Medium format redefined

[Chris Livsey]

If the pricing model were adapted to which part that provides the most value, digital backs would be a lot cheaper and Capture One would be a very expensive piece of software.

That software is easier to "pirate" and hardware much harder to clone the current pricing model may be correct.

[torger]

That software is easier to "pirate" and hardware much harder to clone the current pricing model may be correct.

Yes, I should have been clearer. I think they have a wise pricing model, I wouldn't do otherwise. Make the customers pay via hardware is an excellent model. I sell some consumer software and I know how hard it is to get paid, you need to have Adobe-style volumes before you can make any real money on it.

What I wanted to illustrate is that due to the necessity to focus on hardware, users have come to think that hardware plays a larger role and software a lesser when it comes to camera color, compared to how it actually is.

If you could sell a camera profile for say $500-$1000 I think we would see some tougher competition in the color rendering aspect. Say if a $1000 profile could lift your 135 camera to medium format quality in terms of color rendition wouldn't that be totally worth it? Probably, but it's more fun to spend money on a really sharp lens or some other hardware instead.

[Theodoros]

OP here, hello…

What I meant was that during the good old film era it was extremely easy to define different formats, it simply was the size of the film which determined it. The image quality was determined by the film size, basically. Along with the film size came different focal length lens sets for each format, which in turn also defined the "look" of each format (mostly lack of DOF with bigger formats). All this was simple because film emulsions were the same for all formats, so IQ was directly tied to the film size.

Now this simple equation size = quality does not hold anymore, as a modern high quality small sensor can and does surpass many so called MF sized sensor in both resolution and especially DR. So what I was suggesting was to redefine MF to mean certain level of IQ regardless of the sensor size. Traditional MF "look" features like shallow DOF can be produced by faster lenses on smaller sensors, so the "look" remains the same.

I am approaching this more from the theoretical angle, scaling a size X sensor up or down with the correct lenses/apertures should give us optically exactly the same results (except diffraction effects). So it should be the end result which determines the "format", not just the sensor size.

Carry on...

HI,

I think that MF bodies do follow the traditional path that was introduced with film...  There are "modular" cameras that take MFDBs (instead of film backs) and there are DSLR type cameras like Pentax 67 or Exakta 66 was... There are some "modern" features added in their specs (like AF for instance) but this is to be expected as things advance with time... It's not really different than it was with the later film cameras (Rollei, Contax) than the first generation of MF cameras during the film era...

What has really changed is the light sensitive areas, where with film one could have the same emulsion/technology used with a 35mm camera, and the same again with an MF camera the difference only being in size... But I have a feeling that there is a tendency for this to also change and return back to the roots, I believe that we won't see anymore sensors coming of the CCD type, IMO all future sensors will be CMos and although they won't be upsized versions of FF DSLR sensors, they will be of very similar technology and performance characteristics... In fact I believe that the later introductions (Sony's MF sensor, Leica S007) prove much of the case...

[Chris Livsey]

Yes, I should have been clearer. I think they have a wise pricing model, I wouldn't do otherwise. Make the customers pay via hardware is an excellent model. I sell some consumer software and I know how hard it is to get paid, you need to have Adobe-style volumes before you can make any real money on it.

Even Microsoft are giving it away free now 

[EricWHiss]

snake oil is alive and well... not 6 stops of DR advantage, but 3 stops difference in aperture for a MF which is at best 2.5 times in sensor size vs FF camera... for all other systems (P&S vs m43 vs APS-C vs FF) 2 times difference = 1 stop...  but MFs has some magical dragon urine sprayed over it so that does not work anymore  

I'm was posting about DOF (depth of field).  Not sure where or how you got to DR.  But its one of those things - either you see it or you don't.  

[AlterEgo]

I'm was posting about DOF (depth of field).

me too... "6 stops of DR advantage" is a local meme from the days of "16 bit raw files", so to say

[EricWHiss]

I got to the 3 stops difference in aperture by direct comparison in studio with AFi-ii 12 compared to Nikon d800e.  It's really quite amazing the difference.  If you shoot a model at f/16 with the AFi-ii 12 you can't even get their whole body from front to back within the envelop of DOF, but at f/8 you can get that and more with the same framing.  There probably is a mathematical relationship that expresses this but I'll just go by experience.  Stopping down FF DSLR 3 more aperture stops seems about right to get to the same DOF.

[torger]

The math of DoF:

Say if we prefer 4:3 format, then we get 32x24mm from 135 and 54x41 from 645, which is 40mm diagonal vs 67mm, factor 1.7. To match the look of an 80/2.8 medium format lens would require a 80/1.7 = 47mm and 2.8/1.7 = f/1.6, closest typical real lens would be a 50/1.4.

The 135 format has lenses with very short depth of field, so I don't think anyone uses MFD to get shorter, as you probably can get even shorter with 135. To match Canon's 85mm f/1.2 you'd need 150mm f/2 and few (any?) medium format systems have that.

