Author Topic: Hasselblad X1D: Contining Impressions and Learning Curve  (Read 15393 times)

David H. Hartman

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #15 on: May 12, 2017, 21:31:51 »
If the aperture and shutter speed remain constant photon shot noise is less of a problem with a larger sensor. More total light is collected by the larger sensor. The intensity per/unit of square measure is the same so the larger area collects more. (I hope I typed that sensibly and correctly this time :) If the final presentation is the same, e.g. 11x14" print the color fidelity and noise levels should favor the medium format.

Dave Hartman

I'm sure many money wrenches can be tossed into this none off which involve shot noise (or so I surmise)

I'm not too excited about the mid-medium format camera as it's not a big enough step up in format size to be worth a second set of lenses, that's for me. It's all theoretical for me as the cost of a second system is prohibitive, particularly a medium format system.

Dave

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I don't like photon shot noise like I don't like death and taxes.

Dave
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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #16 on: May 12, 2017, 22:28:54 »
Only makes sense if the pixels on the larger format also each are larger. The sensor area itself is not the primary determinant. One could as well argue that the larger format confers a potential disadvantage by putting more stress on the optics to be sufficiently corrected to cover a greater image circle and still have adequate sharpness and low levels of colour aberrations.

simsurace

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #17 on: May 12, 2017, 22:58:02 »
You can theoretically produce a scaled version of your lens that should perform the same. I'm assuming no size or weight constraint by the user. Generally the engineering problems come with downsizing stuff, don't they?

The ideal sensor would have an infinite number of pixels and a fill factor of one. You would record the position of each photon, and all the binning and averaging would be done in post. 😄
But we would need faster computers, since there are on the order of 10^12 photons that hit an FX sensor.
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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #18 on: May 12, 2017, 23:12:50 »
Scaling is not that easy to implement in practice. There may be production or size constraints that limit the degree of what one could diminish or enlarge a given design.

We need to keep in mind that what we mount onto our camera virtually always are mass-production items with all that this entails.

simsurace

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #19 on: May 12, 2017, 23:27:29 »
Scaling is not that easy to implement in practice. There may be production or size constraints that limit the degree of what one could diminish or enlarge a given design.

We need to keep in mind that what we mount onto our camera virtually always are mass-production items with all that this entails.

Yes, I understand that we cannot get this off the shelf and there are practical limitations. I think that a copy of the Otus lens that covers 8x10 would be rather hard to construct. But theoretically, one could make copies of Michael's favorite Zeiss lenses to put on the Hasselblad, and they should not perform worse. The scaling factor is rather modest. On the contrary, they would probably perform slightly better because the same level of absolute tolerance would result in better relative tolerance.
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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #20 on: May 12, 2017, 23:46:05 »
The "small" Otus for FX carries already a very high price tag. Imagine the cost of an upscaled version with much more heft and smaller potential sales volume. Not convinced Zeiss would embark on such a venture.

David H. Hartman

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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #22 on: May 13, 2017, 12:23:00 »
So, the very same sensor and photo site "knows" its total area is limited, all other parameters being identical? How strange, perhaps we see the marks of artificial intelligence (AI).  I cannot see that in-camera processing or later "equivalencing" has been eliminated as a variable here either. Furthermore the graphed data points are from a model not measured. If the model is misleading so will the data and conclusions be.

David H. Hartman

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #23 on: May 13, 2017, 12:51:34 »
Graphs based on Lies, Damned Lies and Statistics?

I keep reading the size of the format is significant, perhaps more than pixel size. This must  assume that the image will be printed modestly large, a print for the wall not a mural, or presented on a high quality display. Clearly the exposure must be the same.

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. Assuming the IQ of each lens is the same which RAW file will hold the most real data? Now if we make 22x30cm (9x12in) print or a 28x42cm (11x17in) print from the DX and the FX RAW file the potential is the print from the larger collection of data (photons) will make the better print. I'm sure a few monkey wrenches can be thrown in the works but potentially we can make a better print from more data which should be a better sample. 

Anyway that's what I've read for a time.

Dave Hartman

Graphs based on DxOMark data?
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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #24 on: May 13, 2017, 13:15:54 »
The darned "equivalence" approach can be twisted any way one prefers to support almost any supposition one wants.

