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07-08-2011, 05:23 PM   #1
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645D vs Nikon D3x, What should we test?

I'm delighted to be in possession of both the 645D as well as the Nikon D3x "Digital Masterpiece" this week, and we'll soon be conducting an in-depth comparison between the two, with a focus on pro features - and which is better for what purposes. We'll also be going over some of the 645D's highlights on the homepage

In the meantime, I'll be happy to entertain any questions about the cameras' features, or perform any user-requested tests in addition to what we have planned. I'm all ears!

Review is now posted: Pentax 645D Review and Comparison with Nikon D3x - Introduction


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07-08-2011, 05:30 PM   #2
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Two rather different cameras... Interested to see what will come out of this comparison.
07-08-2011, 06:26 PM   #3
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How did this comparison come about?
07-08-2011, 07:18 PM - 1 Like   #4
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?! huh?

Tongue firmly in cheek (I hope Adam doesn't mind some fun at his expense!):

"I'm delighted to be in possession of both the Pentax 6x7 as well as the Pentax Spotmatic II this week, and we'll soon be conducting an in-depth comparison between the two..."

or perhaps:

"I'm delighted to be in possession of both the Canon 5Dc (FF) as well as the Canon XT/350D (APS-C) this week, and we'll soon be conducting an in-depth comparison between the two..."

Comparing a FF 24x36 camera with a medium format camera?

Okay, "focus on pro features - and which is better for what purposes", I'm guessing this is a features-only comparison?

07-08-2011, 07:21 PM   #5
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I have a user test request: Can I be the user that tests it? It'd be amazing for my LEGO photo blog (see my thread in the Challenges/games/stories forum)
07-08-2011, 07:50 PM   #6
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QuoteOriginally posted by rhodopsin Quote
?! huh?

Tongue firmly in cheek (I hope Adam doesn't mind some fun at his expense!):

"I'm delighted to be in possession of both the Pentax 6x7 as well as the Pentax Spotmatic II this week, and we'll soon be conducting an in-depth comparison between the two..."

or perhaps:

"I'm delighted to be in possession of both the Canon 5Dc (FF) as well as the Canon XT/350D (APS-C) this week, and we'll soon be conducting an in-depth comparison between the two..."

Comparing a FF 24x36 camera with a medium format camera?

Okay, "focus on pro features - and which is better for what purposes", I'm guessing this is a features-only comparison?
In all fairness, though, the 645D doesn't have a typical MF sensor - it's kind of a cropped MF (44mm x 33mm) whereas MF sensor is usually 48mm x 36mm. And the D3x has a great reputation for landscapes, so it will be fascinating to see how much of an IQ difference there is between the two cameras.
07-08-2011, 08:25 PM   #7
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Back to Adam's thread, I would share a few suggestions:

- It is not just about bodies but also lenses. A real comparative review should try to get comparable-quality lenses, and not just the 'kit' lenses. For example, I would love to see a series of comparison with different types of primes for example. This might include/encompass third-party lenses.

- Could the review include some specific type of shootings? Like landscape, sports, BIF, portrait? For example I love to shoot some dynamic motion and actions. I rarely see some real-world comparison (incl. percentage of keepers).

- Can the review discuss backward compatibiity? This is a great asset of the K-series bodies.

Thank you for taking into account any of the above.
07-08-2011, 10:29 PM   #8
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I'd like to know which is better for sports photography...

07-08-2011, 10:47 PM   #9
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Both are flagships of competing brands...I think it is an interesting comparison.

An opening viewpoint on how each camera targets different purposes would ad credibility to the review. The Nikon (or K-5) might be a better pic for some types of photography where the 645 is designed for something different. There is a crossover for both, and depending on the photographer, that crossover could sway them towards one or the other.

100% crop would be interesting....

Dynamic range, tonal quality, especially for landscape would be interesting....
07-09-2011, 01:03 AM   #10
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Crop factor aside... on the resolution front the 645D is a beast!

But when we get to color, tonal and noise performance, the marks are just too close to call imo.
And so it won't be until the DR and AA MOIRE advantages kick in that the D3x will stand-out in the comparison(which is pretty bid deal imo).

Beyond that, we have form that will push the D3x along. To which I'd add, on location(and possible in the studio) the D3x works like a well oiled machine, not to mention having the tactical advantages of thethering, flash support and so on and so forth.

