Lens question

[mkh]

I have a new Tamron lens. Someof the images are tack sharp and others aren't. In fact on a few of the images I've taken I can't find anything place where the focus is sharp. Some of the ones that are sharp have a very limited depthof field (an inch or less at 300m 5.6 and 10' to subject).

Is the problem most likely with the lens or me? THe ratio of good to bad images is about the same as what I get from the kit kens or maybe a little less. SHould I swap it for another lens? SHould I just hope to get better at focusing and not shaking?

[ddelallata]

I used to have that lens.... at 300 and f/5.6 your DOF will be a few mm at best. You have to set the camera to AV and set an aperture of 22 etc to get a little more DOF, specially with macro work. As far as sharpness.......it is a good lens, but you can't expect L quality from a $130 lens. I managed to take some really good pictures with that lens, so don't get discouraged so quickly. One other thing, at smaller apertures like stated above, you will need a tripod to prevent blur on your photos due to the longer exosure time required with very small aperture settings. Happy shooting :)

[mkh]

Thanks David.

I kind of think the problem is
1) me
2) not enuf DOF
3) Shutter speed to low and zoom to high for me to handhold

What is confusing to me is that I have a couple of images where I can't find anything in focus even thoug I never shoot without focus confirmation.

[defordphoto]

Hmmmm, let's move this to the Lens forum... ;)

[mkh]

Hmmmm, let's move this to the Lens forum... ;)

OK Jim.

How do I do that?

Note: I thought this was general enuff to go here.

[Skip Souza]

mkh,
If you are getting a photo that has no place on it that is in focus then I would suspect camera shake. What is your shutter speed? Hand holding rule of thumb is 1/focal length or 1/300 of a second at 300 mm if you are fairly steady. Some will argue the you must include the crop factor which makes it 1/480 sec.
If you can fins some place that is in focus then you probably suffering from narrow dof.
Most non L lenses will improve their sharpness by stopping down the aperture. My Tamron 28-300 really improved past f/8

[mkh]

Thanks Skip. I hadn't thought of that explanation.

I must be pretty shaking as some were like 138mm at 1/100 or 88mm at 1/100. In fact all of the images in question were shot at 1/100 of a second. Though I do have some at 1/00 that were sharp although with narrow DOF.

All of the images were shot using a monopod but this was the first time I have ever used a monpod so I may need more practice.

It's begining to look like we've answered my question - its 20% lens (i.e. small DOF) and 80% me (I shake too much).

[Skip Souza]

Just cut back on the coffee :-)
About the time I "came to terms" with my Tamron and started getting more good shots per bad shots I sold it for the 70-300 DO. But I had improved.

[Cadwell]

Thanks Skip. I hadn't thought of that explanation.

I must be pretty shaking as some were like 138mm at 1/100 or 88mm at 1/100. In fact all of the images in question were shot at 1/100 of a second. Though I do have some at 1/00 that were sharp although with narrow DOF.

All of the images were shot using a monopod but this was the first time I have ever used a monpod so I may need more practice.

It's begining to look like we've answered my question - its 20% lens (i.e. small DOF) and 80% me (I shake too much).

You can't blame your lens for small depth of field or rather, not that specific lens anyway. Depth of field is a function of focal length, aperture and subject distance. All manufacturers 300mm lenses of all models will have the same depth of field with the same values for those parameters.

A guideline for hand-holding shutter speed is 1/(focal length) You may want to factor in the crop factor as well (there's some debate over this) so at 100mm you would want a minimum of 1/160th shutter speed. At 300mm you'd want about 1/500th....

[mkh]

Yea, I know the DOF part is not specific to this lens but a general issue.

I think most of the problem is me.

Last night I wsa shooting a bottle that was about 10 ft ftom me. The bottle was sharp but the books setting next to it were soft. The books were an inch tothe left but 2 inches in front of the bottle - that's a small DOF. I took shots at 300mm and different f stops. As I stopped down the DOF got better so it appears as if the lens functions fine. I need to work on technique.

[defordphoto]

OK Jim.

How do I do that?

Note: I thought this was general enuff to go here.

The EOS Digital Camera forum is for just that: Cameras. It is not a general forum. The Lens forum is for: Lenses. You cannot move threads, but you can post them in the proper forums.