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06-15-2008, 07:57 PM   #46
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QuoteOriginally posted by jeffkrol Quote
Actually comparing the histograms is a bit revealing:
Adding a 1/2 stop EC to the one would equal the other, though it seems a straight EC would only move that tighter blob to the right. They would still look different until you spread the histogram out a bit........

OR adjusting the contrast/gamma;
Jeffkrol,

Your conclusions about the A/F/FA lenses seems to go along with mine especially looking at the sample histograms you provided.

It seems to me that the DA lenses have been designed specifically to try to compress the histogram data into a more managable level.

As you later point out, this may also have to do with the way that the sensor captures light with regards to the micro lenses and other criteria etc.

There is much more to this than the supposed self confessed "experts" on this forum would have us believe and it is definitely a design consideration, not a design fault. I think you will also find that this is one of the reasons why Pentax is replacing all the FA lenses with DA versions so that they follow this desired exposure pattern.

As for the so called under exposure issue, I am of the opinion that one needs to learn to use their equipment and know how exposure works. A camera does not "know" what is required of it other than to render a scene 18% grey(film) and 12-13%(?) grey digital capture.

The propensity of Pentax to be concerned with the preservation of highlights may of course be somewhat negated if the Samsumg/Pentax patent becomes a reality:
https://www.pentaxforums.com/forums/pentax-news-rumors/27554-interesting-sams...plication.html

06-15-2008, 08:54 PM   #47
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Interesting idea Lance, it explains the seeming emphasis of my FA lenses on the high mids as opposed to the more balanced rendering of the DA's. Also the FA lenses tend to handle the highlights and blown highlights in a harsher manner than DA lenses.

Over all my DA lenses give far better color and tone than my FA's (admittedly I don't own too many of either!!) which is not surprising as they are designed for digital capture.

Each camera maker makes choices as to how its products work. Pentax has opted to meter to preserve a fair amount of highlights. If you don't like this strategy you can use positive exposure compensation or you can switch to Canon and have brighter images with more blown highlights.
06-15-2008, 09:37 PM   #48
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I agree with arbutusq’s comment that “Pentax has opted to meter to preserve a fair amount of highlights.”---this is yesterday's news. Overall, I am delighted with Pentax’s philosophy and with my K20, but I am not going to call it perfect and I’m not going to deny it has room for improvement. I picked it two and a half months ago, after extensive research, because it was the best choice I could make. Indeed, I invested over 2 and a half grand into the system already. I know a keeper when I see one.

Underexposure, particularly for preservation of highlights, can be a good thing. I can deal with underexposure. However, because of metering inconsistency, dealing with underexposure becomes more of an issue than it should be. The problem can be exacerbated if you use many lenses, thereby opening the doors to metering complexity, through the dizzying permutations of adjustments which need to be kept record of. I can make music with the camera, but feel the instrument needs a bit of fine tuning.

I do not see the point in posting images here; clearly, many minds are already set on the issue. Metering inconsistency does not reveal itself in one image, EXIF data or not. I do not wish to argue—I know what my camera does. There are much more fruitful things to do with time, like capturing great shots with the K20.

Thanks to all who extended a helping hand.


Regards,

Ernest



Humanity subdues inhumanity as water subdues fire.

Mencius 6A:18.
06-15-2008, 11:11 PM   #49
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QuoteOriginally posted by arbutusq Quote
Interesting idea Lance, it explains the seeming emphasis of my FA lenses on the high mids as opposed to the more balanced rendering of the DA's. Also the FA lenses tend to handle the highlights and blown highlights in a harsher manner than DA lenses.
I am glad that you see what I am talking about.

QuoteQuote:
Over all my DA lenses give far better color and tone than my FA's (admittedly I don't own too many of either!!) which is not surprising as they are designed for digital capture.
I actually prefer the colour and tone rendering of my FA's(especially the FA* lenses and Limiteds) but prefer the exposure results from the DA's as they can more easily keep the histogram within the bounds of the exposure range of the sensor. Having said that, the K20D seems to have excellent headroom for highlights when compared to the K10D.

The thing is, I have just learnt to live with the slight differences of their exposure which means that I need to dial in about 1/3rd less exposure with the FA lenses as compared to the DA lenses where the DA lenses are pretty much correct exposure in most "normal" situations.

QuoteQuote:
Each camera maker makes choices as to how its products work. Pentax has opted to meter to preserve a fair amount of highlights. If you don't like this strategy you can use positive exposure compensation or you can switch to Canon and have brighter images with more blown highlights.
I completely agree, here. I have *never* found the exposure of *any* of my Pentax cameras to be a problem but quite the contrary and found the exposure results excellent.

Pentax could have left their metering results as they get from the FA lenses, but opted, I do believe, to alter this with the DA lenses and dialled in about 1/3rd to 1/2 a stop less exposure thus ensuring that the highlights do not get blown.

If Pentax left their metering results like they would have obtained with the FA lenses, then I think many would have said that the results are more in keeping with Canon and Nikon and we would hear more of highlight clipping.

