 (bought on ebay for few bucks) with a new one.
I've already got (from ebay too) the new lens assembly (sensor included) and it looks to me genuine and unused.
The replacing part of "work" doesn't seem too difficult, but i've serious doubts on the adjustment part that is necessary after the replacement of the optical unit (according to service manuals floating around the web like the one for DIGITAL IXUS 75/70).
So, here my question(s)

-any similar diy experience?
-is there any info about the various adjustment data that are stored in the camera and a "way" to manipulate them?


If the ixus115 "lens replaced" will not work (possibly wrong focusing is my concern) i'll try to use it as prime-focus camera on my old vixen viper telescope by completly removing its optics.
-any similar diy experience for this alternative?

Thanks in advance to all of you
« Last Edit: 30 / November / 2014, 09:12:35 by fabri22 »
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Offline stagdriver

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Re: Lens unit replacement
« Reply #1 on: 30 / November / 2014, 15:54:26 »
Not sure if this IXUS is special, but I have replaced the entire lens units on  many A1200, A1300, A2300, A2400 and A4000 and IXUS 105. Additionally I have often made one good camera from the  parts of several broken cameras by swapping out and matching up the parts (not always from the same model of camera). I have found the parts of several models interchange quite readily, and to date I have been quite pleased with the results and at no time have I felt that any adjustments were required as the resulting picture quality has always been as expected.
As regards the focussing, I have found that the focus override / subject distance varies from camera to camera (even new un-molested ones). To produce relevant Subject distance figures I simply produce a plank of wood with paper stickers at 25mm intervals to produce a chart of values that relate to focussed images at the 25mm intervals. Generally I have found that once the distance exceeds 500mm  its pretty accurate. Its the smaller distances that need the attention. every camera I own except the older models such as a530 are all inaccurate regarding subject distance so I produce a true subject distance chart for each. I recently purchased 2 A4000's both new and both are different, but produce identical pictures once used with the true subject distance from my charts.
Hope this is of some use in answering your question.
regards
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Offline ahull

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Re: Lens unit replacement
« Reply #2 on: 30 / November / 2014, 17:51:22 »
Quote from: fabri22 on 30 / November / 2014, 06:53:29
Not sure this is the right section for asking.
On next week i've planned to replace the broken lens unit in a ixus115 (bought on ebay for few bucks) with a new one.
I've already got (from ebay too) the new lens assembly (sensor included) and it looks to me genuine and unused.
The replacing part of "work" doesn't seem too difficult, but i've serious doubts on the adjustment part that is necessary after the replacement of the optical unit (according to service manuals floating around the web like the one for DIGITAL IXUS 75/70).
So, here my question(s)

-any similar diy experience?
-is there any info about the various adjustment data that are stored in the camera and a "way" to manipulate them?

I have replaced a few lens units, and they worked without adjustment. There are functions in the firmware that relate to adjustment, but to my knowledge there has been little or no work to figure out what they do.

Quote

If the ixus115 "lens replaced" will not work (possibly wrong focusing is my concern) i'll try to use it as prime-focus camera on my old vixen viper telescope by completly removing its optics.
-any similar diy experience for this alternative?

Thanks in advance to all of you

Removing the lens completely is not a simple as it sounds. Take a look through this thread for more info.
http://chdk.setepontos.com/index.php?topic=8801.0
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Offline fabri22

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Re: Lens unit replacement
« Reply #3 on: 01 / December / 2014, 11:23:55 »
Quote from: stagdriver on 30 / November / 2014, 15:54:26
...I have been quite pleased with the results and at no time have I felt that any adjustments were required as the resulting picture quality has always been as expected...

Quote from: ahull on 30 / November / 2014, 17:51:22
I have replaced a few lens units, and they worked without adjustment. There are functions in the firmware that relate to adjustment, but to my knowledge there has been little or no work to figure out what they do.

Thanks for encouraging posts stagdiver and ahull.

