Cheap canon portrait lense?

[Dao]

Personally, I think it is better to make the correction so that beginners will not assume the focal length of the lens changes with camera sensor size or have any confusion about it,

 

[Village Idiot]

the 50 1.8 is good, it becomes an 80 1.8 on your Rebel with the 1.6x crop sensor, which puts you in portrait range.

when you get a few bucks, 100mm f2L, the 85mm f1.2L is a great lens as well but I shoot a lot of Nikon film gear and I'm biased to my Nikkor 105 2.5. also the 100 f2.8, though a little cheaper, and not an L, is a great lens. I'm not a professional, more like a darned-good ameteur, but I know the Canon lineup extensively, from the first EOS 650 from the 80's (I have one) to the 1Ds Mark 4.

a cheap lens if you can find one that covers the whole portrait range is the 70-210 f4 EF, it has a good macro mode and from 100-150mm tack sharp and next to no chromatic abberation. it's a classic lens made for 35mm film cameras and you can find them for 100 dollars us to 200 dollars us. there's a few specimens on ebay. It's not my 70-200 f4L but for the price nothing can touch it.

Putting a lens onto a camera with a crop sensor does not change the focal length of the lens, just the field of view. It gives the lens an apparent field of view of 80mm while the focal length of the lens remains at 50mm. The focal length is determined by physical measurements of the lens itself..

An explanation from dpreview:

The focal length of a lens is defined as the distance in mm from the optical center of the lens to the focal point, which is located on the sensor or film if the subject (at infinity) is "in focus". The camera lens projects part of the scene onto the film or sensor. The field of view (FOV) is determined by the angle of view from the lens out to the scene and can be measured horizontally or vertically. Larger sensors or films have wider FOVs and can capture more of the scene. The FOV associated with a focal length is usually based on the 35mm film photography, given the popularity of this format over other formats.

What you're saying is true, but practically speaking, it doesn't make that much difference whether we're talking cropped or actual focal length. Sure, the bokeh will behave like the non-cropped focal length, but that's probably not too big of a deal either.

It's depth of field, not bokeh. Bokeh is the word created to describe the quality of the oof area. That totally depends on the aperture blades and not the focal length. The dof will also not behave the same. A smaller sensor uses more of the center if the lens, which will in turn cause a narrower dof than the same lens on a full frame sensor. That's one reason that FF cameras are so popular.

Another factor is the distortion characteristics if a lens. 16-17 is wide on a FF sensor. 10-12 is wide on a crop. A 10mm lens on an APS-C sensor is equal to the field of view of 16mm on a FF camera. The 16mm lens will generally distort less than the wider 10mm lens unless that 16mm lens was made by tribesmen in Swahili (no offense to any Swahiliish people here).