So for me, as much as I am a fan of the Pentax stuff. The D3x would be the ultimate rig for those looking to shoot big prints in a controlled setting and most likely in the field too! Even if I craved the resolution and uninhibited output of the 645D.

Last edited by JohnBee; 07-09-2011 at 01:28 AM.
07-09-2011, 03:54 AM   #11
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An interesting and often forgotten question is the ability to separate the subject from the background. The fact that the fastest lenses for Pentax 645D is only f/2.8 (f/2.4 if you use the P67 105 mm) on a cropped sensor, makes it even more interesting to compare to let's say a simple 50/1.4 on the D3X. Stop it down to f/2.2 and you've got the same DOF and probably a very good bokeh. Can that be matched by the Pentax lenses wide open, or do you have to stop them down as well? What does the bokeh look like?

The "crop factor" between 24x36 and 33x44 is only 1.27, so there's a lot to be had with f/1.4 lenses on the smaller format. The step from 33x44 to 6x4.5 (56x41.5 mm) is the same; 1.27, which makes up better for the "slow" lenses.
07-09-2011, 04:10 AM   #12
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QuoteOriginally posted by Makten Quote
An interesting and often forgotten question is the ability to separate the subject from the background. The fact that the fastest lenses for Pentax 645D is only f/2.8 (f/2.4 if you use the P67 105 mm) on a cropped sensor, makes it even more interesting to compare to let's say a simple 50/1.4 on the D3X. Stop it down to f/2.2 and you've got the same DOF and probably a very good bokeh. Can that be matched by the Pentax lenses wide open, or do you have to stop them down as well? What does the bokeh look like?

The "crop factor" between 24x36 and 33x44 is only 1.27, so there's a lot to be had with f/1.4 lenses on the smaller format. The step from 33x44 to 6x4.5 (56x41.5 mm) is the same; 1.27, which makes up better for the "slow" lenses.
Shallow DOF is not a problem. Here's an example:
https://www.pentaxforums.com/forums/pentax-medium-format-645-6x7-645d/128964-...lens-test.html

Anyone interested in a previous 645D/D3x test can see it here:
http://www.luminous-landscape.com/forum/index.php?topic=50977.0
07-09-2011, 04:15 AM   #13
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QuoteOriginally posted by JohnBee Quote
The D3x would be the ultimate rig for those looking to shoot big prints in a controlled setting and most likely in the field too! Even if I craved the resolution and uninhibited output of the 645D.
You're wrong. The resolution is everything for landscapes. The lack of AA filter is the win here. Although D3X sensor has wider DR, the 645D's CCD has better linearity and tonal reproduction.
BTW, I would like to see Distagon 21 vs Pentax DFA 25 comparison, although I'm almost sure the pentax will be better due to larger sensor.
PS Don't be a fanboy like many pentaxians here who's still trying to insist "there's no difference between FF and APS-C". The difference in IQ between even cropped MF and amateur/reporter 35mm format is easily noticeable as well as the difference between APS-C and FF.

Last edited by Emacs; 07-09-2011 at 04:20 AM.
07-09-2011, 04:56 AM   #14
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QuoteOriginally posted by Thomas Quote
Shallow DOF is not a problem. Here's an example:
https://www.pentaxforums.com/forums/pentax-medium-format-645-6x7-645d/128964-...lens-test.html

Anyone interested in a previous 645D/D3x test can see it here:
645D vs D3x
Sorry, but that example says nothing. You can get shallow enough DOF with an APS-C sensor at that distance without problem. What I want to know if what something like this would look like:



That's f/3.5 on 24x36 but I wouldn't mind the same DOF with the same sharpness, acutance and definition, but with a tad softer bokeh.
Mostly it's not the amount of blur that interests me, but rather its character and ability to draw your attention to the subject. You don't have to have very short DOF for that, but you'll want a good bokeh.

07-09-2011, 06:42 AM   #15
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I don't know what lenses are with it, but seeing comparising portrait's would be great.

Anything like this https://dl.dropbox.com/u/20195454/_S5Z8877a.jpg wich is made with K-5, 85mm, f8, iso160 would be great.

For D3x anything like 130mm would be great and for 645D 166mm (maybe 150mm lens is great for such a portrait).

A shallow dof portrait or situation with lots of contrast and colours would also be great.
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