[Yamanobori]

Perhaps you can add to the conversation and tell us what you are going to do and why.

[kenyee]

The Nikon is a more general tool. The Pentax is a more specific one. Perhaps the choice is simple after all....

That's what it basically comes down to.
And back to the audio analogy...it's like buying an Oppo-95 vs. a Krell drive/decoder combo. They both mostly get you there...one is a bit better, but it's up to you to decide whether the extra performance is worth the bucks The Oppo-95 has is a bit more flexible, but the audio isn't as good, sometimes.

I'd do as someone suggested...borrow/rent a D800 (you can actually rent them already and they're not that expensive). Borrow the 645D again from your friend. Take the same landscape shots (what you have sold for money) and use them as you would want to use the camera normally. Print them out at full size. Crop and print at whatever size you sell for. Let your eyes decide. Let your customers decide (don't tell them which print is which). Come back and tell us what the result is

That's the methodical/analytical way to do it.

The other way is whatever you want by the end of the week and if you don't like it, switch

[Makten]

I agree with you on the sensor size. SO much complaining that the APS-C is not good enough, that they all need a bigger FF sensor. But then suddenly questions arrise if the smaller sensor of the D800 is good enough over the bigger sensor of the 645D.

It's not the APS-C sensor that's not good enough. It's the lenses that are too long and/or too slow because they were made for a larger format, just like those for the 645D.
Then of course cost is a significant factor. An APS-C pro camera with pro lenses isn't much cheaper than ditto FF (35/1.4 on APS-C equals 50/2 on FF), while the 645D is muuuuuuch more expensive.

[Yamanobori]

It's not the APS-C sensor that's not good enough. It's the lenses that are too long and/or too slow because they were made for a larger format, just like those for the 645D.
Then of course cost is a significant factor. An APS-C pro camera with pro lenses isn't much cheaper than ditto FF (35/1.4 on APS-C equals 50/2 on FF), while the 645D is muuuuuuch more expensive.

??? The 55mm lens made for the film 645 is an f/2.8 just like the new 55mm made for the 645D. Since when did f/2.8 become too slow? The Zeiss 18mm lens is an f/3.5 whereas the 25mm 645D lens is an f/4, not exactly slower in any significant way. The lens that gives me 76 degree angle of view on the 645D is exactly the right focal length to give me a 76 degree angle of view which for me makes an ideal wide. Naturally, the crop factor bias is simply picking sides (as well as showing a fuzzy understanding of focal length)--I could also claim that it makes my telephotos better.

Your expectation for price parity across formats is surprising since you have so much experience of different formats.

Folks, you are not going to pick any winners here. In order to do that you will need to frame an argument in an artificial way and assume the "quality" you choose to frame your argument has some natural superiority.

[Pål Jensen]

It's not the APS-C sensor that's not good enough. It's the lenses that are too long and/or too slow because they were made for a larger format, just like those for the 645D.
Then of course cost is a significant factor. An APS-C pro camera with pro lenses isn't much cheaper than ditto FF (35/1.4 on APS-C equals 50/2 on FF), while the 645D is muuuuuuch more expensive.

Not true. A 35/1.4 do not equal a 50/2; as they will not give the same exposure at the same DOF. The 50mm will also not yield the same DOF at the smalles aperture (as long as we talk Pentax lenses).
FF is MUCH more expensive than APS; thats why APS outsells FF with considerable margin.

[chicagonature]

I would never use the 14-24 for landscape photography; too much flare....
Otherwise I agree that the biggest problem for the Pentax 645 cropped system is the wide angle issue: $5000 and 1kg is too much in all respects. Having said that, I guess the coming 28-45 (or whatever its pecise focal lenght range is) may solve the problem at least partially.

However, one should consider that if you buy into the Pentax 645 system you buy into a system that outperform FF. By owning the lenses you have access to a camera system that goes beyond and will stay beyond FF.

From what I've read, the flare mainly occurred in tests when direct sunlight entered the lens from an angle outside the lens' field of view. For instance, on Photozone (http://www.photozone.de/nikon_ff/447-nikkor_afs_1424_28_ff?start=1), the lens tester said that sunlight coming from slightly behind the lens produced flare. Well, in that case, "Just block the light with your body, silly!"

Do you have experience with this lens?

[chicagonature]

Well, it has always been know that art is primarily an economic problem. It is always about getting the best deal.

