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04-06-2011, 04:01 PM   #1
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sigma 50-500 os, should I keep it?

Hello,

I just took some quick test shots to see how good this copy of the Sigma 50-500 OS is at 500mm. All pictures are 100% crops from shots taken in very bad light with a K-5 body at ISO 200 in JPG format. I added a shot with my DA* 50-135 as a point of reference.

1. Sigma 50-500 OS, 500mm, F6.3 - pretty soft

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2. Sigma 50-500 OS, 500mm, F7.1 - clearing a little up

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3. Sigma 50-500 OS, 500mm, F8.0 - not too bad

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4. DA* 50-135, 135mm, F6.3

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I suspect that I'm a little spoiled by the DA*50-135. I knew in advance that the bigma is a little soft wide open at 500mm. I'm just wondering if this is what I can expect from this lens or if I should rather look for a better copy? Thanks!

04-06-2011, 04:43 PM   #2
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The sharpness should be fine as long as you zoom it out to about 450mm. That's just how the lens is.

You might be interested in checking out our review: Sigma 50-500mm F4.5-6.3 APO OS HSM Lens Review

Adam
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04-06-2011, 06:47 PM   #3
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Try focusing in live view at 500mm and see if you get different results.
04-06-2011, 07:12 PM   #4
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Are these centre of the field samples or corner samples.
Wide open that's definitely too soft for the centre of the image.
Try again in better light and checking your focus.

04-06-2011, 10:19 PM   #5
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I suspect that the much of the softness you are seeing is actually a focus issue. How far away was the test subject from the lens?

When I first bought my Sigma 50-150mm f/2.8, I tried doing some in-door focus-chart tests, and was initially discouraged. I later realized that this lens simply is not designed to focus at close distances. At closer than 10 or 15 feet, focus can be inconsistent. Beyond that, it's spot on.

With the 50-500mm being designed to be used primarily as a long zoom, it may have similar problems when focusing at close distances. So before drawing a final conclusion, I would shoot with the lens in the real world and see if your pictures are sharp enough.
04-07-2011, 04:45 PM   #6
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@Adam
Thank you for pointing me to the review. I didn't know about it yet. I'll check the differences at 450mm and 500mm this weekend.

@Clinton
This was actually a very good idea. I tried to focus in live view and touched the focus a little up manually. See the results below.

@Ash
Yes, the crops are close to the center.

@Edgar_in_Indy
It really seems to be a focus issue. The object distance was 3-4 meters which isn't really a telephoto distance but this lens is able to focus from as close as half a meter (1:3.1 macros at ~200mm) away. I probably should upgrade the K-5 firmware to get better focusing in poor lighting.
I'll check out the lens under more realistic conditions this weekend.


This looks already much better to me :

LV + manual focus, 500mm, ISO 200, F6.3



LV + manual focus, 500mm, ISO 200, F8.0



Thank you very much for your suggestions. I love coming here and logging off as a happier person.
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04-07-2011, 05:32 PM   #7
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You may have a slight back or front focus issue. Live view does it's own logic to focus the lens, so it is sometimes more accurate than normal focus; especially if there is a focusing issue.

A "lens align" LensAlign® Focus Calibration System can help you with this, but for a cheap solution you may want to try a ruler at a 35(ish) degree angle away from you, with some sort of high contrast focus target in the exact middle to see which way the focus is off (if at all).
04-09-2011, 04:41 PM   #8
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firmware v1.03 improved auto focus

@Clinton

I've heard about the LensAlign system and it's DIY versions. I didn't bother with micro focus adjustments yet since I mainly did landscape photography with high F numbers. I'll look further into this subject.

I updated my K-5 to firmware version to v1.03 today. I instantly got better auto focus results in my "test". I really don't want to bore you guys with boring test pictures. I just had to stick with the same test conditions to see if the firmware version made a difference.
I think it's easy to recognize that it did! I read that not everyone is satisfied with the low light focus functionality in the latest firmware. At least in my case it really does work better under the light conditions of my "test".

1. 500mm, F6.3, ISO 200, AF, FW 1.03, 100% center crop

2. 500mm, F8, ISO 200, AF, FW 1.03, 100% center crop

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04-09-2011, 05:00 PM   #9
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more realistic telephoto test

Today I took a picture from 20 meters away. I actually measured the distance. I thought the three dimensional painted wooden mask doubles well as a more realistic lens test subject. The attached picture is an unsharpened 100% crop from the center. I'm satisfied with the result. The retained detail responds well to sharpening in post processing.
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04-09-2011, 09:12 PM   #10
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I'd say the latest firmware had a substantial impact on your AF.
06-02-2011, 02:19 AM   #11
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Tough some people give negative opinion about this lens I believe it is one of the ever successful lenses exist in market actually. I have one without OS version and I'm quite happy with its performance. I have the opinion that F/8 is the sweet spot of this lens. K5’s high ISO performance allows users to shoot with high shutter speed when diaphragm is adjusted to F/8. This makes a lot easier to have sharper results. Here I share 1 shot that I had few days ago in a shady weather condition. When you look at 100% crop, you can see the sharpness of details for objects even in long distance is pretty acceptable.

Complete Photo; F/13 - 1/1000 shutter speed - ISO 400 @ 500mm



100% crop


Last edited by cem.kumuk; 06-02-2011 at 02:27 AM.
06-02-2011, 07:24 AM   #12
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This is a pretty interesting thread, thanks. I need to check calibration on a few lenses myself - maybe this weekend I'll have the chance.
06-17-2011, 05:36 AM   #13
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I've got a sigma 50-500 and shoot surfing with it, though the DS I use is somewhat "interesting" with it's pedestrian autofocus. I'm pretty happy with the results, but do look forward to trying it with a K-something soon...



06-18-2011, 06:18 AM   #14
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Fantastic shots. What was the focal length for those shots? And you're shooting with a camera with no stabilization?
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