[Fauxton]

(long reply)
If you are shooting in low light the 645Z is better than the Nikon 850, the only other camera I'd consider for your skill level. See attached screenshot from photonstophotos.net Note that this graph uses camera ISO not computed ISO. As Pentax camera ISO is very close to computed ISO the graph for the 645Z is likely fairly accurate. Nikon camera ISO is less than computed ISO (the 810 camera indicates 100 ISO when the computed ISO is really 75) so the difference in the graph below is likely greater than what you see.


You already have lenses and you know what you want to add. The Pentax 645Z can also provide more detail than the 850Z although it may be a toss up at anything printed less than 30x40. Below I've included a screenshot (from dpreview) of cameras close to the expected performance of the 850 - the two high resolution Sonys and the Nikon 810 for comparison. The 645Z has better resolving capability against all of those and I expect that the 850 would be fairly similar to either Alpha's only having 46MP to 42MP.

Lenses are another thing to consider closely. The Pentax 645 system has some very very good lenses as you know. And the thing about smaller formats is that the lenses need to perform by a factor of their crop factor in order to say they perform similarly. For example the lwph of a 4/3 lens has to be twice as high as that of a 35mm lens to be considered equal in terms of equivalent performance resolving power. The same thing holds true for the 35 mm to 645 performance. A 35mm lens needs 1.7 times the lwph of a 645 lens to be considered equal performance resolving power wise. You have that performance in the 645 lens system, despite Nikon's and third party lenses in the Nikon mount there are few lenses in the Nikon system that come close in performance to the 645 system.

Also the system itself need be considered. The 645 simply doesn't have the same options as the 35 mm systems particularly Nikon's and Canon's. Some things easily accomplished on their systems just won't be easily accomplished on the 645Z. But you already know what those are having a 645D and only you can assess if that will affect your work.

Simply put the 645 system is a superset of smaller formats. With your skill, that system puts you in a different league than just about anyone on this forum. Marketing wise these two things could well be the differentiator that will get you the work where others will not. And that is a powerful position to be in marketing wise.
Good luck!
Jim

Attached Images

   

[texandrews]

To me, if you already have the 645 lenses, then it's a no-brainer: get the Z. If you're made of money, get the Z and the Nikon, but get a K1 also (because you can use your 645 lenses with an adapter, with a Cambo Actus, maybe with a Rhinocam, & etc...).

If you need a camera to do double duty, stills and video, then it's the D850.

The D850 looks to be a terrific camera on paper. We'll see how it does in actuality. Nikon has had a bit of a spotty record lately...

[Gerd]

Subject. high ISO performance:

I have the D810, the 645Z and the Fuji GFX.

The D810 is a power at ISO 64 in the studio. But with higher ISO performance it has nothing to counter the 645Z and the GFX. You can see the difference as from ISO 800. It remains to be seen where the D850 of the ISO performance will actually stand. You should also consider the PixelPitch. The D810 has a pixel pitch of 4.87 μm. The new D850 should have a PixelPitch of 4.35 μm (Sony A 7 RII of 4.5 μm). This will make it the D850 not really easy to make very good high ISO achievements. I would be glad if it would be on the level of the D810. For comparison the 645Z / GFX have a PixelPitch of 5.32 μm. If you want to have really good picture quality, the small pixels of the D850 also restrict the choice of lenses at Nikon.

Subject. Flash:
The 645z has fewer possibilities/performance with the flash than the Fuji GFX and the D810 (D850 presumably synonymous). The new lightning triggers have enabled the 645z a lot, but unfortunately there are many deficits. For example - the 645Z can not easily flash on the second curtain (this is annoying at moving images in many situations). The 645Z tries to calculate the flash power with a TTL device (which is necessary for HSS and SuperSync). For this purpose, it requires minimal aperture, shutter speed, and distance measurement. If one of these factors is missing, the 645Z will stop the flash. What the case is with manual lenses without aperture transmission. The GFX does not. It always triggers TTL even if the aperture value is missing. And it also triggers the flash "always" without TTL device. That goes with me to 1/160s without which a shading or a curtain in the picture is to be seen. The manufacturer/flash support is unfortunately with Nikon and Fuji significantly better. What I find very bad, but Pentax itself has since made no decisive step.

I can not draw a clear summary.
In the studio (almost) 100% decides the light I set. The differences between the formats/cameras are then only to be seen, if one knows exactly what one must pay attention. The situation is different in ambient light or mixed light. Since the 645Z and the GFX are in my opinion clearly advantage. The tonal values are however the small medium format cameras - with me - always better as well as the details. I use the GFX with all Pentax 67/645 lenses as well as many Mamiya RZ / RB / 645 lenses. The camera lens combinations deliver excellent results. But clearly with the reference in the GFX (with the Pentax / Mamiya lenses) at the time without AF.

Greeting Gerd

[skierd]

I just remembered that Ming Thein did a great blog post evaluating the 645Z and D810 when the z came out against the 645D and the Hasselblad CFV39.

