Exposure using flash on K200D with M lens

Takumar55 · 08-18-2013, 04:33 PM

Hoping someone can help with my exposure metering problems on my K200D with M lens, using the built-in flash. When I am in low light indoors, when I use the flash with a large aperture, I often get completely blown out photos.

Without flash, I am following Adam's procedure here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html
So I set the camera on M, set the aperture manually using the aperture ring on the lens, press the green button to meter, and then take the picture. This seems to work fine.

With flash, using the same procedure, I get completely blown out photos at large apertures. It is as if the camera does not set the shutter speed properly with the flash. There must be some setting I am missing.. Looking at the manual, there is a sentence that reads "the built-in flash fully discharges for lenses without a function to set aperture lens ring to A". This sounds like it addresses my situation, but it also implies that the flash can "partially" discharge? So related question is - does the flash vary in intensity depending on exposure needs? And then does this mean that you basically cannot use the flash with M lenses? Or that there is a set aperture or shutter speed that syncs with the flash?

Last edited by Takumar55; 08-18-2013 at 04:46 PM. Reason: typos

Adam · 08-18-2013, 04:52 PM

When using a flash, the aperture is what primarily controls the exposure. Most older flashes have a table on the back that tells you what aperture to use at what distance/intensity combination. If your flash doesn't have such a table, then a bit of trial-and-error will be required, so go ahead and lock set your shutter speed to the flash sync speed and test a variety of aperture settings.

There is no automation whatsoever when using flashes with M and K lenses on modern Pentax DSLRs, as they use P-TTL (calculated) and not TTL (real-time) flash metering. The only DSLRs that do support TTL flashes are the *ist D, DS, and DS2.

**maxfield_photo** · 08-18-2013, 05:04 PM

Do you have your camera set to "allow" the use of the aperture ring? If the flash can't read the aperture I believe it will always fire at full power in pTTL mode.

There is a pretty simple hack for the K-mount that involves unscrewing the ring and shorting the "A" pin with some tin foil. Once you've done that, the camera will think every lens you mount has an "A" position on the aperture ring, and all you have to do is dial in the aperture on the camera to match your lens.

Oh, and don't use Auto ISO

Takumar55 · 08-18-2013, 05:42 PM

Originally posted by Adam

When using a flash, the aperture is what primarily controls the exposure. Most older flashes have a table on the back that tells you what aperture to use at what distance/intensity combination. If your flash doesn't have such a table, then a bit of trial-and-error will be required, so go ahead and lock set your shutter speed to the flash sync speed and test a variety of aperture settings.

There is no automation whatsoever when using flashes with M and K lenses on modern Pentax DSLRs, as they use P-TTL (calculated) and not TTL (real-time) flash metering. The only DSLRs that do support TTL flashes are the *ist D, DS, and DS2.

Forget to mention I'm using the built-in flash.

But it sounds like I need to figure out which aperture and shutter combinations work with the built-in flash, and then set them accordingly?

Takumar55 · 08-18-2013, 05:46 PM

Originally posted by maxfield_photo

Do you have your camera set to "allow" the use of the aperture ring? If the flash can't read the aperture I believe it will always fire at full power in pTTL mode.

There is a pretty simple hack for the K-mount that involves unscrewing the ring and shorting the "A" pin with some tin foil. Once you've done that, the camera will think every lens you mount has an "A" position on the aperture ring, and all you have to do is dial in the aperture on the camera to match your lens.

Oh, and don't use Auto ISO

It's an M lens, so I don't think I can use the "allow" feature. But what you say here matches with what the manual says - the wording there is just a little ambiguous.

Thanks for the shorting tip. I've seen it mentioned, but never thought about what it meant.

No Auto ISO - using Manual mode on the camera.

**RKKS08** · 08-18-2013, 05:49 PM

The built-in flash of the K200D is specified with GN (maximum Guide Number) of 13 for ISO 100 and metric system.
As the built-in flash cannot change the area its light covers, GN13 is independend from lens focus length.
If the flash always uses its full capacity, you get the correct aperture by deviding the GN by the object distance in meters (for ISO 100).

