4honor wrote:
The first picture is the full picture, the second one is the 100% of the first picture to show the blurriness... not that it was necessary...
Well, the reason I asked that question is that to my eye, the area of sharpest focus in the picture is along the yellow line I have drawn on your picture below (please let me know if you want the picture pulled.)
In a non-tilt rectilinear lens (e.g. 50 f/1.8,) the focus plane is parallel with the sensor plane. In other words, every item that is at best focus in the photo should be the same distance from the plane that the sensor surface defines. I can't see any way that the yellow line is equidistant from the sensor plane. The tilt to the picture makes it a little hard to judge precisely, but my guess for an equidistant line which is about that far (i.e. front focused) from the sensor at ground level would be the blue line that I drew.
This picture is potentially a clue that one or more elements in the lens is misaligned. I would recommend that you shoot some more pictures (a brick courtyard will work) with the camera carefully aligned with the sensor perpendicular to the brickwork, and take some shots at different focus points. In each case, the area of sharpest focus should be a straight line, horizontal across the photo. If that looks OK, start taking pictures of brick walls from various distances, again with the sensor plane carefully aligned (this time parallel to the wall surface.) If any part is in focus, all of it should be in focus. If none of it is in focus, then you have a focus issue.
well... since you shot it wide open I figured you wanted shallow DOF and really, for that effect, I think you'd want shallower DOF than you got (right?)... ignoring the other problems... so then you either need much faster (f1-1.2... expensive) or longer.
What dark slider presents looks reasonable... and that the lens has a problem... fix the lens and add others.
EltonTeng wrote:
Let's see some samples with EXIF. Mine performed reliably on a 20D.
You can get everything in focus with a 200mm shot at F11.
You can also have razor thin DoF at 200/11. It depends on how close you are to the subject and how far the background is from them.
Notwithstanding what Darkslider very aptly suggests, IMHO you have to make choices. Wide open shots reduce your DOF. Telephoto lenses reduce your DOF and increase the risk of camera shake. All other things being equal, shallow DOF means a higher risk of OOF shots, particularly if you want full-body shots and then pixel-peep them at 100%. So going for longer lenses is going to make your life harder, not easier.
Secondly, if you want full-body shots, your "natural" focal length on a crop would be 35mm, very close to the "historic" 50mm on 24x36 that served so many so well. My suggestions is: get a 35mm f:2. It is a very good lens, not overly expensive, and faster than any zoom you can get. Get the shots you want in proper focus.
The only drawback will be that your minimal DOF will be more than with a longer lens.
wing tong wrote:
For a full body shot on a 1.6x camera, you can try the 35mm range - of course the Canon 35L would be preferred depending on your budget.
If he can afford a 35L then he shouldn't be shooting a Rebel XSi.The 35/2 is a wonderful lens on the 1.6 crop cameras. I absolutely loved mine on my Kiss X2; however, you probably need to sort your focus problems out before spending another dime.
IMO, canon rebels and xxD absolutely stink when it comes to low DOF AF at anything but close range.
I tried a 50D, 40D, and 20D today with a 135L at f/2 and 50 1.4 at 1.4 at some semi-distant trees and branches and it was just terrible, focus was ALL over the place.
i used the contrat focus of 50D during liveview and suddenly all the pics were repeatablu tack sharp. but the regular phase detect AF precision was just horrible, sometimes missing by plus or minus 70' on a tree 300' away.
so the 50mm canon's have notoriously poor AF and combine that with the fact that canon doesn't appear to have designed the AF to work well for shots from subjects more than 8-10' away at low DOF (at least with rebels and xxD's) and you have the mess you have run into.
4honor wrote:
I have been using the 50mm f/1.8 II on my XSi for about two months now, and while it's awesome for portraits when it focuses, I am getting a lot that's not. Granted, I shoot at f/2.8, which is already pretty shallow, but I have seen people who can get super sharp pics at f/1.2! My XSi doesn't have focus problems, because the kit lens is sharp (although it's also got narrower aperture...)
I noticed with my lens, is that when shooting a person, I can stand close for a head shot, it will be in focus nicely. Or when I am using flash, and the flash shoots out the red lines to help focus, it is pretty accurate. The picture may actually be too sharp!
However, when I am standing far away to shoot a full body shot, it doesn't seem to want to focus. I use center focus point, and I think the micro focus thing is working at f/2.8, but about 60% of my pics don't come out sharp. Is the distance hurting it? I think it's ok because sometimes it will still focus very accurate when using live view contrast focus.
