New Sigma 18-50mm f2.8 lens seems a bit soft?

kj1225 · 01-15-2009, 03:52 PM

Last edited by kj1225; 01-19-2009 at 06:05 PM.

HermanLee · 01-15-2009, 04:27 PM

Hi,
welcome to the forum!

It seems most of your pictures are underexposed.
What method do you use for testing the lens?
Do you use tripod or handheld?
Is there enough lighting?
Try to use less busy object for example a person's face under the sun.
Or you can use some testing chart. Browse in the internet and you'll easily find one.
I don't have it with me right now otherwise I can give you one.

If the picture still come out not sharp then maybe there is a back/front focus.

Hope this helps,

Fl_Gulfer · 01-15-2009, 04:39 PM

Send it back and get the Tamron 17-50mm 2.8

kj1225 · 01-15-2009, 04:56 PM

Originally posted by HermanLee

Hi,
welcome to the forum!

It seems most of your pictures are underexposed.
What method do you use for testing the lens?
Do you use tripod or handheld?
Is there enough lighting?
Try to use less busy object for example a person's face under the sun.
Or you can use some testing chart. Browse in the internet and you'll easily find one.
I don't have it with me right now otherwise I can give you one.

If the picture still come out not sharp then maybe there is a back/front focus.

Hope this helps,

hmm I think they might be a little underexposed but I pretty much went by the exposure gauge on the camera and it's telling me that the exposure is fine... I've noticed that too... camera says it's well exposed at the time of the shot but it comes out underexposed most of the time.

I didn't use any specific method... I just took some quick shots around the house to test the new lens and it felt a bit "soft" or not focusing properly.

These were shot indoors so the lighting might be a bit on the low end.

I've been looking at these charts and a lot of them people claim are inaccurate so I'm kind of stuck on deciding which one to use.

Any other feedback is appreciated!

Thank You!

asdf · 01-15-2009, 06:14 PM

Originally posted by kj1225

I haven't looked at your photos, but here are some general comments: Don't expect sharpness, wide open. Supposedly, modern lenses get sharp at around f/5.6-8 (within their DOF). IQ may degrade at close focusing distances. Mirror slap and the shutter cause vibrations. So shoot black text on white paper (or one of those charts) in RAW with a STEADY tripod, a cable switch and 2s mirror lockup at a moderate distance. Compare it to another good lens you have under the same conditions. You'll need a lot of patience if you want a fair comparison: I was doing it recently and I quickly got sick of it.

Finally, it may not really make a difference in real life conditions, especially if you tend to scale your images and save them in a lossy format.

Buddha Jones · 01-15-2009, 07:19 PM

From the reviews I read, it is a bit soft, I'd return it and get the Macro version if you are a fan of Sigma products. If not then I would go with the Tamron as FL Gulfer advised or optimumly get the DA*16-50mm.

kj1225 · 01-16-2009, 06:07 PM

hmm I do have the new Macro version EX DC Macro

Marc Sabatella · 01-16-2009, 06:48 PM

The posted images are *way* too small to judge sharpness. Obviously, the whole image is not in focus - the depth of field is too shallow for that. But the part that is in focus appears to be perfectly shapr as far as one can see in those tiny images. We'd need something much larger - or at least, a small area cropped out of the full size image - to judge sharpness.

As for exposure, it's relative. The camera tries to make things look "average" - like an 18% gray card. If your scene is brighter than average, it wiill come out dark = that's normal. It will also come out dark if there is anything in it that is unusually bright - a light source, or a reflection of one, for example - as the camera will make everything else darker so the highlight sin't too bright for the camera to handle. Part of the technique of using a DSLR is to learn to anticipate those situations and override the camera's suggested exposure. Most books on photography will explain the process.

tarsus · 01-16-2009, 10:22 PM

I also have an 18-50 f2.8 macro that WILL NOT take a sharp picture. It is going back.

kj1225 · 01-19-2009, 06:57 PM

new Images are up!

