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Is there a compelling reason to move to MF?

ErikKaffehr

Well-known member
Hi Jerome,

Let's look at a practical expirement by Jim Kasson:

Leica 90mm f/2 Apo Summicron-M ASPH at f/2. Jim shot 41 expsures at around three meter distance utilizing the full rnage of his Stackshot rail and evaluated MTF for each exposure.

Done that he plotted MTF for red, green and blue channels. You can see that MTF has three peaks. Those represent different planes of focus.

I would say B peaks about 2.62 and G about 3.93, so we have something 1.3 mm shift of focus.


Next image is same lens stopped down to f/4. Here I would say the blue curve peaks at 1.31 while the green one is probable centered about 2.40. So the shift been the color planes here is around 1.1 mm.


So the optimal color planes were 1.3 mm apart at f/2, and 1.1 mm at f/4. That is a small improvement.

The plane of optimal focus has also shifted something like 1.5 mm., by stopping down.

The main effect of stopping down was that the peaks got broader. That reduces the visible effect of the color plane shift. That broadening is caused by the increased depth of field but also by diffraction when stopping down beyond optimal aperture.

Here is the corresponding graph for the Otus at f/1.4:


And at f/4:



The aberration is the shift of best focus colour planes. It causes colour fringing and the amount of the fringes we see is aperture dependent.

Best regards
Erik





I don't understand how you can write at the same time "does not vary with aperture" and "stopping down reduces the visible effects". Maybe you are confusing longitudinal and lateral chromatic aberration? In any case, longitudinal chromatic aberration varies with aperture and lateral chromatic aberration does not: https://en.wikipedia.org/wiki/Chromatic_aberration#Types
 

fotografz

Well-known member
I agree with the above from mjr

I backed off to a 37 meg larger than 135 sensor as a format and pixel size that works for me and for what I now do. I no longer had a need for 60 meg 645 or the Multi-Shot camera I once had.

Dual shutter with high sync speed zoomed to the top of my priorities and more DR was never a particular issue for the past few camera models anyway.

The only benefit I see from my Sony A7R-II is that of convenient size, as long as I can also keep the lenses relatively small. For that convenience I am willing to live with horrible ergonomics and unnecessary complexity. The camera offers decent speed and higher ISO but not industry leading … so it is more of a jack-of-all-trades and a master of none. In general, that is not a damning statement, but instead offers a wide appeal to a lot of folks … including myself. It is not the tool I select when IQ is the goal, but it is no slouch at that either.

I'd venture a guess that all of us would benefit from spending more energy on what we are shooting as opposed to what we are using. Most everything out these days works pretty darned well and looking down the road won't change that … unless it is an innovation the likes of shrinking a high meg camera the way Sony did.

- Marc
 

jerome_m

Member
Hi Jerome,

Let's look at a practical expirement by Jim Kasson:

Leica 90mm f/2 Apo Summicron-M ASPH at f/2. Jim shot 41 expsures at around three meter distance utilizing the full rnage of his Stackshot rail and evaluated MTF for each exposure.

Done that he plotted MTF for red, green and blue channels. You can see that MTF has three peaks. Those represent different planes of focus.

I would say B peaks about 2.62 and G about 3.93, so we have something 1.3 mm shift of focus.


Next image is same lens stopped down to f/4. Here I would say the blue curve peaks at 1.31 while the green one is probable centered about 2.40. So the shift been the color planes here is around 1.1 mm.


So the optimal color planes were 1.3 mm apart at f/2, and 1.1 mm at f/4. That is a small improvement.

The plane of optimal focus has also shifted something like 1.5 mm., by stopping down.

The main effect of stopping down was that the peaks got broader. That reduces the visible effect of the color plane shift. That broadening is caused by the increased depth of field but also by diffraction when stopping down beyond optimal aperture.

Here is the corresponding graph for the Otus at f/1.4:


And at f/4:



The aberration is the shift of best focus colour planes. It causes colour fringing and the amount of the fringes we see is aperture dependent.

