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01-25-2016, 10:30 AM   #16
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QuoteOriginally posted by monkeyboy Quote
found this post while researching my own 60-250 issue... and lo-behold, the same small tab was off kilter just a smidge. I pushed back with my finger just a bit and my problem went away (so far!).
Well, one of the tabs finally broke off for me which leaves the lense in a virtually unusable state...

Since it seems no one has been able to convert a 60-250 to screw drive only via:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/208353-how-...ml#post2202789

and not sure that would even work with the mising tab(?), it seems I have 2 options.... repair for ~$300 via Precision or buy a new one for ~$830. I would only consider a new one if I new that problem was addressed better in newer versions of the lens...???

01-25-2016, 10:49 AM   #17
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QuoteOriginally posted by monkeyboy Quote
Well, one of the tabs finally broke off for me which leaves the lense in a virtually unusable state...

Since it seems no one has been able to convert a 60-250 to screw drive only via:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/208353-how-...ml#post2202789

and not sure that would even work with the mising tab(?), it seems I have 2 options.... repair for ~$300 via Precision or buy a new one for ~$830. I would only consider a new one if I new that problem was addressed better in newer versions of the lens...???
If anyone can figure out how to convert the 60-250 to screw drive then you will not need the SDM contacts. I have a 60-250 and the hack to the lensrom that works with the other SDM lenses has a weird effect. It tries to use screw drive but reverts to SDM. Some have reported it seems to fight back and forth or even be focal length related. I don't have any ideas about what to try. All ideas welcome. My lens works fine so this is merely for future or for others benefit - if anyone has suggested modifications to the Lensrom file I will try them.
01-25-2016, 01:16 PM   #18
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try taping the contacts with a strip to isolte them - maybe that will work. It's just an idea.

Another Idea, change the code "C0" by "80" (like on the 50-135) and "E3" by "F1" - again - just an idea.
And save your Lensrom before doing that
01-25-2016, 01:30 PM   #19
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QuoteOriginally posted by Duc-Driver Quote
try taping the contacts with a strip to isolte them - maybe that will work. It's just an idea.

Another Idea, change the code "C0" by "80" (like on the 50-135) and "E3" by "F1" - again - just an idea.
And save your Lensrom before doing that
I have tried on my 60-250 to change the C0 to 80 in the 3rd column. I even tried changing every instance in the file (but that was just something to try I didn't expect it to work). What is the E3 to F1? That's the first I have heard of that. Which part of the file and why?

01-28-2016, 08:59 AM   #20
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sorry, make E3 to 80 won't work...i'll have a look in the lensrom next days.
But I think, it would be possible..the question is, how

edit. there is a "C0" in the 6th column. Maybe change that to "80" too

Last edited by Duc-Driver; 01-28-2016 at 09:09 AM.
01-28-2016, 12:01 PM   #21
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QuoteOriginally posted by Duc-Driver Quote
sorry, make E3 to 80 won't work...i'll have a look in the lensrom next days.
But I think, it would be possible..the question is, how

edit. there is a "C0" in the 6th column. Maybe change that to "80" too
In the file I have there are three C0's outside of "column 3". Changing those did not improve things.

I finally understand the "E3" comment. Each lens model seems to have a different code there (maybe not all of them are different but all that I have checked). Even the DA 55-300 has markers like that around the "80" codes. I don't know if changing them would be a smart idea without more clear info on what they control.

Just for grins I tried wiping the 0400 - end of file section to "FF" as some lenses are that way. (I knew this was unlikely to work) This coupled with changing C0 to 80 did not work. The lens was totally confused. It didn't report f/stop, no autofocus, etc. I restored my original file and all was well.
01-29-2016, 02:28 AM - 1 Like   #22
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Uncle, I'm rooting for you to figure out the 60-250. I'm almost ready to buy the lens (gray unit).

It's the fear of SDM failure that's keeping me from pulling the proverbial trigger.
01-29-2016, 06:50 AM   #23
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QuoteOriginally posted by drypenn Quote
Uncle, I'm rooting for you to figure out the 60-250. I'm almost ready to buy the lens (gray unit).

It's the fear of SDM failure that's keeping me from pulling the proverbial trigger.
I'm hoping others work on it too. My limited time for experimentation means we will all be old before I stumble into the solution.

02-01-2016, 09:53 AM   #24
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QuoteOriginally posted by drypenn Quote
Uncle, I'm rooting for you to figure out the 60-250. I'm almost ready to buy the lens (gray unit).

It's the fear of SDM failure that's keeping me from pulling the proverbial trigger.
Same here, unless Uncle can help us, I would not take a chance on buying this lens. Such a shame for these SDM's to fail.
02-01-2016, 10:15 AM   #25
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QuoteOriginally posted by csa Quote
Same here, unless Uncle can help us, I would not take a chance on buying this lens. Such a shame for these SDM's to fail.
Yikes! I'm not Obi Wan. We need more great minds on this than me.
02-01-2016, 10:26 AM   #26
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05-03-2016, 10:10 PM   #27
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QuoteOriginally posted by UncleVanya Quote
In the file I have there are three C0's outside of "column 3". Changing those did not improve things.
In column 03 of rows
0X20, 0X60, 0XA0, 0XE0 (where X ranges from 0..7)
did you find 32 "C0" and did you convert all of them to "80"?

