[larkis]

I have a bit of a dilemma. I own the 645D system and a few lenses in the normal and telephoto focal range, but I need a wide angle for some of the shooting I like to do once in a while. With the D800 being quite a nice camera I'm wondering if it's a better choice to get a D800 body and a wide angle nikon lens. The price for the camera and a lens would probably end up being close to the price of the pentax lens alone. The 645D still provides a nicer image, but considering there are not a lot of reviews of the SMC Pentax-DA 645 25mm F4 AL [IF] SDM AW that I can find it's a hard choice to make.

I'm not sure of going with a D800 and a zeiss wide angle would get me to about the same spot as the 645D with the 25mm offering. The added benefit of going with a D800 would be a backup camera body that is in a comparable resolution range and also the faster autofocus/handling for street shooting.

Any constructive comments for the pro's and con's would be welcome.

[Emacs]

I'm not sure of going with a D800 and a zeiss wide angle would get me to about the same spot as the 645D with the 25mm offering.

Test samples with 25mm has quite strong CA. CZ Distagon 21 (which is about the equivalent of 25mm on 645D) is much better in this regard. The resolution of this zeiss is also very high. I even doubt if 25mm is clearly better performer (sharpness, distortions, abberations at the most used apertures).

[Anvh]

Which 25mm, Pentax has 2 now.

From what i see here the DFA is quite stellar though besides the CA but you can fix that in PP quite easily and make a profile for it,
https://www.pentaxforums.com/lensreviews/SMC-Pentax-D-FA-645-25mm-F4-Lens.html

[larkis]

Which 25mm, Pentax has 2 now.

From what i see here the DFA is quite stellar though besides the CA but you can fix that in PP quite easily and make a profile for it,
SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW Reviews - 645 Wide-Angle Primes - Pentax Lens Reviews & Lens Database

It is this one: SMC Pentax-DA 645 25mm F4 AL [IF] SDM AW (basically the re released one) unless I can still find the other one in Canada.

[Anvh]

There is a D-FA and a DA version.
the DA version doesn't work on full frame 645 camera's
https://www.pentaxforums.com/news/pentax-re-releases-645-25mm-f4-lens.html
The price should be the same.

btw downloaded the PEF files of the DFA and with lightroom 4 it's just one click to enable CA removal and it's gone so i ain't worried about that.
Photo is from the edge and off an out of focus area so don't judge the sharpness on this one.

[tuco]

If you do more than landscapes, the D800 + lens will give you more picture variety and handheld extreme low light shooting for the buck.

[Emacs]

btw downloaded the PEF files of the DFA and with lightroom 4 it's just one click to enable CA removal and it's gone so i ain't worried about that.

This correction has its cost. It reduces resolution, so +1 point for relatively CA-less distagon and D800.
Although I would recommend to wait for future Leica M10. If M10 will have Sony 36Mp sensor, it will be a better choice than D800 + CZ 21 when used with Super Elmar 21.

[Anvh]

Resolution staid the same...

[Yamanobori]

This correction has its cost. It reduces resolution, so +1 point for relatively CA-less distagon and D800.
Although I would recommend to wait for future Leica M10. If M10 will have Sony 36Mp sensor, it will be a better choice than D800 + CZ 21 when used with Super Elmar 21.

The 18mm Distagon would be more of an equivalent to the DA 25mm. The 21mm Distagon is a nice lens, but it does suffer from flare.

Also, I doubt you could show a loss of resolution in CA correction.

The M10 might be a nice camera, but I fail to see how this would actually save the OP money as the body alone would be more than the DA25mm.

[Zygonyx]

If cost is your priority, i am not quite sure but the Nikon can be an excellent choice, but i would rather use the FX 14-24mm f/2.8.

In my pentaxian case, i just wait to use more intensively my new 645 D-FA 25/4, both on 645D and 645NII, where it's 15mm focal equivalent is an interesting extension albeit on film only...

[Anvh]

The D800 is of course the better all-rounder but since the OP is also looking at the 645D he probably know the up and downsides of both formats.

About the handling, the 645D does not feel very large in your hands, it feels like a FF dslr.

[desertscape]

So Pentax produces an expensive 25mm with problematic CA? Not good. If this is like most wide lenses with this problem, it is lateral chromatic and that can't be reduced by stopping down like longitudinal chromatic. The Nikon is looking better and better.

[Yamanobori]

So Pentax produces an expensive 25mm with problematic CA? Not good. If this is like most wide lenses with this problem, it is lateral chromatic and that can't be reduced by stopping down like longitudinal chromatic. The Nikon is looking better and better.

But Pentax does not produce a 25mm 645 lens with problematic CA, so you are OK.

[westmill]

The D800 is a simple and logical choice. At the end of the day, its a backup camera and allows you more scope for your work.
Billboard size prints would still not be as good as your 645 due to the larger sensor but file sizes must be almost the same.
I would see it as the D800 could open more new pic possabilitys you may not have considered with 645.
Thats just my point of veiw anyway.

[Ryan Tischer]

As a landscape shooter that does a fair amount of hiking, I'm going to go with the 25mm, as another camera body + lens weighs more (and takes up more space in my bag) than just the 25mm. Another consideration, if applicable to your style of photography, is just getting the 35mm prime (assuming you don't already have it) and a nodal slide. Then you could photostitch to a wider angle...of course, this doesn't always work well with moving objects, like waves, and sometimes fast moving clouds, and puts a CPL filter out of the question