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08-07-2014, 08:11 AM   #1
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so, has anybody actually compared 645D and 645Z output?

say, in terms of colour rendition, tonal range, noise … all the good stuff? I am looking for other opinions than my own.

08-07-2014, 08:16 AM   #2
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if someone will send me their 645Z, i'll be happy to compare.
08-07-2014, 08:17 AM   #3
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All I need is both cameras and a few lenses.
08-07-2014, 09:39 AM   #4
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QuoteOriginally posted by hsteeves Quote
say, in terms of colour rendition, tonal range, noise … all the good stuff? I am looking for other opinions than my own.
I think I've seen several posts (here? I think so int he "post your photos" thread, and elsewhere...) that have compared them. Supposedly the color rendition is not as good/accurate---although i wonder about this. Seems to me like it's still early days, cameras maybe aren't profiled yet, PP programs not fully dialed in, & etc. Also,I don't trust myself to gauge color accuracy, that's what color checker cards are for, aren't they? When I'm doing repro, there's no way I'd do it without one. Too many variables. So it's always adjusted in post.

I've also taken that online test to see how acute your eyes/brain are on this, and wasn't in the top percentile....I think I have a pretty fine color sense, but accuracy is a different kettle of fish.

08-07-2014, 10:06 AM - 3 Likes   #5
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QuoteOriginally posted by hsteeves Quote
say, in terms of colour rendition, tonal range, noise … all the good stuff? I am looking for other opinions than my own.
I'm curious to hear your opinion. I'm in the process of comparing them. If only 80+ hours a week of work stuff would go away, I could get a lot more fun stuff accomplished. #firstworldproblems

I'll be making more thorough comments including test files available at some point, but here's my short summary so far. First, the 645D still kicks butt... for image quality, it's in no way obsolete. (The 645Z however does trump it in terms of shootability, as we discussed before.) Anybody who can live with the slower shooting style imposed by the 645D, lack of Live View, etc. and is thinking about getting into the Pentax 645 digital system at the current low price of the 645D, go for it. The camera is still amazing.

Second, the 645Z files are unquestionably better in most regards, and this is immediately visible to me. The level of detail is better, though not staggeringly so as predicted from the modest increase from 40 MP to 51 MP. But the interesting thing is the level of detail is in fact better on every lens that I've shot so far... putting down the idea that the old 645 glass can't deliver enough resolution for the new sensor. Even at 51 MP on a cropped sensor, I don't think we're lens limited yet, even on A series glass, as long as it's good glass in the first place.

Noise is amazingly low up to ISO 800, and very workably low at ISO 1600 & 3200. Once noise comes on, it's still very grain-like. It looks a bit different to me than the noise from the 645D's CCD sensor, but still not objectionable... nothing at all like the stuff I had to deal with on my Canon 35mm bodies once noise was a factor on those exposures. The 645Z sensor also has excellent dynamic range. I haven't tried to quantify it in any way, but I have no worries that it's in any way deficient compared to the 645D; given the excellent dark tone noise performance and great highlights, there's a lot of great tonality in every exposure across a far greater range of ISO's than the 645D could ever dream of.

As an example, I just worked up a first cut of a 645Z image last night (will post it shortly). I shot a 5-exposure bracket @ ISO 100 and was going to HDR the sequence. That's because I routinely push & pull exposure across different tones with lots of curves adjustments, etc. and I want the cleanest source file to start with. But on examination I decided not to bother with HDR this time around. I pulled the 2nd darkest exposure which had just about the best "ETTR" histogram, and started out by running the lightest noise reduction possible in Topaz DeNoise. But the original file was already so clean that even in the darkest tones, the noise reduction had no visible effect. However in one place in the highlights, the NR did smooth the tones enough to introduce some slight posterization once I applied my curves, B&W layers, etc. So I re-started the post work and eliminated the NR in the beginning -- no posterization. Once I completed everything, I decided it actually looked a little too smooth so I threw some extra grain in.

Final factor I'll comment on for now -- in the few cases where I shot the 645D and 645Z side by side, I definitely do see colour rendition differences in Adobe Camera Raw with the Adobe Standard DNG profiles selected for both cameras. The 645D files initially render more colourfully, while I'd say the 645Z are more neutral.

