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Revolume

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I know literally nothing about lenses, but have decided to go with the 7D for short films, mainly because of the depth of field without an adapter. What lens would I want for the shortest depth of field, with some bokeh in the background, etc. Also what would I use for something like sports where I want almost everything in focus?
 
http://www.dofmaster.com/dofjs.html

Generalities:

1. The wider the lens (35 is wider than 50, 18 is much wider than 35), the more DOF you will have. More meaning deeper, meaning more stuff will be in focus

2. The smaller the F-Stop (F8 is smaller than F4) the more DOF you will have.

3. All else being equal, the further away you are from the subject, the more DOF you will have.

4. The smaller the sensor, all else being equal, the more DOF you will have.


You do not want the "shortest" depth of field. You will not be able to maintain focus. On an 85mm F1.8 with the lens wide open at F1.8, if you were 10ft away from what you were shooting, you'd have less than 3" of depth. You couldn't put both eyes into focus if the subject turned their head.

People WAY WAY WAY over-do this. Fairly shallow depth has it's place, but understand when that is. As for sports, shoot down at F8 or F11 if you've got the light, and shoot fairly wide. Something like a 35mm or a 50mm should be excellent.
 
Thanks. Do you have any specific lenses you can recommend? Also on a completely unrelated note, do you know how they got the colors in the SNL intro?
 
Usually a 24mm-28mm for a wider perspective, a 50mm for nice portrait telephoto, and an 85mm for something a little longer.

If you want the true-to-life perspective like the 50mm lens on a full-frame sensor, a 30mm lens will be something to look into as well. :)

When choosing a lens for the 7D, just take the focal length (say, the 50mm), times it by 1.6 (the crop factor on the 7D), and your new focal length is now 80mm.
 
50mm f/1.4 is good basic lens for low light performance and shallow DOF on any camera.
 
If you are tight on money, the Canon EF 50mm f1.8 is a good bargain, focusing is a little harder though with the small focus ring.
 
I consider myself to be a total beginner too, Have only had my 7D's for less than a year. Before that I never even touched a DSLR before. So I was in the same shoes you are now. I read and read and read..then just bought things people suggested not even knowing the heck I was buying. I still have a crap load to learn but since I've been using it more now on a weekly basis for a documentary project... I start picking up on a lot of things. I still don't fully understand the whole focal point, multiply this, crop that.. All I know is which lens I like to use when I'm out there shooting...and that's due to me actually using the camera and lens.

50mm 1.8 gets A LOT of play time on my 7D... after that is my 28-75. The whole depth of field thing I'm still trying to learn. Reading what Peronne said I just learn something that sounds so stupid not to know. I always shoot at 1.8 thinking it'll be the fastest and clearest... and I kept getting frustrated because I constantly had to pull focus.
Now I know not to shoot it wide open like that!
 
As to what lenses to get; if you are on a budget it may be a good idea to get a 2.8 zoom in the 17-55 range to start (assuming you are using t2i or 7D). You can always add more later, but that will cover you for most focal lengths in basic kit. The canon 17-55 2.8 IS is the best option. Tamron makes a 17-50 VC for a little over half the money that is still good. Sigma and tokina also make similar ranges. Once you get one good lens, you can add more. Just don't skip on that main lens.
 
Timbit said:
If you are tight on money, the Canon EF 50mm f1.8 is a good bargain, focusing is a little harder though with the small focus ring.
Click to expand...

This is where us old-timers will recommend a manual focus lens.

There is no AF in the video mode on this camera, so you are going to be operating manually anyway. And frankly, there are literally dozens of good 50-55mm manual lenses out there that are excellent. I just bought two and they were delivered today. An excellent one will cost $90-$120 and will absolutely SHAME the Canon AF 50 that you guys are talking about in terms of mechanical design.

I offer the following two examples:

Nikon:
http://cgi.ebay.com/NIKON-NIKKOR-50...51673963?pt=Camera_Lenses&hash=item35a7fd7b6b

(I just bought one like this and I had nearly forgotten how sweet they can be)


Pentax:
http://cgi.ebay.com/ASAHI-PENTAX-SU...57261249?pt=Camera_Lenses&hash=item3360329ac1
 
PerroneFord said:
This is where us old-timers will recommend a manual focus lens.

There is no AF in the video mode on this camera, so you are going to be operating manually anyway. And frankly, there are literally dozens of good 50-55mm manual lenses out there that are excellent. I just bought two and they were delivered today. An excellent one will cost $90-$120 and will absolutely SHAME the Canon AF 50 that you guys are talking about in terms of mechanical design.

