Is pixel size the only advantage of med format digital backs?

[alexo]

<p>I've been perusing various sites, looking into the advantage of a medium format digital back vs full frame digital camera. It seems that the biggest argument for going to medium format digital is the pixel pitch - the size of the individual pixels, which allow better light gathering abilities, thus rendering a better, more accurate image.<br>

Of the backs that I've looked into, most seem to use 6 micron pixels. I own a Canon 5D II, which uses 6.4 micron pixels. <br>

<br />So, aside from allowing me greater resolution at the same pixel size, is there any other advantage to med format digital? Would my images from my Canon look essentially the same at a given PPI as a med format image? (Assuming we don't go larger than 300PPI) Is there anything that I'm missing? I understand there are differences in implementation, software, AA filters, etc, but I'm talking specifically from a format related perspective.</p>

<p>Thanks</p>

[ellis_vener_photography]

Two real world differences is that for a given angle of view, the large the recording area, the longer the focal length lens

you'll need to cover the same vertical or horizontal angle of view. Given that a 75mm lens for an MFD the depth of field at

any given f-stop is shallower than for a 50mm lens on your Canon, at the same f-stop that will make a difference in the

appearance of your image.

 

- A second difference is that the cameras handle differently which can make you think (slightly) differently about how you

are going to make a specific image.

 

Which Medium format system are you looking at?

[brian yarvin]

<p>By far and away, for working high-end professional photographers, the biggest advantage to medium format backs is the amazing service that those dealers offer. If you've having trouble with a Canon, I can assure you that nobody from the company is going to drive out to your studio with a couple of loaners to try while they troubleshoot your gear on-site. PhaseOne will have somebody there, period.<br>

<br />There are also differences in the nature of the files that some retouchers and printers call "thickness." That is; somehow, the files these backs produce are easier to retouch and don't fall apart in a sort of sawtooth histogram so easily.</p>

<p>As for the "format related perspective," the differences are there, but pale when compared to the way dealers treat you. The differences between raw conversion software or the way certain lenses render are much greater.</p>

[alexo]

<p>Thank you for your replies. I'm less interested in the focal length lenses needed to achieve the same angle of view (I've shot with med format film cameras, so I'm aware of that), nor am I interested in the service aspect.<br>

I'm more interested in the actual image quality comparison as it relates to pixel size, unless I'm missing something in concentrating primarily on pixel size and there are some other features at play. Brian mentioned something about "thickness". What is it about these files that makes them easier to retouch? What do you mean these files don't fall apart? What makes them not fall apart?<br>

Will an image made from a med format camera with 6 micron pixels look the same (barring focal length differences) as an image made from a 6 micron FF camera provided we don't go over 300ppi?<br>

<br />Thanks again </p>

[ellis_vener_photography]

In 2015, small pixel pitch differences by themselves won't make a noticeable difference. But a medium format back with a

pixel pitch of 6 microns will likely have a higher total pixel count than a 24x36mm format sensor with roughly the same

pixel pitch, and that will make a difference.

 

Which is why I asked "which medium format back?"

[alexo]

<p>I've been looking at various phase one backs and all of them have a pixel pitch of 6 microns. They range from 40 to 80 mp. I understand the resolution difference. However, what I'm asking is this:<br /><br />Is there a difference in image quality between a 6 micron FF camera and a 6 micron MF camera if we do NOT go beyond the resolution capabilities of the FF camera?</p>

[Ed_Ingold]

Is a medium format pixel better than a small format pixel? Possibly, but not dramatically so, all else being equal. MF

claims to deliver 16 bits rather than 14 bits. The raw dynamic range might be a stop or so better. Most MF sensors are

cooled, at least with a fan, but thermoelectrically for higher end models. There is more space available for electronics,

ostensibly for better processing.

 

 

The real differences are in the things outlined by Ellis, which you wish to ignore.

 

 

From my personal experience, a 16 MP MF back holds its own compared to a Sony A7ii (24 MP), or even an A7Rii (42

MP), but with fewer convenient features, slower operation, greater size and weight. The higher the resolution, the more

care needed to realize that advantage. The A7Rii and MF seem to be converging with respect to technique when

resolution counts. For most applications, though, smaller size and more flexibility wins hands-down.

[alexo]

<p>Thank you. That answers my question. I appreciate everyone taking the time to post.</p>

[gareth_williams2]

<p>I agree with all of the above. Theoretically at least the advantages are:<br>

a) Bigger pixels <br>

b) Higher resolution - 60 to 80 megapixels<br>

c) Full 16 bit rather than upscaled 14 bit providing better tonality and colour<br>

d) No built in filtration to soften the image.<br>

Recently full frame SLRs have upped their game in regard of b and d but maybe Phase one/Leaf will bring in a new generation of backs and the old good big one beating a good little one will be back to as it was. <br>

Whether one's technique is up to exploiting the advantages of Medium format is another question altogether!</p>

 

[rodeo_joe1]

