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10-14-2011, 04:44 AM   #1
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Is my Sigma 150/500mm performing as it should?

I got myself a Sigma 150-500mm around easter.

I was looking SO much forward to this step up in quality at the tele end. Then I got it, and my feelings were a bit mixed. There is the weight thing, which shouldn't come as a surprise - and in fact with the tripod-collar-handle and stabilization, it is possible to use it hand held with a bit of practise (and workout). Which is good, because in spite of all good intensions I rarely get to mount it. I use it for wildlife mostly, and most chances I get are too spontaneous for tripods - and when I do sometimes go on a proper birding trip, the good tripod is usually being hogged by our telescope...

Well then, I have been practising. It has been my most used lens the last half year. But I'm still ambiguous. First I told myself that the lack of sharpness at 500mm was due to the lens being slow, and ISO 400 being a bit noisy on my k7. Now I have a k5, ISO 400 should be spectacular, but I still get slightly fuzzy results. I have met other Bigma wielders in the field (with other bodies too) and simultaneous comparisons always show my pics to be less sharp.

Also, I find there is a bit more CA than I hoped, and the bokeh isn't exactly pretty. At least not after unsharp mask, although I try to be gentle. And without unsharp mask, everything is very wooly.

Then I worried a bit that perhaps the focus point was a bit off. But I can't seem to make sense of that either. I tried testing. I tried trial-and-error focus compensation in both directions. Nothing seems to help awfully much.

Maybe this IS all I should expect?

You guys have wonderful eyes, and there are so many clever people in here, so if you would offer your opinions, I would be very grateful. I attach a couple of great egret shots I took this morning. They are resized on flickr, cropped just slightly and given a bit of unsharp mask. I think passing them through flickr strips the exif, but they are all ISO400, f6.3, and the shutter time is 1/350, 1/350 and 1/250.

I tried focusing on the eyes, AF-S, center focus point, focus and recompose.

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Last edited by MetteHHH; 10-14-2011 at 04:46 AM. Reason: Adding a few details
10-14-2011, 06:07 AM   #2
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I am a novice in DSLR and in photography. So I can not give sophisticated opinion or recommendations. I tried to make some DOF calculations for camera and your lens. Online Depth of Field Calculator Assuming that Pentax K-5 sensor has the same crop factor as K7 and assuming that focal length is 500 mm (maximum zoom) and aperture F6.4, the Hyperfocal distance for your lens is about 1969 meters. If your object is, for example, about 100 m far, the DOF is about 10.1 m wide (the near limit is 95.2 m, the far limit is 105.3 m). It might explain why the grass and other objects before and behind the bird are fuzzy.
10-14-2011, 06:16 AM   #3
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Thanks Alberts. I'm perfectly alright with a shallow DOF though - in fact in a motive like this, I would prefer the surroundings to be out of focus. I only stopped down to f6.3 to see if I could improve the sharpness a bit... but it didn't really work out.

True that with this lens I find the bokeh a bit ugly, but too much depth would detract attention from the bird. Anyway ugly bokeh is the least of my worries, if only the bird would be a bit sharper...

BTW: I didn't use a tripod, but I did use a car window for support.

Last edited by MetteHHH; 10-14-2011 at 06:16 AM. Reason: Misspelled name
10-14-2011, 06:30 AM   #4
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My Sigma 150-500 isn't the when it's best wide open. Nor right at the 500mm end. When you're using both, and relying on SR with a less than ideal exposure time for 500mm, well you're probably not going to get the greatest result See what you can do about those three and that might improve your results.

10-14-2011, 06:40 AM   #5
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Thanks Nass, and you do make sense... but...

I could go ISO800, I guess, but I can't do much about the lack of proper sunshine in Denmark. So, I rarely get to use much better exposure times than this. And as for 500mm - that IS the focal length that I bought the lens for. I mean, the egret is the point of taking this shot, and zooming out to 400mm and getting nice sharp boring grass isn't very satisfactory.

As for stopping down... well, that would mean even higher ISO. And in spite of k5 being better than k7, I don't want four figure ISO on a shot that will need cropping.
I just can't help wondering why the guy next to me with a Bigma seems to get sharper images at 500mm, same conditions.

But I guess you are saying that this IS all I can expect, given the lens and my circumstances. Which is really the answer I was looking for, so thanks!

