Did I possibly damage my lens? Olympus 12-40mm

About two weeks ago I was using my GH5 and Olympus 12-40mm f/2.8 PRO Lens and when I went to take the lens of the camera, I accidentally dropped it. It only fell onto grass which was soft and it got a bit muddy. On my initial inspection it didn't look like there was anything wrong with it, no craks or damage I could see, just a bit of mud.

I cleaned the lens and haven't used since until I upgraded to a Panasonic GH6. When I have tested it over the past few days, in video at least since Photoshop doesn't currently support GH6 RAW image files, the results I am getting are not that sharp and some looked a bit soft and I have tried various aperature settings and 4K All-I 10-bit 4:2:2 and 5.7K H.265 10-bit 4:2:0. I can't test ProRes yet until I get my CFExpress cards.

I had a look at the lens and noticed the lens element you can see from the back of the lens, moves back and fourth freely when I move the lens about in my hand. Is that normal or do I need to get it repaired?

The only other lens I have is an Olympus 60mm Macro so because of the focal length difference, I can't test it the same way as the 12-40 to see if the lens does have an issue or not.

DNature wrote:

I had a look at the lens and noticed the lens element you can see from the back of the lens, moves back and fourth freely when I move the lens about in my hand. Is that normal or do I need to get it repaired?

Yes, get it repaired.

The rear lens-element on my copy does not move.

cc99 wrote:

DNature wrote:

I had a look at the lens and noticed the lens element you can see from the back of the lens, moves back and fourth freely when I move the lens about in my hand. Is that normal or do I need to get it repaired?

Yes, get it repaired.

The rear lens-element on my copy does not move.

I checked mine too. My rear element is also screwed in tightly.

Are the three screws in the same ring as the electrical contacts tight? Seems like an odd place to be damaged.

Have you tried simply taking a picture with it, and another of it? Does AF lock? I'm sure the GH6 is fully capable of AFing a 12-40 and the 60 an excellent lens for photographing the rear of the 12-40. Post both pics.

Bassam Guy wrote:

cc99 wrote:

DNature wrote:

I had a look at the lens and noticed the lens element you can see from the back of the lens, moves back and fourth freely when I move the lens about in my hand. Is that normal or do I need to get it repaired?

Yes, get it repaired.

The rear lens-element on my copy does not move.

I checked mine too. My rear element is also screwed in tightly.

Are the three screws in the same ring as the electrical contacts tight? Seems like an odd place to be damaged.

Have you tried simply taking a picture with it, and another of it? Does AF lock? I'm sure the GH6 is fully capable of AFing a 12-40 and the 60 an excellent lens for photographing the rear of the 12-40. Post both pics.

I have contacted OM Digital Solutions about the lens but it does loom like it needs repaired.

I have tried using the AF button on the back of the camera and it wouldn't always lock focus and kept going out of focus. The lens contacts seem fine as do the screws. The issue is with the lens element inside the back of the lens, the one you can see inside the lens with the grey ring around it. It moves around.
The only image I have is of this screenshot of an unedited V-Log video 4K 10-bit 4:2:2 ALL-I and I had focused the lens properly and it just looks soft/ not properly in focus. This was at 40mm Pixel to Pixel. I tried f/4 5.6 and f/8 and not much difference.

The issue is with the lens element inside the back of the lens, the one you can see inside the lens with the grey ring around it. It moves around.

So, you don't mean the actual back-most element, but the lens element visible behind it, within the lens. That would be part of its focusing unit (marked '1' in the below image). I don't have the 12-40mm but there are several lenses in which the focusing unit floats freely about when the lens doesn't receive power from the camera. The 12-40mm may well be one of those, and in that case what you see would be perfectly normal.

MSC focusing unit in the 12-40mm f/2.8

The only image I have is of this screenshot of an unedited V-Log video 4K 10-bit 4:2:2 ALL-I and I had focused the lens properly and it just looks soft/ not properly in focus.

You can't judge focus accuracy from a single shot, let alone from a screenshot of a contrast-poor video still that has no particular subject.

What I would do: Put the camera on a tripod or table, use manual focus (using the magnifier function if possible), focus on a contrasty flat subject about 10 feet removed (e.g. a well-lit newspaper page hung on the wall) , use  the self-timer or remote trigger, electronic/silent shutter, use a short exposure time and lowish ISO. With all that, you will have eliminated most potential causes of unsharpness. 
When the test images are sharp, the lens as such is OK but it might still have problems auto-focusing. So, repeat the test and take a few shots in S-AF mode (single center AF point, de-focus the lens before each shot) and see how those turn out.