Review: The Pentax 645Z, part II: compared to the 645D, Nikon D800E and Hasselblad CFV-39 – Ming Thein | Photographer

[Pablo Villegas]

Subject. high ISO performance:

I have the D810, the 645Z and the Fuji GFX.

The D810 is a power at ISO 64 in the studio. But with higher ISO performance it has nothing to counter the 645Z and the GFX. You can see the difference as from ISO 800. It remains to be seen where the D850 of the ISO performance will actually stand. You should also consider the PixelPitch. The D810 has a pixel pitch of 4.87 μm. The new D850 should have a PixelPitch of 4.35 μm (Sony A 7 RII of 4.5 μm). This will make it the D850 not really easy to make very good high ISO achievements. I would be glad if it would be on the level of the D810. For comparison the 645Z / GFX have a PixelPitch of 5.32 μm. If you want to have really good picture quality, the small pixels of the D850 also restrict the choice of lenses at Nikon.

Subject. Flash:
The 645z has fewer possibilities/performance with the flash than the Fuji GFX and the D810 (D850 presumably synonymous). The new lightning triggers have enabled the 645z a lot, but unfortunately there are many deficits. For example - the 645Z can not easily flash on the second curtain (this is annoying at moving images in many situations). The 645Z tries to calculate the flash power with a TTL device (which is necessary for HSS and SuperSync). For this purpose, it requires minimal aperture, shutter speed, and distance measurement. If one of these factors is missing, the 645Z will stop the flash. What the case is with manual lenses without aperture transmission. The GFX does not. It always triggers TTL even if the aperture value is missing. And it also triggers the flash "always" without TTL device. That goes with me to 1/160s without which a shading or a curtain in the picture is to be seen. The manufacturer/flash support is unfortunately with Nikon and Fuji significantly better. What I find very bad, but Pentax itself has since made no decisive step.

I can not draw a clear summary.
In the studio (almost) 100% decides the light I set. The differences between the formats/cameras are then only to be seen, if one knows exactly what one must pay attention. The situation is different in ambient light or mixed light. Since the 645Z and the GFX are in my opinion clearly advantage. The tonal values are however the small medium format cameras - with me - always better as well as the details. I use the GFX with all Pentax 67/645 lenses as well as many Mamiya RZ / RB / 645 lenses. The camera lens combinations deliver excellent results. But clearly with the reference in the GFX (with the Pentax / Mamiya lenses) at the time without AF.

Greeting Gerd

Thanks!

This is what I'm affraid with the 645Z, that I won't be able to do some things with flash and HSS, I was unaware that HSS only works with AF lenses, I have a Cactus V6ii for the 645D, but have never tried to use it with manual lenses, only the 3 FA I have and found no problem in my limited testing.

I do love the feel, the sound and even the weight of Medium Format, I shoot a lot of Medium Format film for personal stuff, but it's very expensive, per picture. I would love to stay in Medium Format digital, but I'm affraid I will be limited by some things, like I am now with the 645D. And going the GFX route is more expensive for me. I would need to spend just $6,500 for the body. Having to sell my 645D and lenses just to get a single lens or maybe two. The only reason I have a 645D is a found a bargain here in Mexico, a 645D body(3,000 actuations) and 3 FA lenses (45mm,75mm and 200mm) for $1,500 USD.

That's why I'm considering the 645Z, it will be the least expensive for me, since I only need the body and two relatively cheap lenses(120mm Macro, 150mm 2.8) around $700 USD each.

I have a lot to think, but have the time to do it, I still need to see if I can make it into the market and if it's worth paying that much in gear. For my personal work I would keep the 645D and add a FF 35mm, and keep shooting all of them.

[skierd]

You can get the 75 or the 135 leaf shutter lenses which will get you high speed sync up to 1/500, but they aren't autofocus.

I believe A lenses (and therefore all 645 lenses) transmit aperture data to the body.

I'd love to find a deal on the 645D like that!

[Gerd]

You can get the 75 or the 135 leaf shutter lenses which will get you high speed sync up to 1/500, but they aren't autofocus

The LS lenses can be an alternative (I use them occasionally), but it depends on what is required. For example, Can you with 1/500s with aperture open not really against the sun flashing.

I believe A lenses (and therefore all 645 lenses) transmit aperture data to the body.

That's right.

But I also use the 67mm SMC Pentax 105mm F2.4 which is a very nice portrait lens. Or even a Hasselblad 110mm F2. Since the 645Z refuses the TTL function, because the aperture is missing. And I can not work with HSS or SuperSync.

Greeting Gerd

[normhead]

I'd only consider an D850 for sports. The K-1 is overkill most of the time.I went K-1 instead of 645z after a note from someone who just sold their 645z. The 645s kill your creativity. With no shake reduction, it's harder to shoot on the fly, you need a tripod for everything...set up times are ridiculous. In your situation I'd definitely go K-1 (although I would check to see that every lens I'd ever need is available from Pentax first. That's the big weakness of Pentax is the limited lens line up. I'd keep my 645D for the studio and use the K-1 in the field.

