Soft lens question

This was shot with IS on. here is the full shot scaled down

I hate to pixel peep but I always hear tack sharp. What is tack sharp? I am expecting to much?

It's a smidge soft, but not bad. You are shooting wide open on the long end, which is usually considered slightly less sharp than the wide end. It's roughly comprable to my 24-105.

I wouldn't use this one image as a final judge of the lens performance, you are shooting handheld at only 1/100. Even with IS on, your keeper rate won't be perfect.

If you aren't going to do the formal tripod test, one way around this is to shoot a large series of images then go back and look through them to find the sharpest of the bunch. If you find one where you nailed focus and it is acceptably sharp, then you know what the lens is capable of.

Another option is to flip to manual mode, knock down the ISO and knock up the shutter speed to completely kill all ambient light, then shoot with flash. That will get rid of almost all of motion blur problems and allow you to more clearly see the performance of the lens.

were you actually shooting at f/4, and what part of her did you focus on?......was it autofocus or manual?

The crop seems OOF to me - However, to really have an idea of what your lens looks like you should shoot at ISO 100, in the studio or in the shade with natural light, using a tripod and manual focus. Only then, will you see your lens performance enough to decide if it's 'soft' or not. The shot you posted is not a good test.

It's not tack sharp in the strictest sense - it looks like slight misfocus, but could also be subject movement. But it's well within the range of "sharp", and it'll improve nicely with proper sharpening. Besides, at what print sizes are you going to be making that sharpness at the pixel level actually matters?

Another point to make is that of your level of expectations. The image crop you posted responds well to sharpening, and this could easily be made into a 16x20 print. For a handheld shot, wide open, that's not bad at all.

Is the lens going to be "tack sharp" wide open? No, not if tack sharp is the sharpest things can possibly be. Pretty much every lens does better closed down a stop or two. Plus you can't expect the 24-105 to be as good as every other lens. Mine is a great lens, and I don't hesitate to use it for anything. However, I don't expect it to be better than my 85L (it's not).

This is off a tripod NO IS

Am I wrong to expect IS to make a shot almost tripod sharp? It seems most all of my shots so far are about on par with the one I posted which is just OK as far as sharpness goes.

1 more a little bigger.

What's the exposure on the tripod shot?

The photo with the child: it seems the focus is on his right eye...

The Tripod shot was F4 ISO 100 1/100. and yes it was his right eye I focused on.

For f/4 (wide open!) in low light and probably hand held it is just fine. With a bit of sharpening it should be great. If you want sharper shoot at a slightly smaller aperture, though this would be plenty sharp at normal print sizes.

The 24-105 is a great 35-70, but not quite as good outside that range.

I was very happy from the sharpness of my 24-105. It was slightly sharper at 24mm than at 105mm but this is really pixel-peeping.

Happy shooting, Yakim.

105mm.

>>The Tripod shot was F4 ISO 100 1/100. and yes it was his right eye I focused on.<<

Well then, I don' think your lens is faulty. Looks normal to me from what I can tell looking at your samples.

Tommy:

You really are pixel peeping. Your lens is fine, and I'd bet a weeks pay it's well within spec. Your first image overall looks sharp. You are zooming way in on the eye probably over 100% crop.

Print some 8x10s and see how sharp this image is. Also, make proper use of sharpening if shooting Raw and adjust shaprness accordingly if Jpg.

In both portraits you focused on the tip of the nose. So the eyes would be behind the focus point. DOF with F4 at that distance will still include the eyes, but it stands to reason that there is gradual fall off. Get into the habit of focusing on the eyes and then recomposing the shot before shooting. This also will allow you to not alway have the subject centered which get's boring.

Remember IS is intended to give you more "acceptable" images. It's not meant to be as good or better than a good tripod.

Your probably right. 1 question i have is if I am able to get one razor sharp image would that mean everything is Ok and its just a question of me focusing or subject movement. Would having the UV filter cause any distortion? I have a high quality B+W 2 coated filter on it but I hear you can loose a little using a filter.

Yakim what exposure are you using at 24mm

Well, you do NOT need a UV filter unless you are at high altitudes. Personally, I don't use one.

I don't think it's necessarily a function of aperture either. I shoot portraits at f/2.8-f/4 on a regular basis, with my 24-70L and it's definitely not soft. I think it's just a matter of nailing the focus on the relevant area(s) (taking into consideration the DOF at any given aperture) and then, printing the picture at whatever size you wish looking at it from an appropriate distance. i am sure it will look great.

