GH4 Water Damage on 14-140 lens?

[roxics]

I got back from my last shoot and put my video on the big screen to notice several of my outside wide shots have two dark grey spots on them. One in the top center and one in the center right of the frame.

Video example

It seems to only appear when the lens was at its widest focal length and stopped down between f16-f22.
The only thing I can think is that it's water damage on an inside lens element from the shoot before where I was in the pouring rain.
I wonder if there is a simple cheap way to fix this. Probably ND filters and not stopping down so much right?
The NDs I have aren't very good and cast a blue haze over the image, so I try to avoid using them, hence stopping down. Even though that's not a great idea either, it works in a pinch, or at least it did until this issue.

 

[Cary Knoop]

I would not shoot with f16-f22 on a MFT camera, you are in serious diffraction territory with those apertures.

 

[icarusfilm]

With long range zoom lenses like that you are good at f8 thats where the lens will perform at its best through out the range.
You will get better results with an ND if you do a proper white balance even if the NDs are not stellar it will it still wield better results than shooting at f16-22.

I got back from my last shoot and put my video on the big screen to notice several of my outside wide shots have two dark grey spots on them. One in the top center and one in the center right of the frame.

Video example

It seems to only appear when the lens was at its widest focal length and stopped down between f16-f22.
The only thing I can think is that it's water damage on an inside lens element from the shoot before where I was in the pouring rain.
I wonder if there is a simple cheap way to fix this. Probably ND filters and not stopping down so much right?
The NDs I have aren't very good and cast a blue haze over the image, so I try to avoid using them, hence stopping down. Even though that's not a great idea either, it works in a pinch, or at least it did until this issue.

 

[Ned Kelly]

roxics, Looks like your sensor needs a clean.

 

[estarkey7]

Looks like dust in the lens. I have the same issue with a Panasonic 42.5 f/1.7 lens. Wide open, it's great, stop down to f/8, and it's visible. Go to f/16 and it's the subject it's so prominent!

 

[Shirozina]

It's dust spots on the lens or most likley the sensor cover - shooting at these small apertures creates huge depth of field and depth of focus so anything near the lens or nr the sensor will start to be rendered. Get some good quality ND filters with a multi coating so they won't flare and you can shoot at wider apertures ( you will get more resolution as well)

 

[Bern Caughey]

As others pointed out the spots are most likely simply ‘dust’ on the sensor, &/or lens. Yours appear to be extremely small bits of ‘dust’ as I’ve seen much larger spots on footage before. I typically shoot m4/3 lenses no deeper than f/8, & usually wider, but sometimes close down all the way for a Sunburst effect, & suddenly realize my system needs a good cleaning.

Due to the short focal flange distance of m4/3, & E-mount, dust on the rear of the lens, or SpeedBooster, is much more of an issue than with systems with longer focal flange distances, such a EF, so be sure to clean the backside of the lens thoughly too.

One way to test for dust is to shoot a white wall, or cloud-less sky. Stop down the lens to it’s minimum aperture, throw the image completely out-of-focus, & expose to somewhere around Middle-Grey, then check the results at high magnification. With a hybrid camera I’ll shoot a still instead of footage as it’s easy to check right on the camera’s EVF/LCD. With a zoom use the widest focal length, & test all the lenses you’ll use on the project.

And don’t forget to clean your filters too.

If you suspect you’ll be shooting with deep f-stops it’s good practice to carry lens wipes & fluid, a lens pen, a sensor brush, & a bulb blower.

 

[roxics]

Thanks for the feedback everyone. Guess I'll be investing in new NDs to keep my lens open more. Possibly cheaper than a new lens as well. Do you have any NDs you can recommend for this lens? 62mm thread size.

 

[markoconnell]

I've got Hoya variable NDs on my frequently used lenses and Schneider-Kreuznach. The Schneider has hard stops at each end which I like, the Hoyas just spin. For sensor cleaning VSGO swabs from B&H.

 

[Bern Caughey]

Wet Cleaning with a Sensor Swab is usually unnecessary, & I suggest starting with a good bulb blower, followed up by a wipe down with a quality Sensor Brush, preferably an Arctic Butterfly from Visible Dust.

If the Sensor Brush cannot thoroughly clean the sensor then it’s time for a Wet Cleaning. The OP is using a GH4 so should be able to perform a Wet Clean himself, but if he was using a camera with IBIS it be best to have the camera cleaned professionally.

 

[markoconnell]

I've cleaned the sensor on my GH5 with no problems. fwiw

 

[Bruce Foreman]

Wet Cleaning with a Sensor Swab is usually unnecessary, & I suggest starting with a good bulb blower, followed up by a wipe down with a quality Sensor Brush, preferably an Arctic Butterfly from Visible Dust.

If the Sensor Brush cannot thoroughly clean the sensor then it’s time for a Wet Cleaning. The OP is using a GH4 so should be able to perform a Wet Clean himself, but if he was using a camera with IBIS it be best to have the camera cleaned professionally.

The trick to cleaning cameras with "sensor shift" (IBIS) is to turn the camera ON and remove the lens. With the camera ON the sensor is held in place so you can do a gentle wet cleaning. Peter Gregg markets his improved designed "Sensor Sweep" which I think is a better way to go than Sensor Swabs and Eclipse (or other cleaning fluid). On IBIS this is from his website:

"Cameras that have sensor that move around inside the body to accomplish stabilization can be cleaned with the SensorSweep system. The sensor won't stay still with the camera OFF and you can damage something accidentally (we are not responsible, pay attention - just turn the camera ON and then remove the lens. The sensor will lock into place. Then gently clean the sensor. On some cameras the sensor WILL be charged, but this is a non issue. Camera reps have stated this over and over, and this is how they clean the sensors at their service centers."

www.petergregg.com