sharpness Sony 70-300mm SEL lens

[sundial215]

My 70-300 lens on occasion produces images that are not in focus when set to 300mm.  I tend rule out camera motion because I am shooting at 1/1000 sec. and resting the camera on a solid rest.   At first I thought it was because many of my earlier out of focus shots were wide open at f5.6.  So today I tried shooting a sign that was 282 meters away and shot at 5.6, 8, and 11.  The middle one, f8, was clearly out of focus.  I am generally satisfied with this lens on my A7r2 camera, especially at the shorter FLs. The lens is generally sharp, and very easy to carry and use.  Please see the composite of the three images.  All are enlarged to 100%.

Has anyone else experienced such issues with this lens or, with the A7r2 camera?

 

 

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[tinplater]

Haven't had or heard others address this problem.  Would be of interest to try the lens on a different camera and see if you can determine if this is a lens or body issue.

[thefsb]

Hi sundial215, I strongly suspect defocus blur is to blame, not unsharpness or camera shake.

1. It doesn't look like camera shake

2. sharp at F5.6 and 11 and dramatically unsharp at F8 would be a bizarre defect

3. critical focus of a subject at range 282 m with a 300 mm lens can be tricky

i'll try this myself when i have time with 7RM3 and let you know

[Iansky]

I also have this lens but have not experienced these problems and I mostly shoot at f8 - all images are nice and sharp.

You say the camera was resting on a solid rest, if this was as stable as a tripod and you had image stabilisation turned on there is a possibility this could be part of the problem however I would have expected the problem to be the same across all 3 apertures.

Gremlins perhaps.......hope you find a viable solution.

[thefsb]

@sundial215 I shot some tests of the antennas on top of the Prudential Tower 435 m away using aperture bracketing. I cannot reproduce your effect. The shots at F8 were best but all were good.

If I were you, I'd try to repeat the tests several times. If you have a precise test recipe that reproduces the results then you can use that to send the lens for repair.

Edited October 26, 2018 by thefsb

[sundial215]

Thanks all for your on target advice.  I will try to see it this issue continues as I use the lens.   

[SandyW]

I have been using the Sony A7 series cameras since they first came out, first the A7 then the A7ii and now the A7iii.  I use almost exclusively legacy prime manual focus lenses, and occasionally the Sony  FE 70-300 zoom.  The brand of legacy glass is Konica HexanonAR, several different lenses, 15mm to 300mm. My "go to" is the 21mm F2.8.

Edited November 2, 2018 by SandyW

[Mike J M]

Did you check if you were on continuous or single shot focusing? I've occasionally had out of focus shots when on continuous focusing of stationary objects using any of their zooms. Not common or reproducible but it has occurred. It doesnt seem to happen on single shot. 

[Lescatalpas]

On 11/2/2018 at 8:17 PM, Mike J M said:

Did you check if you were on continuous or single shot focusing? I've occasionally had out of focus shots when on continuous focusing of stationary objects using any of their zooms. Not common or reproducible but it has occurred. It doesnt seem to happen on single shot. 

I agree, I have experienced that on rare occasions. When in burst mode, it is possible to see difference in sharpness between the shots.

[michelb]

When french magazine Chasseur d'Images tested this lens a while ago ( just after its introduction) , they noticed this weird behaviour and were supposed to follow-up on it but i never saw an update.

[howgus]

An odd quirk with manual focus on Sony A7 cameras, which applies to both MF Assist and focus peaking:  focus operation takes place at the selected aperture, rather than wide open, and at f8 manual focus is very difficutl.  Autofocus opens the lens wide during focus then stops down for the shot, automagically.  If you have  time during shooting, open the lens wide, focus, then stop down to f8.  I believe you will be surprised by the results, especially with a fast lens.  If so, call Sony and complain!

[AZWolf]

On 10/26/2018 at 9:22 AM, Iansky said:

I also have this lens but have not experienced these problems and I mostly shoot at f8 - all images are nice and sharp.

You say the camera was resting on a solid rest, if this was as stable as a tripod and you had image stabilisation turned on there is a possibility this could be part of the problem however I would have expected the problem to be the same across all 3 apertures.

Gremlins perhaps.......hope you find a viable solution.

I shoot full time and test every lens I get- that's added up to quite a few over my 30+ year career. Based on this I would test it with a solid tripod and turn off the image stabilization. If you have any doubts at all about the tripod being rock solid then try it both with and without IS. I would also use howgus's manual focusing method above using the magnification assist and the low focus peak setting can't hurt. I'd also do the series with autofocus (single shot only, don't use continuous).

I can't remember if all these variations are recorded in the metadata and depending on your software you may or may not be able to see it- so might just be easiest to write it all down. Also as someone else suggested, do each test several times and if you have another camera body to try, do that. With these methods you should be able to nail down the source of the problem.

Good luck and keep us posted!

Cheers,

Joel