So, for a distance of 4 meters the aperture at ISO 100 would be 13/4 --> F3.25. Set aperture to one of the nearest half aperture stops, F2.8 or F3.5 (depending on subject).
If you are too far away to get a valid aperture (aperture value gets too small for this lens), adjust ISO instead.

**seventhdr** · 08-18-2013, 05:50 PM

Originally posted by Takumar55

Hoping someone can help with my exposure metering problems on my K200D with M lens, using the built-in flash. When I am in low light indoors, when I use the flash with a large aperture, I often get completely blown out photos.

Without flash, I am following Adam's procedure here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html
So I set the camera on M, set the aperture manually using the aperture ring on the lens, press the green button to meter, and then take the picture. This seems to work fine.

With flash, using the same procedure, I get completely blown out photos at large apertures. It is as if the camera does not set the shutter speed properly with the flash. There must be some setting I am missing.. Looking at the manual, there is a sentence that reads "the built-in flash fully discharges for lenses without a function to set aperture lens ring to A". This sounds like it addresses my situation, but it also implies that the flash can "partially" discharge? So related question is - does the flash vary in intensity depending on exposure needs? And then does this mean that you basically cannot use the flash with M lenses? Or that there is a set aperture or shutter speed that syncs with the flash?

You're correct. If you use a K or M lens (any lens that does not have an A setting), the built-in flash which is P-TTL on a K200D will fire at FULL power.

Your options are, unless you want to modify a lens, to use A series or newer lenses (A, F, FA, FA J, or any DA seriees lens) preferably with the aperture on the lens set to A, or use an external flash that allows you to control the flash power (either a flash with its own light sensor (Auto flash) or a flash with manual controls (Manual flash)).

Regards

Chris

**seventhdr** · 08-18-2013, 05:52 PM

Originally posted by Takumar55

Hoping someone can help with my exposure metering problems on my K200D with M lens, using the built-in flash. When I am in low light indoors, when I use the flash with a large aperture, I often get completely blown out photos.

Without flash, I am following Adam's procedure here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html
So I set the camera on M, set the aperture manually using the aperture ring on the lens, press the green button to meter, and then take the picture. This seems to work fine.

With flash, using the same procedure, I get completely blown out photos at large apertures. It is as if the camera does not set the shutter speed properly with the flash. There must be some setting I am missing.. Looking at the manual, there is a sentence that reads "the built-in flash fully discharges for lenses without a function to set aperture lens ring to A". This sounds like it addresses my situation, but it also implies that the flash can "partially" discharge? So related question is - does the flash vary in intensity depending on exposure needs? And then does this mean that you basically cannot use the flash with M lenses? Or that there is a set aperture or shutter speed that syncs with the flash?

You're correct. If you use a K or M lens (any lens that does not have an A setting), the built-in flash which is P-TTL on a K200D will fire at FULL power.

Your options are, unless you want to modify a lens, to use A series or newer lenses (A, F, FA, FA J, or any DA seriees lens) preferably with the aperture on the lens set to A, or use an external flash that allows you to control the flash power (either a flash with its own light sensor (Auto flash) or a flash with manual controls (Manual flash)).

Regards

Chris

Takumar55 · 08-18-2013, 05:57 PM

Thanks for the responses! I just tried the same shots using my A lens, and it works fine. So everything's exactly as you've all described here. I'll have to be cognizant of what I can and can't do with the M lens. Good to know it's just my lack of knowledge here and nothing worse.

Takumar55 · 08-18-2013, 06:01 PM

Originally posted by RKKS08

The built-in flash of the K200D is specified with GN (maximum Guide Number) of 13 for ISO 100 and metric system.
As the built-in flash cannot change the area its light covers, GN13 is independend from lens focus length.
If the flash always uses its full capacity, you get the correct aperture by deviding the GN by the object distance in meters (for ISO 100).

So, for a distance of 4 meters the aperture at ISO 100 would be 13/4 --> F3.25. Set aperture to one of the nearest half aperture stops, F2.8 or F3.5 (depending on subject).
If you are too far away to get a valid aperture (aperture value gets too small for this lens), adjust ISO instead.