Ultra-short DoF is rather gimmicky though and doesn't make good portraits, so it's not a loss. I've heard that many prefer the bokeh of MF lenses, and that there are some finer smoother quality in the transition from in focus to out of focus. I don't think that has to do with the format, but possibly due to that you have simpler lens designs. The high res ultra-wide aperture 135 lenses are certainly not simple designs, and maybe some aspects of the bokeh suffers from that.

A big drawback with most MFD lenses as I see it is that they use apertures that are not round, leading to ugly bokeh highlights. It's a problem on my tech camera too, due to the Copal shutter, fortunately I don't use bokeh often in my shooting style but if I would I would not be happy about that. All high end 135 lenses have round apertures.

With the newest high end 135 lenses designed for high res sensors like Otus and Canon's new 35mm/1.4 I've noted a real improvement in bokeh, bokeh fringing is almost completely gone. While 135 format is still overall lagging behind in resolving power due to the lenses, these new lenses is changing the landscape.

I think that the choice of MFD of the SLR type will be less about resolution or depth of field in the future, but more about if you like the camera ergonomics, and the raw converter workflow and the rendering (color etc) you get in that workflow. It remains to be seen how well the current pricing model will work for the new landscape. I think we will see the system come closer also in price, the high res 135 is already notably more expensive than earlier (due to increased lens complexity), and we have seen lower MFD prices here and there, like the new Leica S.

[fdisilvestro]

Another way to see it, given a specific output size (e.g. an 8 x 10 print) and a specific angle of view, then the DOF is determined by the diameter of the entrance pupil of the lens used, regardless of the format of the capture medium.

In the example given by Torger, that value would be = 80/2.8 = 28.57 mm, which will be the same entrance pupil of a 47 mm @ 1.6. Just in case, those numbers have small rounding errors, the exact figures will be a 47.407 mm lens at an aperture of 1.6592

This gives slightly less than 2 f-stop difference between medium format and 35 mm in terms of DOF.

I agree with torger that other factors such as sharpness, optical distortions, bokeh characteristics and so on influence the perception of DOF

[Theodoros]

Although the numbers say one thing... One must consider the aspect ratio too, with 4:3 aspect ratio, one works nearer to the subject than if the ratio was 3:2...

[fdisilvestro]

The calculations (both Torger's and mine) were based on a 4:3 aspect ratio

32 x 24 mm for 35 mm
54 x 40.5 mm for medium format

Aspect ratio, angle of view and output size have to be the same, otherwise you are comparing apples to oranges.

[Theodoros]

OK... but what about the position of the entrance pupil... the distance of it from the Light sensitive area also affects DOF... And since it is not a constant distance it is a parameter that hasn't been taken into account with the calculations.

[Manoli]

For Theo and Francisco, this is for you
For the rest of us, Torger's perfectly sufficient (and accurate) approximation will do just fine.
Pythagoras anyone ?

The math of DoF:

Say if we prefer 4:3 format, then we get 32x24mm from 135 and 54x41 from 645, which is 40mm diagonal vs 67mm, factor 1.7. To match the look of an 80/2.8 medium format lens would require a 80/1.7 = 47mm and 2.8/1.7 = f/1.6, closest typical real lens would be a 50/1.4.

[fdisilvestro]

Thanks Manoli for the presentation.

Just to clarify, there is indeed an influence of focal lenght and pupil factor in the DOF. This affect close range focus, especially in the macro region.
For distances above 1 m. the differences are negligible.

OK... but what about the position of the entrance pupil... the distance of it from the Light sensitive area also affects DOF... And since it is not a constant distance it is a parameter that hasn't been taken into account with the calculations.

That is why you need to consider a specific output size and ange of view. The size of the Circle of Confusion CoC will be smaller in the 24*32 sensor than in the 40.5*54, but the required enlargement from the 24*32 sensor to get the output size will be greater. So yes, it has been taken into account in the calculation (provided we are considering object distances above 1 m.)

[ErikKaffehr]

Hi Anders,

Thanks for talking about the math… I tried to post on it but I felt it was a to extensive subject to discuss at depth.

My guess is that with really good lenses, like Otus and Sigma Art, smaller formats can be quite competitive with larger formats. I just bought a Sony A7rII and I am pretty sure it can perform on par with my Hasselblad 555/ELD and P45+ combo.

The reason I keep the P45+ is that it is fun to shoot with, I would miss it for sure. But, very clearly, when it matters I will go with my Sony A7rII or the still pretty good Alpha 99.

Best regards
Erik

The math of DoF:

Say if we prefer 4:3 format, then we get 32x24mm from 135 and 54x41 from 645, which is 40mm diagonal vs 67mm, factor 1.7. To match the look of an 80/2.8 medium format lens would require a 80/1.7 = 47mm and 2.8/1.7 = f/1.6, closest typical real lens would be a 50/1.4.

The 135 format has lenses with very short depth of field, so I don't think anyone uses MFD to get shorter, as you probably can get even shorter with 135. To match Canon's 85mm f/1.2 you'd need 150mm f/2 and few (any?) medium format systems have that.

