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Lens test - Is this normal

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PixelDave

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So far my pictures look great with my 24-70 but I did some testing using a focus chart and wanted to get some feedback if this looks good.

Shot at 50mm and 70mm at f/2.8 and f/8.0

Originals









Crops

50mm @ f/2.8



50mm @ f/8.0



70mm @f/2.8



70mm @f/8.0

 
looks good to me, but both Nikon and Canon indicated that the 45 degree test shot is not an accurate way to test a lens.
 
PixelDave said:
Does it seem a little soft at 2.8?
Click to expand...
Yes, but this test is done at close range. Some lenses are not at their best this close. Try a larger target further away. My 28-70mm is not sharp, especially at 70mm this close, unless it is closed down.

Steve
 
Focus seems to be perfectly fine. Sharpness - according to photozone.de, the lens gains about 200 lw/ph at 70 mm when stopping down from f/2.8 to f/8. So it's normal for the edges to sharpen up when closing the aperture.

Now, what I'm wondering - the exposures look a bit different (color temperature). Were you shooting with flash? Also, was the camera tripod-mounted, and what was the shutter speed?

BG
 
No lens will be as sharp wide open as it will be stopped down a bit.
Boris
--
Stubborn and ardent clinging to one's opinion is the best
proof of stupidity.
Michel de Montaigne

http://public.fotki.com/borysd/
 
Yes I did use a flash and the camera was mounted on a tripod.

Even the center sharpness seems to be off which should not be the case.
BasilG said:
Focus seems to be perfectly fine. Sharpness - according to
photozone.de, the lens gains about 200 lw/ph at 70 mm when stopping
down from f/2.8 to f/8. So it's normal for the edges to sharpen up
when closing the aperture.

Now, what I'm wondering - the exposures look a bit different (color
temperature). Were you shooting with flash? Also, was the camera
tripod-mounted, and what was the shutter speed?

BG
Click to expand...
 
PixelDave said:
Yes I did use a flash and the camera was mounted on a tripod.
Click to expand...
Just curious... I noticed the EXIF data said all photos taken at 1/60s and ISO200 in apeture priority mode but with different apeture setting. This suggests flash. But the EXIF says no flash reurn was detected. It looks like the maker notes are stripped.

Steve
 
Not sure what you mean.

I took the picture at ISO 200 with manual flash power. Initially I had WB set to auto, I later changed it to flash and also set my shutter speed to 1/250.

Again my results are the same.
SteveL54 said:
PixelDave said:
Yes I did use a flash and the camera was mounted on a tripod.
Click to expand...
Just curious... I noticed the EXIF data said all photos taken at
1/60s and ISO200 in apeture priority mode but with different apeture
setting. This suggests flash. But the EXIF says no flash reurn was
detected. It looks like the maker notes are stripped.

Steve
Click to expand...
 
PixelDave said:
Yes I did use a flash and the camera was mounted on a tripod.

Even the center sharpness seems to be off which should not be the case.
Click to expand...
Ok. Well, I don't exactly know what's going on here. One thing I've been thinking about is this: Sometimes, when I tested my wide aperture lenses (85/1.8 and the 50ies) with flash at f/2, 1/60 & flash, the flash light did not overpower the background light, giving rise to some fuzzyness (from hand shake) that disappeared when closing down (reducing the ambient light captured and leading to a more flash-dominated exposure). Making the room you shoot in darker and lowering the ISO may be a way to force something similar in your test - but I don't think this is the issue here.

In any case, good luck figuring out what's going on. Don't forget that stopping down maybe not only increases sharpness, but also contrast (which is usually not measured in the lens tests, but can have quite an impact on the perceived image quality).

BG
 
Check this out. These are located pretty close to center.

Seems like more then contrast, I also did the test at 1/250s


BasilG said:
PixelDave said:
Yes I did use a flash and the camera was mounted on a tripod.

Even the center sharpness seems to be off which should not be the case.
Click to expand...
Ok. Well, I don't exactly know what's going on here. One thing I've
been thinking about is this: Sometimes, when I tested my wide
aperture lenses (85/1.8 and the 50ies) with flash at f/2, 1/60 &
flash, the flash light did not overpower the background light, giving
rise to some fuzzyness (from hand shake) that disappeared when
closing down (reducing the ambient light captured and leading to a
more flash-dominated exposure). Making the room you shoot in darker
and lowering the ISO may be a way to force something similar in your
test - but I don't think this is the issue here.

In any case, good luck figuring out what's going on. Don't forget
that stopping down maybe not only increases sharpness, but also
contrast (which is usually not measured in the lens tests, but can
have quite an impact on the perceived image quality).

BG
Click to expand...
 
Unless we are dealing with macro lenses, lenses are normally corrected for best performance at longer distances. Thus testing say by photographing a ruler 50 cm away is not the best way to get an impression of the lens' abilities. Ideally, it should be tested at a distance it is intended to be used at. As it has been said already, many lenses are soft close up, especially at wide apertures. I recently bought a used 135/2.8 AI-S and in tests it is indeed soft at 2.8 within 2-3 meters. Beyond 5 meters it's sharp at 2.8 though with a little less contrast than when stopped down a stop or two. In addition, the DOF may also extend further in one direction than in the other, leading one to falsely believe that the lens is back- or front focusing.

I may be lazy, but usually I don't test by using test charts, rulers etc. I shoot real subjects at various distances and apertures. If the pics looks good and OK - well, then it is OK. Only if something seems to be wrong, will I do more elaborate and "scientific" tests in order to create proof that can legitimate returning the lens. These days, with all the technical opportunities, I think it is important not to get lost in a gear obsession, but keep the mind focused on what is important in photography: The subject, the light and the "decisive moment".
 
I ran the same test at 5-7 feet. This lens shouldn't have any problems at this distance. The images simply do not seem tact sharp like some of my other lenses.

I started shooting these test charts after I noticed the lens appeared soft wide open.
olstrup said:
Unless we are dealing with macro lenses, lenses are normally
corrected for best performance at longer distances. Thus testing say
by photographing a ruler 50 cm away is not the best way to get an
impression of the lens' abilities. Ideally, it should be tested at a
distance it is intended to be used at. As it has been said already,
many lenses are soft close up, especially at wide apertures. I
recently bought a used 135/2.8 AI-S and in tests it is indeed soft
at 2.8 within 2-3 meters. Beyond 5 meters it's sharp at 2.8 though
with a little less contrast than when stopped down a stop or two. In
addition, the DOF may also extend further in one direction than in
the other, leading one to falsely believe that the lens is back- or
front focusing.

I may be lazy, but usually I don't test by using test charts, rulers
etc. I shoot real subjects at various distances and apertures. If the
pics looks good and OK - well, then it is OK. Only if something seems
to be wrong, will I do more elaborate and "scientific" tests in order
to create proof that can legitimate returning the lens. These days,
with all the technical opportunities, I think it is important not to
get lost in a gear obsession, but keep the mind focused on what is
important in photography: The subject, the light and the "decisive
moment".
Click to expand...
 
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