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08-17-2020, 07:53 AM   #16
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QuoteOriginally posted by BarryE Quote
Texandrews, I've considered the Theta, the trouble is my agent is likely to buy his own copy soon as all he has do is plonk it in a room, hide out of sight and fire the camera from his phone. Then get his staff to put video tours together. I fear it doesn't take too much skill.
You are correct, that's what the agents will start to do. So, now comes the value add---what you do with the Theta captures after capture. I haven't done it yet, but will start experimenting in about a month: Garden Gnome software (or something like it, but it was recommended to me by another museum photographer).
QuoteQuote:
The argument against HD video is that it shows warts and all, whereas stills can be used to enhance a property.
Precisely, hence the real need for value add. And Covid will recede eventually, and /or we will all have to come to terms with mitigating risk during the remainder of the pandemic. Don't get me started about my own country's imbecilic response. As for Brexit, IMO that was shockingly stupid, even given pernicious EU bureaucracy. Can't help you there, got our own idiocy to deal with.

QuoteQuote:
PS works a treat with continuous lighting - I've used it a lot. It's not so good with flash. Pity ...
I need to work with P/S---just haven't because of the Z and being quite busy. Interesting about the flash aspect...

And indeed "good enough" is one of the biggest hurdles these days business wise. Even at the museum it's becoming a problem.

08-17-2020, 08:08 AM - 1 Like   #17
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If you're getting it for personal projects, get a Pentax 67, and shoot portra. It'll get you stop worrying about megapixels, and you'll definitely get the MF look with the big 6x7 negatives.
08-23-2020, 06:20 AM - 2 Likes   #18
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QuoteOriginally posted by Tjompen1968 Quote
The difference between APS-C and FF is small, FF to MF is big.
This statement is not supported by physics.

The difference between formats can be expressed by the so-called "crop factor" which can be calculated as the square root of sensor size quotients. When the aspect ratios between sensor formats are equal then the crop factor describes the quotient between sensor diagonals but since APS-C/FF vs MF have different aspect ratios, the aforementioned calculation approach is preferable.

The crop factor from APS-C to FF is 1.5 (can be slightly higher, depending on the exact sensor dimensions; for Canon it is actually 1.6).
The crop factor from FF to full-MF is 1.64. Hence, the difference between FF and full MF would be rather comparable to the difference between APS-C vs FF as opposed to being "small vs big".

However, the 645Z (and 645D) use a crop-MF format.
The crop factor from FF to crop-MF is just 1.29. Hence, the difference between Pentax APS-C and Pentax FF is bigger than the difference between Pentax FF and Pentax MF.

This means that everything else being the same (here, in particular sensor technology), the jump from APC-C to FF is more noticeable than that from FF to MF in terms of IQ.

Sensor technology has slightly improved from the days of the 645Z to when the K-1 was introduced which is why the 645Z does not even provide the theoretical .37 stop advantage in dynamic range but only a .13 stop advantage (measurements by DxOMark).

So in terms of dynamic range, I'd say it would be pointless to use a 645Z in favour of the K-1, and personally I'd call the advantages the 645Z has in terms of tonal range and colour sensitivity marginal.

In summary, I wouldn't go for a 645Z if I were after higher IQ but I'd completely understand if someone preferred to work with a bigger viewfinder and preferred the handling of the 645 system overall.
08-23-2020, 08:12 AM   #19
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QuoteOriginally posted by Tjompen1968 Quote
I did some testing and on the still life I used for testing the K-1 with PS was very close to the files from the 645z. Would say they are very, very close. I did both upscaling and
downscaling of the sizes to match. Would be very difficult to se any difference in a blind test.

When not shooting still life, well then the 645z is what I choose pretty much every time it is landscape or portraits on the agenda.

* I use the K-1 and PS when I digitize 135-film. That is better than the 645z due to the drop in MP shooting 2:3 with 4:3
Thanks for your 2 posts here. That's interesting but logical about the film digitization.

I haven't done it yet, but your K1 P/s vs 645Z test is something I somewhat expected (and has been mentioned by others, although I think your "test" is more valid as you have both cameras)---happy for me in the event I need something from the K1mkII that I can't get with my Z kit FL-wise.

How I wish the Z had P/S !

