Strobe/Exposure Difficulties HELP!

Ed n Georgia · 03-22-2011, 01:48 PM

OK, here's my issue that I hope someone can shed some light on.

I'm shooting in studio using monolights, K7 and an assortment of Lens.

I'm metering my exposure with a Sekonic L358.

I set up and take readings with my meter.

Using a single strobe, I take a reading four times about 30 seconds apart.

Meter is set for 1/125 and ISO 200

each time I meter, I get the same reading f/16

So, in manual, I set my K7 to ISO 200, 1/125 and f/16 and take a couple of shots.

Each time, my shots seem to come out horrible underexposed by, at least, 1-1/2 - 2 stops.

I'm firing wirelessly using Pocket wizard Plus II triggers.

Is there something I'm missing here? I have two K7s and get the same result with both. I had similar results using a K20D.

Anyone have any ideas you'd like to share?

TIA

Ed

aurele · 03-22-2011, 02:30 PM

If each time the metering is 2 stops higher than reality, just reduce by 2 stop the diaph each time.

be carefull, the Sekonic is doing well only for lenses below 90mm.

Oscar1 · 03-22-2011, 06:24 PM

I have two of the damned K7s. They take turns being in the shop for repair.

I've tried using the sunny 16 rule with both of them f/16 @ 1/125 and neither of them has ever exposed correctly. I have to open both of them up to f/11, or more, to get the exposure correct.

So, it doesn't surprise me at all that you're having exposure issues with your K7s. Hope you get the problem solved soon.

30+ years with Pentax. but, probably not for much longer.

alohadave · 03-22-2011, 06:53 PM

Originally posted by Ed n Georgia

Is there something I'm missing here? I have two K7s and get the same result with both. I had similar results using a K20D.

Anyone have any ideas you'd like to share?

TIA

Ed

What mode is the flash in?

Ed n Georgia · 03-22-2011, 07:07 PM

Originally posted by alohadave

What mode is the flash in?

I'm using a monolight so there is no mode.

HawaiianOnline · 03-22-2011, 07:10 PM

Can post a shot of someone using the lightmeter next to your subject?

Ed n Georgia · 03-22-2011, 08:34 PM

Originally posted by HawaiianOnline

Can post a shot of someone using the lightmeter next to your subject?

To what end?

I "do" know how to use the meter.

mtansley · 03-23-2011, 06:29 AM

Not trying to be insulting here since you know how to use the meter (same one that I'm learning to use with my K20d) but is the sekonic accurate or do you have the exposure compensation accidentally set on the meter? Would having or not having a UV or skylight filter on the lens make any difference?

At one point I had three different meters (before I decided on the 358) and checked them all together for amusement (they all reported the same f stop so I assumed each was correct)

Michael

Ed n Georgia · 03-23-2011, 08:42 AM

Originally posted by mtansley

Not trying to be insulting here since you know how to use the meter (same one that I'm learning to use with my K20d) but is the sekonic accurate or do you have the exposure compensation accidentally set on the meter? Would having or not having a UV or skylight filter on the lens make any difference?

At one point I had three different meters (before I decided on the 358) and checked them all together for amusement (they all reported the same f stop so I assumed each was correct)

Michael

Michael, somehow, or another, I've ended up with two of the L-358 meters. I get the same readings from both.

There's no exposure compensation on the meter, or the K7.

I borrowed a Canon 40D and tamron 17 - 50 lens from the local B&M yesterday to run a comparison. I used the same lens on my K7.

Using the settings indicated by the L-358, The 40D was spot on. the K7 was about a stop and a half underexposed.

i had the exact same situation with my k20D.

So, my conclusion is that there's a problem with the K7.

Well, off to repair again.

mtansley · 03-23-2011, 11:49 AM

That's really strange that both your cameras could underexpose the same way. Rather scary too.

I could understand it if you were using one of the automatic modes, but using manual, you're controlling everything. The shutter speed doesn't matter since you're using a strobe so somewhere both your cameras are misadjusting the aperture.

Oh well, if I run into the same problem, I'll know where to look.

Michael

HawaiianOnline · 03-23-2011, 09:37 PM

Are you using the same lens for all the underexposed shots, or do multiple lenses underexpose?

EDIT: Just noticed that you said you're using the Tamron 17-50 f2.8 on both of your K-7s and your K20D. Did you try any other lens?

