Hacker News Reader

Comment by anovikov | Hacker News Reader

I can say precisely which lens was used to make that photo: Canon EF 17-40 L USM on a DSLR. Or some other very, very similar lens. No photographer can mistake this for anything.

Like this:

http://www.flickr.com/photos/meonoctis/5661946485/in/set-721...

View on HN

For most people shooting Canon gear the 24-105L is the much more common go-to lens for street shots like this.

For true pros, the 16-35L would be more common than the 17-40L, since it is an f/2.8 instead of f/4.0 lens. It's almost a given that anyone shooting Canon owns the 24-105L, so when opting for a wider angle lens the 17-40 and 16-35 are your two most common choices. The 16-35 gives you the wide-angle, PLUS lower f/stop (The 24-105L is f/4.0 also)

I don't think you can tell with any degree of certainly which specific lens was used for these shots.

Agree, i cannot. Probably not 24-105, but any other of these easily.

I thought the backdrop looked familiar. The first and third photos were taken next to the Sokos Hotel Vaakuna (located across the rail depot), where I stayed when I was in Helsinki in late June, at the time of the summer solstice (20+ hours of light). I'm no photography expert like anovikov, but I can attest that the street lighting was nowhere near as bright as depicted in these photos, even at 2am when it was darkest (dark = same brightness in the sky as first photo).

Now it's perfectly normal to slightly alter promotional collateral as long as there's some YMMV caveat. But with such a flagrant abuse of consumer trust as presented here, it calls into question just how desperate Nokia is that they need to misrepresent a core feature of their savior product.

The lighting was artificial[1]. I don't mind that part as much though, it's the professional camera that's more disingenuous.

[1] https://sphotos-a.xx.fbcdn.net/hphotos-ash3/578446_101510870...

Files from a larger chip go into print collateral alot better... This is pretty much to be expected. File would be PS'd as well, that's one of the reasons they do this, as the colour-space transitions to CMYK etc can be damaging. They do need to have better disclosure though. Starburst is telltale DSLR.

Wait...why can you say (very, very precisely) that lens (or similar) was the one used? Because of this other picture? I see no resemblance... Would you mind elaborating? I have no idea what you are implying or why.

I just mean it is a lens with a very similar optical schema than the Canon 17-40L. The diffraction pattern around light sources is very similar. I played around with this lens some time before with my previous DSLR (now i am a Nikon user) and enjoyed it really. I don't mean it was exactly that lens, but something very close - definitely not fixed f/2.0 cheap lens of a smartphone, that kind of halo with 'rays' around light sources is possible only with a lens having many internal components which will be too thick to fit into a smartphone, and not f/2.0, and of course too expensive for a smartphone.

So i fully agree with the article saying it was a fake.

Gotcha. Definitely didn't doubt the article; just wondering what you meant. Thanks!

Also the article is most likely wrong about calling these artifacts purely diffraction-related, creating diffraction images that big and visible would require too small focal ratio, which is unlikely for night conditions, because they increase exposure time which is already too long. These are just a consequence of internal back-reflections inside the lens optics which manifest itself on extreme contrast parts of image (bright light vs dark sky). Especially obvious on astronomical images, where control of focal ratio is manual and it's almost always open fully to collect as much light as possible - of course, focus depth is of no meaning for astronomy - and the quality of this lens allows for perfect images even when wide open. Bright stars always looks like this on Canon 14-40L.

i don't understand what you are saying here. astronomical images don't look exactly like that - they have fewer "spikes" - but they are similar. the spikes are either from diffraction caused by the secondary mirror support (which light passes through in a reflecting telescope) or readout artifacts in the CCD, particularly when it saturates (although that looks quite different - a single vertical line, often).

i agree that the spikes (in astronomy images) don't come from blade edges in a diaphragm aperture, but they are still diffraction spikes (from the secondary support) and "everyone" (as far as i know / remember) refers to them as such.

you can see the secondary support in the top right image at http://en.wikipedia.org/wiki/Reflecting_telescope - the four radial "things" that hold the cylinder in the "end" of the telescope (on the right).

so what are you referring to with "internal back reflections" and how does that give spikes (rather than ghosts)?

[above from (past) personal experience as an optical astronomer on research telescopes - i am not sure if you are confused, or if there's some kind of problem i never understood. perhaps you work on a system where this is an issue?]

I am speaking about astronomical images not in general, but those taken with the Canon EF 17-40 f/4 L USM lens. They are almost always taken with the diaphragm wide open, and contain same kind of spikes -> spikes are not from diffraction.

The shine on the lights appear very similar, to me. But I am no professional

Just as an aside, what is with the comments? Does every user have their own "award" to present?

Wow, never been so downvoted before. I didn't realize everybody was so familiar with the Flickr website and this award business was common knowledge. For the record, I did Google it and couldn't find any relevant information.