08-23-2020, 08:25 AM   #20
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QuoteOriginally posted by Class A Quote

So in terms of dynamic range, I'd say it would be pointless to use a 645Z in favour of the K-1, and personally I'd call the advantages the 645Z has in terms of tonal range and colour sensitivity marginal.
Well, some points:
  • What is marginal to one person could be significant to another
  • The "marginal" tends to become less so in more difficult/critical situations.
  • The "marginal" isn't important to most photography---the vast majority of photography types and photographs.
  • I live in the "marginal", however.
  • I know what my eyes have told me definitively; I also know that in good light these differences do indeed become vanishingly small. I shoot in a lot of low light situations with very demanding expectations---here's where the "marginal' is, in this case, based on my observations.
  • While I'm not going to say the testing that has been done is wrong, DXO has had more than one critic. In fact, just about every tester has had more than one critic, and the only one who has successfully answered them I think is Jim Kasson---but he has not tested any Pentax gear.
  • I maintain that current testing isn't testing some things completely or at all. I think that's been true for just about everything outside of photography as well.
The poster above I believe has correctly identified the point at which there is almost no difference at all between K1 files and 645Z files. The method to get there also has its issues.
08-23-2020, 09:05 AM - 1 Like   #21
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QuoteOriginally posted by Tjompen1968 Quote
Have you shot the 645z?
No, but I don't need to in order to compare sensor sizes. Only the size differences (and sensor technology) are relevant for what the OP was after.

QuoteOriginally posted by Tjompen1968 Quote
The crop factor is 0.82 or 0.73 or 0.79 depending on how you calculate since the sensor is 4:3 and not 2:3.
I mentioned the problem of the different aspect ratios in my post and stated that going by surface area makes most sense (if one is after an IQ comparison).
You stated reciprocal values, which is fine if you take FF as the standard. However, these values don't make it easy to compare the size difference jumps, hence I always provided the factor needed to proceed from the smaller to the larger format.

QuoteOriginally posted by Tjompen1968 Quote
The surface area of the MF sensor is 1437 mm square vs FF sensor 862 mm square i.e 1.67 times the surface area.
Yes, but one needs to take the square root of 1.67 in order to arrive at the crop factor. Once you do that you get the number I stated (which represents a smaller jump in image size, compared to the APS-C -> FF step).

QuoteOriginally posted by Tjompen1968 Quote
Same calculation for APS-C to FF gives us 367 mm square i.e 2.35 times the surface area.
Again you should take the square root of that number to arrive at the crop factor.

Note that using the crop factors helps your view, because comparing the sensor size increase (2.25-2.35 for APS-C -> FF, compared to 1.67 for FF -> MF) exaggerates the bigger jump from APS-C to FF. The crop factor comparison (1.5-1.53 vs 1.29) makes the jumps look more similar (and rightly so).

QuoteOriginally posted by Tjompen1968 Quote
Also we are talking about 24 vs 36 vs 51 MP.
The OP wasn't interested in resolution.

QuoteOriginally posted by Tjompen1968 Quote
That gives us; APS-C 0.065 MP/mm2, FF 0.042 MP/mm2 and MF 0.035 MP/mm2.
That's irrelevant for what the OP wanted to know.

QuoteOriginally posted by Tjompen1968 Quote
Then if you put the images taken with the K-1 and 645z you will find that the difference is noticable.
I'm not disputing that but
  1. that could be due to a number of reasons (e.g., camera profiles), and
  2. the OP seemed to be specifically interested in DR, which I covered with my post.
08-23-2020, 09:15 AM - 1 Like   #22
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QuoteOriginally posted by texandrews Quote
What is marginal to one person could be significant to another
I don't think a DR difference of 0.13 stops can be viewed as "significant" no matter how you slice it.

If that kind of difference is important to you then you'll know it and can agree to disagree with those that call these kind of differences "marginal".

QuoteOriginally posted by texandrews Quote
The "marginal" tends to become less so in more difficult/critical situations.
I submit that the number of scenes that one can successfully capture with a 0.13 stop better headroom but cannot capture without it is very small.

Note that no standard output format supports the capture dynamic range, so the final product will always feature considerably less dynamic range and other parameters like tonal range are probably similarly compromised. So effectively we are talking about whether one can manage with a single shot capture or needs two shots in order to avoid some minimal noise increase in lifted shadow areas.

QuoteOriginally posted by texandrews Quote
DXO has had more than one critic
Yes, but most of the time the criticism is unsubstantiated.

Crucially, I'm not aware about any criticism about consistency. One may dispute some of their assumptions but they'll equally apply to all measured cameras, hence allow fair comparisons. I once read their testing methodology and found their process to be professionally designed.
08-23-2020, 10:59 AM   #23
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QuoteOriginally posted by Class A Quote
I don't think a DR difference of 0.13 stops can be viewed as "significant" no matter how you slice it.