03-22-2011, 01:48 PM	#1
Ed n Georgia Veteran Member Join Date: Dec 2009 Location: Georgia Posts: 940	Strobe/Exposure Difficulties HELP! OK, here's my issue that I hope someone can shed some light on. I'm shooting in studio using monolights, K7 and an assortment of Lens. I'm metering my exposure with a Sekonic L358. I set up and take readings with my meter. Using a single strobe, I take a reading four times about 30 seconds apart. Meter is set for 1/125 and ISO 200 each time I meter, I get the same reading f/16 So, in manual, I set my K7 to ISO 200, 1/125 and f/16 and take a couple of shots. Each time, my shots seem to come out horrible underexposed by, at least, 1-1/2 - 2 stops. I'm firing wirelessly using Pocket wizard Plus II triggers. Is there something I'm missing here? I have two K7s and get the same result with both. I had similar results using a K20D. Anyone have any ideas you'd like to share? TIA Ed

03-23-2011, 09:37 PM	#11
HawaiianOnline Veteran Member Join Date: Jan 2007 Location: Hawaii Posts: 613	Are you using the same lens for all the underexposed shots, or do multiple lenses underexpose? EDIT: Just noticed that you said you're using the Tamron 17-50 f2.8 on both of your K-7s and your K20D. Did you try any other lens? Last edited by HawaiianOnline; 03-23-2011 at 10:17 PM. Reason: Did not want to double post

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03-22-2011, 02:30 PM	#2
aurele Veteran Member Join Date: Jan 2011 Location: Paris, France Photos: Albums Posts: 3,217	If each time the metering is 2 stops higher than reality, just reduce by 2 stop the diaph each time. be carefull, the Sekonic is doing well only for lenses below 90mm.

03-22-2011, 06:24 PM	#3
Oscar1 Inactive Account Join Date: Oct 2009 Posts: 231	I have two of the damned K7s. They take turns being in the shop for repair. I've tried using the sunny 16 rule with both of them f/16 @ 1/125 and neither of them has ever exposed correctly. I have to open both of them up to f/11, or more, to get the exposure correct. So, it doesn't surprise me at all that you're having exposure issues with your K7s. Hope you get the problem solved soon. 30+ years with Pentax. but, probably not for much longer.

03-22-2011, 06:53 PM	#4
alohadave Veteran Member Join Date: Jan 2008 Location: Quincy, MA Photos: Gallery \| Albums Posts: 2,024	Originally posted by Ed n Georgia Is there something I'm missing here? I have two K7s and get the same result with both. I had similar results using a K20D. Anyone have any ideas you'd like to share? TIA Ed What mode is the flash in?

03-22-2011, 07:07 PM	#5
Ed n Georgia Veteran Member Join Date: Dec 2009 Location: Georgia Posts: 940 Original Poster	Originally posted by alohadave What mode is the flash in? I'm using a monolight so there is no mode.

03-22-2011, 07:10 PM	#6
HawaiianOnline Veteran Member Join Date: Jan 2007 Location: Hawaii Posts: 613	Can post a shot of someone using the lightmeter next to your subject?

03-22-2011, 08:34 PM	#7
Ed n Georgia Veteran Member Join Date: Dec 2009 Location: Georgia Posts: 940 Original Poster	Originally posted by HawaiianOnline Can post a shot of someone using the lightmeter next to your subject? To what end? I "do" know how to use the meter.

03-23-2011, 06:29 AM	#8
mtansley Veteran Member Join Date: Oct 2008 Location: Ajax, Ontario, Canada Photos: Gallery Posts: 1,139	Not trying to be insulting here since you know how to use the meter (same one that I'm learning to use with my K20d) but is the sekonic accurate or do you have the exposure compensation accidentally set on the meter? Would having or not having a UV or skylight filter on the lens make any difference? At one point I had three different meters (before I decided on the 358) and checked them all together for amusement (they all reported the same f stop so I assumed each was correct) Michael

03-23-2011, 08:42 AM	#9
Ed n Georgia Veteran Member Join Date: Dec 2009 Location: Georgia Posts: 940 Original Poster	Originally posted by mtansley Not trying to be insulting here since you know how to use the meter (same one that I'm learning to use with my K20d) but is the sekonic accurate or do you have the exposure compensation accidentally set on the meter? Would having or not having a UV or skylight filter on the lens make any difference? At one point I had three different meters (before I decided on the 358) and checked them all together for amusement (they all reported the same f stop so I assumed each was correct) Michael Michael, somehow, or another, I've ended up with two of the L-358 meters. I get the same readings from both. There's no exposure compensation on the meter, or the K7. I borrowed a Canon 40D and tamron 17 - 50 lens from the local B&M yesterday to run a comparison. I used the same lens on my K7. Using the settings indicated by the L-358, The 40D was spot on. the K7 was about a stop and a half underexposed. i had the exact same situation with my k20D. So, my conclusion is that there's a problem with the K7. Well, off to repair again.

03-23-2011, 11:49 AM	#10
mtansley Veteran Member Join Date: Oct 2008 Location: Ajax, Ontario, Canada Photos: Gallery Posts: 1,139	That's really strange that both your cameras could underexpose the same way. Rather scary too. I could understand it if you were using one of the automatic modes, but using manual, you're controlling everything. The shutter speed doesn't matter since you're using a strobe so somewhere both your cameras are misadjusting the aperture. Oh well, if I run into the same problem, I'll know where to look. Michael