Question about Sony 28-70 F3.5-5.6 lens

[wm17959]

I recently bought the Sony A7iii camera with the standard lens that it comes with, but I feel like the focus should be sharper than what I'm getting. I did a test with the camera on a trip-pod but I'm not getting the super-sharp focus I was expecting to get. Does a more expensive lens really make that big of a difference or could there be another issue?

[Chrissie]

When looking at this lens comparison database you'll find, that your lens is placed at 190th rank of all lenses tested so far in the "Sharpness" test category. 

In this link I've already narrowed down the search criteria to result only in your lens. Click on the lens's name in the bottom row, to the right of the lens's picture, to drill down to the individual test results. In the top-right block "DXOMARK score" you'll find, that the test results put this lens right in the middle between "excellent" and "poor". (I didn't want to call this "mediocre", but you can't probably argue that either).

Click on this little question mark right next to the "Sharpness" String, in the bottom right "Lens Metric Scores" block, for a description of how "sharpness" is measured by DXO.

Now back to your question: could other lenses do better?

Go back to the first page, and relax the search criteria to see more lenses, then click on the "Sharpness" column header to sort the resulting table by sharpness. Or click at this link to get the same result.Note the price tag associated with the #1 candidate 

 

[Chrissie]

P.S.: also please note, that the top eleven ranks in the "Sharpness" category have all been taken by prime lenses. Zoom lenses are inherently less sharp. You can also filter the database for zoom lenses only.

Edited December 12, 2018 by Chrissie

[tinplater]

5 hours ago, Chrissie said:

P.S.: also please note, that the top eleven ranks in the "Sharpness" category have all been taken by prime lenses. Zoom lenses are inherently less sharp. You can also filter the database for zoom lenses only.

This is true, however high quality zooms can outperform low quality primes and low quality zooms.  I have found, for my use, the Sony 24-70 2.8 to be a superb compromise when you need  constant speed with best in class optical performance.  The Tamron 28-75 2.8 is reported to be excellent at a significantly lower price.

[Lescatalpas]

I own the 28-70 kitlens too. I bought it as part of my entry into the a7 series. (a7ii) For a kitlens , which usually has a bad reputation, it is way above average and certainly acceptable. Of course there are better ones, you get what you pay for. But please find here some links to what I think are good quality pictures taken with this lens. (both on tripod) .

 

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[tinplater]

Les, you are such an artist.  I had this lens for perhaps a year or so but found its sharpness and contrast lacking, I couldn't come close to producing the images you have with that lens.  Hopefully I just had a poor copy.  Will post a few sample images taken at relatively high shutter speed and small aperture, still lacking in sharpness to my taste.  My luck with the 24-70 2.8 is exactly the opposite.

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Edited December 12, 2018 by tinplater
clarification

[tinplater]

Another less than sharp example:

 

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[tinplater]

And another (this site severely limits size of files so you can't really appreciate the resolution)  In this case focus was on golfing buddy.

 

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Edited December 12, 2018 by tinplater
added info

[Chrissie]

I would like to add another consideration to this topic: it's actually the combination of body and lens, which ultimately determines the outcome. The lens which the TO is talking about, has been tested to deliver a "PMpix" value of 25, which I interpret as a perceived resolution of 25 Mpixels. And this was tested in combination with a 42 MPix sensor (A7R2). I would assume, that on that body/lens combo the lens was the limiting factor.

OTH, the A7iii of the TO has a sensor of 24 MPix, and I would likewise assume, that a sample lens which has been tested to deliver an P-MPix value above 40 on a 42 Mpix sensor (A7R2/3) pretty much exhausts what the sensor of a A7R2/3 can resolve. But the same lens would still not be able to push the maximum resolution of a 24 MPix sensor, like in the A7 iii, upwards, beyond 24 MPix. In the latter case, obviously the sensor limits the available resolution.

To sum this up: the lens which we are talking about seems to be a near-perfect match to the A7iii body, as both have their limits pretty much at the same 24-25 MPix range.

Maybe @wm17959 can post (or link) a picture of maximum sharpness which he was able to achieve, and let owners of that lens do the judgement.

 

Edited December 12, 2018 by Chrissie

[Lescatalpas]

@Chrissie: both my samples have been shot with an a7riii!   @tinplater: to post better pictures post them as a link to Flickr, which I believe you use as well. 

