Pentax *istD

jlm2664 · 10-15-2009, 08:32 PM

I recently switched from my trusty Pentax 35mm SLR to an entry lever Pentax DSLR, an *istD so I was able to utilize my lens collection. I can't seem to get the lightning correct. It seems as if everything is underexposed? Anyone know of this problem/camera combination. Even changing the ISO setting has little effect on light. Thouhgt I did pretty well with my 20+ years of experience now I feel as if I am starting from scratch. Any help is appreciated.

THanks,
Jeff Morgan

**Ash** · 10-15-2009, 09:21 PM

Hi Jeff.
You have what was once a pro-level camera - very good even in today's standards.
You will have to post some examples, though as it is hard to know what's going on without photos with EXIF data (metadata).

Also tell us what lens you're using on it - are all your lenses giving you under exposure?
Have you tried shooting in different modes to see if the under-exposure is consistent?

Spock · 10-15-2009, 09:33 PM

Check it's not set to spot metering.

**Lowell Goudge** · 10-16-2009, 10:36 AM

I have an *istD and find that it is actually one of the best metering cameras on old lenses, so your problem seems to be a little abnormal.

Here are a couple of things to check,

Unlike some cameras the *istD exposure compensation works in manual mode. Some people question why but it is actually a good thing, because some specific lenses need compensation over the whole range. Your body might have the compensation setto something other than 0. to change, press the +/- button on the upper right corner of the back of the camera, and turn the front thumb wheel.

As mentioned above some lenses (i find screw mount lenses specifically) tend to need exposure correction, and I set the exposure compensation to correct for this, You can also do this, to add or subtract 1-2 stops.

Changing ISO won't change the metereing performance because the meter will know the new ISO setting and apply the same (apparently incorrect) adjustments

When you say the camera under exposes, is this based upon viewing the viewing screen or the histogram? The vioew screen can be a little dark and misleading on th e*istD. You should base everything on the histogram.

To check the metering with your camera, the best way is to focus on a uniformly lit grey surface. I find roads, sidewalks and block walls are the best.

Metering on a surface like this and taking a shot should yeild a photo with the histogram peaking sharply in the middle, or if you are using a photo editor, have an average greysccale value of about 120.

If this checks out, it is just your view screen is dark, and this can be adjusted through the menus, but don't trust this for exposure, use the histogram.

Post some images if you are still having problems

jeffkrol · 10-16-2009, 02:46 PM

Originally posted by jlm2664

I recently switched from my trusty Pentax 35mm SLR to an entry lever Pentax DSLR, an *istD so I was able to utilize my lens collection. I can't seem to get the lightning correct. It seems as if everything is underexposed? Anyone know of this problem/camera combination. Even changing the ISO setting has little effect on light. Thouhgt I did pretty well with my 20+ years of experience now I feel as if I am starting from scratch. Any help is appreciated.

THanks,
Jeff Morgan

Lowell's advice is good except the D was calibrated to more of a 90 peak in RGB space.... Take a grey card or white wall and the peak will be way to the left of center (90)...
Headroom in Highlights : Where is Zone V in The Digital World? | LibRaw
More in line w/ this:
Current ISO standard, however, recommends that the metering calibration point is less then 18% by half a stop to increase the room in the highlights. The standard suggests 18%/SQRT(12)=12.73%. Adding the slack the standard allows the total headroom is somewhat less then 3 stops, 2.97 eV.

Steve.Ledger · 10-16-2009, 04:01 PM

I confirm this for the *istDS. As soon as I switched to RAW and Lightroom, problem gone.

**Lowell Goudge** · 10-16-2009, 04:08 PM

Originally posted by jeffkrol

Lowell's advice is good except the D was calibrated to more of a 90 peak in RGB space.... Take a grey card or white wall and the peak will be way to the left of center (90)...
Headroom in Highlights : Where is Zone V in The Digital World? | LibRaw
More in line w/ this:
Current ISO standard, however, recommends that the metering calibration point is less then 18% by half a stop to increase the room in the highlights. The standard suggests 18%/SQRT(12)=12.73%. Adding the slack the standard allows the total headroom is somewhat less then 3 stops, 2.97 eV.

interesting point, my comments are based upon actual measurements over many lenses (19 in total) in Adobe color space.

jeffkrol · 10-16-2009, 04:42 PM

Originally posted by Lowell Goudge

interesting point, my comments are based upon actual measurements over many lenses (19 in total) in Adobe color space.

