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05-02-2010, 07:18 AM   #1
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A comment regarding the K7 sensor and flash results

Firstly, after trolling through a large number of similar threads which are universally hijacked into "which camera is better", let me state I am not out to compare different brands.

I've recently bought an AF-360 to go with my K7. I've been shooting a bunch of flowers recently, and have generally been quite impressed. I'm still learning about flash, so please don't savage me for the examples posted.

My point is this. The K7 seems to thrive when (and only when) it gets absolutely correctly exposed pixels. If not, it seems fairly ordinary. Please don't take this the wrong way, as I find the K7 to be *the* easiest SLR (film or digital) to get acceptable results out of. I really mean this.

However it seems only to *Shine* (and it can!) in terms of recorded image IQ when the exposure is correct. My question is related to why this is:
I've noted this effect when shooting both RAW and JPG. I do not use the shadow correction, but have noted the highlight correction to be useful in some settings (contrasty light).

1) Is it a CMOS vs CCD question? My *IST DS and K200D were arguably better in daylight (ISO 100-400) in terms of fineness of results, but not as good for getting acceptable results across the frame, all of the time.

2) Is is a metering question? I usually add 0.3 EV to account for the slight noisy pixels I get as the cam works to prevent blown skies. I find the flash exposures (P-TTL and Auto) to be dead on (although focusing accuracy is another issue).

3) Any other comments? I do find that there is quite a lot of posterisation in the skies, and noise in the shadows with contrasted scenes.

4) Is it due to being in daylight and getting better saturation from the flash on contrasted days?

Examples (both are shot with the 21mm):

Good:

Not so good:

Another not so good (albeit at ISO 800), shot with the 55-300mm:



Last edited by Clarkey; 05-02-2010 at 07:24 AM. Reason: posting removed formatting.
05-02-2010, 07:39 AM   #2
hcc
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Thank you for the post. It would help if you indicate:
- which lens(es) you used,
- if the same happened with all lenses, or with some lenses,
- what mode you used on the K-7, and
- do you shoot in RAW or JPEG?

I have had some problem similar to your 2nd shot with my DA18-250mm, but I have had much less problme with my Voigtlander Nokton 58mm under identical conditions. With my K-7, I use the P-mode primarily and JPEG 6 Mp*** with minimum in-camera PP.

Like yourself, I look forward to read the posts from more experienced Pentaxians...
05-02-2010, 08:00 AM   #3
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Could you please rephrase what your question actually is?
I don't get it.
It is clear that a correctly exposed image is always better than a not correctly exposed one.
05-02-2010, 09:29 AM   #4
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Original Poster
Sorry folks.
As indicated above, the lenses used above are the 21mm and the 55-300mm. I shoot RAW and JPG, and have encountered the same issue. Likewise across different lenses. Obviously the limited lenses give me more IQ due to their increased sharpness/ contrast/ colour etc.

Program, AV, TAV or manual modes all seem to give the same effect.

To use an analogy, in film days, I guess I am talking exposure lattitude. I am commenting that the K7 appears to shoot more like slide film than modern negative film: when an exposure is correct, it is great. Where is is even slightly off, I get average results. It seems that this effect is more prevalent on the K7 than either the K200D or the *IST DS I have owned previously.

Again, this is a comment rather than specific questioning, however I wrote in the questions above to try and prompt some responses along my line of thinking.

05-02-2010, 09:31 AM   #5
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QuoteOriginally posted by blende8 Quote
Could you please rephrase what your question actually is?
I don't get it.
It is clear that a correctly exposed image is always better than a not correctly exposed one.
Agreed. At the end of the day, a correctly exposed image will bring out the best of any combination of lenses and recording medium.

But I knew that already. What I am interested in is the K7's apparent requirement for *perfect* metering to give excellent results.

Last edited by Clarkey; 05-02-2010 at 06:28 PM. Reason: Clarifying reason for thread
05-03-2010, 07:43 AM   #6
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The middle shot with the dominate sky......the "posterisation" in the upper third of the sky looks more like JPEG compression artifacts to me. If you started from RAW, try processing it at 16 bits/channel and see if it's still evident.

Regards.
Terry
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