01-15-2009, 03:52 PM	#1
kj1225 New Member Join Date: Dec 2008 Posts: 4	New Sigma 18-50mm f2.8 lens seems a bit soft? UPDATED! Just did some tests and wanted to see if I can get some opinions on the sharpness of my new lens! UPDATED SHOTS FOR YOUR JUDGMENT! These were taken under the following conditions: -Tripod Used -Sufficient natural daylight through a window behind the camera -ISO 100 -Image Stabilization OFF -Cable Switch was used 18mm F2.8 1/250 sec FULL IMAGE - http://images32.fotki.com/v1088/filez3Yf/ed98c/1/1452034/7149810/CameraTest011909001.jpg 100% CROP - http://images33.fotki.com/v1136/fileI3Q9/ed98c/1/1452034/7149810/18mmf2_8crop1.jpg 18mm F5.6 1/60 sec FULL IMAGE - http://images32.fotki.com/v1092/fileQrjk/ed98c/1/1452034/7149810/CameraTest011909002.jpg 100% Crop - http://images47.fotki.com/v1397/fileLdBh/ed98c/1/1452034/7149810/18mmf5_6crop1.jpg 18mm F8 1/45 Sec FULL IMAGE - http://images40.fotki.com/v1242/filemlsU/ed98c/1/1452034/7149810/CameraTest011909003.jpg 100% Crop - http://images36.fotki.com/v1161/fileAsUa/ed98c/1/1452034/7149810/18mmf8crop1.jpg 29mm F2.8 1/250 Sec FULL IMAGE - http://images32.fotki.com/v1108/filecbWy/ed98c/1/1452034/7149810/CameraTest011909004.jpg 100% Crop - http://images45.fotki.com/v1361/filefrf3/ed98c/1/1452034/7149810/29mmf2_8crop1.jpg 100% Crop #2 - http://images31.fotki.com/v1057/fileoffe/ed98c/1/1452034/7149810/29mmf2_8crop2.jpg 29mm F5.6 1/60 Sec FULL IMAGE - http://images40.fotki.com/v1302/fileh0px/ed98c/1/1452034/7149810/CameraTest011909005.jpg 100% Crop - http://images38.fotki.com/v1216/filepykT/ed98c/1/1452034/7149810/29mmf5_6crop1.jpg 100% Crop #2 - http://images40.fotki.com/v1303/photos/1/1452034/7149810/29mmf5_6crop2-vi.jpg 29mm F8 1/45 sec FULL IMAGE - http://images30.fotki.com/v481/fileDuPm/ed98c/1/1452034/7149810/CameraTest011909006.jpg 100% Crop - http://images40.fotki.com/v1339/fileb8ii/ed98c/1/1452034/7149810/29mmf8crop1.jpg 100% Crop #2 - http://images39.fotki.com/v1235/photos/1/1452034/7149810/29mmf8crop2-vi.jpg 29mm F11 1/15 Sec FULL IMAGE - http://images35.fotki.com/v1163/filepX2B/ed98c/1/1452034/7149810/CameraTest011909007.jpg 100% Crop - http://public.fotki.com/kj1225/sharpness-test/29mmf11crop1.html 100% Crop #2 - http://images39.fotki.com/v1294/photos/1/1452034/7149810/29mmf11crop2-vi.jpg 38mm F2.8 1/250 sec FULL IMAGE - http://images33.fotki.com/v1068/file6Tdl/ed98c/1/1452034/7149810/CameraTest011909008.jpg 100% Crop -http://images33.fotki.com/v1139/fileWY2Y/ed98c/1/1452034/7149810/38mmf2_8crop1.jpg 100% Crop #2 - http://images34.fotki.com/v1193/photos/1/1452034/7149810/38mmf2_8crop2-vi.jpg 38mm F5.6 1/45 Sec FULL IMAGE - http://images32.fotki.com/v1063/file7jG0/ed98c/1/1452034/7149810/CameraTest011909009.jpg 100% Crop - http://images45.fotki.com/v1360/fileECX2/ed98c/1/1452034/7149810/38mmf5_6crop1.jpg 100% Crop #2 - http://images41.fotki.com/v1344/photos/1/1452034/7149810/38mmf5_6crop2-vi.jpg 38mm F8 1/30 Sec FULL IMAGE - http://images33.fotki.com/v1136/fileVcn9/ed98c/1/1452034/7149810/CameraTest011909010.jpg 100% Crop -http://images35.fotki.com/v1210/filetzy4/ed98c/1/1452034/7149810/38mmf8crop1.jpg 100% Crop #2 - http://images45.fotki.com/v1421/photos/1/1452034/7149810/38mmf8crop2-vi.jpg 38mm F11 1/10 Sec FULL IMAGE - http://images38.fotki.com/v1219/file7l6i/ed98c/1/1452034/7149810/CameraTest011909011.jpg 100% Crop - http://images42.fotki.com/v1435/fileq4O0/ed98c/1/1452034/7149810/38mmf11crop1.jpg 100% Crop #2 - http://images45.fotki.com/v1360/photos/1/1452034/7149810/38mmf11crop2-vi.jpg 50mm F2.8 1/180 Sec FULL IMAGE - http://images42.fotki.com/v1434/filec7Fk/ed98c/1/1452034/7149810/CameraTest011909012.jpg 100% Crop - http://images42.fotki.com/v1436/fileUI55/ed98c/1/1452034/7149810/50mmf2_8crop1.jpg 100% Crop #2 - http://images43.fotki.com/v1437/fileLyEB/ed98c/1/1452034/7149810/50mmf2_8crop2.jpg 50mm F5.6 1/30 Sec FULL IMAGE - http://images45.fotki.com/v1360/fileBwdS/ed98c/1/1452034/7149810/CameraTest011909013.jpg 100% Crop - http://images31.fotki.com/v1093/filencVc/ed98c/1/1452034/7149810/50mmf5_6crop1.jpg 100% Crop #2 - http://images32.fotki.com/v1063/file1xX9/ed98c/1/1452034/7149810/50mmf5_6crop2.jpg 50mm f8 1/20 Sec FULL IMAGE - http://images41.fotki.com/v1340/filejKXH/ed98c/1/1452034/7149810/CameraTest011909014.jpg 100% Crop - http://images46.fotki.com/v1446/fileEafz/ed98c/1/1452034/7149810/50mmf8crop1.jpg 100% Crop #2 - http://images44.fotki.com/v1419/filey8Vq/ed98c/1/1452034/7149810/50mmf8crop2.jpg 50mm F11 1/8 Sec FULL IMAGE - http://images43.fotki.com/v1439/fileG2kM/ed98c/1/1452034/7149810/CameraTest011909015.jpg 100% Crop - http://images35.fotki.com/v1206/fileFL3o/ed98c/1/1452034/7149810/50mmf11crop1.jpg 100% Crop #2 - http://images42.fotki.com/v1434/fileqAbm/ed98c/1/1452034/7149810/50mmf11crop2.jpg There seems to be a good amount of vignetting at wider angles... is it something I should be worried about? Thanks in Advance for the input! Last edited by kj1225; 01-19-2009 at 06:05 PM.

