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10-17-2013, 08:38 AM   #1
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overexposed

I have had some issues regarding any closeups macro photography.
using the Pentax K30 and a sigma 70-300 APO-DG I am getting a lot of blown out whites.
I have tried reducing the compensation and when the whites are ok the dark areas are to dark, and i mean way to dark.
I have also tried spot, center weighted and multi segment metering, with highlight and shadow correction on and off.
tried modes P, Av and Tv.

distant shots seem to come out just fine, but macro and closeups have this issue.

Red flowers over saturate obliterating any texture most times.

Lavenders turn white

In rare cases the picture comes out fine, but usually nothing like it appears in the viewfinder or live view screen as far as exposure is concerned.

Is this a lens issue ? or a setting in the camera I am not aware of.

I will post examples when i figure out how

Thank you

De Wolf


Last edited by Tom S.; 10-17-2013 at 11:00 AM. Reason: link to personal site removed.
10-17-2013, 11:02 AM   #2
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I have removed the link to your personal site, since you already posted it another post. To receive help here, please post specific pictures (it's very easy to do) so we know exactly what you are asking about and can offer suggestions or help.
10-17-2013, 11:52 AM   #3
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I was getting some inconsistent results with similar gear so I did the following:

- turn OFF highlight and shadow correction (for now) - I find it can mess up exposures on some scenes by trying to adapt what I was compensating for.

- try shoot in Manual mode, select aperture and shutter values that get you close to a good exposure then adjust them as needed to get a resulting image that looks somwhat good.

- view the histogram of the resulting image, RGB preferred to luminance. If you have bright areas like pale lavender color or whites then you should have some peaks at the right end of the histogram but they should not be pushed up against the right edge of the graph. If any of the R, G or B channel histograms are pushed up against the R side and there are no really strong hilites or backlight then you are over-exposing and you can increase the shutter speed to bring it all down.

I have only used my K30 a little for closeup work so far, using a 50-200mm WR lens. The results were consistently excellent, even in Av mode, tho I often had to compensate +1/3 to +2/3 to get the exposure (histogram) coming up a little closer to the R side.

If you can post some examples we may be able to tell a bit more but usually you can solve this kind of issue by shooting in Manual with those internal auto-corrections turned off. If you also shoot raw files you can then make a lot more subtle corrections to your liking afterwards.
10-19-2013, 09:03 AM   #4
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I do have the same problem with my Pentax DFA 100 mm f/2.8 WR lens especially on apertures f/11 and up (to f/32). I don't have any problems on f/2.8.
I think I have located this problem today to the aperture pin on the lens. When moving it to "aperture open" it will go back very slowly to the small aperture where the pin on other lenses will go back very quickly.
When pushing the aperture pin somewhat to the outside of the lens you will hear a "click" inside the lens and when you let the pin go, it will go back very quickly again.

Is there someone aware of this problem with the DFA 100 mm WR version?
Probably you will have the same issue?

10-19-2013, 01:26 PM   #5
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QuoteOriginally posted by Edzo Quote
Is there someone aware of this problem with the DFA 100 mm WR version?
Probably you will have the same issue?
Does not seem to be very common, there have been couple cases how ever.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/209261-pentax-...ky-blades.html
10-19-2013, 01:48 PM   #6
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QuoteOriginally posted by Ex Finn. Quote
Does not seem to be very common, there have been couple cases how ever.
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/209261-pentax-...ky-blades.html

Thanx! I will look over there.
I not seems to be sticky blades because they return quickly when pulling the pin a little bit away.
10-19-2013, 02:06 PM   #7
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QuoteOriginally posted by Edzo Quote
Thanx! I will look over there.
I not seems to be sticky blades because they return quickly when pulling the pin a little bit away.
I agree, after reading your previous post I tried your trick of pulling the aperture lever outwards before releasing and it indeed did make the lever move normally.
10-20-2013, 02:55 AM   #8
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QuoteOriginally posted by Ex Finn. Quote
I agree, after reading your previous post I tried your trick of pulling the aperture lever outwards before releasing and it indeed did make the lever move normally.
Thank you for your reply.
On the Dutch Pentax Forum there is another guy with the same issue.
It looks like it has to be a known issue by Pentax and I wonder whether this could be a warranty issue however my warranty period has expired last year.

The service department of Pentax Netherlands has moved to France recently, so I hope they are more known to this kind of issues over there than they were in the Netherlands.........