Which brings us back to the ancient conundrum.... what was the correct metering constant for the D?. Mine would peak at 90. Sent it in for repairs (unrelated) and it came back recalibrated as 90ish.... the old D arguments dating from it's release actually seemed to show 2 calibration standards.. which was extremely odd. Set at 90 my camera had an extremely hard time rendering white white since +2EV was not enough. Won't go into the long history since it really only applies to these "old" bodies.
As to old lenses (which may really not apply to the OP since his collection is undefined) they were variable to a certain degree especially at aperture extremes (fully open or full stopped down) but what the heck. Of course all this is based on only MY sample and is insignificant actually.. not sure you were around for these but it's a somewhat interesting read:
Re: Not quite: Pentax SLR Talk Forum: Digital Photography Review
Are you a 90 or 127.5 Pentaxist?: Pentax SLR Talk Forum: Digital Photography Review
On the Ds:
DS back from repairs, 6 weeks, underexposure problem not fixed!: Pentax SLR Talk Forum: Digital Photography Review
It was an obsession for awhile

You may find a few familiar faces here:
To feed your fire: Pentax SLR Talk Forum: Digital Photography Review
My sig quote from Erwin Puts pretty well sums up my feelings on the matter....
'The exposure meter is calibrated to some clearly defined standards and the user needs to adjust his working method and his subject matter to these values. It does not help to suppose all kinds of assumptions that do not exist.'
Erwin Puts
gosh I love that line

jlm2664 · 10-17-2009, 07:46 PM

Thanks for all of the advice. It was set to spot metering. Still a learning process. I am going to shoot some test shots to compare tomorrow and update everyone. I currently have 2 Pentax AF lenses, a 28-80 and an 80-200, both of which I have used quite a bit with my ZX-5 film camera and never had any problems. I have been getting an underexposure problem with both lenses in different conditions. Thanks again for the help.

Spock · 10-17-2009, 08:09 PM

Originally posted by jlm2664

It was set to spot metering.

I thought so!
Don't feel too bad - I did the same thing last weekend on a bush walk with my K7 - took a lot of interesting photos and only realised the next day why my exposure was all over the place.

**Ash** · 10-18-2009, 12:03 AM

I didn't suspect it, but it can happen to us at the best of times.
In any case, don't be afraid to bump up EC by +0.7 or so to get adequate exposure, and see how you like the results...

10-15-2009, 08:32 PM	#1
jlm2664 Inactive Account Join Date: May 2008 Location: tennessee Posts: 6	*Pentax istD** I recently switched from my trusty Pentax 35mm SLR to an entry lever Pentax DSLR, an *istD so I was able to utilize my lens collection. I can't seem to get the lightning correct. It seems as if everything is underexposed? Anyone know of this problem/camera combination. Even changing the ISO setting has little effect on light. Thouhgt I did pretty well with my 20+ years of experience now I feel as if I am starting from scratch. Any help is appreciated. THanks, Jeff Morgan

10-16-2009, 02:46 PM	#5
jeffkrol Veteran Member Join Date: Sep 2006 Location: Wisconsin USA Photos: Gallery Posts: 8,434	From a D user Originally posted by jlm2664 I recently switched from my trusty Pentax 35mm SLR to an entry lever Pentax DSLR, an *istD so I was able to utilize my lens collection. I can't seem to get the lightning correct. It seems as if everything is underexposed? Anyone know of this problem/camera combination. Even changing the ISO setting has little effect on light. Thouhgt I did pretty well with my 20+ years of experience now I feel as if I am starting from scratch. Any help is appreciated. THanks, Jeff Morgan Lowell's advice is good except the D was calibrated to more of a 90 peak in RGB space.... Take a grey card or white wall and the peak will be way to the left of center (90)... Headroom in Highlights : Where is Zone V in The Digital World? \| LibRaw More in line w/ this: Current ISO standard, however, recommends that the metering calibration point is less then 18% by half a stop to increase the room in the highlights. The standard suggests 18%/SQRT(12)=12.73%. Adding the slack the standard allows the total headroom is somewhat less then 3 stops, 2.97 eV.