I haven't delved any deeper into the differences yet, and have not yet fixed an opinion whether one is more desirable or "right" than the other. The 645D's DNG profile is old by this point in time, and it's hard to say whether they both were produced with the same degree of rigour and both were baselined against the same standards by whomever developed them. They look different enough to me that I'd say they are not tracking the same baseline for colour reproduction. But this is something I'll be looking at more closely as I go along. For all the other IQ factors, I'm satisfied so far that the 645Z upholds all the high standards I came to expect with 645D files.
08-07-2014, 11:43 AM   #6
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sorry Royce but I am inherently too lazy to do detailed comparisons. I am just enjoying the shooting Z experience so much more than the D and the thing that bugs me is that most of the physical differences were in place to be adapted to the D when it came out. C'est la vie.
08-07-2014, 11:50 AM   #7
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QuoteOriginally posted by hsteeves Quote
say, in terms of colour rendition, tonal range, noise … all the good stuff? I am looking for other opinions than my own.
I've tested 645z for 12 days, sometimes with my 645d.
1. Colour of 645z is good enough, but 645d can be better at ISO 100 and 200, may be 400, but not at 800 and 1600.
And of course only if you have a photo, because 645z can catch much more than 645d.
2. Tonal range of 645z is 14 f-stops, 645d has 11.5 f-stops. And "black & white" photos of 645z are better too.
3. Noise of 645z is much better, because it has modern CMOS inside, not CCD. ISO 800 is great, ISO 1600 is very good, ISO 3200 is very good too, but only if your exposure is correct. If not, and you need correction in RAW-converter - you will have to use noise reduction a little bit.
4. Autofocus, fps, recording files on an SD card and so on - 645z is much faster, new processor Prime III is a real beast.
5. 86000 rgb pixels for exposure metering are better then 77 grey zones of 645d. 645z is better, especially against sun.
6. 30% more pixels of 645z are clearly better.

If I will have both of them - I will use 645d with ISO range locked on 100-400 only, and for not-moving objects only
645z is much more versatile camera.
08-08-2014, 06:04 AM   #8
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i've tried it and compared it at iso 200.. they both look the same! same color, same contrast, same everything.. the only difference is that the 645Z has more dynamic range.. so in high contrast situations where the 645D would blow out highlights and lose color information ,the Z would retain about 1 or 2 stops more of color.. i really thought i would see some difference between the two but surprise that Pentax was able to more of less keep the "look" the same between two cameras..

08-08-2014, 07:34 AM   #9
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Thanks to both of you for that helpful information. I work with the Pentax 645D and love the colour rendition, so very interesting to hear the comment of acarlay on colour. I also work with A and FA lenses, with which I am very happy (mainly prime lenses although I have two FA zooms). So all in all very good to hear your positive comments on the 645D, so perhaps I can live without the advantages of the 645Z for the time being, although I suspect I will take the plunge in time. Once you get into medium format, it somehow makes photography more challenging but much more satisfying when you get it right. Regards, jmb
08-08-2014, 07:52 AM   #10
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I have the opportunity to pick up another Z body - deeply discounted. Getting another body was not in my budgetary plans but I will not see this price in awhile (going to have to go on the generic mac&cheese for a long while and lower the winter thermostat down to maybe 10C) so I was just considering the justifications. Personally, the handling alone would drive me to a Z over a D.
08-08-2014, 08:04 AM   #11
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Not that I'm trying to spend your money for you but if I could afford a second Z right now, I'd do it already based on what I'm seeing so far. With only a single Z, if it goes down I'm going to feel the loss immediately as I start using it for more types of work that the D can't readily handle. But equally, I still love the files out of my D's when they are usable in a situation. I've got to look a bit more to understand where the colour differences I'm seeing are really coming from...
08-08-2014, 08:22 AM   #12
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QuoteOriginally posted by Royce Howland Quote
Not that I'm trying to spend your money for you but if I could afford a second Z right now, I'd do it already based on what I'm seeing so far. With only a single Z, if it goes down I'm going to feel the loss immediately as I start using it for more types of work that the D can't readily handle. But equally, I still love the files out of my D's when they are usable in a situation. I've got to look a bit more to understand where the colour differences I'm seeing are really coming from...
my D is going and some other stuff. Like you, I have to work around work and sometimes the days are a little long out here on the flatlands.
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