Blurry shots question

[TiCoyote]

I'm having a problem with blurry or soft shots.

When I set the aperture to 2.8 (wide open) and I'm shooting something at a distance (20+ ft) I'm getting shots that come out blurry or soft. Even if I set the shutter speed to 1/2000, I still get this.

I'm shooting with a 50D, Tamron 28-75 f/2.8, and a cir-pol filter. When I shoot objects from close up, maybe 5 ft away, I don't have this problem.

F 2.8
70mm focal length
1/2000 sec
ISO 250
Aperture Priority

 

[Dominantly]

Depth of field- Learns it.

Familiar with how your aperture effects your depth of field, or the sharpness of the part of the photo leading up to your subject, and after your subject (subject being where you put your focal point)?

The lower the number of your aperture (larger the opening in the lens), the more narrow your DOF. For example:
I took this shot of my remote on the back of the couch. I shot this with a 50mm at f/1.4, with the focal point placed on the round center button. You can see how the focal plane is pretty darn thin, and this was me fairly darn close to the remote. If I was trying to focus on a small subject and it, or I moved; it would throw the shot off and I would have a soft subject.

When you zoom, you amplify this.


So you see, it doesn't matter how fast your shutter speed is if you don't have your aperture right for the subject at hand, or the intended look of your photo.

For your shot above, I would take your aperture and put it around f/16 and then focus slightly in front of your subject (geese) and you'll have a nice sharp image. Don't forget to keep your shutter speed number equal to or higher then your focal length to help with the motion blur of a hand held shot.

Here is a DOF calculator and graphic rep to see how this all works.
http://www.dofmaster.com/dofjs.html
I put in your info and it confirmed my guess that your dof was .65 feet, or really small.

 

[freeze3kgt]

maybe its the lens? do you have this problem with only that lens? if not maybe your out of focus

Depth of field- Learns it.

if he was trying to get the geese in focus i would assume at 2.8 at least one of them would be pretty sharp

 

[Petraio Prime]

If you choose about 1/250 sec your dof will be greater and the lens will be sharper. The ducks are in focus. Objects in front of and behind them are out of focus because the lens is wide open. Also, a lens of this sort is not the sharpest at wide open. A Canon-brand lens is likely to be better. Perhaps now you understand why people pay big money for good lenses.

 

[Alpha]

If you choose about 1/250 sec your dof will be greater and the lens will be sharper.

Have you been drinking?

 

[KmH]

There are not many lenses that focus sharply at maximum aperture.

You don't mention which CPL filter you use on the lens. A cheap CPL is worse than a cheap UV because there are 2 pieces of glass in a CPL filter one on the front that can be rotated and a second one behind that.

A CPL also is going to lower the amount of light available for auto focus by up to 2 stops.

 

[Alpha]

There are not many lenses that focus sharply at maximum aperture.

You don't mention which CPL filter you use on the lens. A cheap CPL is worse than a cheap UV because there are 2 pieces of glass in a CPL filter one on the front that can be rotated and a second one behind that.

A CPL also is going to lower the amount of light available for auto focus by up to 2 stops.

If there is enough light to expose correctly at 1/2000 then how would the AF have problems due to low light?

 

[Petraio Prime]

If you choose about 1/250 sec your dof will be greater and the lens will be sharper.

Have you been drinking?

The optimum aperture on such lenses is closer to f/5.6 or f/8. Clearer now?

 

[Petraio Prime]

I did not notice the circular polarizer was used. It may be less than stellar in performance.

 

[TiCoyote]

Petraio, the Tamron 28-75 gets consistently good reviews. Even though it is not the same quality as a Canon-L, this is a pretty easy shot, and I would hope that at least one of the geese would be in focus.

KmH, the filter is a "Sunpak - Made in Japan." True, it's not the best filter, but I've taken photos with and without it, and it seems to do the job.

Regardless of the quality of the lens or the quality of the filter, why are my close-ups coming out, but my longer shots are soft?

 

[AverageJoe]

The 50D (like most Canon's) has several AF points to which the camera sets focus to, I would suggest you set yours to the center point as opposed to all AF points (default setting).

Also, can you re-post that image (or link to a file) that has the EXIF data in it. Is there any possibility you accidentally hit the MF switch on your lens? Or perhaps it didn't lock in enough?

Lots of possibilities, but I'm not seeing anything in that photo that is in focus.

 

[AverageJoe]

Oh one more thing, some lenses have settings (or switches) so that they only focus close or far, does yours have one? I'm not privy to Sigma/Tamaron.

 

[Petraio Prime]

Petraio, the Tamron 28-75 gets consistently good reviews. Even though it is not the same quality as a Canon-L, this is a pretty easy shot, and I would hope that at least one of the geese would be in focus.

KmH, the filter is a "Sunpak - Made in Japan." True, it's not the best filter, but I've taken photos with and without it, and it seems to do the job.

Regardless of the quality of the lens or the quality of the filter, why are my close-ups coming out, but my longer shots are soft?

Hard to say exactly, but shooting that lens wide open with that polarizer is not going to produce the best results. There are other possibilities that we don't have enough information to discuss. A top Canon lens and top of-the-line polarizer would likely produce better results. More expensive lenses show the most difference at their largest openings.

 

[fokker]

If you choose about 1/250 sec your dof will be greater and the lens will be sharper.

Have you been drinking?

Well he is right - just a rather indirect way of stating that stopping the lens down (and thus reducing shutter speed a few stops) will make sure you get stuff in focus and the lens will be more in its 'zone'.

 

[TiCoyote]

I did have the AF on, and it was set to center point only. I have a few shots with this problem, and they all seem to be wide-open, far away.

When I push the shutter button halfway, the shot appears to be in focus.

How do I post EXIF data?