...and this rough calculation worked on the M lens!

**RKKS08** · 08-18-2013, 06:18 PM

Quote:

...and this rough calculation worked on the M lens!

This was the ONLY way you could use flash before the age of (affordable) thyristor flashes began, I think about 1970.

And it is still the recommended technique if you use flash at night outside for photographing people.
This is one of the situations where TTL and xyz-TTL have their limits - totally black background and blown out faces. Contrast measurement of pTTL improves it a bit, but most times old school manual calculation gives much better results.

Takumar55 · 08-18-2013, 06:36 PM

Is there a recommended shutter speed? I remember 60 or 90 being the "flash" speed. In my previous picture, I had the shutter at 90.

Edit: Ah, I see. 180 is max with built-in flash

Not a Number · 08-18-2013, 06:45 PM

You could always create a spreadsheet and make a cheat sheet using the formula f-stop = Guide Number / Distance. You can guesstimate the distance off the scale on the lens focusing ring. It would be like to good old days of using flash bulbs.

**RKKS08** · 08-18-2013, 06:51 PM

Originally posted by Takumar55

Is there a recommended shutter speed? I remember 60 or 90 being the "flash" speed. In my previous picture, I had the shutter at 90. Edit: Ah, I see. 180 is max with built-in flash

If you want to include existing ambient/natural light to mix with the flash light, you may want to use a longer exposure time. You probably must close the aperture a bit more than the calculation recommends, but how much is more a result of experience than precise measurement/calculation.

08-18-2013, 04:33 PM	#1
Takumar55 Senior Member Join Date: Jun 2013 Posts: 120	Exposure using flash on K200D with M lens Hoping someone can help with my exposure metering problems on my K200D with M lens, using the built-in flash. When I am in low light indoors, when I use the flash with a large aperture, I often get completely blown out photos. Without flash, I am following Adam's procedure here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html So I set the camera on M, set the aperture manually using the aperture ring on the lens, press the green button to meter, and then take the picture. This seems to work fine. With flash, using the same procedure, I get completely blown out photos at large apertures. It is as if the camera does not set the shutter speed properly with the flash. There must be some setting I am missing.. Looking at the manual, there is a sentence that reads "the built-in flash fully discharges for lenses without a function to set aperture lens ring to A". This sounds like it addresses my situation, but it also implies that the flash can "partially" discharge? So related question is - does the flash vary in intensity depending on exposure needs? And then does this mean that you basically cannot use the flash with M lenses? Or that there is a set aperture or shutter speed that syncs with the flash? Last edited by Takumar55; 08-18-2013 at 04:46 PM. Reason: typos

08-18-2013, 04:52 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	When using a flash, the aperture is what primarily controls the exposure. Most older flashes have a table on the back that tells you what aperture to use at what distance/intensity combination. If your flash doesn't have such a table, then a bit of trial-and-error will be required, so go ahead and lock set your shutter speed to the flash sync speed and test a variety of aperture settings. There is no automation whatsoever when using flashes with M and K lenses on modern Pentax DSLRs, as they use P-TTL (calculated) and not TTL (real-time) flash metering. The only DSLRs that do support TTL flashes are the ist D, DS, and DS2. Adam* PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

08-18-2013, 05:49 PM	#6
RKKS08 Site Supporter Join Date: Mar 2010 Location: Frankfurt am Main Posts: 1,241	The built-in flash of the K200D is specified with GN (maximum Guide Number) of 13 for ISO 100 and metric system. As the built-in flash cannot change the area its light covers, GN13 is independend from lens focus length. If the flash always uses its full capacity, you get the correct aperture by deviding the GN by the object distance in meters (for ISO 100). So, for a distance of 4 meters the aperture at ISO 100 would be 13/4 --> F3.25. Set aperture to one of the nearest half aperture stops, F2.8 or F3.5 (depending on subject). If you are too far away to get a valid aperture (aperture value gets too small for this lens), adjust ISO instead. Last edited by RKKS08; 08-18-2013 at 05:58 PM. Reason: cosmetic

08-18-2013, 06:36 PM	#12
Takumar55 Senior Member Join Date: Jun 2013 Posts: 120 Original Poster	Is there a recommended shutter speed? I remember 60 or 90 being the "flash" speed. In my previous picture, I had the shutter at 90. Edit: Ah, I see. 180 is max with built-in flash Last edited by Takumar55; 08-18-2013 at 06:42 PM.