10-22-2013, 11:31 AM   #9
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Original Poster
QuoteOriginally posted by dewolf Quote
I have had some issues regarding any closeups macro photography.
using the Pentax K30 and a sigma 70-300 APO-DG I am getting a lot of blown out whites.
I have tried reducing the compensation and when the whites are ok the dark areas are to dark, and i mean way to dark.
I have also tried spot, center weighted and multi segment metering, with highlight and shadow correction on and off.
tried modes P, Av and Tv.

distant shots seem to come out just fine, but macro and closeups have this issue.

Red flowers over saturate obliterating any texture most times.

Lavenders turn white

In rare cases the picture comes out fine, but usually nothing like it appears in the viewfinder or live view screen as far as exposure is concerned.

Is this a lens issue ? or a setting in the camera I am not aware of.

I will post examples when i figure out how

Thank you

De Wolf
ok finally some time and weather to shoot some examples

both sets taken with almost the same settings. A1 and B1 straight from the camera but resized to fit here.
A2 and B2 are post processed and what they look like on the cameras LCD monitor and what they look like through the viewfinder.
My Computer monitor is calibrated with EasyGama.
Both sets shot in the shade.

set A
Exposure Compensation 0
ISO 250
speed 1/400
Aperture 5.6
post processing was -1.92 Gama and -50 Highlight using CS2

Set B
ISO 320
Aperture 4.5

rest same as above including post processing.

Note colour representation = Uncalibrated. < not sure if that's any help.

I have tried Exposure compensation at -1 and -2 to reduce the whites and softness of colour. but the backgrounds end up to dark.

Thanks
De Wolf

Last edited by dewolf; 06-01-2016 at 08:10 PM.
10-22-2013, 10:03 PM   #10
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QuoteOriginally posted by dewolf Quote
ok finally some time and weather to shoot some examples

both sets taken with almost the same settings. A1 and B1 straight from the camera but resized to fit here.
A2 and B2 are post processed and what they look like on the cameras LCD monitor and what they look like through the viewfinder.
My Computer monitor is calibrated with EasyGama.
Both sets shot in the shade.

set A
Exposure Compensation 0
ISO 250
speed 1/400
Aperture 5.6
post processing was -1.92 Gama and -50 Highlight using CS2

Set B
ISO 320
Aperture 4.5

rest same as above including post processing.

Note colour representation = Uncalibrated. < not sure if that's any help.

I have tried Exposure compensation at -1 and -2 to reduce the whites and softness of colour. but the backgrounds end up to dark.

Thanks
De Wolf

Hmm. Your examples seem quite good to me. The first ones (straight from camera) seem "brightish" and the PPd ones "darkish" so somewhere in the middle could be natural..

I believe the issue here is the image contrast. One just can't fit the same kind of dynamic range in photos than there is in nature and what human eye can see. Also, I don't know about your monitor, it might blow highlights as well.. It is normal for the digital cameras, monitors and paper to have a dynamic range of under 10 stops (maybe 5 to 9 stops), while the subjects photographed can have it like 10..20 stops. The aperture and exp.times and ISO don't alter image contrast (dynamic range) much, just the exposure. Except that lens contrast is usually a bit lower at open apertures.

If you want to preserve the frog's parts from blowing to white, you should expose so that they don't (histogram peaks just before the right edge) and then pull up the shadows in post processing (shoot raw, preferably) so that they are to your liking (not too dark). If you don't want to shoot RAW, tou should use low contrast + highlight correction in the camera JPEG settings. At least with high contrast subjects like this.
10-23-2013, 12:48 AM   #11
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QuoteOriginally posted by jaeaetee Quote
I believe the issue here is the image contrast.
I tend to agree.

You can also use the in-camera shadow protection jpeg setting to brighten the dark background in the flower shot.
That's what people refer to as "lifting the shadows" in post processing.

Regards,
--Anders.
10-23-2013, 03:41 AM   #12
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QuoteOriginally posted by jaeaetee Quote
Hmm. Your examples seem quite good to me. The first ones (straight from camera) seem "brightish" and the PPd ones "darkish" so somewhere in the middle could be natural..

I believe the issue here is the image contrast. One just can't fit the same kind of dynamic range in photos than there is in nature and what human eye can see. Also, I don't know about your monitor, it might blow highlights as well.. It is normal for the digital cameras, monitors and paper to have a dynamic range of under 10 stops (maybe 5 to 9 stops), while the subjects photographed can have it like 10..20 stops. The aperture and exp.times and ISO don't alter image contrast (dynamic range) much, just the exposure. Except that lens contrast is usually a bit lower at open apertures.

