I've been using these two cameras for a number of years now, first started with the 900M, needed another then chose the X900M. I do alot of performing arts type recording, where the cameras record (1080 60p) continuously, for an hour, takes a intermission, then on again for another 40 minutes or so. I do most everything in manual mode, since the light conditions always change, I'm usually recording from about 70 feet away, so manual focus is a must (WB=1, Iris 9dB). Never use a digital zoom. I set my focus just prior to the event, using crisp bright light, using the blue assist feature to help me adjust things just right. For both cameras, everything starts off perfect. I'm finding the X900M focus will drift, the picture will lose it sharpness after about 10 minutes or so. It gradually gets worse. I did a test in the house with both cameras using type on a poster, and verified it there too. Few weeks ago I recorded an event where I did not need the manual focus, because I was guaranteed nice even bright light, meaning the focus would not hunt for facial features, and everything came out crisp. Anyone else experience this. Suggestions? This is a big set back for me. Busy time of year and I have many recording to do. Is it heat generated by the camera? These types of events there is no good time to adjust focus, lots of choreography going on, often its like trying to capture a hockey game. Truly, the microphones the performers use do not change location, they are mounted on a pedestal, and each singer comes back to them, that is where I initially focus, and over time, that is where I lose focus on it.

Interesting. Heat (expansion) could be a reason. I assume the locations are vibration free?

I have a TM900 - still going strong - and I know on mine that the lens ring on the front is nice and stiff/damped in action. Wondering if yours is perhaps very loose after years of use? If so, maybe try putting a bit of electricians insulation tape on it (to accurately fix its position to the body once you have nailed focus) and test that. Long shot I know but since it still seems to work fine in AF mode that would be my suggestion.

Thanks for that Andy, funny thing is, the problem camera, the X900M, the focus ring requires more torque to turn it than the TM900.

Hi Greg,

If it was a heat effect I would expect the camera to eventually reach a more or less constant temperature. What I would be trying is refocusing when I guessed the temperature was stable and observing how well focus held for the next hour or two with the camera still running.

You could also let the camera cool down and see if focus returns to your original setting.

If the heat is changing the lens to sensor distance the greatest effects would be at the WIDE ANGLE end of the zoom range. Is this what you are finding and is the shift in focus towards the camera?

.

Alastair-
I'm going to try more testing today to evaluate this problem, and how to overcome it.
Here is my typical setup for recording.
The X900M is my wide angle camera to capture the whole stage, my go to camera. (Focus issue)
The TM900 is my in close, pan, camera.
I then sync these two cameras on the editing timeline, with some acceptable results.

I understand your comment regarding the greatest effect at the WIDE ANGLE end of the zoom range. But can you clarify, or restate "Is this what you are finding and is the shift in focus towards the camera?" .That confuses me.

Hi Greg,

If the the effect is due to heat expanding various components one could expect and increase in the distance of the lens to the sensor. This would show up as the camera shifting focus to a closer distance than you set i.e. in your case the the camera would refocus to less than 70 feet. The effect would be greater at wide angles.

Today is the perfect day for a test. It is 25F outside right now. I'll set up outside, let it run for same duration as my last test.

One other thing to perhaps check is if the fan on the camera is still working??? It could have packed in a while ago (it's a mechanical part after all), and then that perhaps might explain why you're seeing a focus shift problem (if it is indeed due to heat). Does the camera get warmer than the other one?

So when doing your further testing, see if you can hear the fan when it's warmed up (I know that my TM900 is whisper quiet - but it's just possible to hear it after the cam has been on for a while if you put your ear very close to the vent grill).

Fan works, I can verify with a flashlight close to the protective foam.

Took the cameras outside in the cold, Quite brighter, so my iris settings were different. Manual focus. Ran the camera longer than the previous test, night and day difference. (25F outside) Camera is very crisp in detail, start to finish. Next test, indoors, auto focus.

Did some more testing yesterday, this time in the environment of the performing arts building. It was a rehearsal, where they were still adjusting lighting, everything was stop and go. A real worse case condition, but ideal situation where I could test the auto focus feature. Even during the poorest lighting, as long as I was zoomed in close enough to obtain facial feature recognition, the focus of the camera was spot on. Ran the camera for more than an hour, clarity was perfect. It was these same conditions when using manual focus the camera would drift focus, and have poor image quality.Performance is tonight, looks like I just found my new setup procedure.

Results of my new recording procedure. Camera on stage right was not my Panasonic, just my friend who wanted to contribute.
GPS Choir performing O Holy Night on Vimeo