Infoseite // DSLR - combine digital zoom with fixed focal length?

Frage von Interlaced_Killer:

I was just following flash of inspiration:

Of the 12 megapixels, which currently have the DSLR-chips, for example, is required for 720p not even 1 megapixel.

Why do we then need a (; fainter) zoom lens?

I buy me one example for GH1 Panasonic Festbrennweitenoptik with 14 mm (, KB 28 mm equivalent), so keep me in KB 56 mm still 3 megapixels.

Thus, one could zoom in digitally with the focal of 28 - approx 90 mm, unless permitted by the camera, and taking advantage of the luminous intensity of a Festbrennweitenoptik.

Am I correct that, or are there other problems, I do not think I s.The?


Antwort von Zizi:

Basically, now I'd say the time would be no problem if the camera in video mode, a digital zoom can ..
In Mark2 gehts devinitiv not!
I think that here the Manufacturer profits at the overpriced telephoto lenses in danger of seeing and therefore not with their cameras as a function of accessorizing!
Your idea is just as good as simpleton! ;-)


Antwort von Büschel:

The idea would certainly not bad, but the telephoto lenses are not overpriced, since it is primarily still cameras are Stillimage. I wish there have been like shooting with full pixel count, not just video resolution ...


Antwort von Interlaced_Killer:

The smaller the chip, the less is needed for opening the same intensity, since the focal circle is smaller. Therefore, light intensities of compact cameras often have 2.0 or better.

Now, I find it strange that the APS-C and 4/3-Lenses

- Are not more luminous, which would be in equally large lenses and a smaller circle of burning case
- That is, smaller lenses have
- And still are not favorable.

My tip: buy up good Adapters and Vollformatobjektive.


Antwort von WoWu:

@ Interlaced_Killer
That does not work, with the digital zoom and the fixed focal length, because stays with an optical zoom of the diffraction ring of the pixel identical times in relation to size, is associated with a windowing, but the selected window to a relatively larger size and thus increase the blur circle. .. and thus increases the uncertainty.
With the blur, so a de-focusing in HD is very drastically the MTF (, 2 / 100 tel defocusing already lead to the halving of the MTF!)
In addition, the uncertainty synonymous ensures that the motion estimation for compression and a negative change in the Priority Picture Processing takes disproportionately more time to complete. This in turn means that the motion estimation is aborted and show the famous blocks in the Picture. It was also shortened the process time and other processes, such as the edge enhancement is thus synonymous prematurely.
You see, there is the narrow time window of 40 or 20 ms for video a couple of specials that are different negative of the photograph and get along with the familiar image degradation from the digital zoom synonymous a few other, fairly coarse side with him.


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