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12-11-2008, 08:26 AM   #16
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I have to modify my previous statement : this will work only with m42 lenses and some PK-M lenses...

Richard64 : As stated by Lowell, the A pin is recessed, and thus is not shortened by the lens...

You have to cheat to ground it: I carefully applied solder on this A pin, without heating it (as it would certainly damage the mount), but you can do it in a less permanent way by adding some conductive adhesive or even an aluminium foil...

As for P-TTL and Matrix metering, I confirm that once the A pin is grounded, both are really working : the flash works properly (preflash and all) at any selected aperture, and wireless is again available!
It's a little bit more difficult to check the matrix metering function, but at least it's displayed in the review mode of my pics, instead of the CW metering icon...

Now, theorically, they both need additionnal information from the lens (focal length, etc) to perform fully, but I didn't find any flaw in the pics I took... After all, I'm not sure that all PKA lenses are fitted with the data pin to send these information to the body.

Now, regarding my comments about selecting the smallest aperture, it was not about flash anymore, but rather a general comment on how this mod will transform some PK-M lenses into PK-A.
I stress the "some" part of this statement! As Lowell already said, not all PK-M lenses (and, I guess, nearly none, in fact!) are capable of this.
As stated, PK-A lenses have a surface-related lever movement, and PK-M lenses usually have a diameter-related lever movement.

But I've found that some PK-M lenses have this capability... For instance, I have a gorgeous Porst 55mm f/1.2 that can be driven this way right up to f/11, then start overexposing as the lever won't close it enough anymore (I don't care, I'm in portraits anyway!)...
I think that only 3rd party lenses can be expected to work this way, as they usually were made to work with other mounts already working with surface-related coupling.

You just have to try (good thing is that with an aluminium foil, it's quite easy to do!)...


Last edited by dlacouture; 12-11-2008 at 08:35 AM.
12-11-2008, 11:23 AM   #17
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QuoteOriginally posted by Lowell Goudge Quote
I'm surprised you didn't select Auto mode on the AF540, it has it's own sensor, and all you have to do on the flash is set the F-stop you set thelens to, the camera sends the ISO, and you are all set.
Yes, I know now that I could have done this, but I had just gotten the flash, and I wasn't really familiar with how the Auto mode worked yet. I personally might still feel more comfortable using manual mode, though, since I am familiar with what to expect. I think, too, that this is useful to illustrate that it's quite possible to use any flash that is compatible with the camera, and has a manual mode available, with manual lenses.

People seem to expect manually setting flash power to be harder than it is. I think it's useful to at least try it a few times just as a learning experience. It can be really useful to be familiar with manual flash settings if you ever want to use a multiple off camera flash setup. Just be aware of your camera's high speed sync limitation*, don't exceed that shutter speed, and remember that aperture and flash power are the variables now since shutter speed won't affect exposure under these conditions (except at very slow shutter speeds).

*Of course, if you need higher speed sync for fill flash with your Pentax DSLR you can use a new Pentax flash with the special High Speed Sync mode which overcomes this limitation by using a longer flash burst.

Last edited by CFWhitman; 12-11-2008 at 02:10 PM.
12-12-2008, 03:09 AM   #18
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Well, I'm sorry, I leaved an important point out in my previous explanations : for some lenses among those compatible with this method but not truly PK-A (not surface-related), you'll have to select the same aperture on both the camera and the lens...

So, to summarize:
- M42 lenses are easy to use in PK-A mode : just select the widest aperture available on the body (usually, 1.2 if all contacts are grounded), and use your aperture ring as you want.
- fully PK-A compliant PK-M lenses (Lever drives the aperture surface) : put the lens on the smallest available aperture, and drive it from the body.
- partially PK-A compliant lenses (Lever drives neither the aperture surface nor its diameter, but it's still working with this mod) : set the same aperture on both the camera and the lens.
- others PK-M : nothing can be done here, except through a firmware upgrade.