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08-18-2013, 05:04 PM	#3
maxfield_photo Site Supporter Join Date: Mar 2011 Location: Cincinnati, OH Posts: 1,216	Do you have your camera set to "allow" the use of the aperture ring? If the flash can't read the aperture I believe it will always fire at full power in pTTL mode. There is a pretty simple hack for the K-mount that involves unscrewing the ring and shorting the "A" pin with some tin foil. Once you've done that, the camera will think every lens you mount has an "A" position on the aperture ring, and all you have to do is dial in the aperture on the camera to match your lens. Oh, and don't use Auto ISO

08-18-2013, 05:42 PM	#4
Takumar55 Senior Member Join Date: Jun 2013 Posts: 120 Original Poster	Originally posted by Adam When using a flash, the aperture is what primarily controls the exposure. Most older flashes have a table on the back that tells you what aperture to use at what distance/intensity combination. If your flash doesn't have such a table, then a bit of trial-and-error will be required, so go ahead and lock set your shutter speed to the flash sync speed and test a variety of aperture settings. There is no automation whatsoever when using flashes with M and K lenses on modern Pentax DSLRs, as they use P-TTL (calculated) and not TTL (real-time) flash metering. The only DSLRs that do support TTL flashes are the *ist D, DS, and DS2. Forget to mention I'm using the built-in flash. But it sounds like I need to figure out which aperture and shutter combinations work with the built-in flash, and then set them accordingly?

08-18-2013, 05:46 PM	#5
Takumar55 Senior Member Join Date: Jun 2013 Posts: 120 Original Poster	Originally posted by maxfield_photo Do you have your camera set to "allow" the use of the aperture ring? If the flash can't read the aperture I believe it will always fire at full power in pTTL mode. There is a pretty simple hack for the K-mount that involves unscrewing the ring and shorting the "A" pin with some tin foil. Once you've done that, the camera will think every lens you mount has an "A" position on the aperture ring, and all you have to do is dial in the aperture on the camera to match your lens. Oh, and don't use Auto ISO It's an M lens, so I don't think I can use the "allow" feature. But what you say here matches with what the manual says - the wording there is just a little ambiguous. Thanks for the shorting tip. I've seen it mentioned, but never thought about what it meant. No Auto ISO - using Manual mode on the camera.

08-18-2013, 05:50 PM	#7
seventhdr Site Supporter Join Date: Mar 2007 Location: Christchurch, New Zealand Photos: Gallery Posts: 1,453	Originally posted by Takumar55 Hoping someone can help with my exposure metering problems on my K200D with M lens, using the built-in flash. When I am in low light indoors, when I use the flash with a large aperture, I often get completely blown out photos. Without flash, I am following Adam's procedure here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html So I set the camera on M, set the aperture manually using the aperture ring on the lens, press the green button to meter, and then take the picture. This seems to work fine. With flash, using the same procedure, I get completely blown out photos at large apertures. It is as if the camera does not set the shutter speed properly with the flash. There must be some setting I am missing.. Looking at the manual, there is a sentence that reads "the built-in flash fully discharges for lenses without a function to set aperture lens ring to A". This sounds like it addresses my situation, but it also implies that the flash can "partially" discharge? So related question is - does the flash vary in intensity depending on exposure needs? And then does this mean that you basically cannot use the flash with M lenses? Or that there is a set aperture or shutter speed that syncs with the flash? You're correct. If you use a K or M lens (any lens that does not have an A setting), the built-in flash which is P-TTL on a K200D will fire at FULL power. Your options are, unless you want to modify a lens, to use A series or newer lenses (A, F, FA, FA J, or any DA seriees lens) preferably with the aperture on the lens set to A, or use an external flash that allows you to control the flash power (either a flash with its own light sensor (Auto flash) or a flash with manual controls (Manual flash)). Regards Chris

