Stop Down Metering With The Green Button: Wrong Exposure Recomendations

Obs · 10-02-2010, 01:28 PM

So when fiddling around with my k-x in manual mode with my Pentax-M 50mm 1.4 prime lens attached, and brought it out to take some shots, I found that when I stopped down with the green button, it would suggest an unrealistic shutter speed for proper exposure.

For example, I go out to take some flicks on this wonderfully sunny day (I'm talking high-noon sunny), I locate a subject, compose the shot, and stop down the composition using the green button. Now, instead of suggesting a proper shutter speed of 1/6000, it'll offer me something ridiculous, like a 0.3 shutter speed.

Again, I was fiddling with my k-x, and I think I may have "accidentally" pressed the AF AE-L Button while in manual mode. Could that be the reason for all the missugestions? I did notice when I took shots under the shade, or of shady subjects, reasonable shutter speed suggestions were given, but when I took shots under the sun, or shot at subjects under the sun, stopping down with the green button was frequently inaccurate.

Any input would be deeply appreciated, beit harsh or constructive.

Rupert · 10-02-2010, 02:06 PM

I would recommend reading the instructions again......I forgot what they say in this regard. My K10D never did give accurate or even close readings with the Green Button, just useless! My K20D is "reasonably" accurate, it will get you close most of the time. Unless you are in a hurry for an action shot, it is usually no more than a couple of test shots away from hitting it right with no Green Button use, just by experience, but the Green Button is handy, no doubt. Hopefully someone with a Kx can give you better advice than I have...
Best Regards

**boriscleto** · 10-02-2010, 02:26 PM - **1 Like**

Originally posted by Obs

So when fiddling around with my k-x in manual mode with my Pentax-M 50mm 1.4 prime lens attached, and brought it out to take some shots, I found that when I stopped down with the green button, it would suggest an unrealistic shutter speed for proper exposure.

For example, I go out to take some flicks on this wonderfully sunny day (I'm talking high-noon sunny), I locate a subject, compose the shot, and stop down the composition using the green button. Now, instead of suggesting a proper shutter speed of 1/6000, it'll offer me something ridiculous, like a 0.3 shutter speed.

Again, I was fiddling with my k-x, and I think I may have "accidentally" pressed the AF AE-L Button while in manual mode. Could that be the reason for all the missugestions? I did notice when I took shots under the shade, or of shady subjects, reasonable shutter speed suggestions were given, but when I took shots under the sun, or shot at subjects under the sun, stopping down with the green button was frequently inaccurate.

Any input would be deeply appreciated, beit harsh or constructive.

You need to stop down or lower the ISO. The K-x defaults to 0.3 when there is too much light.

Davor · 10-02-2010, 02:56 PM

I have the same problem with older manual focus lenses on my K20d. After some testing found that the best way to get correct exposure is pressing green buton while lens is wide open and after that choose smaller aperture and manualy correct shutter speed (depend how f/stops you close aperture). This is simple, just must know how is EV step defined in your setup (1/2 or 1/3). This give me very good results.

Modern autofocus lenses are wide open whole time (until you press "shut" and take photo) and correct exposure is calculated automaticaly whatever combination you choose. There is no need to close aperture to see what is the right shutter speed. In manual focus lenses body can not do this automaticaly but principle with metering wide open is the same, only corrections you have to made yourself (instead camera). Hope you understand me.

Last edited by Davor; 10-02-2010 at 03:10 PM. Reason: additional text

elho_cid · 10-02-2010, 03:27 PM

Maybe it is a stupid question, but do you use "M" mode with "M" lenses? Because that's where the stop down metering should be used. It won't work correctly in any semi-automatic exposure mode. I'm fine with the stop-down metering accuracy (K10D)

Obs · 10-02-2010, 05:12 PM

Originally posted by boriscleto

You need to stop down or lower the ISO. The K-x defaults to 0.3 when there is too much light.

I think this may be the case. Anytime I took a shot in direct sunlight, my k-x defaulted to 0.3. I'll have an update tomorrow.

Edit: Thank you for all the input guys. Feels great to know there is a forum to rely on when things get fuzzy.

Ira · 10-03-2010, 12:23 PM - **1 Like**

Obs, on the K-x, the +/- button defaults to do the same thing in M mode, and you can assign your green button for something else.

Ira · 10-03-2010, 12:26 PM

Originally posted by Davor

This is simple, just must know how is EV step defined in your setup (1/2 or 1/3). This give me very good results.

Not in M mode on the K-x. In M mode, all the EV button does is stop down to meter and lock in your shutter speed.

