Is f3.5 the limit? 550D, 7D
- Thread starter daktulus
- Start date
Barry_Green
Moderator
Depends on the lens. The kit lens on the 550D is probably an f/3.5. Put a different lens on there and you will be able to get wider apertures.
It is a limit of the lens, the camera just goes to what the lens is capable of. It's no different than a mechanical aperture control on an older lens, except the camera in this instance allows you to control via the camera. In the end, the camera is only as good as the glass you put on it.
You can get pretty shallow with 3.5. If you need more, just move back and zoom in. You can even get a good, shallow DOF at 5.6. We're talking about pretty large image chips in these cameras. f5.6 on a T2i is a heck of a lot more workable than f5.6 on a camera with 1/3" or 1/4" chips.
Fast lenses like 1.8 or better are nice, but challenging. The biggest issue is that, at f1.8, DOF is razor-thin and that makes keeping a subject anywhere close to in-focus a bit of a challenge.
Fast lenses like 1.8 or better are nice, but challenging. The biggest issue is that, at f1.8, DOF is razor-thin and that makes keeping a subject anywhere close to in-focus a bit of a challenge.
Aperture has to do with the opening of the iris in the lens. If the iris is as open as it can get, it's at the limit for aperture. And the diameter of the opening at that point divided into the focal length of the lens gives you your aperture number.
Barry_Green
Moderator
No, the iris is in the lens. The lens itself tells the camera what iris it can go to. f/3.5 is nothing like f/1.8.
Barry_Green
Moderator
You can get mildly shallow DOF with the f/3.5 lens, but nothing like what you can get out of an f/1.4 lens.
Angry Leprechaun
Well-known member
Around the f3.5/4.0 area in my opinion is a pretty good place to be in terms of DOF. That's usually what I stop down to anyway. But what's nice about a lens with a lower f-stop like a f1.4 or even a 2.8, is that your image is sharper and cleaner at wider aperatures. So if you compare a f1.4 lens to an f3.5 lens and have them both at f3.5, the faster lens will look a lot better.
Stephen Mick
Totally Usable
Actually, this isn't always the case. You'd think it makes sense, but lenses don't always make sense, and even multiple copies of the same lens can be different.
For example, I own a Canon 50mm f1.2L lens. It's the second copy I've owned, and the first one went back because at f1.4 it was actually less sharp than a Canon 50mm f1.4 (non-L) I had to compare it with. I returned it and the f1.2 I exchanged it for is noticeably sharper.
I've also noticed that, in some cases, lenses with a smaller max aperture (higher f-stop) can be sharper wide-open than faster lenses at the same f-stop. Generally when I've seen this it's with zoom lenses, but again, it happens. Take the Canon 16-35 f2.8 and the 17-40 f4 lenses. When I was testing out these lenses a few years ago, I noticed that with both of them at f4, the 17-40 was a touch sharper.
Sometimes it has to do with variations from lens to lens, and sometimes it seems to be lens design itself. Yet another reason that, whenever possible, I always buy locally from the best photo store in town. There's no substitute for being able to exchange/return a lens before finding one that's as close to perfect as possible.
insanityfw
Ban Me Please!
This is the 2ti with an old Nikon Ai 85mm/1.8. I think I was running at about 2.8...or around there.
These are very compressed stills pulled from the .move file, but you get the idea.
I used a fotodiox (sp?) adapter off of amazon that cost about $20.
Also, keep in mind that I still, even after years, have no real idea of what I'm doing. I just throw on a lens, play with the iso and aperture until it feels right and go for it.
Best,
J.
These are very compressed stills pulled from the .move file, but you get the idea.
I used a fotodiox (sp?) adapter off of amazon that cost about $20.
Also, keep in mind that I still, even after years, have no real idea of what I'm doing. I just throw on a lens, play with the iso and aperture until it feels right and go for it.
Best,
J.
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steventimothy
Well-known member
ydgmdlu
Veteran
To the OP and others: You should ask yourself what sort of shallow DOF you really want. Are you aiming for the shallowest possible, or are you trying to emulate the look of movies that you see in theaters? Most people generally want to do the latter, and it's not the same as the former. 35mm film is most often shot at f/2.8, f/4.0, and f/5.6. I've read that the real sweet spot is a split between f/2.8 and f/4.0, i.e., f/3.5. Hardly anybody hardly ever shoots wider than f/2.8, other than when lighting conditions demand it.
Barry_Green
Moderator
And, let's pendantically point out, that's f/2.8 to f/3.5 on a 7D-style sensor, not on a 5D-style sensor. On the 5D, you'd get the equivalent DOF at about f/4.8 to f/5.6.