RF100-500 soft at 500. did I get a bad one?

[doug86]

I Purchased a new RF100-500mm last month, and took it out in the field for a month. But out of the box, it wasn't producing sharp images with my R6 body. When shooting some birds in flight, I was next to a friend who had the same lens on his R3, so we swapped lenses and did a test. He shot both his lens, then mine, shooting in manual so the settings remained the same. Same light, same bird about one minute apart. 

Here are the two, side by side. The one on the left is my lens (which I think is soft) and the picture on the right is his lens. What do you think? (Zoomed in with Lightroom) 

[March411]

I believe Rodger has made a valid point after reviewing the images and believe that the challenges would remain the same regardless of RAW vs JPEG.

The results of the two different images could be a result of the focusing system being more accurate when you took the image using your friends lens. I believe that the second point Rodger made is more valid, the subject is less that 20% of of the full image. This will in most cases create softness. Several things can impact long range images and smaller in frame subjects such as atmospheric conditions (atmospheric haze), thin depth of field, vibration or movement is more impactful at greater distances and chromatic aberrations. 

Bench test your lens and find out.

[wq9nsc]

Severe cropping becomes more of an issue as ISO is increased. 

The attached is cropped from 17% of the sensor area of my 1DX III but conditions allowed for the capture to occur at ISO 320 with an EF 800 f5.6 @ 1/1250 f8 thus making severe cropping more viable.  The second photo has about the same crop percentage (18%) but was captured at ISO 100 using a 1DX III with a EF 200-400 f4 extender lens @ 1/1600.  The final shot is also a 17% crop with a 1DX III using an EF 800 f5.6 plus a 1.4X @ 1/1600 and ISO 500. 

I suspect that the bird captures in the original post could have been captured at a slower shutter speed resulting in lower ISO and higher IQ given the cropping.

Rodger

[Waddizzle]

“ Here are the two, side by side. The one on the left is my lens (which I think is soft) and the picture on the right is his lens. What do you think? (Zoomed in with Lightroom) “

You are zoomed in to over 250%.  Where is your locked AF point?  You can use the Canon DPP4 to view where your locked AF is located, too.  

A “one-off” shot like this is inconclusive, IMHO.  You are making the assumption that you should have a 100% keeper rate.  

I also suggest that you perform more controlled testing.  You do not need a second lens or a different camera, either.  Use your own gear, seeing how that is what you would be using.

[ebiggs1]

"A “one-off” shot like this is inconclusive, IMHO.  ... I also suggest that you perform more controlled testing."

No matter what troubleshooting guesses others have made or will make it is useless if you do not heed that advice and mine from above. You simply can not make a meaningful judgement from what your examples show from how you captured them.

This...

"I also suggest that you perform more controlled testing."