Best regards
Erik
Why aren't the peaks in the same order as the wavelengths on these curves? (That is: blue green red or red green blue)
 

ErikKaffehr

Well-known member
It probably depends on the optical correction of the lens. I guess that there is no simple explanation on how the focal plane shifts around for different wave lengths. Also, keep in mind that R, G and B signals are integrated values over what is transferred over the CFA.

A classic achromat would be corrected for two wave lengths that may be blue and green, but that doesn't mean blue and green signals would match.

Best regards
Erik



Why aren't the peaks in the same order as the wavelengths on these curves? (That is: blue green red or red green blue)
 

Paratom

Well-known member
Hi,

In my recent comparison shots I have two "bokeh crops". Both taken at equivalent apertures:

Hasselblad 555/ELD P45+Sony A7rII

Best regards
Erik
Hi Erik,
for me most interesting is not only the bokeh/background itself, but how smooth the sharp area goes into the unsharp.
When I shoot with a sharp M lens (for example 75/2.0 APO) on the Leica M I feel there is a very thin very sharp area which moves quickly into an unsharp area just a view mm/cm longer distance. When I shoot the same with the Leica S at equivalent focal length and f-stop this transition seems much smoother.
I find this specially usefull for portraits at wider f-stops. I can not explain why this happens but I can see it.
 

jerome_m

Member
It probably depends on the optical correction of the lens. I guess that there is no simple explanation on how the focal plane shifts around for different wave lengths. Also, keep in mind that R, G and B signals are integrated values over what is transferred over the CFA.

A classic achromat would be corrected for two wave lengths that may be blue and green, but that doesn't mean blue and green signals would match.

Best regards
Erik
Put these lenses behind a monochromator and we may see what is really going on. I don't think we can deduce much from the little info that is shown here.
 

satybhat

Member
Put these lenses behind a monochromator and we may see what is really going on. I don't think we can deduce much from the little info that is shown here.
Abstraction, all kudos for ringing the cat's bell and drawing out the old-timers.

To me, the more valid question is this:
What really differentiates the big backs from the small backs / cameras ?
For eg. why does Phase demand a 40-50K premium, when with slight compromises, one could have a 645z with 10-12K. Or by how much or what do the phase backs really beat the Leica S? Is it about purely ergonomics - a kinaesthetic addiction- as Torger says? Reliability perhaps? IF anything, the fat pixel backs should demand a classic-car premium.

One thing I am settled on. MF really truly beats the 35mm experience, whether in IQ, bokeh, or usage aesthetics. Just like the 35mm FF beats the M43, which in turn beats the point and shoots, which in turn trump smartphones.

Regards,
 
M

mjr

Guest
Yes, as it's a commercial organisation and not a charity, you would presume that if nobody felt there was value in their products at the prices they charge then they'd simply go out of business, which they obviously haven't. For the revenue they create for me personally, I think the kit I have was a steal!

Mat
 

dougpeterson

Workshop Member
What really differentiates the big backs from the small backs / cameras ?
For eg. why does Phase demand a 40-50K premium, when with slight compromises, one could have a 645z with 10-12K. Or by how much or what do the phase backs really beat the Leica S?
Phase one demands that premium because they can. They are the only ones on the market with 100 mega pixels.
For clarity that premium (list price difference of $39,290) exists for the IQ3 100mp over the Pentax 645Z but I'd argue this is a bit of an apples and oranges comparison. A Credo 50 kit with XF is $20k and a refurb Credo 40 kit with DF+ is $10k. Regardless, the Pentax 645Z is definitely the least expensive, and depending on what you're comparing it to, by a good bit. So why might someone consider an IQ3 series over a different medium format option? I'd offer a short list below that have nothing to do with resolution or the current exclusivity on 100mp. All are unique to Phase One.
- 5-year warranty
- Loaner during any repairs or service, including back/body/lenses
- XF Body features (e.g. auto focus stacking, hyperfocal mode, time lapse, WLF)
- Flash sync up to 1/1600th
- Fastest, robust, professional tethering speed and features
- Uber lenses (e.g. Schneider 35LS Blue Ring)
- Built-in flash transmitter
- Capture One co-development (more than just "support" - they are made for each other)
- Built-in Wireless including live view, camera control, and ratings
- Touch interface on Retina LCD (e.g. tap to check focus on a specific point)
- Review features like focus mask, adjustable exposure warning, hard-clipping indicator, zone system analysis

