Sony F65 Highlight Bloom?

[Christopher Purdy]

Has anyone else noticed an unusual blooming in highlights and hotspots on the F65?

 

In general, I think the F65 is an incredible and sorely underused camera. I've just shot some over/under tests against an Alexa, and it was remarkable to me how well it holds its own. The Alexa might be giving me an extra stop in the highlights, but the resolution on the F65 is far more detailed than anything I've seen from a 4K bayer camera, and unlike its younger brother, the F5/55, that awful chroma noise is virtually nonexistant.

 

But I just can't seem to figure out what's causing this glowing effect. Swapping the lenses and clearing the internal filters didn't change anything, so it's either something in the optical sensor stack or crosstalk from clipped photosites. I'm wondering if it's specific to the unit I was testing, or if it's something other people have noticed as well...

 

 

 

[Mark Kenfield]

Chris, can you post comparison images from the tests that show where the F65 blooms and the Alexa doesn't? I can't say I've encountered blooming with any camera that seemed to be occurring on a sensor level, rather than as an optical artifact.

[Satsuki Murashige]

Has anyone else noticed an unusual blooming in highlights and hotspots on the F65?

 

I haven't noticed this, but then I usually want highlight halation with the F65 so I usually add diffusion. I'll see if I can find some clean frames when I get home tonite.

[Christopher Purdy]

Here's a link to a gallery of some stills from my tests. You can click and then click again to see the full res.

 

http://postimg.org/gallery/11h14e8i8/

They are labeled as Alexa and F65, rated at 400, 800, 1600ASA respectively, at normal exposure for those EIs. No other over or under exposure beyond rating the sensors differently.

 

I can upload some of the overexposed stills as well, but even in these you can see a glaring difference (no pun intended) especially in the 1600ASA frame where the slate catches a glint of the light source.

 

Again, since we could see this on the monitor during testing, lenses were swapped, and the internal clear filter was removed to try and get rid of the blooming, but neither of those things helped mitigate it.

 

The lamp was not panned directly at either camera, but at the ground in between both, and these tests were shot side-by-side simultaneously.

 

These are in Log C and SLog3, but the bloom is even more apparent in 709.

Edited February 4, 2016 by Christopher Purdy

[David Mullen ASC]

That's pretty unusual, I don't think that's normal for the F65. Maybe the OPLF got dirty...

[Satsuki Murashige]

Yeah, I think you've got a dirty OLPF or possibly some condensation issues in there. This is an F65 frame below with only ND filtration, scaled down from 4096x2160. You would expect to see halation on the bright exterior or the overhead fluorescent if your results were normal.

 

 

 

And just for reference, here's another angle from the same scene with a Hollywood Black Magic diffusion filter. This is the amount of halation you would expect to see with this filter.

 

[Christopher Purdy]

Thank you David and Satsuki, I think that clears up that it's definitely not normal for the camera, and is an issue with this particular unit's optical block. I'll talk to the tech about it and see if I can figure out what's going on.

[Ben Rowsell]

I've seen this on an F65 before. The DOP liked the way the camera/lens combo flared/bloomed in testing so we went with that package. Nobody thought too much about it until we got an additional 3rd party body in and it didn't flare in the same way.

 

The conclusion was that the original camera bodies had previously been used on a show that had very high levels of oil based smoke FX. Over time the air filters in the front of the camera had become clogged and allowed oil to pass onto the optical block and leave a film of residue over the glass in front of the sensor.

 

We left it for the rest of our shoot (as per DOPs request), but after the movie the optics were cleaned and filters replaced, and the image went back to "normal" I guess that the issue hadn't been picked up on the previous show as it had happened gradually over a period of time towards the end of the shoot.

 

Ben R

1AC

NZ

Edited February 5, 2016 by Ben Rowsell

[Alex Leung]

I'm currently near the end of a shoot with 2x Sony F65s and we have experienced this exact problem. We have been using oil-based SPFX atmosphere in our sets heavily.

 

We've sent the cameras back to the local Sony Service Centre twice to have the OLPF cleaned in each camera. The blue-ish tinted filter in front of the mechanical rotary shutter is not the OLPF. It is actually a Band Pass Filter. Cleaning that did not solve our blooming issue. The OLPF actually sits between the mechanical rotary shutter and the sensor. As a result, you need to take apart the entire optical head block of the camera to service/clean it. This is absolutely not advisable to do in the field without proper technicians. The cameras need to be sent back to Sony and cleaned in a dust-free clean room.

 

I've been talking to a senior service engineer for the HD and Digital Cinematography Camera Systems Department at Sony in New Jersey. He apparently has cleaned lots of F65s that come out of rental houses in LA, especially after they have been used in dusty and sandy areas like New Mexico. And he says he finds mostly dust on the OLPF.

 

Based on my experience so far, it appears the sensor area is not entirely sealed to the exterior environment. There are two air filters below the lens mount (see attached picture) where the air intake is. Changing them out might help.

 

But my opinion is that if those air filters can't even filter out fine dust/sand particles, there is no hope of it filtering out even finer contaminants like oil-based SPFX atmospheric haze.

 

As far as I understand it, Sony has significantly reduced the amount of support they provide for this camera. Finding parts (such as the air filters mentioned above) is difficult. I have a colleague that finished a shoot recently with this camera and had to bring along a technician to clean the sensors every night. They even tried to get support from Sony Japan with limited success.

