Camera Nitty Gritty - part 7 - Optical Zoom
Published by Steve Litchfield at 9:42 GMT, October 30th 2008
The latest in my continuing voyage of discovery in the world of camera-toting smartphones, I look at the difference optical zoom makes and ask the question "Is it better to have optical zoom or can you get away with just much higher resolution?" I illustrate my points with test shots from the Samsung G810 and INNOV8, plus a guest appearance by the Nokia N93, which also has an optical zoom lens.
"In part 1 of this series, Steve Litchfield looked at exposed camera glass on some phone models and investigated whether scratches really make a difference. In part 2, he investigated the pros and cons of LED/dual-LED/Xenon flashes in camera phones - does Xenon or dual LED flash make that much difference? In part 3, he investigated the fabled 'Megapixel myth' with an objective eye. In part 4, he focussed on the difference between good and poor optics (at the same camera resolution) and in part 5, he pitched all the top smartphone cameras head to head, in detail. In part 6, AAS guest writer Dirk Snoyt took up the theme of camera phone flash research and got all technical on the theme of colours...
Now, I return with a look at the difference optical zoom makes and ask the question "Is it better to have optical zoom or just much higher resolution?"
Read on
Categories: Hardware, Editorial Thoughts
Platforms: General, S60 3rd Edition
News Discussion
snoyt
Nice on Steve, though I'd like to make some additions and comments, it's always easier to comment than to write :-P:
Even though the agressive sharpening of the i850 makes things looks worse than they already are ;^) The higher resolution off the i850 translates to a zoom of 1.26X, pixel resolution wise that is. Meaning good optical zoom would always beat zoomless down always in terms of zooming. About motion blurring I'd say it is a matter of which is of the two lens with CCD is more sensitive.
For some it might not be clear that motion blur occurs of course for both optical and digital zoom in the same amount when shuttertimes are equal. However they are not. 3x digital zoom, means 0x less light than unzoomed and subsequently not causing more motion blur than unzoomed.
The G810 i.e. with optical zoom has f/A = 3.5-6.8. Which makes the difference between zoomed out against zoomed in about 2x less light. Worse yet fixed lenses already in general are twice as more light sensitive than the optical zoomlens of the G810. Thus 4x less when using 3x optical zoom. Needing a 4x larger shutter time and inducing 4x more motion blurring than with a non-zoomed lens. As a result images with optical zoom can look far worse than digital zoomed fixed lens images, 4x is larger than 3x. So keep that optical zoomed camera 'still' or move it with the target object to reduced its motion blur.
Of course these estimates are done with rule of thumb accuracy. And results may vary with different lens and sensor qualities ;-)
genXhippie
I really enjoyed the write up, well done Steve imo.;)
ILoveGadgets
Another top article Steve, and I'm glad you pointed out the difficulties faced by the phone manufacturers in producing phones with optical zoom too - that side is not always appreciated.
However, it just goes to show that if the demand is there then Nokia & Samsung etc. could create a proper camera phone. The technology is there already, all parts just need to be combined. You do get the feeling though that the resultant handset would hardly have super-model proportions so desired by the form-over-functionality-led public.
ILG.
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