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12-30-2007, 10:47 AM   #1
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Manual woes! Help needed please.

Hi everyone

Dealing with my M-50mm, i have noticed a couple of problems. Multi-segment-metering has disapeared from the options menu. And everytime i use the onboard flash its way too powerful.

Is there some way to overcome these drawbacks? Your help as always would be much appreciated.



Regards

Peter

12-30-2007, 11:36 AM   #2
axl
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As far as I know:
K100D / super with manual lenses, is unable to use multisegment metering. I think it has something to do with the fact that body can't get lens info. So it leaves you with centre and spot metering options. As for the flash. It should work in P-TTL way. That means preflash being metered by multisegment exposure reading and then setting correct strenght of main flash. Since using M lenses disables multisegment metering, it would make sense that camera just fires the flash on full, without any metering.
This is just my teory. Would be good if anybody could confirm or write other, more plausible, explanation...
regards
12-30-2007, 11:41 AM   #3
Ole
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axl is right on the mark.

Multi-segment metering is disabled with "M" and "K" lenses, and the flash alsways fires at full power.

For flash photography you will have to resort to guide number calculations and set the aperture manually as per your calculation. And the camera should be in M exposure mode.
12-30-2007, 12:09 PM   #4
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QuoteOriginally posted by axl Quote
As far as I know:
K100D / super with manual lenses, is unable to use multisegment metering. I think it has something to do with the fact that body can't get lens info. So it leaves you with centre and spot metering options.
this is correct. the lens needs to send apature data for multi segment metering,
QuoteQuote:
As for the flash. It should work in P-TTL way. That means preflash being metered by multisegment exposure reading and then setting correct strenght of main flash. Since using M lenses disables multisegment metering, it would make sense that camera just fires the flash on full, without any metering.
This is just my teory. Would be good if anybody could confirm or write other, more plausible, explanation...
regards
P-TTL flash does not work with M lenses because the preflash is done wide open, and the camera needs to be able to control apature electrically to stop it down to the correct place.

I have e-mailed pentax a proposal for this, essentually to tell the camera the max and min apature, then set to min apature and let the camera do the rest. It was on my list for santa's elves to work on, but so far the elves arn't listening to me

12-30-2007, 12:35 PM   #5
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Thanks everyone, but is it possible that the

onboard flash issue can be overcome by using an external flash. I mean a flash that can be operated by a technophobe, inumerate like myself?




Peter
12-30-2007, 01:31 PM   #6
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QuoteOriginally posted by Spooked Quote
onboard flash issue can be overcome by using an external flash. I mean a flash that can be operated by a technophobe, inumerate like myself?
Peter
Peter

the only way to use M series lenses (or older, i.e. k or M42) on a camera that supports only P-TTL is to do one of 2 things with an external flash/

1 - set the flash in manual and calculate the power using guide number, distance ISO and F stop, or

2 - get a flash with auto mode (i.e. its own build in sensor) and tell the flash the Fstop and ISO, and let it calculate exposure using its photosensor (ok for group shots but not good if you like spot metering)
12-30-2007, 01:58 PM   #7
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Hi Lowell

I have my eye on a second hand flash, AF201SA. I have searched everywhere for info regarding this module and find nothing that matches.

Do you know if this has auto mode?

Thanks for your input

Peter
12-30-2007, 04:15 PM   #8
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QuoteOriginally posted by Spooked Quote
Hi Lowell

I have my eye on a second hand flash, AF201SA. I have searched everywhere for info regarding this module and find nothing that matches.

Do you know if this has auto mode?

Thanks for your input

Peter
Peter

You can get the user's manual here

http://www.pentaximaging.com/files/manual/AF%20201Sa%20%20Flash.pdf

Looks like it works just fine in auto mode.

You may need to ask about flash trigger voltage. I didn't see it in the manual perhaps someone can answer.

12-31-2007, 12:49 AM   #9
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QuoteOriginally posted by Lowell Goudge Quote
this is correct. the lens needs to send apature data for multi segment metering,

P-TTL flash does not work with M lenses because the preflash is done wide open, and the camera needs to be able to control apature electrically to stop it down to the correct place.

I have e-mailed pentax a proposal for this, essentually to tell the camera the max and min apature, then set to min apature and let the camera do the rest. It was on my list for santa's elves to work on, but so far the elves arn't listening to me
And I'm bit wiser again.
Thanx for correcting me...

Shame the elves are not listening. I think sometimes they should hear what their user base says...
12-31-2007, 03:08 AM   #10
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Hi Lowell You have been a great help and i am now on my way to pick up the flash. Im not entirely sure what you meant by flash trigger voltage, but ill work it out with the seller.

Thanks again Lowell


Peter
12-31-2007, 04:26 AM   #11
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Flash trigger voltage refers to how much voltage the flash unit sends through the triggering circuitry inside your camera. In the old (pre-digital) days, it really didn't matter how high the trigger voltage was. With modern digital cameras using electronic circuits instead of electrical relays, it is possible for the flash to do serious damage to the camera. You really need to verify the flash trigger voltage for any old flash that you plan to use with a modern camera.

The time to learn about this, ask questions, and do the tests is BEFORE frying your camera.
12-31-2007, 04:33 AM   #12
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Thanks for the input mike, warning heeded!



Peter
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