Is it sharp

[slat]

I have a Tamron 100-400 lens and think it's just a little soft. I have the TAP-in console to make adjustments. I shot these handheld. Is it poor form on my part or is it a bit soft?

IMG_0179 by Steven Emmons, on Flickr

IMG_0165 by Steven Emmons, on Flickr

 

[Ash Telecaster]

Hi Slap,

I'm a total novice but I will share my unwashed opinion as I try to develop my photographers eye. I will be really interested to hear what the more experienced people say.

It looks to me as though the lens is very sharp for the object in focus but goes, not soft, but out of focus very quickly as you move out from it. It doesn't look soft to me as far as I understand the definition of the term. But I am a novice and could be totally off.

I have two thoughts on this.

First, perhaps the lens is designed to work better at a greater distance.

Second, did you try to adjust the F-Stop? Assuming I'm using the terminology properly. As I understand it, sharpness can be better for a given lens at certain apeture settings; ex f3.5, f4, f5....

 

[480sparky]

Both were shot with the lens 'wide open', meaning the aperture was not stopped down. This is typically the worst-performing setting of the aperture most lenses have. Stopping down two stops will go a long way towards increasing sharpness.

Yes, you have to balance that with an increase in ISO, but if you practice good hand-holding techniques, you can eliminate a higher ISO by being able to use a slower shutter speed. If course, this won't work with a dog that's going 200 MPH......

 

[smoke665]

Expanding on the above, your DOF is a function of aperture and distance to the subject. In the first image assuming you were 10 ft away, you only had roughly 6" total in DOF. Increase that to f/8, and your total DOF increases to roughly 11", or increase your distance to 20 ft and leave your aperture at f/4.5 your DOF would be roughly 24".

Then you have the issue as mentioned above that wide open is not the sharpest setting for most lenses. Not sure what the sweet spot on this one is but I wouldn't be surprised if it wasn't f/8 or better.

To me the point in focus looks sharp considering the wide open aperture.

 

[Derrel]

For a 100-400 zoom, wide-open, at relatively close range where DOF is limited, it looks about right. I used to have the Nikkor 400mm f/3.5 ED~IF, a 1981 model. At close range, it is not uncommon to have a mere 5-,6-,7-inch band of SHARP depth of field, and everything else looks less-detailed. At longer ranges, like 50,100,150 feet or more, the DOF increases exponentially compared with closer-range shooting.I also owned the 80-400 VR zoom, for abut 14 years. I have shot a fair amount at 400mm.

The woven nylon, which is mostly a flat surface, shows that the lens is "sharp", as long as the subject is within the well-focused zone. Depth of field, and spot-on focus are of primary importance with a 400mm lens...shutter speed can also be an issue. While reciprocal-focal length is an old rule/guideline, meaning 1/400 is "safe", that's IMHO, not a very good guide, especially on APS-C cameras, or if you have ANY movement, from the wind, or the subject, or vibration from any source, or you hope to crop-in on the image.

Stopping down may help a bit...try /4.8 or f.5.6, but do not let the shutter speed get too low


[edited]

 

[slat]

Expanding on the above, your DOF is a function of aperture and distance to the subject. In the first image assuming you were 10 ft away, you only had roughly 6" total in DOF. Increase that to f/8, and your total DOF increases to roughly 11", or increase your distance to 20 ft and leave your aperture at f/4.5 your DOF would be roughly 24".

Then you have the issue as mentioned above that wide open is not the sharpest setting for most lenses. Not sure what the sweet spot on this one is but I wouldn't be surprised if it wasn't f/8 or better.

To me the point in focus looks sharp considering the wide open aperture.

So I should definitely shoot in aperture priority and stop down to get the best performance from this lens? I'm going to test it on a tripod at various f stops to see where the sweet spot is.

 

[slat]

For a 100-400 zoom, wide-open, at relatively close range where DOF is limited, it looks about right. I used to have the Nikkor 400mm f/3.5 ED~IF, a 1981 model. At close range, it is not uncommon to have a mere 5-,6-,7-inch band of SHARP depth of field, and everything else looks less-detailed. At longer ranges, like 50,100,150 feet or more, the DOF increases exponentially compared with closer-range shooting.I also owned the 80-400 VR zoom, for abut 14 years. I have shot a fair amount at 400mm.

The woven nylon, which is mostly a flat surface, shows that the lens is "sharp", as long as the subject is within the well-focused zone. Depth of field, and spot-on focus are of primary importance with a 400mm lens...shutter speed can also be an issue. While reciprocal-focal length is an old rule/guideline, meaning 1/400 is "safe", that's IMHO, not a very good guide, especially on APS-C cameras, or if you have ANY movement, from the wind, or the subject, or vibration from any source, or you hope to crop-in on the image.

Stopping down may help a bit...try f/4.5 or f/4.8.

I'm already at a f/4.5. Should I stop it down to about f/8.0 or f/9.0?

 

[smoke665]

So I should definitely shoot in aperture priority and stop down to get the best performance from this lens? I'm going to test it on a tripod at various f stops to see where the sweet spot is.

Not necessarily, read the rest of my post about DOF. Think of your camera as a tool, the settings are what you adjust to produce the result you want. How much DOF do you need? In your first shot of the dog, had he been looking directly at you with the settings you used either his eyes would be in focus or the tip of his nose ...not both. DOF is a function of distance to the subject and aperture - the further away you are, the greater the DOF at any aperture, but the smaller (higher the number) aperture, the greater the DOF. There are numerous apps for phones out there that can calculate your DOF for you. My favorite online calculator is Online Depth of Field Calculator

Using a tripod will likely increase your chances of a sharper shot, but so will understanding the exposure triangle, such that you can adjust for an exposure that will give you the desired end result.

 

[dxqcanada]

Sweetspot seems to be about f/8
Tamron 100-400mm f/4.5-6.3 Di VC USD Review | Trusted Reviews

 

[Derrel]

Optical stabilization is great, but it does NOT prevent subject motion from causing blurry pics, so, while f/8 or f/9 might be "the sweet spot" for the lens, it might force the shutter speed to drop too low to stop motion blurring.