Quote from: stagdriver on 30 / November / 2014, 15:54:26
As regards the focussing ...
The focusing part seems to me the Achilles heel of the amazing CHDK ... sometimes.

@ ahull
did that damaged camera end up on the top of your old Olympus monocular microscope? Without optics?
That SticK's sci-fi thread/work is really terrific! ... and demoralizing for low level brains
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Offline ahull

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Re: Lens unit replacement
« Reply #4 on: 01 / December / 2014, 11:33:48 »
Quote from: fabri22 on 01 / December / 2014, 11:23:55
@ ahull
did that damaged camera end up on the top of your old Olympus monocular microscope? Without optics?
Nope, I made myself a camera mount out of plumbing fixtures and used an A560. The damaged camera is still in the parts bin. I fixed a few others however, by changing lens units, including an Ixus 115. 
Subsequently I obtained a couple of other microscopes, so I may re-visit the idea.
« Last Edit: 01 / December / 2014, 11:35:22 by ahull »
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Offline fabri22

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Re: Lens unit replacement
« Reply #5 on: 07 / December / 2014, 09:16:24 »
Well, despite stagdiver and ahull reports, the lens unit replacement on the ixus 117 was a failure.
The camera had noticeable back-focus issues, more evdent when lens on tele.
By screwing in the sensor screws to reduce the gap among sensor plane and lens plane helped a bit with wide angle focusing.
Surely the chinese on ebay sold to me a bad copy, a "myopic" lens unit, as far i can understand the final results.
Tinkering with a useless ixus 117 i decided to transform its defect into a quality and did an infrared camera conversion. Infrared focus point is beyond the sensor plane so that was what i needed.
Then i replaced the hot mirror filter with a small piece of unexposed developed slide film as IR pass filter.
CHDK still helps a lot for RAWs (for optimal development of IR shots), setting focus to infinity (that gives now a perfect far focusing), etc. 
Also i tryed to take some shots without any hot filter or black slide ahead of the sensor and a true 720nm IR filter hand-helded in front of the lens.
There were not noticeable differencies with the other method (other than the annoying filter holding) so i went for the cheap internal black slide film.
I've to learn more about WB, color swapping and false colors in IR photography ...    it's never too late :)
Below my first IR shoot from balcony at home with the revived cheap IR converted ixus 117.




;)
« Last Edit: 07 / December / 2014, 09:20:21 by fabri22 »
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Offline waterwingz

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Re: Lens unit replacement
« Reply #6 on: 07 / December / 2014, 10:22:14 »
Quote from: fabri22 on 07 / December / 2014, 09:16:24
Surely the chinese on ebay sold to me a bad copy, a "myopic" lens unit, as far i can understand the final results.
Is there some other calibration / mounting adjustment you missed?  I think you posted somewhere that adjusting the sensor screws only moved the sensor less than 1mm yet it improved the focus at wide angle.   Seems like a small shim or other mounting adjustment might be enough to get the tele position into focus too?  Hard to predict when I can't actually see the camera of course.

Nice IR effect - how do others get focus to work when they do such converstion I wonder?  Not everyone starts with a "broken focus" camera.
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Offline ahull

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Re: Lens unit replacement
« Reply #7 on: 07 / December / 2014, 10:45:35 »
I'm impressed with the IR results. I have a beaten up ixus 80 that I was going to do the same thing with, but never quite managed to find the time for. This might spur me in to action.

By the way, there seems to be quite a cottage industry in IR converting second hand cameras. I just took a quick look on ebay, they seem to go for pretty hefty prices too. http://www.ebay.co.uk/bhp/infrared-converted-camera

As to the Chinese lens, I suspect these are recovered from scrap cameras, so there is always a risk that there might be alignment issues or other problems. On the very rare occasions that I have ever had any issues with a Chinese ebay sellers, they are usually quite helpful, so they might have been willing to swap the defective unit, or even replace it for free.

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