I'd be curious to learn if you encountered any other value in the above specified positions.

You'll notice that there is an "E3" in the row above each "C0" in column 03.
Try changing all 32 occurrences of "E3" in column 03 to "A3".
This is suggestion #1.

My thinking is that bit #6 (with value 64) of certain values represents the SDM capability.
The values (like "C0") appear so often, because the EEPROM is indexed with focal length and subject distance. For all combinations of focal length and subject distance (given a certain resolution, e.g., 12mm for the focal length), there is a dedicated entry in the EEPROM.

Given the above, I found other candidates for changing values. All the below should always include the changing of all "C0" in column 03 to 80. Here are the further suggestions:

#2: All occurrences of "E3" in column 02 to "A3".
#3: All occurrences of "FB" in column 0F to "BB".

While I have learned a bit about the structure of the EEPROM data from some detective work performed by someone else (in German) and also looked at the related Pentax patent, I make no guarantees. Please attempt any experiment at your own peril. I guess the worst thing that could happen is that the SDM motor and the screw drive motor engage alternatively in quick succession (in terms of the logic they cannot engage at the same time), but it seems you have encountered that case already and it did not cause further harm. Still, I'm making only educated guesses with my suggestions. Things would be a lot easier if the findings of the above referenced detective work matched the format the patent describes, but that's unfortunately not quite the case.

I'd be interested in hearing from you, in case you want to try the above.

Would you be able to share your lens eeprom file?
If found one online and might learn more by looking at another one.

BTW, I don't own a 60-250/4 and most likely never will. I'm just curious and think there ought to be a solution. It is possible, though, that Pentax did something non-standard with the 60-250 and hard-coded its SDM capability into the firmware of respective SDM-capable bodies (relying on the standard approach for some cases and on hard-coding for others).
05-03-2016, 11:34 PM   #28
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You have a ROM file?

QuoteOriginally posted by Class A Quote
In column 03 of rows
0X20, 0X60, 0XA0, 0XE0 (where X ranges from 0..7)
did you find 32 "C0" and did you convert all of them to "80"?

I'd be curious to learn if you encountered any other value in the above specified positions.

You'll notice that there is an "E3" in the row above each "C0" in column 03.
Try changing all 32 occurrences of "E3" in column 03 to "A3".
This is suggestion #1.

My thinking is that bit #6 (with value 64) of certain values represents the SDM capability.
The values (like "C0") appear so often, because the EEPROM is indexed with focal length and subject distance. For all combinations of focal length and subject distance (given a certain resolution, e.g., 12mm for the focal length), there is a dedicated entry in the EEPROM.

Given the above, I found other candidates for changing values. All the below should always include the changing of all "C0" in column 03 to 80. Here are the further suggestions:

#2: All occurrences of "E3" in column 02 to "A3".
#3: All occurrences of "FB" in column 0F to "BB".

While I have learned a bit about the structure of the EEPROM data from some detective work performed by someone else (in German) and also looked at the related Pentax patent, I make no guarantees. Please attempt any experiment at your own peril. I guess the worst thing that could happen is that the SDM motor and the screw drive motor engage alternatively in quick succession (in terms of the logic they cannot engage at the same time), but it seems you have encountered that case already and it did not cause further harm. Still, I'm making only educated guesses with my suggestions. Things would be a lot easier if the findings of the above referenced detective work matched the format the patent describes, but that's unfortunately not quite the case.

I'd be interested in hearing from you, in case you want to try the above.

Would you be able to share your lens eeprom file?
If found one online and might learn more by looking at another one.

BTW, I don't own a 60-250/4 and most likely never will. I'm just curious and think there ought to be a solution. It is possible, though, that Pentax did something non-standard with the 60-250 and hard-coded its SDM capability into the firmware of respective SDM-capable bodies (relying on the standard approach for some cases and on hard-coding for others).
Did you say you had a ROM file? If so, would you mind sharing it? I would like to take a look at it.
05-04-2016, 06:28 AM   #29
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I can post my unmodified rom file later today. I can also try some of these ideas.

As for converting C0 instances, I tried converting all but that did not help.
05-04-2016, 10:37 AM   #30
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Sweet

QuoteOriginally posted by UncleVanya Quote
I can post my unmodified rom file later today. I can also try some of these ideas.

As for converting C0 instances, I tried converting all but that did not help.
That would be great. Class A, are you able to share the one you have as well?
I'm thinking having 3 would be nice, if anyone with an able body (camera) and lense can dump theirs as well, that would be awesome!
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