The actual need for a D850 type camera depends entirely on your ability to make use of it's (to my mind) overkill in it's AF system. If it can make you money go for it. Some of us are happy to pay less, have a slightly slower AF system, get practically the same images, and put the extra money in the bank or buy lenses with it. And I get so many of my shots in informal settings, a camera without in body shake reduction is a definite no go.

[moroccanimager]

'With no shake reduction, it's harder to shoot on the fly, you need a tripod for everything...set up times are ridiculous.'

It is harder but it can be done. I crank up the shutter speed and ISO if necessary to 3200max and the only drawback is buffer times. Attached a gallery of dancers/singers in low light.


https://essaouiraimages.viewbook.com/album/guedra

[normhead]

'With no shake reduction, it's harder to shoot on the fly, you need a tripod for everything...set up times are ridiculous.'

It is harder but it can be done. I crank up the shutter speed and ISO if necessary to 3200max and the only drawback is buffer times. Attached a gallery of dancers/singers in low light.


https://essaouiraimages.viewbook.com/album/guedra

I'm so old these days, "harder" stresses my shrinking attention span. And it's not going to get any better.

[btnapa]

I'd definitely go K-1 (although I would check to see that every lens I'd ever need is available from Pentax first.

+1. Totally agree with @normhead's assessment. I shot plenty of portrait work with my K5IIs and K3 and they did just fine. K1 came in handy for landscapes. For portrait work, K1 is almost an overkill. Where the K1 shines besides the additional resolution is the FF sensor for shallower depth of field which is desirable for portraits. I do not own the 645Z but have shot with it on a few occasions. I Love the camera but for max flexibility, I like the K1 better. If I shot landscapes exclusively, then the 645Z or the GFX might have an advantage.

With all that said, if I had the budget, I would get the 645Z and the K1. As mentioned earlier the 645 lenses are perfectly usable on the K1 (with an adapter). I own a few legacy 645 lenses. As a matter of fact the A120 macro is my go to lens for studio product photography work on my K3 and K1.

[texandrews]

With all that said, if I had the budget, I would get the 645Z and the K1. As mentioned earlier the 645 lenses are perfectly usable on the K1 (with an adapter). I own a few legacy 645 lenses. As a matter of fact the A120 macro is my go to lens for studio product photography work on my K3 and K1.

+1 for btnapa. I am shooting both the Z and the K1 professionally now; together they are an excellent team for careful, stills work. The Z is great except for ultra wide (the 25 is scarce and expensive), where the K1 comes in. The HSS problem of the Z is now resolving itself. I have the 645 to K adapter, but haven't needed (or had time!) to use it yet, so it's good to hear it's working out for btnapa---thanks for that.

BTW, just a comparison note: at work we are fully committed to Canon (there is one Nikon D810 in photo lab) across 3 sub departments. It makes sense for everyone to use the same gear, and the video works out well, especially the touch screen niceties of the 5DmkIV. But in low light I'd much rather be using either my Z or K1, and my experience with the 5DmkIV's AF in low light underwhelms me a lot, given how much everyone slams Pentax. Just sayin'. By low light, I mean shooting in a museum, so it's not that doggone low....practically in use I see no marked difference between the makes.

[btnapa]

+1 for btnapa.

@texandrews, good to hear from you. Although I am committed to the Pentax platform, I like the 850 specs, especially the 4K video. We have to wait and see how the 4K aspect of the camera performs. It is really getting tougher to decide between systems. Since you have had both 645Z and K1 and have shot them at the same time, you are one of the few people on the forum who can actually comment on the quality of the two cameras first hand.

I know it is too much to ask but I would love to see 645Z and K1 images from the same subject matter, same ISO settings, similar focal length to see if they are really that different.

Thanks

[Fcsnt54]

@texandrews, good to hear from you. Although I am committed to the Pentax platform, I like the 850 specs, especially the 4K video. We have to wait and see how the 4K aspect of the camera performs. It is really getting tougher to decide between systems. Since you have had both 645Z and K1 and have shot them at the same time, you are one of the few people on the forum who can actually comment on the quality of the two cameras first hand.

I know it is too much to ask but I would love to see 645Z and K1 images from the same subject matter, same ISO settings, similar focal length to see if they are really that different.

Thanks

There is some detail differences between the two, but I can add to the 645z and k-1 pictures as well. now as far as focal length, are we saying same lens, or equivalent field of view? Cause i can help with both.

[btnapa]

Cause i can help with both.

@Fcsnt54, thanks a bunch for the offer. What I meant was the equivalent focal length so that we are not comparing a wide shot with a long shot. An approximate similar focal length set to the same f-stop (f8-11 or so) to take the lens quality issue out of the equation somewhat. Thanks.