06-16-2008, 04:25 AM   #50
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QuoteOriginally posted by Syb Quote
Oh come on Peter!
The question is not about being amateur or pro, it is just relevant. Why does Pentax' Savox have so few AF-points compared to the other DSLR brands? I would like to know, too...
Hang on - are we talking about metering or focusing here?

SAFOX still has more cross sensors than most AF systems, and certainly as many AF points as other cameras in the same price range.
06-16-2008, 05:52 AM   #51
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In looking through many of the posts (I admit not all) the only question that should be addressed is, for a given level of light, does the metering correctly measure that light, and set the camera parameters accordingly to achieve the exposure level the designers want.

I believe the answer to that question is yes.

The question of whether this takes 1 segment, 40 segment or 100's of segments is nothing related to metering accuracy at all, but as to whether we want the camera to make an educated "guess" as to what an optimum exposure might be.

To meter correctly only takes 1 point, and an understanding of the scene, and the limits of contrast, lighting and the camera's sensor.

Do you benefit from this, I don't know. By using the canikon approach, you are leaving yourselves totally in the hands of how their designers, or programmers think you want an image to appear. That is certainly not metering either.
06-16-2008, 06:19 AM   #52
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QuoteOriginally posted by *isteve Quote
Hang on - are we talking about metering or focusing here?

SAFOX still has more cross sensors than most AF systems, and certainly as many AF points as other cameras in the same price range.
I think sometimes "Less Is More" as long as performance and quality is concerned. I think my low end bottom-of-the-line (at its time) MZ-30 has a more sensitive *single* line sensor (one and only one) than any one used as the central sensor in any Pentax DSLR. It has better low-light responsiveness, the AF is moving more decisively, even if it is compared to the Pentax DSLRs when only central AF point is chosen. The yellow light front focusing symptom is much less too (similar to my MZ-S and my Canon 5D, which the effect is minimal and thus neglectible, Vs the dominant effect of *any* Pentax DSLR).
06-16-2008, 06:30 AM   #53
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QuoteOriginally posted by Lowell Goudge Quote
By using the canikon approach, you are leaving yourselves totally in the hands of how their designers, or programmers think you want an image to appear. That is certainly not metering either.
Not really, metering and exposure has some well-established standards to follow, which the light capturing device should reproduce the scene as far as possible within its limited dynamic range and as close as what human eyes could see on a output device (also with a limited range, aka the colour space, than reality).

I think artistic presentation would be another thing. To make a picture looks darker and brighter is decided upon the photographer for how he/she wants to make the picture looks like but at the first place the camera should *reproduce* things accurately and consistently as said above, for a given scene.

06-16-2008, 08:18 AM   #54
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QuoteOriginally posted by RiceHigh Quote
Not really, metering and exposure has some well-established standards to follow, .
Which Canon "didn't follow" per se:

So that leaves Canon with only the possibility of achieving their target
value of Hu/Hsat by using a non-standard rating of ISO sensitivity—a
rating that is about 0.74 that which would be determined under ISO
12232. In other words, the sensitivity that is designated “ISO 100” by
Canon would probably be rated at about ISO 135 under ISO 12232.

doesn't make them bad, only different.....
http://doug.kerr.home.att.net/pumpkin/Exposure_Calibration.pdf
06-16-2008, 09:34 AM   #55
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The argument made within the first few replies are silly at best..

Regarding AF points.. Single point AF is the fastest and most accurate, next fastest and most accurate is 9-11 points and finally, the slowest and least accurate is 40 to 50 points.. So, why do manufacturers tout so many AF points? Marketing gimmicks.. Do they have a use however? Yes. More points allows for better tracking across the FOV. Does better tracking mean better accuracy? No. What do Canon factory Pro-shooters recommend? Disable multiple point AF and stick with single-point or 9-11 point when shooting with Canon's flagship models. Why? They get the best results by doing so.

As far as metering goes.. The Pentax metering on the K10D works flawlessly. Select single point metering and point it at lit light bulb. The shot will be brightest in the center and quickly fade out to black without blowing the highlights. Next, choose center-weighted metering and point it at the same lit light bulb, the shot will not be blown out but will include some more light around the light bulb. Finally, select multi-segmented-metering, point it at the bulb and you'll see the entire scene properly exposed with no blown highlights..

I've tested this time and time again and each time it works perfectly when using a lens that at least has an 'A' setting on the lens. Set your camera to green mode, point at a lit bulb, take a shot for each metering type and see what I mean.
06-16-2008, 10:48 AM   #56
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QuoteOriginally posted by RiceHigh Quote
Not really, metering and exposure has some well-established standards to follow, which the light capturing device should reproduce the scene as far as possible within its limited dynamic range and as close as what human eyes could see on a output device (also with a limited range, aka the colour space, than reality).

I think artistic presentation would be another thing. To make a picture looks darker and brighter is decided upon the photographer for how he/she wants to make the picture looks like but at the first place the camera should *reproduce* things accurately and consistently as said above, for a given scene.
RH at best I think we can agree to disagree.

Regardless of camera maker, no sensor has the ability to see the dynamic range of the eye, at least yet.

Therefore, for any given sensor, and its own dynamic range, someone has to decide what they want exposed and at what level. To achieve this requires only one metering point.