Subject movement can definitely cause some blur but, I didn't see that in your shots. I saw OOF areas.

Nothing will be sharper than a shot taken using a tripod. IS is good and it may give you images that are as sharp as tripod shots some of the time, but not 100% of the time unless your shutter speed is very fast. IS just ups the odds of a sharp shot. It doesn't guarantee it.

If you want to test your lens see - http://www.bobatkins.com/photography/technical/lens_sharpness.html - but I suspect your lens is just fine.

Filters can lower sharpness if they are not high quality items, but I wouldn't expect a B+W UV filter to have any noticable effect on sharpness.

Looks fine. I've only had one 'soft' lens in my past experiences... 24-70L 2.8... and it was soft... very soft, and had other optical issues as well (Heavy lateral green chromatic abberations at all apertures).. Your lens is not soft, it's perfectly fine. If in doubt, box it up send it to Canon.

"Am I wrong to expect IS to make a shot almost tripod sharp? It seems most all of my shots so far are about on par with the one I posted which is just OK as far as sharpness goes."

It get get very close if the shutter speed is up.

You are probably aware of the handhold rule of a shutter speed no slower than 1/focal_length, with a crop camera you need 1/(1.6*focal_length), so for your 50mm example on an APS-C camera no slower than 1/80.

This is for "acceptable" sharpness without IS. But "acceptable" can be a lot less than what the lens is capable of on a tripod. Adding IS will probably get you close to tripod, but if you use the IS to save on the shutter speed by dropping to 1/20 for example you are lucky to be back to "acceptable". Acceptable can be fairly soft to be honest, a lot depends on technique and the situation.

Testing with 3D subjects is not a good idea because you can't be sure where the lens has focused.

I linked you to a test method in your earlier message I think, here it is again http://www.zen20934.zen.co.uk/photography/LensTests/simplemethod.htm plus a method for testing focus accuracy http://www.zen20934.zen.co.uk/photography/LensTests/Focus%20Test%20Chart.zip.

Here is a link to 100% crops from my 24-105 at 50mm f4 on a 20D if that helps (link)

You can get to other f-stops and focal lengths by using the menu links before the first plot.

"The 24-105 is a great 35-70, but not quite as good outside that range."

One hears a lot of silliness about the suitability of particular lenses for particular shots in these forums and elsewhere, and quite a bit of it concerns the 24-105: It can't produce good bokeh. It is just good as a "walk around" compromise lens. Need a macro for close-up shots. It is poor at 105mm. It is really bad at f/4.

Chinese Lantern Flowers. Almaden Quicksilver Park, California. April 26, 2008. ﾩ Copyright G Dan Mitchell - all rights reserved.

Shot using a hand held Canon 5D. ISO 100. 1/100 with IS engaged. EF 24-105mm f/4 L IS lens at 105mm and f/4. Available light only.

(Almost all of the wildflower photographs in this gallery were made with the same lens and camera.)

Dan

Giampi wrote: "Well, you do NOT need a UV filter unless you are at high altitudes."

And with DSLR cameras you don't need UV filtering there either. DSLRs are not sensitive to UV in the same way film was "back in the day" when we worried about this at high altitudes. (I shoot my share of photos at relatively high elevations - e.g. 8,000' to 14,000'.) I never use a UV filter.

Dan

Thats I appreciate all the responses. I am probably getting myself in trouble by pixel peeping.

To respond about filters. I do use only very high quality filters not for the UV so much as the protect the glass. I really see no difference with or without the filter so I feel better with it on.

Thanks again

t

>> The 24-105 is a great 35-70, but not quite as good outside that range.

I disagree.

>> Yakim what exposure are you using at 24mm

1/1000 in this shot but it really doesn't matter. I got equally good shots at significantly lower speeds. I really like IS.

Happy shooting, Yakim.

Few more tests

Same one f8

I tried the same test with my 50mm 1.4 and its very close. I am assuming this is all good?

Yakim, is this on par with what you would get?

That looks OK Tommy, I presume they are from the centre, you dont specify the focal length.

You could check the corners too where the sharpness will be worse, compare against your 50/1.4. My 24-105 is about the same in the centre but worse on the corners until f8.

Yes Lester thats about what I got too the center was very similar the corners where a little better on the 50. The tests I did where at 55 and I am showing the center. ( I meant to do 50 but I guess I was at 55 ) either way it was pretty close to the sharpness of my 50 1.4 on a tripod.

>> Yakim, is this on par with what you would get?

Yes.

Happy shooting, Yakim.