Obs · 10-04-2010, 09:53 AM

Originally posted by Ira

Obs, on the K-x, the +/- button defaults to do the same thing in M mode, and you can assign your green button for something else.

Correct, I just read that from http://support.pentaximaging.com/documents/908:

"Note: pressing the Exposure Compensation button (the +/- button) on the K-x will automatically set an appropriate shutter speed in Manual exposure mode when using non-"A" series lenses."

So I'll just reassign my green button for something more useful. But yes, I think I finally got the hang of "stopping down" by manually adjusting the aperture lens ring, and using a suitable iso for proper exposure.

Nowhere Matt · 10-04-2010, 10:58 AM

I also think variations come into play but in my undocumented and limited experience there are some lenses that meter much better than others using stop down methods. I have a Sears lens that meters very poorly when closed down beyond f4 and a Lenmar lens that is slightly inaccurate beyond f11 while others such as a Focal, Quantaray and Pentax are generally good at all f stops.
These findings include the K10 and K-7 and may be considered "kooky talk".

Ira · 10-04-2010, 11:27 AM

Matt's correct, but for all of my Taks, things only get funky for me at smaller than F8, which I rarely do anyway. (This is on my K-x.)

Additionally, while we all aim for spot-on perfect exposure, I treat it as if I'm shooting negative film, where an underexposed latitude of one or two stops is acceptable, and fixed in printing--but in our case, PP. I'm sure not saying this is the best way to shoot, but because of this, I don't sweat or worry about the minor metering variances for these M lenses. Plus, since we're shooting M mode, we should be bracketing ANYWAY when possible.

So as Obs said he's getting the habit of turning the ring, he'll soon realize it's no big deal to turn it twice more in opposite directions after the base reading to get that bracketing.

It's an incredible misconception that manual metering is more difficult than the program modes, like Av. I find manual EASIER to work with based on the delicacies of proper metering.

**Lowell Goudge** · 10-04-2010, 11:43 AM

Originally posted by Nowhere Matt

I also think variations come into play but in my undocumented and limited experience there are some lenses that meter much better than others using stop down methods. I have a Sears lens that meters very poorly when closed down beyond f4 and a Lenmar lens that is slightly inaccurate beyond f11 while others such as a Focal, Quantaray and Pentax are generally good at all f stops.
These findings include the K10 and K-7 and may be considered "kooky talk".

once upon a time (1/t ?

) I proposed a little project, specifically people take a common lens like a K1.4 50mm and map out the green button exposure for different cameras, and different focusing screens. I have this for the*istD, K10D and K7, plus additional mappings of the K10D with an *istD screen and a split image screen.

It would be worthwhile.

I additionally suggested people put metering curves in the lens database when they do a review, therefore telling everyone else how the lenses meter.

unfortunately it never happened.

Ira · 10-04-2010, 12:01 PM

Originally posted by Lowell Goudge

unfortunately it never happened.

I can only speak for myself:

I'm too lazy.

violini · 10-05-2010, 04:38 PM

I use Pentax-M 50mm/1.7 and 135mm/3.5 on my K-x and have no exposure problem. I assign Green button to "optical preview". In AV mode, I set the aperture on the lens, focus, press G. button and shoot. Photo taken with 135mm.
------------------
Pentax ME, M50mm/1.7, 135mm/3.5, K-x, K-7, DA15mm. DFA 100mm WR Macro.

Fogel70 · 10-06-2010, 03:43 AM

Originally posted by violini

I use Pentax-M 50mm/1.7 and 135mm/3.5 on my K-x and have no exposure problem. I assign Green button to "optical preview". In AV mode, I set the aperture on the lens, focus, press G. button and shoot. Photo taken with 135mm.

If using Av-mode a K-mount lens with aperture ring it has to be set on A-position for the camera to stop down the lens.
All pre-A lenses will only be used with widest aperture in Av-mode, so for controlling aperture you need to use manual mode.

10-02-2010, 01:28 PM	#1
Obs Inactive Account Join Date: Sep 2010 Location: New York City Posts: 8	Stop Down Metering With The Green Button: Wrong Exposure Recomendations So when fiddling around with my k-x in manual mode with my Pentax-M 50mm 1.4 prime lens attached, and brought it out to take some shots, I found that when I stopped down with the green button, it would suggest an unrealistic shutter speed for proper exposure. For example, I go out to take some flicks on this wonderfully sunny day (I'm talking high-noon sunny), I locate a subject, compose the shot, and stop down the composition using the green button. Now, instead of suggesting a proper shutter speed of 1/6000, it'll offer me something ridiculous, like a 0.3 shutter speed. Again, I was fiddling with my k-x, and I think I may have "accidentally" pressed the AF AE-L Button while in manual mode. Could that be the reason for all the missugestions? I did notice when I took shots under the shade, or of shady subjects, reasonable shutter speed suggestions were given, but when I took shots under the sun, or shot at subjects under the sun, stopping down with the green button was frequently inaccurate. Any input would be deeply appreciated, beit harsh or constructive.

