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09-16-2016, 10:59 AM   #1
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Recently bought Pentax 645D, concerned about it's dynamic range

Hi, I just bought a pretty cheap Pentax 645D body with 3 lenses, FA 75mm 2.8, FA 45mm 2.8 and FA 200mm 4.0.
And I've been doing some tests shots, first to see if anything was wrong with this second hand camera, with only 3,000 actuations.

I love the resolution and IQ, even the color, but I have found that it regularly clips the highlights, specially in bright colors, other than white, like bright yellow. It seems to have very little room in the upper part, for a correctly exposed picture, the highlights in daylight are almost always clipped if it's bright color or white.

Is this normal? I know it won't be like film and that I could shoot in bright daylight and expose for the shadows and get stunning results, but even in some how overcast conditions sepecular highlights hold no information, if the object is burger color.

And don't see how people are using it for landscape other than using bracketed exposures and post process or very controlled light environments with grad filters and polarizer.

Should I do that, treat it like it was slide film?

Thanks in advanced for any response.


Last edited by Pablo Villegas; 09-16-2016 at 11:27 AM.
09-16-2016, 11:21 AM   #2
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Congrats with the purchase.
Did you try https://www.pentaxforums.com/content/645dmanual.pdf page 62?

Edit.
For landscape photography I shoot in RAW and then post processing...ND filter works too...

Last edited by Vasyl; 09-16-2016 at 11:29 AM.
09-16-2016, 11:23 AM   #3
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Digital sensors, unlike film, have their dynamic range extended in the left side of the histogram (signal buried in the dark). Exposure should be set so that wanted details in highlights are preserved, dynamic range is recovered by pulling the left part of the histogram.
09-16-2016, 11:31 AM   #4
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QuoteOriginally posted by Pablo Villegas Quote
Recently bought Pentax 645D, concerned about it's dynamic range
Not sure how much digital experience you have. You might post that as it will better allow people to help you.

The answers will be completely different depending on whether you know how to handle digital or not. If you do and are still having problems then perhaps there is an issue with the camera or the settings. If you have no digital experience then as @biz-engineer states digital is very different and you need to expose for the highlights and pull up the shadows in post.

You might look to see if the previous owner had left some exposure compensation set.

09-16-2016, 11:42 AM   #5
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I have a digital camera where the exposure compensation is easily adjusted without my knowledge. I have learned now to pay attention to it but in the beginning I was having similar problems with perceived dynamic range. When I finally tracked down the problem I found I had 3 stops of exposure compensation dialed in.

I do own and use a 645D and love its colors. If I expose my photographs to keep my highlights, I always get great exposures in post processing. I turn on the blinkies on the high side but I don't even bother with the low side when I am doing landscapes. Of course what I see in my display screen on the camera doesn't always look the best, but that happens a lot with digital. Most of the time I am only looking at the histogram anyway.
09-16-2016, 11:51 AM   #6
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QuoteOriginally posted by Pablo Villegas Quote
Should I do that, treat it like it was slide film?

Thanks in advanced for any response.
Exactly. With digital you should expose as you would for slide film to avoid clipping. And some colors clip early, like yellow and possibly also red (depends on the sensor).
09-16-2016, 11:52 AM   #7
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Thank you all


Custom image is only for JPEG, isn't it? I'm shooting RAW.

It might be the meter in the camera that's over exposing...
It just feels like it has a lot less room for overexposure than my fujifilm X100... And that should not be the case.

And because you have no live view, and it takes forever to actually see the image, it's hard knowing when thos highlights will be blown... I guess I'm gonna have to get used to shooting with it, but it does feel a lot less frogiving than my other digital cameras.

---------- Post added 09-16-16 at 12:01 PM ----------

I have some experience in digital still photography, and a lot of expirience in motion digital cinematography, I'm a DOP.

You can see in this test picture, that the yellow on top of that toy plane is completly lost! And I can't understand why, it's even an overcast day. Yeah, the matrix meter on the camera might have compensated for the shadow background, but still, that shouldn't be enough to make all the detail gone. _IGP3994.jpg | Pablo Villegas | Flickr

On the next picture those oranges on the foreground are almost clipped, or the speculation highlights are clipped... And it's the same conditions. https://flic.kr/p/LQQqVW

I don't believe that has ever happened with any of my digital cameras (Canon 500D, Fujifilm X100) and they both have lower dynamic range than the Pentax 645D.