I am wondering if there are any tips you have with this lens? Or should I get a better lens because USM will give me a better focus? I plan on getting the 70-200mm f/2.8 IS anyways, but I'd still like to use the nifty fifty. Unless I upgrade to the f/1.4 one... Thanks!...Show more →
mh2000 wrote:
85/1.8, 85L, 100/2, 135SF & 135L are all reliable wide open.
even they get touchy if the subject distance becomes too far.
canon AF system simply stinks for anything like that in the consumer models
it can be frustrating at times.
a third party focus screen can help as can liveview 10x zoom MF or contrast focus is your cam has it and the situation allows for it.
learning how to properly use AF, and/or getting a camera with a larger sensor and viewfinder will cure all of these problems- AND make your 50/1.8 become a lens that is easy to love.
I really never see anything better or worse in focus accuracy from L-lenses... personally, my 24-70L and 70-200/4L were both rather unreliable for focus wide open... in what I've shot, it seems to go more with the body than the lens... there could be exceptions, just that I haven't seen them in what I've shot...
>>even they get touchy if the subject distance becomes too far.
canon AF system simply stinks for anything like that in the consumer models
it can be frustrating at times.
the_wrath_of_khan wrote:
Who buys a 50mm lens to shoot from 10 feet away? A 50mm lens is not meant to fit a full adults body in the frame especially not on a crop camera.
I do have a question though, if 50mm isn't good for more than 10', then why is it a good "walk around lens"? What if I was to take a picture of a landscape? And, how's getting a 35L gonna help, won't it just limit me to even less distance? I'd like to zoom in at longer focal lengths to get compression on the models' face/body, it looks more flattering... I thought all lenses are capable of focusing far away, just some are not meant for close distance...
4honor wrote:
Thanks all for the comments and suggestions!
I do have a question though, if 50mm isn't good for more than 10', then why is it a good "walk around lens"? What if I was to take a picture of a landscape? And, how's getting a 35L gonna help, won't it just limit me to even less distance? I'd like to zoom in at longer focal lengths to get compression on the models' face/body, it looks more flattering... I thought all lenses are capable of focusing far away, just some are not meant for close distance...
1) For subject isolation, bring the model out away from the background and perhaps reduce your distance to the model. Your failure rate goes up if you have the subject among the clutter and shoot wide open.
2) Manual focus is preferred (at least by me) in landscape and street photography for the most part. I can direct the camera to focus exactly on what I want. It is often that there is not anything specific for the camera to lock on to via AF in landscape and street scenes. The camera will not know to lock on the orange house across the valley, or the 2nd ABC store sign in Waikiki . Often, the camera will make the wrong decision in a wide frame and lock on the grass 5 feet away instead of infinity. You can also learn to focus based hyperfocal distances to aid your landscape photos.
Not sure what you mean by the below:
I thought all lenses are capable of focusing far away, just some are not meant for close distance...
Thanks for the pointers EltonTeng! I will try more what you said, and practice my focus skills... I just thought that I could point to something with the center focus point, and it will focus that point...
As for the focusing capability, I meant like for the 70-200, you can't focus something with in a foot of the front glass... The lens is not built for that. However, I can use any lens, put it at like f/11, and shoot landscape with it. Someone above was saying why would I shoot 10' away with a 50mm, why not? I would think it still works...
Minimum focusing distance is a limitation to the specific lens. The 100/2.8 macro can focus to around 15 cm from the front element. You need to stop down to F14 or so to get any DOF.
I think Star Trek 2 is saying that you need to select a different lens for full body portraits from 10 feet away especially on a crop body (I could be wrong.) You're not likely to fit the entire person and the surrounding set up. I would recommend you go on www.photo.net and look at the full body portraits and the listed EXIF and equipment.
Awesome! I found an example! This photo shows a full body shot of two grown women, yet the photographer used a 70-200mm f/2.8 IS on a 5D. He shot at f/5, 1/125 s, and 75mm. I want that!!! I hope he was not like a mile away...
Here is another example, although it was probably at f/4...
4honor wrote:
Thanks all for the comments and suggestions!
I do have a question though, if 50mm isn't good for more than 10', then why is it a good "walk around lens"? What if I was to take a picture of a landscape? And, how's getting a 35L gonna help, won't it just limit me to even less distance? I'd like to zoom in at longer focal lengths to get compression on the models' face/body, it looks more flattering... I thought all lenses are capable of focusing far away, just some are not meant for close distance...
they should be, but if you shoot near wide open many don't do great with the canon AF system.
luckily one more often uses landscape f/8 type DOF or can use liveview or manual focus for distant stuff, but sometimes the issues is a pain in the neck.