If you want to preserve the frog's parts from blowing to white, you should expose so that they don't (histogram peaks just before the right edge) and then pull up the shadows in post processing (shoot raw, preferably) so that they are to your liking (not too dark). If you don't want to shoot RAW, tou should use low contrast + highlight correction in the camera JPEG settings. At least with high contrast subjects like this.
ok, since im shooting Raw, then i could use post shadow processing in CS2?

remember this was in the shade. the really bad ones are in the sun. say bees on cream coloured or white flowers. My monitor is an older Samsung, maybe 8 years old and no longer shows white as white, more cream coloured actually.
It was calibrated for gama.
BTW, the lavender flowers seem to lose colour, I get that with anything lavender. Reds seem to be so red that no texture shows through. I was guessing this cameras sensor might be a little off, I don't know.
And to be honest I just don't know enough about " stops" yet and histograms. I just know that sometimes i simply have to shoot in what ever situation im faced with. I expected the camera to be able to expose the image close to reality
rather than having to recover data in PP. Hey, still learning here lol. Thank you for your reply.
10-23-2013, 04:05 AM   #13
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QuoteOriginally posted by dewolf Quote
ok, since im shooting Raw, then i could use post shadow processing in CS2?

remember this was in the shade. the really bad ones are in the sun. say bees on cream coloured or white flowers. My monitor is an older Samsung, maybe 8 years old and no longer shows white as white, more cream coloured actually.
It was calibrated for gama.
BTW, the lavender flowers seem to lose colour, I get that with anything lavender. Reds seem to be so red that no texture shows through. I was guessing this cameras sensor might be a little off, I don't know.
And to be honest I just don't know enough about " stops" yet and histograms. I just know that sometimes i simply have to shoot in what ever situation im faced with. I expected the camera to be able to expose the image close to reality
rather than having to recover data in PP. Hey, still learning here lol. Thank you for your reply.

Yes, you could process in cs2. Have u tried to have a look of your pictures with another monitor/computer? Because that monitor age and cream white thing really sounds quite alarming to me. Many times, when monitors get old they loose highlight gradiation altogether, so that there's not much tone separation. Also, gamma and other calibrations done by eye with calibration software or test images usually suck (just my experience), one might end up with display settings worse than out-of-box.. Regarding the histograms and f-stops, I'm sure u can find a lot of information as you keep shooting and learning

Btw. Here are some good test images:

White saturation - Lagom LCD test
Contrast - Lagom LCD test

How do those test images show with your display?
10-23-2013, 05:11 AM   #14
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QuoteOriginally posted by jaeaetee Quote
Yes, you could process in cs2. Have u tried to have a look of your pictures with another monitor/computer? Because that monitor age and cream white thing really sounds quite alarming to me. Many times, when monitors get old they loose highlight gradiation altogether, so that there's not much tone separation. Also, gamma and other calibrations done by eye with calibration software or test images usually suck (just my experience), one might end up with display settings worse than out-of-box.. Regarding the histograms and f-stops, I'm sure u can find a lot of information as you keep shooting and learning

Btw. Here are some good test images:

White saturation - Lagom LCD test
Contrast - Lagom LCD test

How do those test images show with your display?
welllll. ok i need a monitor lol

i can see the first 4 checkerboard patterns only
and even though i can barely see the second bar on the contrast, there is no difference between 30-32 what so ever.
In the bottom grey scale line no difference between 28-32.
So, before i go any further in testing the camera I will have to replace the monitor.
This old Samsung is 24", I have a newer 22" that is bright white. I will swap them out today and try those again.
Any suggestions on Gama calibration software. I don't have the funds for a spider.
I have tried EasyGama, and Calibrize.

Thanks

DeWolf
10-23-2013, 05:47 AM   #15
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QuoteOriginally posted by dewolf Quote
welllll. ok i need a monitor lol

i can see the first 4 checkerboard patterns only
and even though i can barely see the second bar on the contrast, there is no difference between 30-32 what so ever.
In the bottom grey scale line no difference between 28-32.
So, before i go any further in testing the camera I will have to replace the monitor.
This old Samsung is 24", I have a newer 22" that is bright white. I will swap them out today and try those again.
Any suggestions on Gama calibration software. I don't have the funds for a spider.
I have tried EasyGama, and Calibrize.

Thanks

DeWolf
may I assume by your comments about highlight and shadow correction that they do not function for Raw images ?. I have tried turning them off and on, and i believe if highlight is turned off i can not change the iso to anything below 200.
I have run into this several times and only worked out the problem recently. changing back to auto highlight correction restored by ability to use iso 100. I know the iso isnt the brightness issue, but it does make for cleaner images.
If the highlight and shadow feature do not work on Raw then i can ignore those settings ?

DeWolf
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