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01-15-2009, 04:27 PM	#2
HermanLee Veteran Member Join Date: Jan 2008 Location: Southern California, USA Photos: Gallery Posts: 729	Hi, welcome to the forum! It seems most of your pictures are underexposed. What method do you use for testing the lens? Do you use tripod or handheld? Is there enough lighting? Try to use less busy object for example a person's face under the sun. Or you can use some testing chart. Browse in the internet and you'll easily find one. I don't have it with me right now otherwise I can give you one. If the picture still come out not sharp then maybe there is a back/front focus. Hope this helps,

01-15-2009, 04:39 PM	#3
Fl_Gulfer Veteran Member Join Date: Jul 2007 Location: Florida Gulfer Photos: Albums Posts: 3,054	Send it back and get the Tamron 17-50mm 2.8

01-15-2009, 04:56 PM	#4
kj1225 New Member Join Date: Dec 2008 Posts: 4 Original Poster	Originally posted by HermanLee Hi, welcome to the forum! It seems most of your pictures are underexposed. What method do you use for testing the lens? Do you use tripod or handheld? Is there enough lighting? Try to use less busy object for example a person's face under the sun. Or you can use some testing chart. Browse in the internet and you'll easily find one. I don't have it with me right now otherwise I can give you one. If the picture still come out not sharp then maybe there is a back/front focus. Hope this helps, hmm I think they might be a little underexposed but I pretty much went by the exposure gauge on the camera and it's telling me that the exposure is fine... I've noticed that too... camera says it's well exposed at the time of the shot but it comes out underexposed most of the time. I didn't use any specific method... I just took some quick shots around the house to test the new lens and it felt a bit "soft" or not focusing properly. These were shot indoors so the lighting might be a bit on the low end. I've been looking at these charts and a lot of them people claim are inaccurate so I'm kind of stuck on deciding which one to use. Any other feedback is appreciated! Thank You!