If you're comparing specifically to the 645Z or S2 then you can add (some of these are not unique to P1 and would apply to Hassy as well)...
- WLF
- Option to use with a view camera
- Option to use with a tech camera
- Modular upgradability
- Wide availability in major rental houses and production studios
- Wide availability of Phase One Certified Professional techs with advanced training

Some might find this list easily worth the difference, others might find it not worth a dime, others might find some of the unique features of the Pentax (e.g. weather sealing, somewhat lighter) worth more than the phase for their particular needs even if they were the same price. They are very different cameras with very different pros and cons (and obviously different price points).
 

torger

Active member
Yes Phase One has been and still are excellent to be first with the greatest, and of course they charge extra for that. However unfortunately some of the bad reputation concerning MFD pricing is because everyone looks at the latest products from Phase One, forgetting about the other brands out there, and indeed the many pre-owned options.

If you really need to "keep the distance from the 135 crowd" in as many aspects as possible, well then you should to be on the Phase One constant upgrade program, but if you find other qualities in the format there are many other alternatives that are more economical.

And when the format becomes economical enough, there's less need to "justify". I know a few that use legacy medium format just for the fun of using something different, appreciating the good quality they get but not really caring if the latest DSLR with the latest lenses is better or worse.
 

jerome_m

Member
Yes Phase One has been and still are excellent to be first with the greatest, and of course they charge extra for that. However unfortunately some of the bad reputation concerning MFD pricing is because everyone looks at the latest products from Phase One, forgetting about the other brands out there, and indeed the many pre-owned options.
Indeed. My first MF was an H3D-31, bought in 2012. At the time, the Nikon D800 was all the rage. The H3D-31 cost me about the same as the then brand new D800. Of course, the D800 was just out and the H3D-31 was ancient.

Interestingly, I was able to compare the two cameras and posted about it at the time. The results were not that different, even in low light (where the D800 should have been much better, but Phocus noise reduction was better than I expected).
The resolutions were also comparable.

In the end, I preferred the H, because
  • colors were more pleasing (not more accurate: more pleasing to me)
  • the rendering between the lenses was considerably more homogenous in Hasselblad than in Nikon (a weakness of Nikon)
  • the H had a more accurate AF (slower but more accurate, keep in mind that the D800 was also known for AF problems)
  • the obvious advantages of the D800 (faster, stabilized and faster lenses, etc...) were of no interest to me
  • I liked the handling of the H better (grip and viewfinder, menu system)

I've also read earlier in this thread that MF cameras were supposed to impress the chicks. :rolleyes: Frankly, that was not true at all: most people would think that I had a large camcorder from the 80s.
 

Abstraction

Well-known member
Abstraction, all kudos for ringing the cat's bell and drawing out the old-timers.
Old timers?? I think I've awoken the dead! This is the Zombie Apocalypse! :ROTFL:

To me, the more valid question is this:
What really differentiates the big backs from the small backs / cameras ?
For eg. why does Phase demand a 40-50K premium, when with slight compromises, one could have a 645z with 10-12K. Or by how much or what do the phase backs really beat the Leica S? Is it about purely ergonomics - a kinaesthetic addiction- as Torger says? Reliability perhaps? IF anything, the fat pixel backs should demand a classic-car premium.

One thing I am settled on. MF really truly beats the 35mm experience, whether in IQ, bokeh, or usage aesthetics. Just like the 35mm FF beats the M43, which in turn beats the point and shoots, which in turn trump smartphones.

Regards,
Phase one demands that premium because they can. They are the only ones on the market with 100 mega pixels.

Yeah, I think Jerome hit the nail on the head: Because the can. I am not sure they'll be able to charge this much longer. The writing's on the wall. With Sony fast becoming the sensor supplier for almost all of the camera manufacturers, and with the pixel pitch of the 100mp back equating to the 42mp sensor on the 135 format, thus stressing the lenses just as much, there's becoming less and less of a differentiation among the formats. Furthermore, with Pentax squeezing Phase on the MF market as well, Phase will wind up doing one of two things: Either they will have to make their systems more affordable (at least introduce a line of affordable cameras/backs to compete with Pentax) or they will become so niche and so specialized that the sales figures they're seeing now, will seem like the golden age of digital MF. It seems they're milking the cow while there's still a cow to be milked.
 

stephengilbert

Active member
So there's no compelling reason, is that right?