I offer the following two examples:

Nikon:
http://cgi.ebay.com/NIKON-NIKKOR-50...51673963?pt=Camera_Lenses&hash=item35a7fd7b6b

(I just bought one like this and I had nearly forgotten how sweet they can be)


Pentax:
http://cgi.ebay.com/ASAHI-PENTAX-SU...57261249?pt=Camera_Lenses&hash=item3360329ac1
Click to expand...

+100!!!

The EF 50 1.8 is great for stills though as the autofocus is very accurate. For video, I always use my leica summicron R 50 f2
 
Here's a question to stir the pot:

For video, which is more appropriate: A fixed F-Stop, or a Variable F-Stop?

And most importantly, WHY?! I can't find anyone who can really explain why one is better than the other. I'm beginning to wonder if its a pepsi/coke argument.

On a variable, my assumption is that you're going to have to adjust the f-stop any time you zoom further in or out, which could get tedious...but wouldn't it be more versatile a lens in the long run as far as getting a larger variety of shots on the fly?

And, of course, I'm asking these questions with respect to video.
 
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ArtsnFartsNCrafts said:
Here's a question to stir the pot:

For video, which is more appropriate: A fixed F-Stop, or a Variable F-Stop?
Click to expand...

Well, fixed F-stop really becomes handy when you want to zoom during a shot. If you use a lens with a variable maximum aperture, you'll underexpose if you zoom in to much. You could ruin a long take doing that.

When framing your shot, you might find it's better to zoom in (if you don't have the appropriate prime to cover the desired focal length) before you begin recording. It could jack with your exposure before you even begin the take.

Also, only zooms have the variable F-stop problem, and the widest aperture a zoom lens can manage is 2.8. At that speed, only the most expensive of lenses can maintain that aperture when zooming (Canon 70-200mm 2.8L, for example). So using a zoom for video is not a bad thing at all, but it can kill your exposure, especially if you're shooting at night.

It's not really a better/worse thing, because there are workarounds, and it also hinges on what focal lengths you have in your lens arsenal.
 
ArtsnFartsNCrafts said:
Here's a question to stir the pot:

For video, which is more appropriate: A fixed F-Stop, or a Variable F-Stop?
Click to expand...

Fixed F-Stop, all day, every day.


ArtsnFartsNCrafts said:
And most importantly, WHY?! I can't find anyone who can really explain why one is better than the other. I'm beginning to wonder if its a pepsi/coke argument.
Click to expand...

Ok, imagine the following scenario. This only applies to zoom lenses so we'll talk about that. Let's say as a DP, I am lighting and lensing an indoor shot. Say a family at the dinner table. I've got my softbox rigged overhead to augment the practical in place. I've got daylight hitting at golden hour (which gives me about 20 minutes to get the takes). I've got a couple fixtures around the edge of the set to highlight the food and the faces. I am ready to shoot.

First shot is an establishing shot on a dolly. We need that at 35mm. We get that. Now I need a couple 2-shots, 3-shots, and some over the shoulder shots. I want those at 80mm. So we get off the dolly, and onto sticks and move in. I've got 12 minutes of golden hour left.

On a variable zoom lens, I just lost 1.5 stops maybe. So now, I need to get EVERYTHING 1.5 stops brighter. That means I need to move all the fixtures at the edge of the set. Hopefully there was ND on the windows I can remove so that golden hour still looks right. And now I have to re-rig that light above the table 1.5 stops hotter which means I need to move all the actors away, rig, and get them back in place. Along with checking continuity.

On a fixed aperture zoom, I just reframe for my shots, and shoot.


ArtsnFartsNCrafts said:
On a variable, my assumption is that you're going to have to adjust the f-stop any time you zoom further in or out, which could get tedious...but wouldn't it be more versatile a lens in the long run as far as getting a larger variety of shots on the fly?
Click to expand...

If I have a constant aperture F2.8 lens, I can shoot at F5.6, or F4, or anything I want. On a variable aperture lens, I am FORCED to using the slowest stop on the lens, so I can reframe and keep the same F-Stop, or be forced into adjusting my lighting to match. And if I am doing tight shots, I don't WANT to be shooting them at F5.6. I want them at F2.8 or even F2.0 if I can get it.

Variable F-Stop zooms are a royal PITA for video work. I've got a couple that I am using until I can finish my prime sets. Then they'll leave my bag/case.
 
Varifocal drives me up the wall a bit more than the variable F-stop thing for continuous shooting. I'd rather have a parfocal with variable f-stop than a varifocal with constant f-stop...not that that's anything but hypothetical.
 
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