<p>Thickness? Most newer MF digital backs use a 16 bit A/D converter, whereas the current standard for high-end DSLRs is 14 bit. Personally I don't see that as too big a deal where lighting ratios and therefore subject contrast are under control. Especially since lens and body flare are the main limiting factors to dynamic range.</p>

<p>Those extra 2 bits of colour-depth theoretically allow a bit more "fiddling" with the image in post, particularly manipulation of saturation, but you have to be really pushing the envelope for it to be noticeable. If you're that close to the image falling apart you probably should get a better exposure meter or make-up artist!</p>

<p>Gareth. The latest generation of DSLRs don't have any anti-aliasing low-pass filter either, rendering your last point - err, pointless.</p>

<p>One more point is that the aspect ratio of MF backs is more suited to magazine reproduction, being 4:3 or close. The overlong 3:2 ratio of full-frame DSLRs will generally need to be cropped for editorial use.</p>

<p>A DSLR with a 27mm x 36mm sensor and 16 bit A/D could easily be an MF killer IMHO.</p>

[gareth_williams2]

<p>Thanks for pointing out the aspect ratio Joe - missed that. I had pointed out that modern dslrs had left out the filter.</p>

[mike_earussi1]

<p>This is the closest thing I've seen to an explanation:</p>

<p>

<p>but with continued dslr advances I don't think that MF backs are long for this world.</p>

[Ed_Ingold]

<p>Now that we have diverged from the single pixel postulate, there are other factors to consider. A sensor with 6 micron cell spacing will have about 24 MP in an FX, 36x24 mm sensor, but 60 MP in a typical 48x36 mm MF sensor. How does a 60 MP medium format camera compare to a small format camera with 40-60 MP?</p>

<p>While you can't compare MTF curves by different manufacturers, it is probably safe to observe that MF lenses have less contrast and resolution than corresponding FX lenses. Since Zeiss makes prime lenses for both formats, this might be a place to start. Macro contrast (10 lp/mm) run in the low 90's for MF lenses and high 90's for high-end small format. Micro contrast curves (30 lp/mm) are generally below 50% in MF lenses and 60% or higher for small format lenses.</p>

<p>IMO, Considering both MTF curves and articles by photographers versed in both formats (e.g., Luminous-Landscape.com), high resolution medium format cameras tend to be limited by the lenses, whereas small format cameras with similar pixel spacing are limited by the sensor (e.g., Sony A7ii, 24 MP). With small format cameras now reaching 50 MP, only the best lenses approach parity with the sensors. The best performing MF cameras are called "technical cameras", using symmetrical lenses like for a view camera (e.g., Schneider) on a ruggedized body. If anything, they are kludgier than the traditional MF SLR (Hasselblad), and only suited for static subjects.</p>

<p>Medium format images are best served by proprietary software from the manufacture. Raw images are relatively crude until processed in software. On the other hand, small format cameras have extensive in-camera processing capability. Images from the camera are often usable with little or no post processing. MF sensors are mostly CCD, whereas CMOS rules in the small format world. Besides sophisticated processing capabilities, CMOS offers much higher ISO and lower noise. MF sensors are largely stuck at ISO 800 or less, whereas the Sony A7 cameras give good results at much higher speeds (A7S/A7Sii at 104,000 or more, and the A7Rii at 26,500 or more). Auto focusing capability in MF cameras wouldn't rate honorable mention for a new small format camera.</p>

<p>I doubt that MF digital will fade away, for two reasons. When your livelihood depends on your gear, the personalized service you receive from dealers in $40K cameras is essential. Nobody has much good to say about Sony service, and I am fortunate to live close to an excellent Nikon service company. The big bright spot on the horizon stems from the fact that Sony makes most of the MF sensors. If Sony were to create a new product line with super-sized sensors in a body with small format ergonomics (similar to a Leica S), it would be a game changer. We know that Sony can make lenses. Their G lenses are on a par with pure Zeiss offerings. (Zeiss excels at producing a range of lenses with matching image characteristics. Sony can't seem to get filter sizes straight, e.g., 46, 62, 67, 72, ...)</p>

[ondebanks]

<p>Nobody's mentioned depth of field issues, surprisingly.<br>

<br />Wide open, an 80mm f/2 medium format lens and a 50mm f1.2 "full frame" lens give almost identical depth of field and framing for a given camera-subject distance. So it's a tie? No, the transitions from sharp plane to defocus are smoother with the slower aperture lens. Aberrations are much harder to eliminate at f1.2 than at f2. There are distinct format-related advantages to the rendering of the image.</p>

<p>Another technical contributer to the look of the image is the signal to noise curve. Medium format digital has until recently used only CCD sensors; those with larger pixels in particular have a "high signal, high noise" characteristic which renders quite differently to full-frame 35mm digital, all based on CMOS sensors for the past 10 years*, which tend to have a "moderate signal, low noise" characteristic. <br>

* only a few models in the early 2000s, such as the Contax N and Kodak SLR/n, used a full-frame CCD.</p>

<p> </p>