 

I feel cinematographers and camera assistants need to know this is a problem for this camera. Even after our second sensor clean, the problem started re-occurring after 3 shoot days.

[Robin R Probyn]

Interesting.. Sony dont seem to very good at sealing their sensor,s.. both the F5/55 have a tricky quirk.. if the rubber EVF socket cover gets pulled off.. it opens up a small hole that is used to "anchor" the now missing rubber flap..to the camera body.. this hole is directly open to the sensor !.. and light/dust etc will get in.. !!! just to make that whole EVF socket debacle even worse !

Presumably the Fs7 has corrected it as the EVF is in a much better place..

[Aapo Lettinen]

is it possible to arrange some sort of external HEPA filter assembly to the air intake to prevent particle buildup in very dusty/hazy atmosphere?

 

for example a vacuum cleaner tube with a 40mm HEPA gas mask filter attached to the other end ;)

[Alex Leung]

is it possible to arrange some sort of external HEPA filter assembly to the air intake to prevent particle buildup in very dusty/hazy atmosphere?

 

for example a vacuum cleaner tube with a 40mm HEPA gas mask filter attached to the other end ;)

I know HEPA filters can filter out dust but not sure about suspended oil-based SPFX atmosphere. Also, by adding more filtration to the air-intake, you risk overheating the camera. The camera's fan already automatically kicks to Hi once it gets too hot during really long takes.

[Aapo Lettinen]

I know HEPA filters can filter out dust but not sure about suspended oil-based SPFX atmosphere. Also, by adding more filtration to the air-intake, you risk overheating the camera. The camera's fan already automatically kicks to Hi once it gets too hot during really long takes.

 

they should work for any particle based contaminant including liquids but it is of course possible to enhance the effect with for example activated charcoal if needed. is that the main air intake for the camera and how large airflow it is generally?

 

a blower unit like the ones used by industrial painters, asbestos workers, etc. could be used with the filters, so that the camera fan does not need to work harder with them. the filters cost a bit of course (I believe one would need from 3 to 6 gas mask filters for this depending on the airflow) but it would definitely be much less per day than sending the camera to the Service Centre every week, especially with the daily budgets in the productions the F65 is generally used in

[Zsigmond James]

 

they should work for any particle based contaminant including liquids but it is of course possible to enhance the effect with for example activated charcoal if needed. is that the main air intake for the camera and how large airflow it is generally?

 

a blower unit like the ones used by industrial painters, asbestos workers, etc. could be used with the filters, so that the camera fan does not need to work harder with them. the filters cost a bit of course (I believe one would need from 3 to 6 gas mask filters for this depending on the airflow) but it would definitely be much less per day than sending the camera to the Service Centre every week, especially with the daily budgets in the productions the F65 is generally used in

 

I'm currently near the end of a shoot with 2x Sony F65s and we have experienced this exact problem. We have been using oil-based SPFX atmosphere in our sets heavily.

 

We've sent the cameras back to the local Sony Service Centre twice to have the OLPF cleaned in each camera. The blue-ish tinted filter in front of the mechanical rotary shutter is not the OLPF. It is actually a Band Pass Filter. Cleaning that did not solve our blooming issue. The OLPF actually sits between the mechanical rotary shutter and the sensor. As a result, you need to take apart the entire optical head block of the camera to service/clean it. This is absolutely not advisable to do in the field without proper technicians. The cameras need to be sent back to Sony and cleaned in a dust-free clean room.

 

I've been talking to a senior service engineer for the HD and Digital Cinematography Camera Systems Department at Sony in New Jersey. He apparently has cleaned lots of F65s that come out of rental houses in LA, especially after they have been used in dusty and sandy areas like New Mexico. And he says he finds mostly dust on the OLPF.

 

Based on my experience so far, it appears the sensor area is not entirely sealed to the exterior environment. There are two air filters below the lens mount (see attached picture) where the air intake is. Changing them out might help.

 

But my opinion is that if those air filters can't even filter out fine dust/sand particles, there is no hope of it filtering out even finer contaminants like oil-based SPFX atmospheric haze.

 

As far as I understand it, Sony has significantly reduced the amount of support they provide for this camera. Finding parts (such as the air filters mentioned above) is difficult. I have a colleague that finished a shoot recently with this camera and had to bring along a technician to clean the sensors every night. They even tried to get support from Sony Japan with limited success.

 

I feel cinematographers and camera assistants need to know this is a problem for this camera. Even after our second sensor clean, the problem started re-occurring after 3 shoot days.

 

Hi Alex,

 

Where did you source that diagram for the F65 Air Filter assembly? Do you by chance have a repair manual for the camera? The shutter on my camera has gone haywire again after having already been replaced last year, would love to see a diagram for accessing it. Another $16,000 to the service center for repair is out of the question. I have access to a new rotary shutter - just not sure how to install it.

[Alex Leung]

We had a chance to take a look at the air filters mentioned above tonight. It appears the slots where the air filters sit in don't fit the filters snuggly. There are obvious gaps between the filters and the slots. So any large particles can get through without problems.

 

And no, I don't have a service manual for the F65. I got the diagram from the engineer I've been talking to.