Here is how I would like it to work with PK-M lenses:
- Av mode available with a PK-M lens.
- On start, you enter both the focal length and the widest aperture of the lens (I'll eventually accept having to manualy insulate some contacts on the lens).
- set the same aperture on lens and camera.
- lever fully moves (instead of the current PK-A movement)

And that's it... No need for fancy algorithm : just allow a "manual" Av mode with PK-M lenses...
12-12-2008, 05:25 AM   #19
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QuoteOriginally posted by Lowell Goudge Quote
no not all contacts touch the mount, the one that tells the camera that the lens is automatic apature (3rd from the locking pin) is recessed on the camera body, the pin must stick out from the lens this does not work,
Sure, I forgot to mention that, but I am guessing that the camera will detect that all the others are shorted.

QuoteQuote:
As a result the converted Non A lens got the exposure wrong at every setting varrying from -1.5 stops at max apature to +2 stops at min apature. In other words, it was almost useless.
That's my experience too, but it was worth a try

QuoteQuote:
If you are serious about flash work with non A lenses, as I said earlier, you have at this point 2 options, get an *istD (or DS but on the DS the internal flash is not TTL capable) or get an AF540 FGZ and use it in the Auto mode.
I use an AF280T, I have priorities other than a AF540 at the moment. The AF280T has two Auto settings (one for close, one for further away) and it works fine for me. But the point is that I still have to set the aperture the flash tells me to use, but the flash will shut off the light when it has illuminated the subject enough (according to its own sensor). Since the AF280T was very cheap it is a much better solution than adapting a lens.

The *istD is an interesting option. I'm guessing that the AF280T TTL setting will work? So what is it that I lose compared with my K100D (which is also a 6MP sensor)?

Richard

12-12-2008, 05:35 AM   #20
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QuoteOriginally posted by dlacouture Quote
You have to cheat to ground it: I carefully applied solder on this A pin, without heating it (as it would certainly damage the mount), but you can do it in a less permanent way by adding some conductive adhesive or even an aluminium foil...
Just to be clear here. You are talking about the A pin on the camera body.

In the past I have tried putting Al foil over the pins to get focus trap, but I have always found it unsatisfactory - the foil just tears. The thought of getting something - a piece of solder or Al foil - into the recess of the A pin on the body scares me. The last thing I would want is for it to get knocked off into the camera when removing the lens.

Richard
12-12-2008, 05:57 AM   #21
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Yes, on the camera body... I know, this is kind of extreme, but as this mod allows me to use P-TTL flash easily with all my m42 lenses (and my only PK-M lens too, lucky me!), I just made a quick prayer and joyfully applied the soldering iron to my 2-weeks-old brand new k10 (but I tried it on a MZ film body before!).

Well, I've also used some conductive adhesive in the past, with satisfying results (but take copper adhesive, not aluminium)...
12-12-2008, 06:00 AM   #22
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QuoteOriginally posted by richard64 Quote
In the past I have tried putting Al foil over the pins to get focus trap, but I have always found it unsatisfactory - the foil just tears.
I had the same thing on the K100D when trying to minimize the M42 metering problem. Using a double or triple thickness of foil makes a huge difference in the durability of the foil. I also used to use a very thin piece of foam sheet cut to fit over the pins and then wrapped in foil. That not only makes it more durable, it also makes it easier to remove the foil and reuse it several times over.
12-12-2008, 10:58 AM   #23
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QuoteOriginally posted by Mike Cash Quote
I had the same thing on the K100D when trying to minimize the M42 metering problem. Using a double or triple thickness of foil makes a huge difference in the durability of the foil. I also used to use a very thin piece of foam sheet cut to fit over the pins and then wrapped in foil. That not only makes it more durable, it also makes it easier to remove the foil and reuse it several times over.
Necessity is the mother of invention, as they say

I cut a small curved piece from an acetate sheet and then glued foil to it. It was a bit more durable and foil on its own, but only just a bit more. To be honest, I decided that I could live without it

Richard

12-13-2008, 09:57 AM   #24
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QuoteOriginally posted by dlacouture Quote
Well, I'm sorry, I leaved an important point out in my previous explanations : for some lenses among those compatible with this method but not truly PK-A (not surface-related), you'll have to select the same aperture on both the camera and the lens...

