[Rondec]

I own a 645z and have owned and shot everything from M43 up to 8x10 over the years so I do recognise and enjoy the benefits of larger formats, but think we have to be careful not to ascribe qualities that are beyond the realm of what physics permits (as well as what can actually be seen in real life). I was responding to the notion that MF at f5.6 can achieve shallow DOF that has a quality we cannot see on smaller formats (with the suggestion that anyone having actually shot MF would recognise this). Unfortunately it isn't true and isn't close to being true. 80mm at f5.6 on a true 645 format will deliver vastly more depth of field than f1.4 on FF using a 50mm lens, for example (at a given distance). The 645 and 80mm combo cannot overcome the reduced depth of field possible by the much wider aperture of the 50mm lens, which gives the same angle of view on FF. Sure, shoot the 80mm at f2.8 and the 50mm at f2.8 and the larger format will show less DOF.... but if you seek shallow DOF, clearly you would open the 50mm lens up (whereas many 80mm MF lenses are/were f2.8 wide open).

So, while I agree about the fact that 33x44 has the potential to offer shallower depth of field than FF, in practice this is often not the case due to the speed of lenses available (and in the case of the Pentax, options are somewhat limited). Apart from a few specific examples, there is a greater availability of lenses for FF that will offer shallower DOF across a range of focal lengths, especially in the wider focal lengths. A great example would be 90mm on the 645z. Your only native option is the 90mm f2.8 DFA Macro, whereas with full frame, you are looking at 75mm for the same framing. Here, you may have the option of a Summilux 75mm f1.4 which will offer shallower DOF (as would a 75mm f1.8 CV). If you're not shooting Leica M, you could go a touch longer in real terms and grab the Canon 85mm f1.2L (or Nikkor 85mm f1.4), which will offer far shallower DOF and this is simply because big lenses on FF become even bigger on larger formats as the focal length goes up to maintain the same angle of view, meaning the physical aperture is larger etc. In order to produce less depth of field than the Canon 85mm f1.2, Pentax would have to offer a 105mm lens (for same angle of view) significantly faster than f1.8 (I am not sure of the precise maths). But they don't (thought there is a Hassy 100mm f2 and similar). FF usually wins the extreme DOF race (just as they do when you try to figure out what would be needed from MF to produce less DOF than a FF 600mm f4 lens...), but there are other qualities that are strong selling points for the larger formats.

With 'true' 645, achieving shallower DOF than FF is still difficult. 150mm Pentax f2.8 vs (there is no precise angle of view equivalent) 85mm f1.2 L II or 135mm f2 L. The Pentax still does not win the DOF race. It gets much more interesting when you put a 300mm f4.5 on 10x8!

Tonal transition, colour, resolution, lens quality and bokeh are all different issues and even 33x44 (a smaller leap from FF than FF is from APS-C) does offer very real tangible benefits, but depth of field is unrelated to these.

I guess I see shallow depth of field as the least important reason to go with a larger sensor size. Yes, it is a reason for some people, but certainly for a lot of photography it isn't made of really shallow depth of field. But if that is what you are going for, then certainly full frame is going to have the fastest equivalent lenses available.

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Last edited by Rondec; 07-02-2015 at 06:47 AM.

[reh321]

I guess this depends entirely on your definition of "magical". The Pentax 645Z's diagonal is 26% longer than a full frame's diagonal. According to my rough calculations, that gives a camera with slightly more pixels than a Canon 5DS has but each pixel site is larger than those on a Nikon 810. Thus, by simple physics (not magic) it provides more detail than you can get from any current full frame camera while still more than providing the characteristics that people have always claimed for full frame based on physics. Again using physics, it should have the potential for getting even tighter DOF, depending on aperture.

I own a 645z and have owned and shot everything from M43 up to 8x10 over the years so I do recognise and enjoy the benefits of larger formats, but think we have to be careful not to ascribe qualities that are beyond the realm of what physics permits (as well as what can actually be seen in real life). I was responding to the notion that MF at f5.6 can achieve shallow DOF that has a quality we cannot see on smaller formats (with the suggestion that anyone having actually shot MF would recognise this). Unfortunately it isn't true and isn't close to being true. 80mm at f5.6 on a true 645 format will deliver vastly more depth of field than f1.4 on FF using a 50mm lens, for example (at a given distance). The 645 and 80mm combo cannot overcome the reduced depth of field possible by the much wider aperture of the 50mm lens, which gives the same angle of view on FF. Sure, shoot the 80mm at f2.8 and the 50mm at f2.8 and the larger format will show less DOF.... but if you seek shallow DOF, clearly you would open the 50mm lens up (whereas many 80mm MF lenses are/were f2.8 wide open).

