Hasselblad X1D: Contining Impressions and Learning Curve

[JohnMM]

Clearly the exposure must be the same.

Why?

Let's say we take a photo with a D810 in DX with a 70/2.8 lens with an exposure of 1/800 at f/5.6 and then one with the same D810 in FX with a 105/2.8 lens with the same exposure of 1/800 at f/5.6. We'll assume the subject is the same and the subject distance is the same.

If you are going to keep the same perspective and framing, why change the DOF?

[David H. Hartman]

Why?

More exposure less photon shot noise; less exposure more photon shot noise.

If you are going to keep the same perspective and framing, why change the DOF?

It's a gift and one that can't be refused.

Dave

[Ilkka Nissilä]

It's a gift and one that can't be refused.

Usually lenses have adjustable apertures and you can set the depth of field where you want it and format choice should not stop you from making creative decisions like that. Of course there can be limitations (aberrations at wide apertures and availability issues with lenses) but your statement makes it seem like there is no choice. Or am I missing some humor?

[David H. Hartman]

Usually lenses have adjustable apertures and you can set the depth of field where you want it and format choice should not stop you from making creative decisions like that. Of course there can be limitations (aberrations at wide apertures and availability issues with lenses) but your statement makes it seem like there is no choice. Or am I missing some humor?

No, not humor. It's part of a discussion on dynamic range and format size where many contend that a larger format will give more DR than a smaller one because the larger format collects more total light where all else remains constant. This theory may be true or it may not because it's based on DXOMark's, "lies, damned lies and statistics."

I posted a group of links to graphs of various popular Nikon FX camera where the graphs show the same camera in DX format mode gives less DR than it does in FX mode. I think these are a page back.

If all else remains the same, shutter speed, f/stop, distance, angle of view but the format changes from larger to smaller one will gain DoF. It's a gift of the smaller format.

Dave

[Jack Dahlgren]

Dynamic range is a function of the capacity of the photosite and accuracy in measuring it - noise.
A photosite that is too small will get saturated with electrons when struck with too much light - thereby clipping the highlights. It will also be somewhat more subject to signal noise as the noise is a larger proportion of the electricity being transmitted.

Larger sensors can have larger or smaller photo-sites, or the same size as smaller sensors.

As the constant improvement of digital photo sensors shows, the most important element is not the size of the format as that plays a very small part in the quality of images. The largest leaps in dynamic range are made in the lab and the fab.

I think the rational photographer is one who chooses the format which allows them to achieve their goals.

[Ilkka Nissilä]

If all else remains the same, shutter speed, f/stop, distance, angle of view but the format changes from larger to smaller one will gain DoF. It's a gift of the smaller format.

But if the user of the larger format doesn't need the extra SNR or DR, they can sacrifice that and stop down the lens to match the depth of field of the smaller format. Things were different with film because film speed was basically fixed, so people got used to thinking in terms of what exposure was required to get a good image on a given speed of film. Today the variable ISO and great dynamic range of many sensors allows the user to choose the depth of field they prefer rather than think of it as a side effect of format choice. And diffraction affects the image in a similar way if the depth of field is fixed across formats. So if you've got diffraction limited lenses of sufficient maximum apertures you can get basically the same image from different formats - this is what equivalence theory covers: which settings to use on different formats to get the same image. If your lenses are aberration limited then there is a likelyhood that the larger sensor gives the more detailed image, at least in the center.  OTOH your smaller system is smaller. But aberrations are not really covered by equivalence theory.

I don't think there is any controversy really. It's just different generations thinking using terminology they're familiar with and not really understanding each other. 

[David H. Hartman]

What I've found is this...

D5 v. D5

D5 v. D500

D5 v. D5 v. D500

What science wants is independent verification.

[BW]

Why on earth would a camera sensor have better dynamic range in Dx format than in Fx format? The sensor doesnt know if only a part of it is read out. If you use RAW format, it is the same if you crop the image afterwards. This is pseudoscience and proof to why it is of no value to discuss sensor performance decopled from real world experience. It all boils down to what one find pleasing to ones eye and to what gear one find suited to the task at hand. If one find that MF does the job well, ok, if it is MFT that is equally ok. One doesnt need to draw a curve in a diagram to prove anything. The very existence of Canon users have proven that long ago That is just my two last cents

[Bjørn Rørslett]

It's even worse, Børge.

What people discuss are model outputs without even questioning if the model is appropriate or even applicable. Where is the simple consideration of whether circular arguments are introduced in the model chain? I have yet to see these models take into account the basic fact that by comparing two formats printed to a final fixed and similar size, the magnification of detail along the image chain will be different and thus also will the effective aperture. Just the normalisation removes a degree of freedom that later never can be recovered. It introduces circularity.

The only imaginable use of these models is comparing two cameras having the *same* format. Everything else  is not only apples-to-orange, it is fundamentally flawed and hence just a waste of time and internet bandwidth.

[chambeshi]

It's even worse, Børge.

What people discuss are model outputs without even questioning if the model is appropriate or even applicable. .....

"All models are wrong but some are useful"

Attributed to the late George E. Box, son in law of Ronald A. Fisher who founded parametric statistics and much else besides. Here's the original source if you are interested in reading further:

Box, G. E. (1976). Science and statistics. Journal of the American Statistical Association, 71(356), 791-799.

[JohnMM]

What I've found is this...

D5 v. D5

D5 v. D500

D5 v. D5 v. D500

What science wants is independent verification.

As far as I know the numbers come from DxOMark and the analysis is by Bill Claff himself. Both have been described in more or less detail and discussed extensively. What else does "science" want ? Does it want someone to independently repeat DxOMark's measurements ? Who is going to pay for it ?

[Bjørn Rørslett]

Whether input data points are good or bad is immaterial if the model they are used for is not appropriate or is flawed. If the model, however, is sound, then quality of the input obviously matters.

[BW]

"Sciene" want anyone to stop measuring the degree of "nothingness" in an empty space of emptyness..

[simsurace]

I opened a separate thread under http://nikongear.net/revival/index.php/topic,5905.0.html for anyone who wishes to further discuss the topic of equivalence.

[David H. Hartman]

What else does "science" want ? Does it want someone to independently repeat DxOMark's measurements ? Who is going to pay for it ?

Yes, that's the idea. If an experiment can be replicated and the results are the same or nearly the same that gives credence to the theories involved. If the experiment is repeated and different results are obtained then something is wrong. Maybe the original theories need refining or maybe they are just wrong.

The object of repeating an experiment is to prove or disprove.

Dave Hartman

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It seems logical that the extra sampling of light, of photons, yields an advantages to the larger image sensor. If and what advantages is another matter. Maybe the graphs of dynamic range are true? Maybe I'm too willing to believe and they will be disproved?

Dave