I know it is really fashionable for landscape photographers to use ultra wides, but the OP may not want to use the 25mm. I am not sure a 500mm will be that great for landscape either.

The price for medium-format lenses has more to do with production/sales volume and tolerances than simply material costs.

Ultra wide angle lenses give a very different look and experience that other lenses cannot and solves some creative problems.

(The 500mm lens is simply an example of the financial savings using older, yet still very good, lenses.)

[Pål Jensen]

From what I've read, the flare mainly occurred in tests when direct sunlight entered the lens from an angle outside the lens' field of view. For instance, on Photozone (Nikkor AF-S 14-24mm f/2.8G ED (FX) - Review / Test Report - Analysis), the lens tester said that sunlight coming from slightly behind the lens produced flare. Well, in that case, "Just block the light with your body, silly!"

Do you have experience with this lens?

If the lens flare when the sun is outside the field of the lens the sun will flare horribly when the sun is in the frame.
Super wide zooms are generally not well suited for landscape phography because they are all prone to flare (the wider and faster the worse all things equal). Even the Pentax 16-50 is not well suited. If I had bought a D800 I wold have chosen the 24-70 + a 20mm.....

[Yamanobori]

Ultra wide angle lenses give a very different look and experience that other lenses cannot and solves some creative problems.

Every focal length gives a different look and experience to other focal lengths. Focal length happens to be very important in lens choice. Ultra wides are simply less common. Personally, I do not find ultra wides very interesting for landscapes--to much focus on foreground at the expense of background. I find it is difficult for photographers to get passed the "wow neat" factor of ultra wides and actually make an interesting picture. Kind of like swing-lens panoramic cameras and fisheye lenses. I think that ultra wides are a bit of a crutch and give pat solutions to a landscape--it is so much harder to actually decide what should be in an image rather than just including everything. IMVHO. YMMV.

[Ryan Tischer]

If the lens flare when the sun is outside the field of the lens the sun will flare horribly when the sun is in the frame.
Super wide zooms are generally not well suited for landscape phography because they are all prone to flare (the wider and faster the worse all things equal). Even the Pentax 16-50 is not well suited. If I had bought a D800 I wold have chosen the 24-70 + a 20mm.....

Certainly not every landscape shot that I take has the sun glaring into it...in fact most don't. For some situations the flexibility of a zoom is best...like when you don't have the option of 'zooming with your feet' and don't know which focal length will 'perfectly' fill your composition and can't haul around more than three lenses. I can think of many times where a sudden change in light didn't leave me much time to adjust and just being able to zoom, instead of resetting tripod legs on an uneven surface saved enough time to make the difference between capturing and not capturing the shot with the 'magical light' that was happening before me.

Other times, a prime is best, like say, shooting mesa arch sunrise in canyonlands, where you need to arrive several hours before sunrise just to get a spot and have plenty of time to contemplate how you want to set-up your composition. And, of course, the flare!

I used to shoot a lot of landscapes with my 5d mark II and 16-35 f/2.8L II...now I have a 645D with the 35mm A...I LOVE the clarity and less flare problems, but still missing the convenience of the zoom...not that I plan on going back to the Canon system at anytime in the future!

I went to the 645D because I do a lot of large prints and wanted better clarity, and making panos often isn't always a solution for me, given that I shoot a lot of moving water, waves, etc. on Lake Superior.

I guess the point that I'm trying to make is that to each their own, even among landscape shooters.

[Makten]

??? The 55mm lens made for the film 645 is an f/2.8 just like the new 55mm made for the 645D. Since when did f/2.8 become too slow?

55/2.8 on the 645D eqauls a 43/2.2 on 24x36. If you want short DOF, that's not very impressive. There are plenty of f/1.4 lenses for the 24x36 format, and from that perspective f/2.8 might be "too slow".

The Zeiss 18mm lens is an f/3.5 whereas the 25mm 645D lens is an f/4, not exactly slower in any significant way. The lens that gives me 76 degree angle of view on the 645D is exactly the right focal length to give me a 76 degree angle of view which for me makes an ideal wide.

And the Pentax is four times the price of the Zeiss.

Naturally, the crop factor bias is simply picking sides (as well as showing a fuzzy understanding of focal length)--I could also claim that it makes my telephotos better.

Your expectation for price parity across formats is surprising since you have so much experience of different formats.

Folks, you are not going to pick any winners here. In order to do that you will need to frame anYeah, argument in an artificial way and assume the "quality" you choose to frame your argument has some natural superiority.