So, while I agree about the fact that 33x44 has the potential to offer shallower depth of field than FF, in practice this is often not the case due to the speed of lenses available (and in the case of the Pentax, options are somewhat limited). Apart from a few specific examples, there is a greater availability of lenses for FF that will offer shallower DOF across a range of focal lengths, especially in the wider focal lengths. A great example would be 90mm on the 645z. Your only native option is the 90mm f2.8 DFA Macro, whereas with full frame, you are looking at 75mm for the same framing. Here, you may have the option of a Summilux 75mm f1.4 which will offer shallower DOF (as would a 75mm f1.8 CV). If you're not shooting Leica M, you could go a touch longer in real terms and grab the Canon 85mm f1.2L (or Nikkor 85mm f1.4), which will offer far shallower DOF and this is simply because big lenses on FF become even bigger on larger formats as the focal length goes up to maintain the same angle of view, meaning the physical aperture is larger etc. In order to produce less depth of field than the Canon 85mm f1.2, Pentax would have to offer a 105mm lens (for same angle of view) significantly faster than f1.8 (I am not sure of the precise maths). But they don't (thought there is a Hassy 100mm f2 and similar). FF usually wins the extreme DOF race (just as they do when you try to figure out what would be needed from MF to produce less DOF than a FF 600mm f4 lens...), but there are other qualities that are strong selling points for the larger formats.

With 'true' 645, achieving shallower DOF than FF is still difficult. 150mm Pentax f2.8 vs (there is no precise angle of view equivalent) 85mm f1.2 L II or 135mm f2 L. The Pentax still does not win the DOF race. It gets much more interesting when you put a 300mm f4.5 on 10x8!

Tonal transition, colour, resolution, lens quality and bokeh are all different issues and even 33x44 (a smaller leap from FF than FF is from APS-C) does offer very real tangible benefits, but depth of field is unrelated to these.

You'll notice that most of my comment refers to Image Quality, not to Depth-of-Field, because IQ is what FF users usually crow about when comparing their investments to crop-sensor cameras. If I understand your words correctly, the main issue with MF is lenses actually available, not what could be done in theory.

[batmobile]

Yes, exactly: theory vs what is practically available. I'm thrilled with the improvements I have noted with my 645Z over my A7R for pure image quality, for sure.

I hope that Pentax will produce a top notch portrait lens for the 645z and that it is fast! That said, I personally won't be buying one, as I tend not to need the additional quality for my portraits and would use FF anyway. For studio users, I can see why they are eager for something in the sweet spot i.e. 110mm and f2 or faster. That would be really nice on 33x44. 150mm is a bit long for most people I think, but the 150mm f2.8 undoubtedly has a lovely signature to it.

Ironically, I am probably one who regards the 33x44 format as lovely, because I would rather not have to deal with the shallower DOF endemic to much larger sensors (as I shoot scenics and landscapes mostly).

You'll notice that most of my comment refers to Image Quality, not to Depth-of-Field, because IQ is what FF users usually crow about when comparing their investments to crop-sensor cameras. If I understand your words correctly, the main issue with MF is lenses actually available, not what could be done in theory.

[Pål Jensen]

Theres no need for faster lenses for the 645 system (except for possible low light shooting). Thin DOF isn't a problem for MF; usually the problem is getting enough of it. 99.99% of all images has some significant DOF. Hardly anyone use ultra fast lenses for portraits or in the studio wide open cause there's hardly any DOF; you can only get the eyes in focus in your portrait - not the rest of the face.

[Zygonyx]

Theres no need for faster lenses for the 645 system (except for possible low light shooting). Thin DOF isn't a problem for MF; usually the problem is getting enough of it. 99.99% of all images has some significant DOF. Hardly anyone use ultra fast lenses for portraits or in the studio wide open cause there's hardly any DOF; you can only get the eyes in focus in your portrait - not the rest of the face.

Let me strongly desagree with this statement.
This points of insufficient speed lenses AND insufficient MF sensors size just hamper Pentax MF development.
Hence if nothing is done, no doubt a powerful FF with a decent lens choice, is a great threat to existing 645 system.

Btw : i am a 645 owner and shooter, both digital and film.

[batmobile]

To a large extent this is true and I very rarely covet extremely limited depth of field. I would go as far as to say that I find the fixation upon shallow depth of field as a crutch for otherwise weak photography, however.... where very fast lenses come in handy is in isolating subjects at distance, where depth of field increases for a given aperture. While you may not want to shoot wider than f2 or f2.8 at 70cm using a 85mm lens on FF, shooting the same subject at 2m or 3m may leave you wanting a faster aperture, as at f2.8 depth of field is already growing rapidly. This is why the Canon 50mm f1.2L is so beautiful, because of how it renders subjects at moderate (and not close) distance wide open.

Overall though, I agree. I find it odd that so many Leica 'street photographers' fixate over lens performance wide open when the kinda sorta point of the genre is to kinda sorta see what's going on in the street! This is why the Ricoh GR is so phenomenal, because it has a smaller sensor and amazing performance throughout the aperture range.

Theres no need for faster lenses for the 645 system (except for possible low light shooting). Thin DOF isn't a problem for MF; usually the problem is getting enough of it. 99.99% of all images has some significant DOF. Hardly anyone use ultra fast lenses for portraits or in the studio wide open cause there's hardly any DOF; you can only get the eyes in focus in your portrait - not the rest of the face.