10-04-2010, 11:43 AM	#12
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	Originally posted by Nowhere Matt I also think variations come into play but in my undocumented and limited experience there are some lenses that meter much better than others using stop down methods. I have a Sears lens that meters very poorly when closed down beyond f4 and a Lenmar lens that is slightly inaccurate beyond f11 while others such as a Focal, Quantaray and Pentax are generally good at all f stops. These findings include the K10 and K-7 and may be considered "kooky talk". once upon a time (1/t ?) I proposed a little project, specifically people take a common lens like a K1.4 50mm and map out the green button exposure for different cameras, and different focusing screens. I have this for theistD, K10D and K7, plus additional mappings of the K10D with an istD screen and a split image screen. It would be worthwhile. I additionally suggested people put metering curves in the lens database when they do a review, therefore telling everyone else how the lenses meter. unfortunately it never happened.

10-05-2010, 04:38 PM	#14
violini Veteran Member Join Date: Aug 2010 Location: Winnipeg MB Photos: Gallery Posts: 350	I use Pentax-M 50mm/1.7 and 135mm/3.5 on my K-x and have no exposure problem. I assign Green button to "optical preview". In AV mode, I set the aperture on the lens, focus, press G. button and shoot. Photo taken with 135mm. ------------------ Pentax ME, M50mm/1.7, 135mm/3.5, K-x, K-7, DA15mm. DFA 100mm WR Macro. Last edited by violini; 02-03-2011 at 07:05 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Green Button Stop-Down Metering Acting Differently	woefulwabbit	Pentax DSLR Discussion	22	03-29-2011 09:56 PM
Green Button Metering with Manual Lens	zombieCat	Pentax DSLR Discussion	4	02-15-2010 06:07 AM
green button to set exposure	slow2focus	Troubleshooting and Beginner Help	3	12-14-2009 08:25 PM
k10D metering with M lenses in M mode - K200D doing a better job w/ Green button	mrpackerguy	Pentax DSLR Discussion	8	10-03-2008 11:53 AM
K10D Exposure w/Green Button in M mode	carpents	Pentax DSLR Discussion	28	04-28-2007 05:46 PM

10-02-2010, 02:06 PM	#2
Rupert Veteran Member Join Date: Sep 2006 Location: Texas Photos: Gallery \| Albums Posts: 25,123	I would recommend reading the instructions again......I forgot what they say in this regard. My K10D never did give accurate or even close readings with the Green Button, just useless! My K20D is "reasonably" accurate, it will get you close most of the time. Unless you are in a hurry for an action shot, it is usually no more than a couple of test shots away from hitting it right with no Green Button use, just by experience, but the Green Button is handy, no doubt. Hopefully someone with a Kx can give you better advice than I have... Best Regards

10-02-2010, 02:26 PM - 1 Like	#3
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	Originally posted by Obs So when fiddling around with my k-x in manual mode with my Pentax-M 50mm 1.4 prime lens attached, and brought it out to take some shots, I found that when I stopped down with the green button, it would suggest an unrealistic shutter speed for proper exposure. For example, I go out to take some flicks on this wonderfully sunny day (I'm talking high-noon sunny), I locate a subject, compose the shot, and stop down the composition using the green button. Now, instead of suggesting a proper shutter speed of 1/6000, it'll offer me something ridiculous, like a 0.3 shutter speed. Again, I was fiddling with my k-x, and I think I may have "accidentally" pressed the AF AE-L Button while in manual mode. Could that be the reason for all the missugestions? I did notice when I took shots under the shade, or of shady subjects, reasonable shutter speed suggestions were given, but when I took shots under the sun, or shot at subjects under the sun, stopping down with the green button was frequently inaccurate. Any input would be deeply appreciated, beit harsh or constructive. You need to stop down or lower the ISO. The K-x defaults to 0.3 when there is too much light.

