Pixel Refresh & Sensor clean - stops banding?

Blackout

Blackout

Veteran
Now I know what sensor clean is supposed to do.. send a charge so that micro particles of whatever are repelled. I am not sure exactly what pixel refresh does but I like the sound of it.

I had a pretty much banding free camera, and my b cam banded a bit. All of a sudden my banding free 'a' camera started showing the dreaded blue/red line band streaks and I freaked. I did a pixel refresh and sensor clean 5 times if a row and then viola... all the banding noise was gone, even shooting on the kit lens at iso 1250, which is usually a big noisy mess and a no no!

http://www.youtube.com/watch?v=qbVeZEX5zwo&fmt=37

Only lit bv a 60 wat bulb, iso 1250... no banding and very little noise.

original shows NO noise or banding... I uploaded the actual original .mts file to youtube and it is now my consensus that it does NOT handle the native 50mbit hacked gh1 files as well as it handles the 20 mbit sony mp4 files.

Anyway does anyone know exactly what 'pixel refresh' does as opposed to sensor clean?

I suggest anyone with the dreaded "banding" and "streaks" issues try what I did and do 5 of them in a row.

Don't know if this causes any wear and tear on the camera parts or not, but it completely removed my banding, streaks, and noise with high iso shoots.

- Blackout
 
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I just figured it refreshed the LCD in case stuck pixels occurred or something. I didn't get an English version of the manual with my camera though, so I haven't been able to check.
 
Oh I thought it had something to do with the pixels of the sensor chip. I am not sure where the heck my manual is at. In any case... it went from lots of banding, especially on the very dark right side of the screen - to none.
 
From the manual:


[PIXEL REFRESH] It will perform optimization of imaging device and image processing.


• Imaging device and image processing is optimized when the camera is purchased, and it needs to be optimized annually after the purchase.​


• Turn the camera off and on after the pixels are corrected.​



[SENSOR CLEANING] Dust reduction to blow off the debris and dust that have affixed to the front of the imaging device is performed.​



• Dust reduction function will operate automatically when the camera is turned on, but you can use this function when you see dust. (P167)​




If this camera is like most SLR's, the sensor is probably vibrated with an ultrasonic transducer to shake dust free.​


 
Well.. then the pixel refresh is doing something good.. cause it got rid of the banding.... all though the manual says do it annually and I have done it like 20 times in 6 months.
 
Axthor said:
[SENSOR CLEANING] Dust reduction to blow off the debris and dust that have affixed to the front of the imaging device is performed.


• Dust reduction function will operate automatically when the camera is turned on, but you can use this function when you see dust. (P167)​




If this camera is like most SLR's, the sensor is probably vibrated with an ultrasonic transducer to shake dust free.​
Click to expand...

Is it advisable to leave the sensor cap off during this?
 
The manual says that pixel refresh will perform optimisation of the imaging device and image processing...
It also says it needs to be optimised annually after purchase.

oops you beat me...
 
I have a feeling that a lot of the issues folks were having a year ago with this camera was them being shipped with dirty sensors. I could be wrong. But it seems to make a little sense especially knowing that not everyone was experiencing these issues.
 
I would definitely NOT do a sensor clean with the lens off. I would have the lens and cap ON.
Do it a few times.. and do the pixel refresh a few times... and check again... my banding completely disappeared.
 
Yep, I just tried the same. Didn't seem to make any difference at all. I watched all of your GH1 videos, and seeing them was one of the reasons I went with the GH1 over the T2i or 7d.. everything else about the camera I love.. but its useless to me if I cannot get around this banding.
 
Blackout said:
Now I know what sensor clean is supposed to do.. send a charge so that micro particles of whatever are repelled. I am not sure exactly what pixel refresh does but I like the sound of it.
Click to expand...


'Pixel Refresh' is Olympus' (and therefore Panasonic's) description of 'pixel mapping'

Pixel mapping is performed by all camera makers to find and correct 'dead' or 'hot' pixels.

A dead pixel is permanently switched off, and is black. A hot pixel is one that is stuck open - resulting in bright specks.

Pixel mapping locates the affected pixels, remembers where they are, and then interpolates the data that they should have recorded by using data from adjacent pixels.

With other cameras you have to send it in to the manufacturer to have the pixel mapping software run on the sensor. Only Olympus have the facility in-camera - and have done so for as long as I can remember, certainly as far back as the E-10

It's a brilliant addition to their cameras - yet they they barely make mention of it..Odd.

Whether it helps banding, I don't know - but I doubt it.
 
Hmmm. Then I just got lucky I guess. It definitely appeared to make a difference to me. Again, look at the dark spots of my fish video. This is 1250 iso with kit lens only a 60 watt bulb is on. Normally, I didn't get banding but got lots of weird noise. This is pretty clean and NO banding issues whatsoever:

http://www.youtube.com/watch?v=qbVeZEX5zwo

I have a shot before I did sensor refreshes and cleans and it was noisy and had the streaks you speak of.

It's even noise free in my uncompressed version.. youtube added some strangeness.. it doesn't like the GH1 mts files native... it far prefers the vegas flavor of mp4.

20mbit mp4 out of vegas to youtube looks ALMOST identical unless your face is right up to the screen.
 
I've been testing all day, and everything I've shot today has had banding in it.. the only thing that didn't have banding didn't make sense since it was in the same room with the same lighting as something else I shot that DID have banding.... doh.. I'm almost to the point of returning it and getting a T2i or 7d instead.
 
GH1 works great in contrasts of light. (no banding)
Sometimes, no matter how much light gets into, but this contrast occurs.
In the fishbowl, you have enough contrast of light. Despite using a 60W light bulb.
So, you will not see bands there.


Note: (Sorry for my English, I am using a translator, I hope you understand.!)

For now, the burnin process, refreshment of pixels and sensor cleaning, do not seem to work!

Cheers,
Hernán.
 
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