[Pål Jensen]

Considering that a moderate slow wide angle zoom for the 645 weigths 1,4kg and cost $5000, and even only covers a cropped MF sensor, a superfast lens will simply be beyond imagination even if it is a prime. I cannot see how this is hampering Pentax.
Low light work with fast lenses is best achieved with FF. The law of incredibly diminishing returns is starting to set in as soon as you talk very fast MF lenses...

---------- Post added 07-02-15 at 11:13 PM ----------

Overall though, I agree. I find it odd that so many Leica 'street photographers' fixate over lens performance wide open when the kinda sorta point of the genre is to kinda sorta see what's going on in the street! .

Street photography. Wasn't that F:8 and be there?

[reh321]

Street photography. Wasn't that F:8 and be there?

Exactly. The idea was to have the camera set up in advance: F/8 because it gave an appropriate DOF with their lenses, and then whatever shutter speed worked with that aperture (and hope that the lighting doesn't change radically after setting everything).

[Zygonyx]

@batmobile : Ok with your overall position. BUT as far as photography potential is concerned AND as far as bigger lenses are unavoidable with MF versus FF, MF HAS to provide a greater potential unless it is a bit "superflu".
Hence my last intervention.

@Pal : may i remind you that you already often complain about weight of recent imho slow 645 lenses... what about Leica or m4/3 systems for you ?
I have recently tried Leica Q, and i think this is a "must" as far as everyday or street photog are concerned.
Plus dont ignore "superfast" MF lenses do exist e.g. f/2.

[patarok]

Not if your subject is moving. All I'm really saying is that whatever one's needs, there is a camera system to satisfy it. Buy what you want, and be happy!

Where does this sweet smell come from...?

Man! "buy what you need and be happy".... lmfao... as if everybody would be capable of buying himself a new camera system including complete lenspark every week.
I didnt buy my Pentax yesterday. Nor do i plan to invest in another system plus lenses... My lenspark is nearly totally complete.
And that is why i dont like to see a FF-Body where i have a sensor with more than 32MP... in no way... i want crisp pictures... and i want fast framerates.. and if possible i would like to see 4K video. i stand to that..

STUDIO SHOOTINGS = no moving objects... real models are at least able to stand still and actually i meant product photography... show me your dancing glasses, wristwatches, knives, etc. and i will tell you your future... :P

And all i am saying is: Dont waste money. And:

NOT EVERYBODY IS CAPABLE OF THROWING

6200 DOLLARS IN WORDS: SIXTHOUSANDTWOHUNDRED

OUT OF THE W I N D O W !!!

Let me assure you, that we are happy that you have no problem buying every week a new camera.
But most Pentaxians are wise people who think about the worth of things. And... i throw my 2 cents on the table and say most of us...
Deal careful with their money...

I dont want to say you are one of those guys from companies like "Modern Mind MARKETING" but if i only I would get a dollar every time when one of those "self proclaimed SPIN DOCTORS" are posting about other systems and so on, and totally screw up the threads headline... I guess i would by now be able to buy myself a 645Z...

[Big Dave]

Today I went to my local camera store to get a new gimbal head. The Tamron rep was there at the time and between him and the store owner I have these rumors.


#2. The new full frame Pentax will have the Sony 42 MP sensor from the a7R II..

The A7RII sensor has builtin features that won't work with a dslr and add to cost, as well as reduce yield. I could see Pentax using the existing FSI sensor from the D810. It is optimized for a dslr and is a more mature process giving higher yield and lower cost. The 5 axis FF IBIS would be an easy match and is fantastic. I can shoot at three to four stops slower with my A7II, then I could with my A7R or A7. 36mp sensor with EFCS and IBIS would be great. This together with Pentax weather proof body would be a no brainer for many pros.

[monochrome]

The A7RII sensor has builtin features that won't work with a dslr and add to cost, as well as reduce yield. I could see Pentax using the existing FSI sensor from the D810. It is optimized for a dslr and is a more mature process giving higher yield and lower cost. The 5 axis FF IBIS would be an easy match and is fantastic. I can shoot at three to four stops slower with my A7II, then I could with my A7R or A7. 36mp sensor with EFCS and IBIS would be great. This together with Pentax weather proof body would be a no brainer for many pros.

Winner! Winner! Chicken Dinner!

[Zygonyx]

The A7RII sensor has builtin features that won't work with a dslr and add to cost, as well as reduce yield.

If there are build in features, they can also be build off.
When talking about sensor one should never forget that these are like multilayered cakes, and that you can use the same matrix with different compounds

[Big Dave]

If there are build in features, they can also be build off.
When talking about sensor one should never forget that these are like multilayered cakes, and that you can use the same matrix with different compounds

The dslr version of the A7RII sensor would require a major rework and a complete new series of engineering samples to start mass production. It takes time to debug a new process with the related lower yield and increased cost. I know that it will happen, but it isn't a cost effective route for Pentax's first dslr FF body in my opinion. I base this on my eighteen years in semiconductor fabrication with Sony.

[monochrome]

Everybody just wait. Feels to me like Ricoh will release a cutting edge tech camera, but I'm worried about Milbeaut. I don't think video will be great and many will dismiss a stills-optimized without even seeing it.