10-16-2009, 04:42 PM	#8
jeffkrol Veteran Member Join Date: Sep 2006 Location: Wisconsin USA Photos: Gallery Posts: 8,434	Originally posted by Lowell Goudge interesting point, my comments are based upon actual measurements over many lenses (19 in total) in Adobe color space. Which brings us back to the ancient conundrum.... what was the correct metering constant for the D?. Mine would peak at 90. Sent it in for repairs (unrelated) and it came back recalibrated as 90ish.... the old D arguments dating from it's release actually seemed to show 2 calibration standards.. which was extremely odd. Set at 90 my camera had an extremely hard time rendering white white since +2EV was not enough. Won't go into the long history since it really only applies to these "old" bodies. As to old lenses (which may really not apply to the OP since his collection is undefined) they were variable to a certain degree especially at aperture extremes (fully open or full stopped down) but what the heck. Of course all this is based on only MY sample and is insignificant actually.. not sure you were around for these but it's a somewhat interesting read: Re: Not quite: Pentax SLR Talk Forum: Digital Photography Review Are you a 90 or 127.5 Pentaxist?: Pentax SLR Talk Forum: Digital Photography Review On the Ds: DS back from repairs, 6 weeks, underexposure problem not fixed!: Pentax SLR Talk Forum: Digital Photography Review It was an obsession for awhile You may find a few familiar faces here: To feed your fire: Pentax SLR Talk Forum: Digital Photography Review My sig quote from Erwin Puts pretty well sums up my feelings on the matter.... 'The exposure meter is calibrated to some clearly defined standards and the user needs to adjust his working method and his subject matter to these values. It does not help to suppose all kinds of assumptions that do not exist.' Erwin Puts gosh I love that line Last edited by jeffkrol; 10-16-2009 at 04:54 PM.

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10-15-2009, 09:21 PM	#2
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Hi Jeff. You have what was once a pro-level camera - very good even in today's standards. You will have to post some examples, though as it is hard to know what's going on without photos with EXIF data (metadata). Also tell us what lens you're using on it - are all your lenses giving you under exposure? Have you tried shooting in different modes to see if the under-exposure is consistent?

10-15-2009, 09:33 PM	#3
Spock Pentaxian Join Date: Aug 2009 Location: Perth, Western Australia Photos: Albums Posts: 674	Check it's not set to spot metering.

10-16-2009, 10:36 AM	#4
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	I have an istD and find that it is actually one of the best metering cameras on old lenses, so your problem seems to be a little abnormal. Here are a couple of things to check, Unlike some cameras the istD exposure compensation works in manual mode. Some people question why but it is actually a good thing, because some specific lenses need compensation over the whole range. Your body might have the compensation setto something other than 0. to change, press the +/- button on the upper right corner of the back of the camera, and turn the front thumb wheel. As mentioned above some lenses (i find screw mount lenses specifically) tend to need exposure correction, and I set the exposure compensation to correct for this, You can also do this, to add or subtract 1-2 stops. Changing ISO won't change the metereing performance because the meter will know the new ISO setting and apply the same (apparently incorrect) adjustments When you say the camera under exposes, is this based upon viewing the viewing screen or the histogram? The vioew screen can be a little dark and misleading on th e*istD. You should base everything on the histogram. To check the metering with your camera, the best way is to focus on a uniformly lit grey surface. I find roads, sidewalks and block walls are the best. Metering on a surface like this and taking a shot should yeild a photo with the histogram peaking sharply in the middle, or if you are using a photo editor, have an average greysccale value of about 120. If this checks out, it is just your view screen is dark, and this can be adjusted through the menus, but don't trust this for exposure, use the histogram. Post some images if you are still having problems

10-16-2009, 04:01 PM	#6
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	I confirm this for the *istDS. As soon as I switched to RAW and Lightroom, problem gone.

10-16-2009, 04:08 PM	#7
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,891	Originally posted by jeffkrol Lowell's advice is good except the D was calibrated to more of a 90 peak in RGB space.... Take a grey card or white wall and the peak will be way to the left of center (90)... Headroom in Highlights : Where is Zone V in The Digital World? \| LibRaw More in line w/ this: Current ISO standard, however, recommends that the metering calibration point is less then 18% by half a stop to increase the room in the highlights. The standard suggests 18%/SQRT(12)=12.73%. Adding the slack the standard allows the total headroom is somewhat less then 3 stops, 2.97 eV. interesting point, my comments are based upon actual measurements over many lenses (19 in total) in Adobe color space.

10-17-2009, 07:46 PM	#9
jlm2664 Inactive Account Join Date: May 2008 Location: tennessee Posts: 6 Original Poster	Thanks for all of the advice. It was set to spot metering. Still a learning process. I am going to shoot some test shots to compare tomorrow and update everyone. I currently have 2 Pentax AF lenses, a 28-80 and an 80-200, both of which I have used quite a bit with my ZX-5 film camera and never had any problems. I have been getting an underexposure problem with both lenses in different conditions. Thanks again for the help.

10-17-2009, 08:09 PM	#10
Spock Pentaxian Join Date: Aug 2009 Location: Perth, Western Australia Photos: Albums Posts: 674	Originally posted by jlm2664 It was set to spot metering. I thought so! Don't feel too bad - I did the same thing last weekend on a bush walk with my K7 - took a lot of interesting photos and only realised the next day why my exposure was all over the place.

10-18-2009, 12:03 AM	#11
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	I didn't suspect it, but it can happen to us at the best of times. In any case, don't be afraid to bump up EC by +0.7 or so to get adequate exposure, and see how you like the results...