1. That maximum aperture.
With most 50mm lenses having at least a maximum aperture of 50mm that can only mean one thing. Most of your pictures will be out of focus if you decide to use it wide open. The depth of field is so narrow that the focus has to be absolutely bang on otherwise everything in that shot is going to be blurred. Apart from the thing you didn't want to be sharp and that will be razor sharp as you didn't get the focus right.
2. Backgrounds too blurred.
That widest aperture strikes again! It's a symptom of using those big openings. Everything in front of or behind the focus point is blurred beyond recognition. Who wants that? Surely we want to see everything in fine detail don't we?
3. There's nothing to it..
That lens is tiny with very little weight to it. There's hardly anything to get hold of. Wouldn't you rather have a big fat zoom lens to grab hold of when you are steadying that camera? Where's the weight in your camera bag going to come from? It's not from the 50mm lens that's for sure.
4. Where's the zoom?
There's no way to get closer to your subject with that lens. You've got to move your feet to fill the frame. No twisting the wrist for closeness here. It's one foot in front of the other and What a drag that is right? This means you've got to give way more thought to your composition. No lazy standing around on the spot. Actual moving is required.
5. It's cheap as chips.
There's no bragging about how much your gear costs when you're using a 50mm. It's perhaps the cheapest lens there is for one with such a large maximum aperture. Why, most anyone could afford this lens. Precious little opportunity for lording it over those photographers with cheaper less-glamorous kit with this lens. This is a cheap lens. They're made really cheaply and taking the Canon featured above as an example, look rather ugly. It couldn't be more unexotic. Do you want to be seen out with this?
6. It's not wide. It's not a tele.
Look through the viewfinder with this lens and things are going to look very similar to what you see when you survey that scene with your eye alone. There's no ultra-wide vista grabbed by this lens, nor is there any glorious isolation of just a small portion of that view. What's the point of that view then?
Of course the reality is, we love this lens for all of the above reasons. All of that lovely razor sharpness when you hit the focus spot just right, combined with a soft out-of-focus background make this a heck of a lens for isolating your subject. Portraits, landscapes, street, the angle of view is brilliant for many general scenes and avoids any frivolity you get from a wide-angle or a big telephoto. It's light, goes in to your camera bag no problem, is very discrete and costs very little compared to may other lenses. 'Nuff said.
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