Last edited by Pablo Villegas; 09-16-2016 at 12:02 PM.
09-16-2016, 12:08 PM   #8
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QuoteOriginally posted by Ole Quote
Exactly. With digital you should expose as you would for slide film to avoid clipping. And some colors clip early, like yellow and possibly also red (depends on the sensor).
When I switched over to digital the rule of thumb I read somewhere was exactly that. Treat as if shooting slide film and expose for highlights. You can be amazed out how much shadow detail you can pull out.

09-16-2016, 12:24 PM   #9
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The yellow in the underbelly shadow of the plane behind the propeller is very well exposed yet the top is overexposed. It looks like your camera is exposed for the shadows, not the highlights.

I agree that the overall scene does not seem to be overly contrasty. Is your spotmeter turned on or are you using matrix metering for that photograph?

If it is matrix metering than I would try dialing in a bit of compensation and see how much it takes to bring the photo back into proper exposure. If you have more than one lens, try a couple while doing this. This might give you an idea of how your meter is working.

Also turn the camera to manual and use a hand held meter to see what happens with metering external to the camera.
09-16-2016, 12:42 PM   #10
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QuoteOriginally posted by Pioneer Quote
The yellow in the underbelly shadow of the plane behind the propeller is very well exposed yet the top is overexposed. It looks like your camera is exposed for the shadows, not the highlights.

I agree that the overall scene does not seem to be overly contrasty. Is your spotmeter turned on or are you using matrix metering for that photograph?

If it is matrix metering than I would try dialing in a bit of compensation and see how much it takes to bring the photo back into proper exposure. If you have more than one lens, try a couple while doing this. This might give you an idea of how your meter is working.

Also turn the camera to manual and use a hand held meter to see what happens with metering external to the camera.
Thanks, that was with the matrix meter... And yeah it might be overexposed about a stop because of the shadow background...

But a stop is enough to blow highlights on an overcast day?

Or my camera is defective.

Nothing was done to the pictures. But I can't recover the highlights.
09-16-2016, 12:57 PM   #11
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Can you share the picture in raw?

Edit.
I would try to shoot the same scene but with different exposure settings first:
- multi-segmented
- center weighted
- spot

Last edited by Vasyl; 09-16-2016 at 01:09 PM.
09-16-2016, 01:05 PM   #12
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Not home right now... I'll have to find where to upload the file. But sure. Tonight.

Thanks
09-16-2016, 02:53 PM   #13
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I'm not concerned by the picture you shared. The overall balance looks good and if you had to provide a straight exposure of that scene it's a reasonable compromise.

It may be an overcast day but those are still specular highlights. If I shot that scene on slide film I would expect similar results.

I've shot a lot of Pentax DSLRs but not the 645D. Older Pentaxes metered VERY conservatively to protect highlights. As a result many inexperienced photographers and reviewers complained that out-of-the-camera images looked dark and flat. But they processed very well, giving great results for those who shot raw and worked with the files.

I feel like at some point around the K5 / 645D Pentax got tired of the criticism and shifted the metering bias on Matrix to allow brighter images at the risk of blown highlights. It didn't matter to those who used exposure compensation or metered manually - and everyone else got a bit brighter image OOTC.
09-16-2016, 04:08 PM   #14
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QuoteOriginally posted by filmamigo Quote
I'm not concerned by the picture you shared. The overall balance looks good and if you had to provide a straight exposure of that scene it's a reasonable compromise.

It may be an overcast day but those are still specular highlights. If I shot that scene on slide film I would expect similar results.

I've shot a lot of Pentax DSLRs but not the 645D. Older Pentaxes metered VERY conservatively to protect highlights. As a result many inexperienced photographers and reviewers complained that out-of-the-camera images looked dark and flat. But they processed very well, giving great results for those who shot raw and worked with the files.

I feel like at some point around the K5 / 645D Pentax got tired of the criticism and shifted the metering bias on Matrix to allow brighter images at the risk of blown highlights. It didn't matter to those who used exposure compensation or metered manually - and everyone else got a bit brighter image OOTC.
Thanks, I know that slide film is like that, but slide film has a 5 stop dynamic range, not 12, like this camera.

I'm gonna shoot some test tomorrow of the same scene with my 3 lenses and a Sekonic lightmeter. And with two other digital cameras, something doesn't seems right.
09-16-2016, 07:43 PM   #15
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Here's the RAW DNG file... Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.

it's very strange, because the shot its not even overexposed, if anything it's underexposed.
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