'Specific Situation' Lens Question (Newbie)

[Chris Rex]

Hello there... Newbie here, looking for some advice

Here's my situation:
I am going to be ordering a Canon body (t3i or 690d) and want to pick a non-kit lens to go with it. 90 percent of the time the camera will be used to take indoor, full-body portraits. There will be ample lighting in the form of Flashes or Hotlights (continuous). The shooting area is VERY small. So much so that I will often be only 5-7 feet from the subject. Because of the close proximity, I am anticipating having to shoot in the 20-26mm range in order to capture the full body (I understand that I will lose some of the nuances that zooming would allow, but I have no choice). I am not concerned about outdoor shooting at this point in time.

My budget is 'as cheap as possible without being crap' As of now, I am looking at lenses in the range of 17-50 f/2.8 (tamron/Sigma), to similar lenses with a slightly larger range, but slightly slower (ex: Sigma macro 17-70, f/2.8-4, other slower 18-?mm 3.5/5.6 lenses).

I guess my main question stems from depth of field. Considering I will have enough light, do I NEED something as fast as the 2.8? Despite the adequate lighting, my thought was that the depth of field it offered was the reason to go that route, but is the dof TOO narrow at that wide range, considering full body (I'm not looking to have parts of the body in focus and parts out of focus... but rather the whole subject in focus, with maybe the immediate background out of focus)? I know there are calculators out there, but being quite new, do not know how to interpret those calculators for my situation.

So, quite simply: With ample lighting and close proximity, wanting dof to cover the full subject, but not much more, at ~5 feet... do I get a 'relatively' more expensive fixed 2.8 lens, or do I save a few bucks because the 2.8 will not benefit me in this specific scenario (or maybe just get a non-2.8, BETTER IQ slower/ variable speed lens)?

ANY advice or counterpoints would be great appreciated. Thank you in advance!

-Chris

 

[IgsEMT]

For DOF, I'd recomend using a dof calculator - you can google it.
Faster lenses, even in 3rd party, still have an advantage as their built quality is usually bit superior. Re Tamron 17-50, I colleague of mine uses it w/ his Nikon and is VERY happy.
Purchase it from a reliable store that has a return policy that would give you enough time to try out the glass and return it if you don't like it.

good luck
joe

 

[subscuck]

Unless you want a zoom to be used eventually as a walk around lens, you could also consider the Sigma 30mm 1.4 or Canon 35mm 2.0. Given your space, they might be a little tight, but either will deliver better IQ than the zooms you mentioned, as well as better bokeh (if that matters).

 

[enzodm]

At short focal lentghs DoF is rarely very shallow. At 20mm, you have about two feets.

 

[Nikon_Dude]

To be exact, at 20mm and f2.8, with a subject 5 feet away you have 2.23 feet. Can be doubled by increasing the distance to 7 feet.