Everything else, all other points etc are based upon the camera "interpreting" the scene based upon programmers inputs for how much they want to over or under expose any given scene with a wide range of exposure based upon how big the light and dark areas are, and where they are located in the viewfinder.
06-16-2008, 12:46 PM   #57
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QuoteOriginally posted by RiceHigh Quote
Not really, metering and exposure has some well-established standards to follow, which the light capturing device should reproduce the scene as far as possible within its limited dynamic range and as close as what human eyes could see on a output device (also with a limited range, aka the colour space, than reality).

I think artistic presentation would be another thing. To make a picture looks darker and brighter is decided upon the photographer for how he/she wants to make the picture looks like but at the first place the camera should *reproduce* things accurately and consistently as said above, for a given scene.
RiceHigh speaks TRUTH! (At least in the first paragraph, ignoring the bit about colour space (not related directly to exposure).) The problem is what a reasonable interpretation of "reproduce" is. As we should all know by now, the human eye/brain has a far greater dynamic range than the best of current sensors. We should also know that currently available computer displays and printing systems support a range narrower than most cameras.

So...we should all be very thankful that we EVER get results that are even CLOSE to what we originally conceived in the minds eye.

Steve
06-17-2008, 10:17 AM   #58
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RH, there are some links for you below to post sensational article in your blog that 40D underexpose. If that many references not enough you can sure google for more, this is only from first page...

By the way my 300d almost never gets exposure right, it is always automatically corrected in RAW processing software and I never really paid attention to that as I've never shot jpeg.

====================
Canon EOS 40D DSLR digital camera review
However, there is one black mark in the otherwise blot free copybook that is the 40D: the metering. The evaluative metering system on the 40D seems predisposed to underexpose by around a stop, itself quite common on Canon’s I’ve tested over the years. However, the balance of the metering system is – or at least seems – biased to underexpose on most shots, particularly high contrast scenes where on each occasion it would underexpose heavily.
====
Brand new 40D underexposing, help appreciated: Canon EOS 40D/30D/20D/10D Forum: Digital Photography Review
Just unwrapped my new 40D. I am doing some test shots, indoors in available incandescent lighting. Shootiing with brand new 50 1.4 and 24-70 2.8. ISO at either 400 or 800, Aperture Priority. It seems like both lenses are exposing identically 2/3 stops underexposed. I also shot in all 4 modes, evaluative, spot, center weigte, partiall...same results with both lenses.

===============
Canon 40D vs 20D high ISO test The World According to Roland
I also agree with the others that the 40D image is slightly underexposed maybe by 1/3 stop. If exposure compensation was used on the 40D to bring it up to the same luminance as the 20D image, the noise would increase further again.

==========
DCRP Review: Canon EOS-40D
My only photo quality complaint is that the the 40D has the tendency to underexpose. I took hundreds of photos on my vacation, and the majority of them were underexposed by 1/3 or 2/3-stop. I'm sure a lot of this had to do with the crummy UK weather, but I wanted you to at least be aware of this possibility.
06-17-2008, 10:22 AM   #59
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QuoteOriginally posted by Andrews Quote
RH, there are some links for you below to post sensational article in your blog that 40D underexpose. If that many references not enough you can sure google for more, this is only from first page...

By the way my 300d almost never gets exposure right, it is always automatically corrected in RAW processing software and I never really paid attention to that as I've never shot jpeg.

====================
Canon EOS 40D DSLR digital camera review
However, there is one black mark in the otherwise blot free copybook that is the 40D: the metering. The evaluative metering system on the 40D seems predisposed to underexpose by around a stop, itself quite common on Canon’s I’ve tested over the years. However, the balance of the metering system is – or at least seems – biased to underexpose on most shots, particularly high contrast scenes where on each occasion it would underexpose heavily.
====
Brand new 40D underexposing, help appreciated: Canon EOS 40D/30D/20D/10D Forum: Digital Photography Review
Just unwrapped my new 40D. I am doing some test shots, indoors in available incandescent lighting. Shootiing with brand new 50 1.4 and 24-70 2.8. ISO at either 400 or 800, Aperture Priority. It seems like both lenses are exposing identically 2/3 stops underexposed. I also shot in all 4 modes, evaluative, spot, center weigte, partiall...same results with both lenses.

===============
Canon 40D vs 20D high ISO test The World According to Roland
I also agree with the others that the 40D image is slightly underexposed maybe by 1/3 stop. If exposure compensation was used on the 40D to bring it up to the same luminance as the 20D image, the noise would increase further again.

==========
DCRP Review: Canon EOS-40D
My only photo quality complaint is that the the 40D has the tendency to underexpose. I took hundreds of photos on my vacation, and the majority of them were underexposed by 1/3 or 2/3-stop. I'm sure a lot of this had to do with the crummy UK weather, but I wanted you to at least be aware of this possibility.
I'll have to look into that. You know Canon did recieve some flak because of their "iso fudge" and seemed to be dropping down to the "normal standards" others are following. I suppose this underexposure flak is due to them now adhering to the iso standards. DP reviews "iso sensitivity" test will confirm somwhat, though I'm not enamoerd w/ their testing.
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