01-15-2009, 06:14 PM	#5
asdf Veteran Member Join Date: Jan 2009 Location: Canada Posts: 1,252	Originally posted by kj1225 Hey guys just got a new Sigma 18-50mm f2.8 Lens for my Samsung GX-20 DSLR. I've read that the quality control of Sigma is sub par compared to other lens manufacturers and also read that some owners of this lens had to exchange a few before getting a sharp one. I took some test pictures (Links below) and I feel that it's a little soft and wanted to get some opinion on it. Thanks! http://images47.fotki.com/v1403/fileivZR/921a5/1/1452034/7136406/sigma1850f284.jpg http://images43.fotki.com/v1438/filervmY/921a5/1/1452034/7136406/sigma1850f281.jpg http://images47.fotki.com/v1399/fileAEAE/921a5/1/1452034/7136406/sigma1850f2810.jpg http://images42.fotki.com/v1435/fileAfdb/921a5/1/1452034/7136406/sigma1850f2811.jpg http://images43.fotki.com/v1438/fileTjct/921a5/1/1452034/7136406/sigma1850f2812.jpg http://images43.fotki.com/v1439/fileG6V4/921a5/1/1452034/7136406/sigma1850f2813.jpg http://images45.fotki.com/v1431/fileP7vI/921a5/1/1452034/7136406/sigma1850f2815.jpg http://images45.fotki.com/v1426/filejs5d/921a5/1/1452034/7136406/sigma1850f2816.jpg http://images45.fotki.com/v1427/fileShvj/921a5/1/1452034/7136406/sigma1850f2817.jpg http://images43.fotki.com/v1438/filee8T8/921a5/1/1452034/7136406/sigma1850f283.jpg http://images47.fotki.com/v1398/filevCzA/921a5/1/1452034/7136406/sigma1850f285.jpg http://images43.fotki.com/v1438/fileteMq/921a5/1/1452034/7136406/sigma1850f286.jpg http://images47.fotki.com/v1399/fileAOb3/921a5/1/1452034/7136406/sigma1850f287.jpg http://images43.fotki.com/v1438/filevw1s/921a5/1/1452034/7136406/sigma1850f288.jpg http://images42.fotki.com/v1435/fileKE8I/921a5/1/1452034/7136406/sigma1850f289.jpg Is there a better way to test the sharpness of my new lens? I haven't looked at your photos, but here are some general comments: Don't expect sharpness, wide open. Supposedly, modern lenses get sharp at around f/5.6-8 (within their DOF). IQ may degrade at close focusing distances. Mirror slap and the shutter cause vibrations. So shoot black text on white paper (or one of those charts) in RAW with a STEADY tripod, a cable switch and 2s mirror lockup at a moderate distance. Compare it to another good lens you have under the same conditions. You'll need a lot of patience if you want a fair comparison: I was doing it recently and I quickly got sick of it. Finally, it may not really make a difference in real life conditions, especially if you tend to scale your images and save them in a lossy format.

01-15-2009, 07:19 PM	#6
Buddha Jones Veteran Member Join Date: Sep 2006 Location: Charlotte, NC Photos: Gallery Posts: 2,587	From the reviews I read, it is a bit soft, I'd return it and get the Macro version if you are a fan of Sigma products. If not then I would go with the Tamron as FL Gulfer advised or optimumly get the DA*16-50mm.

01-16-2009, 06:07 PM	#7
kj1225 New Member Join Date: Dec 2008 Posts: 4 Original Poster	hmm I do have the new Macro version EX DC Macro

01-16-2009, 06:48 PM	#8
Marc Sabatella Veteran Member Join Date: Sep 2006 Location: Denver, CO Photos: Gallery Posts: 10,685	The posted images are way too small to judge sharpness. Obviously, the whole image is not in focus - the depth of field is too shallow for that. But the part that is in focus appears to be perfectly shapr as far as one can see in those tiny images. We'd need something much larger - or at least, a small area cropped out of the full size image - to judge sharpness. As for exposure, it's relative. The camera tries to make things look "average" - like an 18% gray card. If your scene is brighter than average, it wiill come out dark = that's normal. It will also come out dark if there is anything in it that is unusually bright - a light source, or a reflection of one, for example - as the camera will make everything else darker so the highlight sin't too bright for the camera to handle. Part of the technique of using a DSLR is to learn to anticipate those situations and override the camera's suggested exposure. Most books on photography will explain the process.

01-16-2009, 10:22 PM	#9
tarsus Senior Member Join Date: Feb 2008 Location: Mount Shasta Posts: 185	I also have an 18-50 f2.8 macro that WILL NOT take a sharp picture. It is going back.

01-19-2009, 06:57 PM	#10
kj1225 New Member Join Date: Dec 2008 Posts: 4 Original Poster	new Images are up!

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