[tinplater]

Per Les's suggestion, here are the three images posted to flicr

 

https://www.flickr.com/photos/80137966@N03/albums/72157703099792271

[Lescatalpas]

1 hour ago, tinplater said:

Per Les's suggestion, here are the three images posted to flicr

 

https://www.flickr.com/photos/80137966@N03/albums/72157703099792271

(have left you a message underneath the golfer picture in Flickr)  Don't know what you did in post, but the lines in the sky are normally caused by overdoing something in post-processing.  I normally post my pictures to Flickr full size. Maybe your's is reduced in size? Could also be a cause of the lines in the sky.

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Edited December 12, 2018 by Lescatalpas

[tinplater]

56 minutes ago, Lescatalpas said:

(have left you a message underneath the golfer picture in Flickr)  Don't know what you did in post, but the lines in the sky are normally caused by overdoing something in post-processing.  I normally post my pictures to Flickr full size. Maybe your's is reduced in size? Could also be a cause of the lines in the sky.

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Don't know the cause of the lines...they are not in the original and the image is straight out of camera (JPEG) with no PP.  They do no appear to be in the initial reduced size image posted here on forum.

[Chrissie]

In another thread @tinplater mentioned, that he is shooting jpeg, not raw. This is also, what the EXIF of the Golfer picture on flickr says.

JPEG is a format which uses lossy compression. These lines in the sky are compression artefacts, in my view.

When comparing the size of the downloaded jpeg-file (210 kB) to the filesize of an uncompressed image (2732 kB) of the same dimensions (1024 by 683 Pixels), I arrive at a compression ratio of ~13, which is where you can definitely expect to see visual artefacts of compression already.

Note to self: assist @tinplater in debugging his file download from camera issues. It is a shame having to  forgo the benefits of raw shooting and processing because of something probably very simple.

Edited December 13, 2018 by Chrissie

[Lescatalpas]

@Chrissie It is indeed a pity not to use Raw with such a fine camera. Re: the artefacts in the sky; they are absent in the picture posted without the link to Flickr. But we are digressing, I think the 28-70 kitlens is not so bad. 

[tinplater]

I am not shooting RAW for two reasons...my computer (2009 Mac) just takes for ever to process the files (so plea is into Santa) and my Lightroom 6 can't process the new A7III arg files.  I may eventually just bite the bullet and become an Adobe subscriber, but for now am content with JPEG as it meets my amateurish purposes.  I do, when appropriate, shoot RAW plus JPEG and use the JPEGS to identify which RAW image I may process.

As to the cause of the lines, they are not present on my original image when viewed full size on my computer.

[Lescatalpas]

22 hours ago, tinplater said:

I am not shooting RAW for two reasons...my computer (2009 Mac) just takes for ever to process the files (so plea is into Santa) and my Lightroom 6 can't process the new A7III arg files.  I may eventually just bite the bullet and become an Adobe subscriber, but for now am content with JPEG as it meets my amateurish purposes.  I do, when appropriate, shoot RAW plus JPEG and use the JPEGS to identify which RAW image I may process.

As to the cause of the lines, they are not present on my original image when viewed full size on my computer.

Hopefully you have been good the past year, so Santa will reward you.  ?  I warmly recommend the Adobe subscription approach, you are always up to date with lightroom classic, have full access to photoshop plus lightroom cc for when you are travelling. 

[tinplater]

Thanks Les...however I am going to have to be REALLY good (probably next year), my laptops are perhaps 10-15 years old and never used now that most hotels have a business center!

[thefsb]

Don't forget that web sites commonly process images, sometimes in rather heavy-handed ways. For example, this site is based on the antique IPB and likely uses PHP's GD extension. And the person who wrote that part of the program was probably not expert in image processing, coding, or in the strengths and weaknesses of GD, and had different priorities from us photogs. These mutilations can compound as material bounces around the web. And browsers also have to process images and different browsers do different things (iiuc, this problem isn't as bad as it was). And everyone's computer screen looks different, some people even have software that radically alters the color based on time of day.

So the nastiness we see might not be at all related to shooting in JPEG.

[thefsb]

On 12/11/2018 at 11:01 PM, wm17959 said:

I recently bought the Sony A7iii camera with the standard lens that it comes with, but I feel like the focus should be sharper than what I'm getting. I did a test with the camera on a trip-pod but I'm not getting the super-sharp focus I was expecting to get. Does a more expensive lens really make that big of a difference or could there be another issue?

I didn't have much luck with that lens either.

My first E-mount camera was an NEX-6 on which I used adapted old RF and SLR primes. I bought it thinking it would be nice to have native AF lens. DxOMark's numbers influenced my choice. I didn't use it much. That didn't change when I replaced the camera with an A7. Eventually I gave it away with the A7.