[Kiko Jones]

Hi. I have a question for you guys. I had been shooting with my k30 trying out different lenses and different zooms in particular. I am into street photography, but I am not the kind of photographer who would get to close to his subjects. I had been using a sigma 28-300 f3.5 lens as my walk around lens for several reasons, particularly because it si compact and that is a plus when you are walking around with your camera taking pictures of people.

My issue is that when I am taking pictures of subjects at the max of my zoom range they come out blurry, even with a aperture of f22 which is the maximum for this lens. My question is, why and how do I avoid that? I would like to get pictures that even when I crop them might get good quality images. I mean the images doesn't have to be "tack sharp" but at leas with some definition. Would a tripod help? or do I need to get closer? Would a teleconverter help? Share some wisdom please and thank you in advance.


Peace to you all.


jro

[Santoku]

Hi. I have a question for you guys. I had been shooting with my k30 trying out different lenses and different zooms in particular. I am into street photography, but I am not the kind of photographer who would get to close to his subjects. I had been using a sigma 28-300 f3.5 lens as my walk around lens for several reasons, particularly because it si compact and that is a plus when you are walking around with your camera taking pictures of people.

My issue is that when I am taking pictures of subjects at the max of my zoom range they come out blurry, even with a aperture of f22 which is the maximum for this lens. My question is, why and how do I avoid that? I would like to get pictures that even when I crop them might get good quality images. I mean the images doesn't have to be "tack sharp" but at leas with some definition. Would a tripod help? or do I need to get closer? Would a teleconverter help? Share some wisdom please and thank you in advance.


Peace to you all.


jro

Couple of things may be happening. First, once you get past about f/11+ diffraction sets in and the image starts to become soft, which might render itself to you as blurry. Likely more importantly, the longer the focal length of the lens, the harder it is to stabilize it, thus increasing the chance of motion blur in photos, especially if you are hand-holding the camera. At long focal lengths, hand-held you need to increase your shutter speed to compensate. One rule I have heard is to set the shutter speed for your focal length, accounting for the dSLR crop factor. Too shoot at those high f-stops, you are letting in less light, therefore the camera needs to slow the shutter speed down to get enough light for a proper exposure, then increasing the chance of motion blur.

When you are shooting at the long end, you will likely need it about the f/9-f/10 range to get the sharpest shot you can with that lens. However, you will also need to increase your shutter speed, probably in the range of 1/300-1/500 at least. This will then necessitate using a higher ISO/sensitivity. You will have to test this out to determine just how high the ISO get's bumped with those settings, and then determine if you can live with or deal with the noise in post processing.

Just a few thoughts.

[hnikesch]

If your lens is like most tele zooms it sharpest about f8 plus that will keep shutter faster reducing camera movement

Hans

[rbefly]

Hello Kiko, Welcome to the Forum!
I believe there are at least two problems at work here;
First, if you check the lens reviews, several users mention that this lens is 'soft' at maximum focal length.
Second, most likely camera shake is compounding the situation. At 17.3 oz (490 gr) for the lens and 23 oz (650 gr) for a K-30, you're supporting 40 ounces handheld, trying to focus, compose, press the shutter and hold everything steady. Camera shake, even the slightest bit, is magnified by the focal length of the lens, so a tiny bit of movement that might go unnoticed at 50mm is a huge factor when multiplied six times.
Stopping way down to f/22 is counter-productive also. When you do, you lower the shutter speed even more (unless you raise the ISO to compensate, bringing image quality even lower) so I would advise sticking to f/8.0 or so and setting an ISO that gives you a shutter speed of (no less than) 1/300s.
A third possibility; With a slow shutter speed (lower than 1/200s, roughly) you might be holding the camera steady, but the subject is moving!
The general 'rule' with a telephoto lens is to use a shutter speed that's equal to the focal length. That's 1/300s, whether it's fully extended or not.
So, try shooting in TAv mode, shutter speed 1/300s, f/stop f/8.0 and let the camera (lightmeter) select an ISO that will provide the proper exposure.
If all else fails, try a tripod!
Good Luck!
Ron

[dms]

Also, at long focal length a filter can degrade image more, Also if there is heated ground/boards/pavement air motion will degrade the image. You need to analyze the situation--but if it happens at all conditions (and w/o filter) it may be the lens is not sharp. Set up a support for the lens (even a home made V shaped wooden one plus towel) and test the lens out. If the lens is sharp at a known (good) setup, then properly using means you need to work at the details.

[JinDesu]

Maybe your focus is off also? Have you tried checking how the lens performs under manual focus with Liveview on a tripod?

[lister6520]

Can you upload some sample photos to get a better idea of what the problem is?

The very narrow aperture is definitely part of the problem as already suggested as is possible autofocus calibration being needed.

Since you use it predominantly at maximum focal length do the calibration also at max focal length and use a subject that is at a distance similar to what you most often shoot rather than using a nearby calibration chart. I find easiest way to calibrate is focus and shoot in live view, switch to OVF, half press again the shutter while carefully observing how the focus moves. Adjust the AF calibration and repeat until you get to the point when there is least movement (or none at all) between live view and OVF.

Additionally, if you are using shake reduction:
1. Allow for the shake reduction to stabilise - once you are steady half press the shutter, wait for the hand icon to be steadily lit and only then press full. If you realease the shutter before that the SR might make the picture more blurry instead of sharper.
2. If the lens has its own stabilisation (as various Sigma do) make sure that you do not switch on both the stabilisation in the lens as well as the in-body SR of the camera. Use either the in camera SR or the stabilisation in the lens but never both at the same time.

If you are not using shake reduction then try it out. I find it very effective and have been able to shoot at 500mm at 1/150 second (with some luck even 1/50), four or five times slower than the rule of thumb.

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Last edited by lister6520; 09-30-2013 at 11:06 AM. Reason: Corrected incomprehensible sentence

[TER-OR]

Long-zoom focus is often soft - not as noticable when focusing relatively close like 100m, but quickly noticable at distance.

Also, I've noticed atmospheric haze is a big problem. I take shots of almost any aircraft I see, and while airliner images are usually in focus, they're washed out and soft. I attribute this to moisture in the atmosphere etc.

That's all I can really add here...

[formercanuck]

In general - Sigma superzooms (I have the 18-200mm) tend not to be the sharpest tool in the shed, but are VERY useful for general purpose. I found a HUGE difference between my 18-200mm f3.5/6.3 and Rokinon 85mm f/1.4 in terms of sharpness and light.

The wide angle settings give pincushion, while the longest reach has some barrel. I have found that to use (at least the 200mm), you'll need some decent light outdoors and the middle is typically the only really sharp spot (rule of thirds). On a similar note - at the far end you may end up with items out of focus due to
a) camera settings (i.e. too slow of a shutter for image) I try to stay above 1/100 myself, along with too low of ISO.
b) small aperature (leading to not enough light see A)
c) items out of the plane of focus - I've had this problem with my Sigma.

[lister6520]

Depending on the atmospheric conditions I can usually get sharp images at much larger distances that that. In this photo the church in the foreground is one mile distant, while the one in the background is about three and a half miles away.

At one mile the sharpness seems unaffected, with edges transitioning within two pixels. At three and a half miles there is however a very significant degradation.

The lens is the Sigma 150-500 set to 370mm F8. Shutter speed is 1/160. It was shot handheld in a moderate wind and with stabilisation switched on but I'm not sure whether it was the one in the lens or the camera.




https://dl.dropboxusercontent.com/s/uoc4yxm3nbqcsq2/_IGP3184LR.jpg