08-18-2013, 05:52 PM	#8
seventhdr Site Supporter Join Date: Mar 2007 Location: Christchurch, New Zealand Photos: Gallery Posts: 1,453	Originally posted by Takumar55 Hoping someone can help with my exposure metering problems on my K200D with M lens, using the built-in flash. When I am in low light indoors, when I use the flash with a large aperture, I often get completely blown out photos. Without flash, I am following Adam's procedure here: https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...k-x-k-7-a.html So I set the camera on M, set the aperture manually using the aperture ring on the lens, press the green button to meter, and then take the picture. This seems to work fine. With flash, using the same procedure, I get completely blown out photos at large apertures. It is as if the camera does not set the shutter speed properly with the flash. There must be some setting I am missing.. Looking at the manual, there is a sentence that reads "the built-in flash fully discharges for lenses without a function to set aperture lens ring to A". This sounds like it addresses my situation, but it also implies that the flash can "partially" discharge? So related question is - does the flash vary in intensity depending on exposure needs? And then does this mean that you basically cannot use the flash with M lenses? Or that there is a set aperture or shutter speed that syncs with the flash? You're correct. If you use a K or M lens (any lens that does not have an A setting), the built-in flash which is P-TTL on a K200D will fire at FULL power. Your options are, unless you want to modify a lens, to use A series or newer lenses (A, F, FA, FA J, or any DA seriees lens) preferably with the aperture on the lens set to A, or use an external flash that allows you to control the flash power (either a flash with its own light sensor (Auto flash) or a flash with manual controls (Manual flash)). Regards Chris

08-18-2013, 05:57 PM	#9
Takumar55 Senior Member Join Date: Jun 2013 Posts: 120 Original Poster	Thanks for the responses! I just tried the same shots using my A lens, and it works fine. So everything's exactly as you've all described here. I'll have to be cognizant of what I can and can't do with the M lens. Good to know it's just my lack of knowledge here and nothing worse.

08-18-2013, 06:01 PM	#10
Takumar55 Senior Member Join Date: Jun 2013 Posts: 120 Original Poster	Originally posted by RKKS08 The built-in flash of the K200D is specified with GN (maximum Guide Number) of 13 for ISO 100 and metric system. As the built-in flash cannot change the area its light covers, GN13 is independend from lens focus length. If the flash always uses its full capacity, you get the correct aperture by deviding the GN by the object distance in meters (for ISO 100). So, for a distance of 4 meters the aperture at ISO 100 would be 13/4 --> F3.25. Set aperture to one of the nearest half aperture stops, F2.8 or F3.5 (depending on subject). If you are too far away to get a valid aperture (aperture value gets too small for this lens), adjust ISO instead. ...and this rough calculation worked on the M lens!

08-18-2013, 06:18 PM	#11
RKKS08 Site Supporter Join Date: Mar 2010 Location: Frankfurt am Main Posts: 1,241	Quote: ...and this rough calculation worked on the M lens! This was the ONLY way you could use flash before the age of (affordable) thyristor flashes began, I think about 1970. And it is still the recommended technique if you use flash at night outside for photographing people. This is one of the situations where TTL and xyz-TTL have their limits - totally black background and blown out faces. Contrast measurement of pTTL improves it a bit, but most times old school manual calculation gives much better results.

08-18-2013, 06:45 PM	#13
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	You could always create a spreadsheet and make a cheat sheet using the formula f-stop = Guide Number / Distance. You can guesstimate the distance off the scale on the lens focusing ring. It would be like to good old days of using flash bulbs.

08-18-2013, 06:51 PM	#14
RKKS08 Site Supporter Join Date: Mar 2010 Location: Frankfurt am Main Posts: 1,241	Originally posted by Takumar55 Is there a recommended shutter speed? I remember 60 or 90 being the "flash" speed. In my previous picture, I had the shutter at 90. Edit: Ah, I see. 180 is max with built-in flash If you want to include existing ambient/natural light to mix with the flash light, you may want to use a longer exposure time. You probably must close the aperture a bit more than the calculation recommends, but how much is more a result of experience than precise measurement/calculation.