If that kind of difference is important to you then you'll know it and can agree to disagree with those that call these kind of differences "marginal".


I submit that the number of scenes that one can successfully capture with a 0.13 stop better headroom but cannot capture without it is very small.

Note that no standard output format supports the capture dynamic range, so the final product will always feature considerably less dynamic range and other parameters like tonal range are probably similarly compromised. So effectively we are talking about whether one can manage with a single shot capture or needs two shots in order to avoid some minimal noise increase in lifted shadow areas.


Yes, but most of the time the criticism is unsubstantiated.

Crucially, I'm not aware about any criticism about consistency. One may dispute some of their assumptions but they'll equally apply to all measured cameras, hence allow fair comparisons. I once read their testing methodology and found their process to be professionally designed.
Thank you Class A and others for pursuing my original question.

Class A does correctly say that DR was a prime consideration for me. When I use FF instead of APSC I notice this difference, but then I said, that when sensitively processed and printed, the differences can the two formats can be mitigated, somewhat.

I've never done the maths as different technologies and the 'subjectiveness' of a final print (which itself has so much less 'DR' anyway) is what matters, generally, to me and anyway the maths is a bit like statistics, ie it can be adjusted to prove most things.

Trying to get the feel of whether the 645Z might get me that 'something' more, was what I was after, as I was inclined to think that the reduced size MF sensor and older tech, might make the expected DR advantage of the 645Z less significant (when the the original RAW is massaged to the reduced print capabilities). Yes, I appreciate there's more processing scope in the 645Z images, but in a studio situation this should be irrelevant, and in non-controlled lighting conditions, PS and bracketing will cover many other situations. Class A has calculated the DR to be 'marginal'. Marginal is clearly subjective, but I am inclined to believe that for me, 'marginal' would be just that. This does not say that I wouldn't like the 645z for a whole host of reasons, but for that little extra, it may, for me, just be too little.

08-23-2020, 12:36 PM - 1 Like   #24
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This is anecdotal but perhaps useful:

I just spent the weekend shooting landscapes with a rented Pentax 645Z and smc PENTAX-FA 645 120mm F4 Macro (technical tripod-based work, optimizing technique and settings for the most detailed files possible) and while I found the system to be nice, I couldn't help but wish that I were working with my Pentax K-1 and HD Pentax-D FA* 85mm F1.4 ED SMD AW that I recently purchased (I was absolutely floored by this lens from my very first tests, as I've said elsewhere, it's very likely to be my all-time favorite lens). Somewhat to my surprise, the experience of shooting the 645Z felt a bit less refined even with its simpler controls compared to the K-1. For this particular shoot, I needed the 51 megapixels (in 3:4) which is why I chose it. A quick review of the files convinced me that I'm happy to be invested in the K-1 and new D FA* lenses over the Pentax 645 system; aside from the number of pixels, I believe the K-1 (with good glass) is right in line with the 645Z in terms of image quality. I'm very happy with what I captured, don't get me wrong, but if there had been a K-1 III with even 40-ish megapixels, I would have gone that way. Even if Pixel Shift had been an option for this shoot I may have chosen the K-1.

Last edited by naward001; 08-23-2020 at 01:49 PM.
08-23-2020, 03:00 PM   #25
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QuoteOriginally posted by naward001 Quote
This is anecdotal but perhaps useful:

I just spent the weekend shooting landscapes with a rented Pentax 645Z and smc PENTAX-FA 645 120mm F4 Macro (technical tripod-based work, optimizing technique and settings for the most detailed files possible) and while I found the system to be nice, I couldn't help but wish that I were working with my Pentax K-1 and HD Pentax-D FA* 85mm F1.4 ED SMD AW that I recently purchased (I was absolutely floored by this lens from my very first tests, as I've said elsewhere, it's very likely to be my all-time favorite lens). Somewhat to my surprise, the experience of shooting the 645Z felt a bit less refined even with its simpler controls compared to the K-1. For this particular shoot, I needed the 51 megapixels (in 3:4) which is why I chose it. A quick review of the files convinced me that I'm happy to be invested in the K-1 and new D FA* lenses over the Pentax 645 system; aside from the number of pixels, I believe the K-1 (with good glass) is right in line with the 645Z in terms of image quality. I'm very happy with what I captured, don't get me wrong, but if there had been a K-1 III with even 40-ish megapixels, I would have gone that way. Even if Pixel Shift had been an option for this shoot I may have chosen the K-1.
Anecdotal, yes, but useful. In my original post I wondered if the new lenses on a K-1 might be very close to the 645Z. Your experience suggests that it may well be. Thank you.
08-24-2020, 03:20 AM   #26
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I'll pick up GFX if I want 4:3 ratio and max single (long) exposure IQ. Otherwise K-1 goes to the bag. Averaging 2-4 (depending if long exposure is used) K-1 frames equals or excels the DR from that 50MP crop MF.
09-19-2020, 12:00 AM - 1 Like   #27
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I own both K1 & 645Z. I use them for landscape photography and I can tell you categorically that the Z is a better camera for that job - it is the one I will always use first regardless of conditions. The K1 is a backup and it also gets used when I want the field of view of the 15-30 that I can't get with the Z. The image quality difference does come down in part to resolution but there is also something less definable. The dynamic range of the Z is astonishing and the RAW files it produces are SO malleable and workable (as long as you preserve your highlights) that it is nearly always the case that I get my best images when shooting the Z. Also the 4:3 ratios is better. Having said that of course if you are not a committed landscape or commerical photographer and are not planning to print large landscape images then these differences are probably not worth the cost and the K1 is the better choice. You do pay a weight penalty with the Z (especially if you use the 28-45 like I do) but in useability I find the Z really really good. I may in the future sell or upgrade my K1 but I doubt I will ever sell my Z. I might buy a second in the future once the used price drops enough and I aspire to owning the other modern lenses to complete my set (the 35DFA and the 25 DFA). The image quality and build quality is so good I can't really see myself needing anything more for what I do. I have reviews of both cameras on my website.
09-19-2020, 07:22 AM   #28
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QuoteOriginally posted by Gyroscope Quote
I own both K1 & 645Z. I use them for landscape photography and I can tell you categorically that the Z is a better camera for that job - it is the one I will always use first regardless of conditions. The K1 is a backup and it also gets used when I want the field of view of the 15-30 that I can't get with the Z. The image quality difference does come down in part to resolution but there is also something less definable. The dynamic range of the Z is astonishing and the RAW files it produces are SO malleable and workable (as long as you preserve your highlights) that it is nearly always the case that I get my best images when shooting the Z. Also the 4:3 ratios is better. Having said that of course if you are not a committed landscape or commerical photographer and are not planning to print large landscape images then these differences are probably not worth the cost and the K1 is the better choice. You do pay a weight penalty with the Z (especially if you use the 28-45 like I do) but in useability I find the Z really really good. I may in the future sell or upgrade my K1 but I doubt I will ever sell my Z. I might buy a second in the future once the used price drops enough and I aspire to owning the other modern lenses to complete my set (the 35DFA and the 25 DFA). The image quality and build quality is so good I can't really see myself needing anything more for what I do. I have reviews of both cameras on my website.
Summarizes well nearly exactly how I feel about it, also owning both and those lenses----especially the "something less definable" difference. I will add though that the K1/K1mkII does shine as a stills camera, and it is more versatile. But for my personal work it's always the Z.

I use both at work for different purposes, and am about to start some photogrammetry projects, and will use the K1mkII for those---don't need 72-108 Z images in a mesh! The K1mkII is plenty large already.
09-19-2020, 11:10 AM   #29
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QuoteOriginally posted by Gyroscope Quote
I own both K1 & 645Z. I use them for landscape photography and I can tell you categorically that the Z is a better camera for that job - it is the one I will always use first regardless of conditions. The K1 is a backup and it also gets used when I want the field of view of the 15-30 that I can't get with the Z. The image quality difference does come down in part to resolution but there is also something less definable. The dynamic range of the Z is astonishing and the RAW files it produces are SO malleable and workable (as long as you preserve your highlights) that it is nearly always the case that I get my best images when shooting the Z. Also the 4:3 ratios is better. Having said that of course if you are not a committed landscape or commerical photographer and are not planning to print large landscape images then these differences are probably not worth the cost and the K1 is the better choice. You do pay a weight penalty with the Z (especially if you use the 28-45 like I do) but in useability I find the Z really really good. I may in the future sell or upgrade my K1 but I doubt I will ever sell my Z. I might buy a second in the future once the used price drops enough and I aspire to owning the other modern lenses to complete my set (the 35DFA and the 25 DFA). The image quality and build quality is so good I can't really see myself needing anything more for what I do. I have reviews of both cameras on my website.
Enjoyed the K-1 and 645Z reviews on your website. The photos are superb. The "something extra" the 645Z brings to the table is visible on your images posted at the site. The Z shots look more natural than the really great K-1 photo. I find this when comparing my K-1 to 645Z photos as well.

Thanks for sharing,
barondla
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