The crucial point, however, is as follows: will a single photosite "understand" the total area of the *same*  sensor is DX or FX? In any case,  I find this assumption highly questionable. What happens later during post-processing stages is another issue, but will not influence the basic first stage of light collection, which is per photosite.

I wish there had occurred some kind of peer reviewing of these models floating around on the 'net before too much trust can be placed on the model predictions.

simsurace

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #25 on: May 13, 2017, 14:24:02 »
The crucial point, however, is as follows: will a single photosite "understand" the total area of the *same*  sensor is DX or FX?
Of course it won't.
These graphs don't talk to the initial light collection, but to the perceptual magnitude of noise in the final image. That's why he uses what he calls "photographic dynamic range", and not "engineering dynamic range".
When we view images (at a standardized size), we don't examine individual pixels, but integrate information across a finite patch of the photograph. We need to normalize the statistics of individual photosites to reflect this*. This is the only part where a model is applied (rightly so, don't you think?). The photon transfer curves and SNRs are measured values, and the site explains how they were measured.

* To make an example: if you make the photosites smaller, they will each record less photons. But will the image viewed at large become noisier? Perhaps, but only if the higher pixel density leads to a lower efficiency of light collection. When those technological obstacles are overcome, the per-pixel noise will be more, but since the pixels are smaller, the noise will not be more bothersome compared to the lower-MP sensor when the image is viewed at a standardized size. So the graphs that were linked by Dave are, to a large extent, independent of the photosite size.
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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #26 on: May 13, 2017, 14:38:09 »
I repeat that with the underlying 'equivalence' thinking one can "prove" almost any measure one wishes.

In the referred charts, modelled output based on unspecified or implied conditions deemed relevant to the average photographer is presented as were it to show the DX sensor is inherently inferior to the FX. Or by extension, any smaller vs. larger format sensor. However, careful consideration should indicate this is a largely circular argumentation and results from intentional differences in the output, not the input.

Fortunately, there is much more to actual photography than blindly relying on dubious models and charts.


simsurace

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #27 on: May 13, 2017, 14:57:49 »
I cannot speak for others, but I'm certainly not blindly following anything.
I also don't think that you can prove everything with the equivalence principles, unless you deliberately misuse them or apply them selectively.
Of course I see many people do that, but this is hardly the fault of those that understand them.
In all these years I haven't seen a single experiment that actually genuinely contradicts any of the principles, nor a more concise summary of digital signal processing principles as they apply to photography.
Simone Carlo Surace
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Bjørn Rørslett

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #28 on: May 13, 2017, 15:23:33 »
Any proficient photographer tends to aim for using the best tools for their work. That encompasses choosing the suitable format for capturing the initial image. Sometimes the "best" format is small, sometimes it is larger, but any sane decision has to be based on very different criteria than what can be gleaned for the noisy information available on the internet.  Severe abuse of concepts and understanding physical laws are wide-spread to the extent that in some user groups they have replaced the facts.

The inevitable information loss (or introduction of noise, which is the same thing) associated with overall degree of magnification of detail along the work flow from raw file to print should receive much emphasis. It is a basic fact that a larger format needs less secondary magnification to get a fixed print size, but is that a relevant basic for comparison if the end user doesn't care about what format they print to? Can a higher initial pixel count negate the issue of magnification loss, or will we face the apparition few know or care about, the ghost of empty magnification? In fact, with most of the gear available today, we can make final prints much bigger than anything deemed feasible only a few decades ago, unless you had an awkward slow-operating view camera of 4x5" or larger. For viewing on a web page, even a measly 2 MPix model would suffice thus most of our captures are truly overkill in terms of the amount of data captured.

I'm definitively not saying techincal information is superfluous or we shouldn't wish for improvements in sensor technology or camera features, merely pointing out the danger of running in circles to bite one's tail if not allowing less technical aspects to play prominently in our photographic life.

simsurace

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Re: Hasselblad X1D: Contining Impressions and Learning Curve
« Reply #29 on: May 13, 2017, 19:07:28 »
Yes, I agree with this perspective. It is clear that artistic vision is very important and that for me the fascination of photography is the combination of science and creativity.
Simone Carlo Surace
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