Yeah, if your pockets are deeeeeep and full of gold, just buy the 645D (and a tripod). But if you want to shoot mostly handheld and/or get the blurriest background, a D800 is a better choice.

[Makten]

Not true. A 35/1.4 do not equal a 50/2; as they will not give the same exposure at the same DOF.

Exposure is irrelevant when comparing different formats. The mentioned examples collects the same amount of light; photons, at a certain shutter speed. ISO 100 on APS-C is NOT equivalent to ISO 100 on FF.

The 50mm will also not yield the same DOF at the smalles aperture (as long as we talk Pentax lenses).
FF is MUCH more expensive than APS; thats why APS outsells FF with considerable margin.

I found that FF was a lot cheaper than APS-C, since I could use old, manual focused and fast lenses on the D700, while their equivalents on the D300 would cost a fortune.

[Pål Jensen]

Exposure is irrelevant when comparing different formats. The mentioned examples collects the same amount of light; photons, at a certain shutter speed. ISO 100 on APS-C is NOT equivalent to ISO 100 on FF.
.

You do not buy a format over another in order for them to collect the same amount of photons so why do this pointless excecise? You buy a format over another because they are different and do not collect the same amount of photons; of course 100ISO and APS is not the same as 100ISO on FF but that is the main reason for choosing FF in the first place. The same exposure is important cause they may give different images and it is the image (if you are aphotographer and not a armchair theorist with nothing better to do) you want regardless of format; ie. one may give motion blur.
95% of all people buy a fast lens in order to let in more light for exposure freedom, particularly in low light, and ease of focus. Only a few buy a lens for exact DOF wide open and no one have fixed ideas of what Exact DOF you must get from a lens at a certain number of stops from wide open which is basis for the equivalency nonsense.
Different formats have different DOF at the same magnification, focusing distance and aperture value. Equalizing them is meaningless because you can from this construct any case of one format over the other by choosing arguments that fits your preferences.
Besides paper thin DOF at F.1.4 is totally irrelevant for landscape photography (and 99% of photography in genereal)

[Yamanobori]

55/2.8 on the 645D eqauls a 43/2.2 on 24x36. If you want short DOF, that's not very impressive. There are plenty of f/1.4 lenses for the 24x36 format, and from that perspective f/2.8 might be "too slow".

Now, you are changing the subject from speed in relation to different formats to DoF. Yes, 35mm has had faster lenses than medium-format. But likewise, they are not slow. And certainly 35mm has f/4 and f/5.6 lenses as well. You are cherry picking your facts.

As far as DoF, that really is a red herring. There are so many ways to get a narrow DoF. Also, lenses, particularly fast lenses, don't work very well wide open. But I guess if you want blurry, wide open may even do that for the foreground too. And most of the photographers I know shoot at specific apertures and so at any given aperture a larger sensor will have less DoF than a smaller one. Please don't come back with the D800 will now have more DoF. Sensor size, aperture, object distance, and focal lengths are just variables you can arrange in anyway you want but won't prove any type of superiority to any system.

And the Pentax is four times the price of the Zeiss.
Yeah, if your pockets are deeeeeep and full of gold, just buy the 645D (and a tripod). But if you want to shoot mostly handheld and/or get the blurriest background, a D800 is a better choice.

Yes, the 645D cost more. Just as medium-format and large-format film is more expensive than 35mm film. But please don't imagine that somehow $3000 is cheap and the poor can now enjoy FF cameras. (BTW, I am far from "rich" in any way you can imagine. I make sacrifices for the tools I work with and am careful with my money. I am very fortunate to have what I have.)

Now, you probably don't realize this, but medium-format cameras can easily be handheld. Even cameras like a Pentax 67 can be handheld. I use my 645D handheld practically all the time. So in that regard there is no difference between the 645D and D800. BTW, you may not have heard, but the internet "experts" have declared that you cannot handhold the D800 and get sharp images--you "need" to put that on a tripod too if you want to "get the most" out of the sensor.

[Yamanobori]

Exposure is irrelevant when comparing different formats. The mentioned examples collects the same amount of light; photons, at a certain shutter speed. ISO 100 on APS-C is NOT equivalent to ISO 100 on FF.

Sorry, that model does not work. The f-number still describes illumination at the sensor plane. Many have tried to equate collection area (entrance pupil) to exposure, but most fail because they ignore magnification which define how those photons are distributed.