Is large sensor DOF aesthetics real or a myth?

[Sheldon N]

I don't think it's a myth, I wonder if it is and that is why I opened this thread. I also shot images with my 5D and 350D, but to be honest couldn't experience any enhanced 3D feeling from the former at the same DOF and that is why I opened this thread in this section. I will probably never have a large format camera or back since I am not interested in having one.

.... lighter lens corrections, lower level of demand in lpmm,... all play in favour of large formats. That will explain an apparently subjective characteristic of large format sizes based just on image quality (sharper images in the focused areas might mean a stronger 3D effect, less corrected lenses might mean a more pleasant transition to the defocused areas and nicer bokeh).

As a side note, I went back and looked through some of my old portraits shot with 4x5 film and a 150mm APO Sironar-S lens (wide open) and compared them to portraits shot on my 1Ds III and the 50mm f/1.2 L lens (wide open). The depth of field calculators say that the 50mm f/1.2 has shallower depth of field, but the 4x5 images have a sharpness/contrast/depth to them that when combined with shallow depth of field presents a much more striking presentation.

The advantage of larger formats is definitely real.

[DeeJay]

Alot of the 3D effect from large format in particular is the sheer size of the film. There's more room for more grain and the tonality will always exceed that of smaller format. Same goes for digital sensors. It's the tonality that makes so much of it's 3D like characteristics. A lot of an images "sharpness" is tonality also. It's recording more reality so looks more real.

Just the same you can fudge an image to look more 3D with unsharp masking in photoshop.

[timparkin]

I used to ponder just the same question and then I started learning about the compromises in lens design for small formats (especially SLRs) and MFDBs. SLR small formats have to be incredibly well corrected because of the small surface area of film/sensor. Hence additional optics are needed and you end up with a few more elements, this inevitably affects abberations away from the plane of focus and can cause 'muddled' oof areas.

The situation is further complicated by the necessity of retrofocus designs for SLR wide angle lenses and also MFDB wide angle lenses. The first because of the mirror not allowing simple lens designs, the latter because MFDB sensors can't cope well with high incident angle light rays (sic).

Large format lenses don't need to be as well corrected in the first place because of the amount of film area and they also can be built to better tolerances based on the scale of their design i.e. working in tens of microns instead of microns.

Have a look at the following diagram and have a think about what all those extra lens elements are doing to out of focus areas.

[ErikKaffehr]

Hi,

It is not an obvious for me that having more elements will have a negative effect on out of focus image areas. That said, I have seen that lenses that may have been aggressively corrected often have less than nice out of focus rendition. So I can see your point, but it's more an empirical finding than one having a solid scientific base.

Another aspect is that we have a bunch of highly corrected "large format lenses",like the HR Digarons, which are essentially intended for medium format (with some shift). The HR Digarons are also aggressively corrected, with some having far better MTF that corresponding 135 lenses. What kind of "bokeh" do those lenses have?

Finally, for extreme wide angles, retrofocus does actually have an advantage that light fall of is significantly less than for conventional design. I would assume that "lens cast" is also significantly reduced on retrofocus designs.

Anyway, thanks a lot for contributing to the discussion and sharing your experience and knowledge!

Best regards
Erik

I used to ponder just the same question and then I started learning about the compromises in lens design for small formats (especially SLRs) and MFDBs. SLR small formats have to be incredibly well corrected because of the small surface area of film/sensor. Hence additional optics are needed and you end up with a few more elements, this inevitably affects abberations away from the plane of focus and can cause 'muddled' oof areas.

The situation is further complicated by the necessity of retrofocus designs for SLR wide angle lenses and also MFDB wide angle lenses. The first because of the mirror not allowing simple lens designs, the latter because MFDB sensors can't cope well with high incident angle light rays (sic).

Large format lenses don't need to be as well corrected in the first place because of the amount of film area and they also can be built to better tolerances based on the scale of their design i.e. working in tens of microns instead of microns.

Have a look at the following diagram and have a think about what all those extra lens elements are doing to out of focus areas.

[hjulenissen]

Suggestions:
MF tends to be handled by dedicated photographers, 1.6x crop less so. That affects image quality perhaps more than the equipment used.

Large sensors tend to have more pixels than small ones. Unless you are diffraction-limited, I believe that may be an advantage for the larger camera.

MF may offer movements, smaller formats generally are used without.

You seem to base your questions on idealized physics. Idealized physics are a great tool to understand the world around us, but they don't capture everything. 35mm f/1.0 lenses are not easily available for my 1.6x crop camera. Those lenses that are available may not be a perfect scaled-down analog of some MF lense, tolerance and all.*)

I am a big fan of great end-results no matter how they are obtained. But I am a sceptic about supposed benefits of a given piece of gear if they cannot be summarized in a compact explanation that I can comprehend, or a fair side-by-side that I can accept.

-h  
*)If a lense designer were given the following task: resolve as many line-pairs as possible on a square area of any size, what dimensions, materials and construction principles would be most sensible?

[ErikKaffehr]

Hi,

One kind of comparison I have seen is shooting with an MFDB using 80/2.8 lens at f/2.8. A comparison image is shot on Nikon D3s using 50/1.4 lens at f/1.4. I guess that most MF 80/2.8 lenses are quite OK at f/2.8 but I have not yet seen a 50/1.4 lens that was not really soft at f/1.4. So MF always wins this round. I'm not really sure I find this example contrived.

If I'd need a shot with very small DoF I would probably shoot with a short (or even long) telephoto lens, at f/2.8 or f/4. But there may be reasons that it is not possible.

Simpler lenses can often have a nice bokeh (out of focus imaging). Complex designs may have a complex (ugly)  bokeh.

Best regards
Erik

Suggestions:
MF tends to be handled by dedicated photographers, 1.6x crop less so. That affects image quality perhaps more than the equipment used.

Large sensors tend to have more pixels than small ones. Unless you are diffraction-limited, I believe that may be an advantage for the larger camera.

MF may offer movements, smaller formats generally are used without.

You seem to base your questions on idealized physics. Idealized physics are a great tool to understand the world around us, but they don't capture everything. 35mm f/1.0 lenses are not easily available for my 1.6x crop camera. Those lenses that are available may not be a perfect scaled-down analog of some MF lense, tolerance and all.*)

I am a big fan of great end-results no matter how they are obtained. But I am a sceptic about supposed benefits of a given piece of gear if they cannot be summarized in a compact explanation that I can comprehend, or a fair side-by-side that I can accept.

-h  
*)If a lense designer were given the following task: resolve as many line-pairs as possible on a square area of any size, what dimensions, materials and construction principles would be most sensible?