Ultra-short DoF is rather gimmicky though and doesn't make good portraits, so it's not a loss. I've heard that many prefer the bokeh of MF lenses, and that there are some finer smoother quality in the transition from in focus to out of focus. I don't think that has to do with the format, but possibly due to that you have simpler lens designs. The high res ultra-wide aperture 135 lenses are certainly not simple designs, and maybe some aspects of the bokeh suffers from that.

A big drawback with most MFD lenses as I see it is that they use apertures that are not round, leading to ugly bokeh highlights. It's a problem on my tech camera too, due to the Copal shutter, fortunately I don't use bokeh often in my shooting style but if I would I would not be happy about that. All high end 135 lenses have round apertures.

With the newest high end 135 lenses designed for high res sensors like Otus and Canon's new 35mm/1.4 I've noted a real improvement in bokeh, bokeh fringing is almost completely gone. While 135 format is still overall lagging behind in resolving power due to the lenses, these new lenses is changing the landscape.

I think that the choice of MFD of the SLR type will be less about resolution or depth of field in the future, but more about if you like the camera ergonomics, and the raw converter workflow and the rendering (color etc) you get in that workflow. It remains to be seen how well the current pricing model will work for the new landscape. I think we will see the system come closer also in price, the high res 135 is already notably more expensive than earlier (due to increased lens complexity), and we have seen lower MFD prices here and there, like the new Leica S.

[Manoli]

Aspect ratio, angle of view and output size have to be the same, otherwise you are comparing apples to oranges.

Francisco, you raise a pertinent point regarding output size.
I went to do some calculations with Bart VdW's 'Depth of Field output quality planner' and was surprised to find it off-line.
[ http://bvdwolf.home.xs4all.nl/main/foto/dofplan/dofplan.html ].

Does anyone have the new URL ?

[Theodoros]

It is long before I've been into a technical conversation and I surely don't want to argue or challenge any others knowledge which I'm sure it more or less presents the real story... Torger's and Fransisco's calculations are correct and they do say most of the story or are enough for one to estimate (about) the DOF difference between MF and FF sensor... However, it is a general truth which may vary a little and usually ends up with MF having even more shallower DOF than the two stops suggested... Not that it makes a real difference that matters so much that one should absolutely consider, but DOF does vary with the position of the entrance pupil and the entrance pupil doesn't have a constant (virtual) position in a lens, but its position varies with parameters... (e.g focusing distance is one parameter) practically, one would find that usually MF lenses have more than two stops shallower DOF and that varies between MF lenses too... (eg. a lens made for a 6x6 camera wiil be usually found to have (slightly) shallower DOF than a lens dedicated for a 6X4.5 camera etc...). There are also differences that may be found between lenses that have a leaf shutter when compared with same focal lengths but with no leaf shutter... It is common with DSLR cameras (either 35mm or MF) the more the mounting distance of a lens, the less the DOF (without this being a rule) that's why Nikkor lenses have usually (slightly) less DOF than an Canon lenses meant for Eos... That said, I don't know anyone that choose Nikon over Canon (or vise versa) because DOF would have a very slight difference...
 

[AlterEgo]

usually ends up with MF having even more shallower DOF than the two stops suggested...

first of all even here, few posts up it was less than 2 stops and then - can be way less because not all MF sensors are that big and not always you reduce the size of 3:2 FF sensor by cropping it to favor the aspect of MF... how about cropping a smaller MF sensor to 3:2 orientation of FF

[Theodoros]

first of all even here, few posts up it was less than 2 stops and then - can be way less because not all MF sensors are that big and not always you reduce the size of 3:2 FF sensor by cropping it to favor the aspect of MF... how about cropping a smaller MF sensor to 3:2 orientation of FF

I don't like what I say being altered and what you say is irrelevant to what I say (as usual with you)... To be more understandable (even from you), the AOV will be determined by the size of the image area and this leads from first view to compare it with another lens that also covers the same image area, but the lens (any lens) has a certain image circle and its DOF depends on the distance from the image area to exhibit this DOF... further more the entrance pupil is a virtual "hole" (but very real) that doesn't have constant position in a lens...  In other words, for whatever calculation to be completely (and accurately) applicable, it also requires the same mounting distance for the two lenses and the same position for the entrance pupil... I hope this advances your knowledge a bit...

[ben730]

It is common with DSLR cameras (either 35mm or MF) the more the mounting distance of a lens, the less the DOF (without this being a rule) that's why Nikkor lenses have usually (slightly) less DOF than an Canon lenses meant for Eos...  

Theodoros
Is this the reason why my Schneider Digitars (35XL + 24 XL) have the longer DOF than the Rodenstocks (32 + 23)?
I never compared them directly, but I always had the impression that the Rodies have much less DOF than the Schneiders,
maybe because of the retrofocus design?
Even the 24 PC-Nikkor (with a D800) seems for me to have less DOF at the same F-Stop as the 35 XL Digitar with a 44 x 33 sensor.
Best regards,
Ben