(Although the answer I was HOPING for was probably something along the lines of "Oh, you forgot to push the magic button that instantaneously improves image quality" )
10-14-2011, 06:50 AM   #6
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I have the same combo (and in Denmark too). I use it in mostly in sunshine. I get decent results using TAv mode with ISO between 80 and 12.000 and shutter times around 1/1000.

Example:

10-14-2011, 07:43 AM   #7
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I would definitely up the shutter speed: 1/250s and 1/350s at 500mm focal is on the low side.
I have a da*300/4 and seldom shoot at less than 1/640s and I try to get most shots, depending on the light availability, at a minimum of 1/1000s.

Then again, there is the risk of a bit of OOF caused by shake but you said that you had stabilized it ...

One more point and you said: And in spite of k5 being better than k7, I don't want four figure ISO on a shot that will need cropping..
I can assure you that the K5 renders high ISO shots beautifully even at ISO 1600, which is a setting that comes up very often when I get some shots in less than ideal situations. I use TAv for wildlife and BIF. Some pics showed ISO 3200 + and I still find them totally acceptable, even when cropped but of course there will be some degree of noise which can easily be taken care of in PP. You just don't want to underexpose.

Various reports/reviews do mention a softness at 500mm but since I do not own such a lens, I would not try to give my personal opinion on that issue.

JP
10-14-2011, 08:37 AM   #8
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As far as your buddies shots being nicer, check out this comparison which shows the Bigma can be sharper than the 150-500 at 500mm.
Juza Nature Photography

All these lenses get better after f8, and a faster shutter speed will be needed if you are doing anything other than heavy tripod and remote shutter technique.
When I had my 170-500 which I believe has similar performance I initially was disappointed with the picture quality at long range but once I started using faster speeds and optimal apertures it really shined.

Fortunately we are blessed with many sunny days where I live, but even still I was pushing ISO way up there.

This example shows what these lenses can do when you find their sweet spot.
This one is at 450mm (not 500) f13 (not f6.3) 1/500 (faster is better) and iso 800
This was from a moving boat using a monopod with the 170-500mm.





Last edited by crewl1; 10-14-2011 at 08:59 AM.
10-14-2011, 08:53 AM   #9
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Is your Sigma APO version? I have APO 50-500 - the old one without OS - and bokeh is at least satisfactory, very good in certain ocasions. The images you have here looks like from non-apo lens.
10-14-2011, 09:24 AM   #10
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Thanks all!

I do have the APO version, I had the lens OS active and supported it on the car window frame. All the same, I know 1/250 is pushing it. Especially for the movements of the bird itself, which stabilization won't really help me with. I guess I should try going a bit higher on the ISO. Crewl1, your greb-lings are really cute!

Also, I suspect maybe I need to try a different unsharp mask from the one in GIMP. It could explain some of the ugliness of the bokeh...
10-14-2011, 10:39 AM   #11
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My experience after owning this lens and camera combo (K-5 and Sig 150-500) for about a year.....you do best at around 400-440mm at the long end. Use f8.0 or faster, put the camera on ISO auto with max at 3200. I have pretty decent results with this...

https://www.pentaxforums.com/forums/post-your-photos/147575-nature-red-should...ille-park.html
10-14-2011, 02:50 PM   #12
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This discussion tends to confirm Lenstip.com's review of both the Bigma and the 150-500, which indicate that the Bigma has noticeably better resolution than the 150-500.

150-500
Sigma 150-500 mm f/5.0-6.3 APO DG OS HSM review - Introduction - Lenstip.com

50-500
Sigma 50-500 mm f/4.5-6.3 APO DG OS HSM review - Introduction - Lenstip.com
10-14-2011, 03:05 PM   #13
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QuoteOriginally posted by MetteHHH Quote
Thanks all!

Crewl1, your greb-lings are really cute!
..
Thanks MetteHHH they were even more fun to watch as they scrambled on the parents back and took a ride.


10-14-2011, 03:13 PM   #14
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I would turn of SR and just make sure your shooting at 1/500s or better, on the K-5 as long as your exposure is decent running upto 1600 ISO is not a big deal. If your SR is set to the wrong focal length it can mess with your images, I have had the problem when using my Tamron Adaptall2 60-300, so I usually set it to the longest focal length or turn it off. Since your lens isn't a manual lens, I would try turning it off!
10-16-2011, 06:32 PM   #15
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Like others have said, I would definitely up the shutter speed.
Also noticed that the legs appear to be a bit sharper than the head, so could it be the focus points as well?

*edit*
Did notice that you said you were focusing on the eyes...but still the legs look sharper.
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