10-02-2010, 02:56 PM	#4
Davor New Member Join Date: Jul 2010 Location: Pazin Photos: Gallery Posts: 22	I have the same problem with older manual focus lenses on my K20d. After some testing found that the best way to get correct exposure is pressing green buton while lens is wide open and after that choose smaller aperture and manualy correct shutter speed (depend how f/stops you close aperture). This is simple, just must know how is EV step defined in your setup (1/2 or 1/3). This give me very good results. Modern autofocus lenses are wide open whole time (until you press "shut" and take photo) and correct exposure is calculated automaticaly whatever combination you choose. There is no need to close aperture to see what is the right shutter speed. In manual focus lenses body can not do this automaticaly but principle with metering wide open is the same, only corrections you have to made yourself (instead camera). Hope you understand me. Last edited by Davor; 10-02-2010 at 03:10 PM. Reason: additional text

10-02-2010, 03:27 PM	#5
elho_cid Veteran Member Join Date: Dec 2007 Location: Prague Photos: Gallery Posts: 1,199	Maybe it is a stupid question, but do you use "M" mode with "M" lenses? Because that's where the stop down metering should be used. It won't work correctly in any semi-automatic exposure mode. I'm fine with the stop-down metering accuracy (K10D)

10-02-2010, 05:12 PM	#6
Obs Inactive Account Join Date: Sep 2010 Location: New York City Posts: 8 Original Poster	Originally posted by boriscleto You need to stop down or lower the ISO. The K-x defaults to 0.3 when there is too much light. I think this may be the case. Anytime I took a shot in direct sunlight, my k-x defaulted to 0.3. I'll have an update tomorrow. Edit: Thank you for all the input guys. Feels great to know there is a forum to rely on when things get fuzzy.

10-03-2010, 12:23 PM - 1 Like	#7
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Obs, on the K-x, the +/- button defaults to do the same thing in M mode, and you can assign your green button for something else.

10-03-2010, 12:26 PM	#8
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by Davor This is simple, just must know how is EV step defined in your setup (1/2 or 1/3). This give me very good results. Not in M mode on the K-x. In M mode, all the EV button does is stop down to meter and lock in your shutter speed.

10-04-2010, 09:53 AM	#9
Obs Inactive Account Join Date: Sep 2010 Location: New York City Posts: 8 Original Poster	Originally posted by Ira Obs, on the K-x, the +/- button defaults to do the same thing in M mode, and you can assign your green button for something else. Correct, I just read that from http://support.pentaximaging.com/documents/908: "Note: pressing the Exposure Compensation button (the +/- button) on the K-x will automatically set an appropriate shutter speed in Manual exposure mode when using non-"A" series lenses." So I'll just reassign my green button for something more useful. But yes, I think I finally got the hang of "stopping down" by manually adjusting the aperture lens ring, and using a suitable iso for proper exposure.

10-04-2010, 10:58 AM	#10
Nowhere Matt Veteran Member Join Date: Nov 2007 Location: Nowhere Land Photos: Gallery \| Albums Posts: 2,362	I also think variations come into play but in my undocumented and limited experience there are some lenses that meter much better than others using stop down methods. I have a Sears lens that meters very poorly when closed down beyond f4 and a Lenmar lens that is slightly inaccurate beyond f11 while others such as a Focal, Quantaray and Pentax are generally good at all f stops. These findings include the K10 and K-7 and may be considered "kooky talk".

10-04-2010, 11:27 AM	#11
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Matt's correct, but for all of my Taks, things only get funky for me at smaller than F8, which I rarely do anyway. (This is on my K-x.) Additionally, while we all aim for spot-on perfect exposure, I treat it as if I'm shooting negative film, where an underexposed latitude of one or two stops is acceptable, and fixed in printing--but in our case, PP. I'm sure not saying this is the best way to shoot, but because of this, I don't sweat or worry about the minor metering variances for these M lenses. Plus, since we're shooting M mode, we should be bracketing ANYWAY when possible. So as Obs said he's getting the habit of turning the ring, he'll soon realize it's no big deal to turn it twice more in opposite directions after the base reading to get that bracketing. It's an incredible misconception that manual metering is more difficult than the program modes, like Av. I find manual EASIER to work with based on the delicacies of proper metering.

10-04-2010, 12:01 PM	#13
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by Lowell Goudge unfortunately it never happened. I can only speak for myself: I'm too lazy.

10-06-2010, 03:43 AM	#15
Fogel70 Pentaxian Join Date: Sep 2009 Location: Stockholm, Sweden Photos: Albums Posts: 3,062	Originally posted by violini I use Pentax-M 50mm/1.7 and 135mm/3.5 on my K-x and have no exposure problem. I assign Green button to "optical preview". In AV mode, I set the aperture on the lens, focus, press G. button and shoot. Photo taken with 135mm. If using Av-mode a K-mount lens with aperture ring it has to be set on A-position for the camera to stop down the lens. All pre-A lenses will only be used with widest aperture in Av-mode, so for controlling aperture you need to use manual mode.