If so, why need it be said over and over? GetDPI used to be clearly different than LuLa. Not so much anymore.
 

Abstraction

Well-known member
So there's no compelling reason, is that right?

If so, why need it be said over and over? GetDPI used to be clearly different than LuLa. Not so much anymore.
I kept quiet for a long while until someone mentioned me and I replied. There's no saying the same thing over and over. I've never belonged to LuLa, so I have no point of reference.
 
M

mjr

Guest
Abstraction, aren't you the guy who a few short weeks ago embarked on this journey without any idea about what mf backs were available, what their costs were or what was involved? And now in that time you have managed to get a handle on the whole market and a view on the future for Phase, Pentax and the rest? Got to love the internet, experts overnight! Haha!

Mat
 

ErikKaffehr

Well-known member
Hi 'Paratom',

You rise an interesting point. Now, I am not really a bookeh guy, so I have little input on this, except I don't see a lot of difference in out of focus rendition between my P45+ using classic Zeiss lenses and my A7rII using a brand new lens design. But, that clearly relates to my kind of shooting.

Now, the point you make is very interesting, because you compare two cameras with very similar pixels, at least if you are comparing the M (typ 240) with the S (typ 007). Comparing the CCD models the sensor pixels would be similar, both coming from Kodak. Comparing a CCD model and a CMOS model, microlenses may be different.

Thanks for sharing!
Erik

Hi Erik,
for me most interesting is not only the bokeh/background itself, but how smooth the sharp area goes into the unsharp.
When I shoot with a sharp M lens (for example 75/2.0 APO) on the Leica M I feel there is a very thin very sharp area which moves quickly into an unsharp area just a view mm/cm longer distance. When I shoot the same with the Leica S at equivalent focal length and f-stop this transition seems much smoother.
I find this specially usefull for portraits at wider f-stops. I can not explain why this happens but I can see it.
 

jlm

Workshop Member
Besides many, many and somewhat redundant postulations, the answers to the original question are in the first four posts
 

Abstraction

Well-known member
Abstraction, aren't you the guy who a few short weeks ago embarked on this journey without any idea about what mf backs were available, what their costs were or what was involved? And now in that time you have managed to get a handle on the whole market and a view on the future for Phase, Pentax and the rest? Got to love the internet, experts overnight! Haha!

Mat
Not quite. I knew which backs were available and their cost, hence my initial question in this post. If you're referring to my other thread, it had to do specifically with tech cameras. So, your presumption isn't correct.

As far as getting a handle on the market, it doesn't require a rocket scientist to do a bit of market research, to see who the players are, what the sales figures are and where the trends are heading. It doesn't necessarily make me an expert, but it does give me a pretty good understanding of where things stand.
 

jerome_m

Member
Yeah, I think Jerome hit the nail on the head: Because they can. I am not sure they'll be able to charge this much longer. The writing's on the wall. With Sony fast becoming the sensor supplier for almost all of the camera manufacturers, and with the pixel pitch of the 100mp back equating to the 42mp sensor on the 135 format, thus stressing the lenses just as much, there's becoming less and less of a differentiation among the formats.
1: Kodak has been the sole sensor supplier for all MF manufacturers for years and there were more of them at the time. The prices were still different.
2: The lenses may be stressed as much, but twice the sensor size equates twice the pixels. Some people need more resolution and can pay for it


Furthermore, with Pentax squeezing Phase on the MF market as well, Phase will wind up doing one of two things: Either they will have to make their systems more affordable (at least introduce a line of affordable cameras/backs to compete with Pentax) or they will become so niche and so specialized that the sales figures they're seeing now, will seem like the golden age of digital MF. It seems they're milking the cow while there's still a cow to be milked.
Phase One has had a line of more affordable cameras for years. They are not as affordable as Pentax, but their price point is chosen to be the same as Hasselblad's. Haven't you noticed? :rolleyes:
 
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