Sharpness Issue

[Malcolm Collins]

I own a Sony a7r111, and a Sony 200-600 G OSS lens, the problem is it is sharp at 200mm, the longer the range the sharpness gets worse. I have tried various settings, all to no avail. Thanks in anticipation Mal Collins.

!st is @ 200mm, 

2nd is @400mm 

3rd is @600mm

zoom up for detail.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[Pieter]

What is the EXIF info? We need this info to rule out user error. There are many possibilities that potentially cause unsharp images at longer focal lengths.

1) Since the lens has a variable aperture, you'll loose light when zooming in. If the shutter speed is fixed, your camera will ramp up the ISO to compensate for correct exposure. Could be that the corresponding increased noise at longer focal lengths causes some mushiness.

2) At longer focal lengths you'll need faster shutter speeds to prevent camera shake blur. If your ISO is fixed, your camera will reduce shutter speed rather than increase it when zooming in to get correct exposure. Camera shake blur could be the issue.

3) At longer focal lengths, atmospheric conditions such as fog, dust or heat haze have a bigger impact on the sharpness of your images. Your camera settings or lens can't compensate for this.

4) It is common for lenses like this that optical sharpness drops a bit at longer focal lengths. Same with this lens:

https://www.opticallimits.com/sonyalphaff/1097-sony200600f5663oss?start=1

More often than not, cause 1-3 are governing in determining the final sharpness of the image over cause 4.

5) Focus might be off in the last image: there's a branch in front of the bird. Could be that the camera locked on to the branch rather than the bird.

Edited January 15, 2023 by Pieter

[XKAES]

Along the same lines, are you using a tripod and Anti-Shake?  Either will be helpful, but they should not be used together -- that can make things worse.

How about a cable release?  Are you using the aperture for that lens that produces the best resolution -- probably f8?

Do you have a camera and lens manual?

 

[Malcolm Collins]

18 hours ago, Malcolm Collins said:

I own a Sony a7r111, and a Sony 200-600 G OSS lens, the problem is it is sharp at 200mm, the longer the range the sharpness gets worse. I have tried various settings, all to no avail. Thanks in anticipation Mal Collins.

!st is @ 200mm, 

2nd is @400mm 

3rd is @600mm

zoom up for detail.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

[Malcolm Collins]

Re sharpness issues.

Exif details are 

DSC02643, 600mm, Shutter 1/1600, f6.3. Iso 6400, Tripod, steady shot off on lens in all pics.

DSC05605, 400mm, shutter 1/8000, f10, Iso6400.

DSC05709, 200mm, shutter 1/4000, f10, Iso 6400.

white balance set manually I think they were on cloudy.

Thanks again.

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

[Pieter]

Settings seem ok. ISO 6400 is pretty high, especially for a high res sensor, but this is constant for all images and makes sense for the 600mm shot, given the aperture and shutter speed. Better try to stay at 3200 or below: your shutter speed has plenty headroom in the other shots.

16 hours ago, XKAES said:

Are you using the aperture for that lens that produces the best resolution -- probably f8?

While this may be sound advise for the vintage lenses Xkaes is using, modern optics are much better corrected at wider apertures. Especially high density sensors (A7Rx, A6xxx) are diffraction limited starting at around f/5.6 with good quality lenses. The 200-600 is best wide open at all focal lengths (refer to the review I linked), but f/8 is fine too. No need to stop down to f/10 for sharpness (though you didn't for the 600mm shot).

To rule out the lens as a cause for your problems, I'd try some controlled testing. Put the camera on a sturdy tripod (or better: on a bean bag on a solid base) with steady shot off. Put aperture at f/6.3 or f/8, ISO 100 and manually focus on a flat  static subject, with the surface of the subject perpendicular to your optical axis. Use a remote trigger or self timer to shoot some test shots at different focal lengths. Be sure to re-focus when you change focal length.

Edited January 16, 2023 by Pieter

[Malcolm Collins]

Thank you, shall try what you suggest tomorrow.

[XKAES]

Another reason to consider stopping down the lens is to increase depth-of-field -- which is incredibly thin with long lenses.  Do you want the entire bird in focus -- or just the head?

[Malcolm Collins]

the whole bird, also like getting birds in flight

[XKAES]

17 hours ago, Malcolm Collins said:

the whole bird, also like getting birds in flight

 

Good luck with that.  It's either use a tripod/monopod (which takes practice) or use a high ISO (and you know what that means).

[johnb5319]

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Hi, for reference, this is a fairly tight crop from the same combo. 1/1600th iso 2000 600mm. So a lower iso. This was hand held but resting on a car windowsill. As you’re from Oz, you’ll recognise the birds! I’m guessing there might be some issue with the lens. Hope this helps. 

[FunWithCameras]

On 2/11/2023 at 9:33 PM, johnb5319 said:

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

Hi, for reference, this is a fairly tight crop from the same combo. 1/1600th iso 2000 600mm. So a lower iso. This was hand held but resting on a car windowsill. As you’re from Oz, you’ll recognise the birds! I’m guessing there might be some issue with the lens. Hope this helps. 

Guessing that's a mated pair of wedgetails. They have amazing eyesight - I'm sure the one on the right is keeping a close eye on you, even if you are a fair way off.

Good shot.

You bring up a key point - when you are out at 600mm, you want to try to steady yourself by resting against something solid, if you can. Even with short shutter speeds, if only takes a slight movement to blur the shot (because the shutter takes time to get the entire frame).

Another point is that shooting from a distance can mean shooting through heat haze or turbulent air, and those can blur your shots. One tip I was given was to shoot bursts, because you may get some blurred and some sharp as the air changes.