So, to summarize:
- M42 lenses are easy to use in PK-A mode : just select the widest aperture available on the body (usually, 1.2 if all contacts are grounded), and use your aperture ring as you want.
- fully PK-A compliant PK-M lenses (Lever drives the aperture surface) : put the lens on the smallest available aperture, and drive it from the body.
- partially PK-A compliant lenses (Lever drives neither the aperture surface nor its diameter, but it's still working with this mod) : set the same aperture on both the camera and the lens.
- others PK-M : nothing can be done here, except through a firmware upgrade.

Here is how I would like it to work with PK-M lenses:
- Av mode available with a PK-M lens.
- On start, you enter both the focal length and the widest aperture of the lens (I'll eventually accept having to manualy insulate some contacts on the lens).
- set the same aperture on lens and camera.
- lever fully moves (instead of the current PK-A movement)

And that's it... No need for fancy algorithm : just allow a "manual" Av mode with PK-M lenses...
dlacouture,

that's great news! That's about exactly what I was hoping for

If only one wouldn't have to solder or glue something to the camera ... This should be feasible in firmware after all. Pentax, how about giving us a little menu point to fake an A lens?

Thanks for all your great replies!
12-13-2008, 10:21 AM   #25
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QuoteOriginally posted by Noisychip Quote
...Pentax, how about giving us a little menu point to fake an A lens?...
Now THAT is an interesting idea, very interesting indeed!

Steve

(Noisychip should work in Pentax development...)
12-13-2008, 02:40 PM   #26
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QuoteOriginally posted by stevebrot Quote
Now THAT is an interesting idea, very interesting indeed!

Steve

(Noisychip should work in Pentax development...)
Thanks, Steve

Who knows, maybe there already is a hack via service menu to do so...? That'd be awesome! Has anybody been searching for this before?

PS: By the way, Pentax, while you're at it: Just throw in a hyperfocal distance display in the info screen, for the current aperture ....
PS II: Of course job offerings are always welcome ;o)
12-13-2008, 04:18 PM   #27
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QuoteOriginally posted by Mike Cash Quote
I had the same thing on the K100D when trying to minimize the M42 metering problem. Using a double or triple thickness of foil makes a huge difference in the durability of the foil. I also used to use a very thin piece of foam sheet cut to fit over the pins and then wrapped in foil. That not only makes it more durable, it also makes it easier to remove the foil and reuse it several times over.
If you have any anti-theft tags (the small white raised boxes with a barcode that frequently comes in or on plastic clamshell packaging), you can cut them open and pull out two very thin, flexible pieces of metal. They're much more durable than aluminum foil. make sure you cut off sharp corners though, as it can cut if you're not careful.
12-13-2008, 10:10 PM   #28
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QuoteOriginally posted by Mike Cash Quote
I had the same thing on the K100D when trying to minimize the M42 metering problem. Using a double or triple thickness of foil makes a huge difference in the durability of the foil. I also used to use a very thin piece of foam sheet cut to fit over the pins and then wrapped in foil. That not only makes it more durable, it also makes it easier to remove the foil and reuse it several times over.
Mike: Do you have any pics of the set up you described? I have been wanting to get better exposure metering with my K10D. Also, do I understand that if I make this adaptation that PTTL/ wireless would also work?

Thanks everyone for this informative thread!!
12-14-2008, 04:00 AM   #29
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QuoteOriginally posted by MSM Quote
Mike: Do you have any pics of the set up you described? I have been wanting to get better exposure metering with my K10D. Also, do I understand that if I make this adaptation that PTTL/ wireless would also work?

Thanks everyone for this informative thread!!
Yes, show us your hardware hacks!

I was just wondering about the following: If someone had a defective K-Mount camera that could donate a lens connection pin of the normal shape (not like the shorter A contact), it should theoretically be possible to replace the A pin on another camera!

Is anyone brave enough to do that??? Has anyone ever unscrewed the mount from his camera???

Guys, this is really getting interesting!
12-14-2008, 05:40 AM   #30
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No pics, sorry. Just tear a bit of foil, lay it across all the pins, hold it down with a bit of scotch tape on either end. This isn't some sort of high-precision irreversible surgery to your camera, fellas. It's just some taped-on aluminum foil.

I only used it to minimize the K100D's tendency to underexpose with M42 lenses. If it does anything other than that, I have no knowledge of it.
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