One thing that irks me more than a lack of information, is a glut of misinformation!
Just recently I was casually browsing through petapixel for any interesting news.
There was some(about some dubious info regarding the ability to see in near infra red!) and then noticed an article about photography on the cheap.
While many parts of this author's writings made sense, there was one particular aspect of it that 1/. made me laugh and 2/. forced me to post this thread.
be wary of stuff you read on the net
In this guy's blog post, he mentions getting a cheap (Nikon) D40 and a few lenses.
It's his interpretation of the lenses that irked me.
He claims that many 18-55 type kit lenses are listed on ebay, and that this is a good lens to be had for cheap .. (probably right .. can't personally remember)
Then he claims that many Tamron 90mm f/2.8 lenses are usually listed and this can be a great all purpose lens. (spot on! )
He says it can do good macro, portraits and so on. (still on the right track )
Then ... (I'll paraphrase, rather than risk copyright infringement)
Note how I underlined the word 'Because', because the implication he made there is that the poor old Dx only 18-55 is still an 18-55mm lens, yet the magical 90mm Tamron is no longer a 90mm lens when attached to the D40 .. it's transforms into a beautiful 135mm f/2.8 macro lens(which I've desperately been seeking since I first started photography!)Because the Tamron 90mm macro lens is a full frame lens, it's equivalent focal length on the D40 is 135mm.
To a newbie, this is completely misleading(if they read it correctly to begin with!).
he simply should have written that both lenses on the D40 will provide a cropped FOV equivalent to a 27-80mm lens in the case of the 18-55, and 135mm lens in the case of the 90mm.
Instead, he's creating confusion by implying that one lens being a full frame type lens gives you magical focal length extending power, while the other being a native camera format lens isn't affected by the sensor's crop factor.
Note to newbies: THEY BOTH DO! the crop factor/equivalence focal length issue is camera specific, not a property of the lens.
Moral of the story(mainly to newbies) .. be wary of the information you're reading.