what watching the 50" HDTV at 1m distance taught me
 

I have recently installed the Panasonic HDTV, 50" monster over my editing seat (and the regular 24" LCD, also full HD). Using Vegas or Edius, I am now able to monitor my EX1's blown-up picture with virtually pixel-to-pixel precision. And I can tell you the quality of images this machine produces is absolutely and ultimately marvellous! In fact it's so good I can hardly see the need for Flash XDR's 50 or 100Mbps, 4:2:2 any more:)

Did I ever say I liked the picture quality from my old V1E better? Really? Well, I am taking it back now!

However, this close inspection also let me find that even though I never noticed it before using the 24" HD LCD, I do have an ever so slight back focus problem. My FW version is 1.03; what would you do mates: send it to Sony for upgrade (Gosh, I was counting on the ability of doing it myself); or try the "Gerald procedure" first? I have some important projects soon, so - considering the Prime Support servicing turn-around might take long, and doing it myself might render it worse instead of perfect - this is quite a dilemma.

Any new facts that might help make my mind up?

Piotr,
I had my camera at Sony Primesupport 3 times and they could not fix the backfocus issue. It always took at least one week turnaround - the first time it was in for 3 weeks...
They even could not fix it with the new firmware. I guess being in Europe you will have to send it to the same service station I had to. There are numerous reports from european owners that they got it back even worse.
I would try the repair procedure by yourself. It´s almost impossible to make it worse if you follow my procedure. I once tried to make the backfocus worse for test purposes and it wasn`t easy...
I successfully "repaired" Sony´s loaner camera with FW 1.03, as did many others.
Go for it! If anything goes wrong - you can still send it in. You can´t loose anything ;-)

cu,
Gerald

Thanks Gerald,

I'll probably do as you say. After all, there have been no reports on any important changes that the 1.05 fw brings over the 1.03...

Being lazy though, I'll probably just display the Siemens star on my 50" plasma, instead of printing 12 A4 cards, as you did. As far as I know, this is how Adam Wilt did his adjustment. My only reservation is related to the fact the the plasma is tilted down some 15 deg, so I'll have to take special care in order for my EX1 to look square at it.

Do you think it'd work?

Never tried it with a screen - but it worked for Adam.
Make sure that no other things are in the view of the camera which could irritate the automatic setup procedure.
I think the most important thing for the software is that it is a high contrast image with sharp edges it can focus on.
I think Adam did the setup in a completely darkened room with only the light of the monitor.

Good luck - let us know!

This is what I'm planning, too - dark room with just the plasma shining...

I'll certailny report back on the results!

I used the 'Gerald' 12 x A4 system and it worked pefectly. It was re assuring to see the auto system lock on to the wide shot and focussed the charts. I think the 1 metre test is interesting as I have a 50" Pioneer plasma and an 730s HDCAM with £10k lenses set to BBC lineup. The EX1 is looking very good when comparing the two but wide angles do highlight that you do get something extra for your HDCAM money!

Piotr:

Please explain how you are doing this test. When I tried I was unable to see if focus was retained zooming out as the subject focused on gets smaller I can no longer see just how good the focus was.

Did you focus on the screen so the camera was loking at itself? Did you use Peaking? Expanded focus?

Mike

I tried it on a 50" plasma a while back with a Siemens Star but it was hard to do for all three ND settings. I cannot remember exactly what happened, but I think it had a hard time figuring out focus from the screen and it ended up getting stuck halfway through the adjustment and essentially crashed. I had to turn off the camera and turn it on again (which freaked me out that it was mid adjustment, although nothing bad happened). Anyways, maybe it will work for you.

B

The tech guy at our local Sony repair facility told me that the latest firmware upgrade v.1.0.5 is supposed to fix the back focus issue when using the in-camera ND filters. This means that the back focus routine should be done with no ND filter engaged and when finished the new firmware will compensate for the ND settings to keep the back focus accurate.

- Don

I'm not a big proponent of using a display as a BF target, although I'm not saying it won't work. Using a dark room with essentially a backlit target can be effective when an "uncluttered" wideangle view is not available to prevent ambiguous autofocus.

Basically when you display a siemens star target on a display, you're testing that displays resolution. This is also the case when you print a chart, only you're testing the printer. However a good laserprinter has a much higher resolution then your screen.

It is worse when you use scanned charts and print those, or use inkjet printers (with bad paper). These will, in my humble opinion, not produce adequate target material.

A low quality/low resolution target will require you to put it further away from the lens to 'compensate' for the poor representation. Conversely you can shoot a good quality target from closer up.

I've attached two screenshots, one of a target I Googled, another of a 'digital original' both at 6400% (max. Acrobat zoom). You can clearly see the difference between a scanned copy and an original.

If you use a good quality target, you should be able to put that 2-3m away from the lens and get good results. You can test if the autofocus has trouble focussing on the target by using PUSH AF (in AF manual mode) when wide. If it focuses ok, it will do ok in the BF adustment.

You can use the same setup to check for BF problems. If you can attach a big(ger) high-res monitor to the camera output that would be a boon. Best to check focus at full res. Same setup used for manual BF adjustment (not on the EX1 as it has none).

Using a printingpress properly printed original has my preference, but I've made a few derivative originals (not scanned) I print off on my 1200dpi laser printer up to A3 with good result.

George/

I agree. A decent photo printer (epson R2400,etc.) has an effective resolution of 360 pixels per inch. A 50" 1920x1080 plasma still only has as many pixels as a 24" 1920x1080 display, they're just larger. A 50" display is roughly 45" in the horizontal direction, giving you a resolution of 42.667 ppi. Less than 1/6th of a chart printed on a home photo printer. For black and white graphics and text, a decent laser printer will resolve approximately 600ppi. The Putora sharpness indicator is my personal favorite, which uses a very high resolution pattern specifically designed to cause interference patterns on a digital image making it VERY easy to see focus.

Thanks for sharing your thoughts George.

You made an interesting point about verifying using "push" auto focus before running the test.

Also, having said that, I wonder if it may be smart to put the camera in 1080 60i (or PAL 50i) mode before performing the BF calibration.

Auto focus work a lot better in interlace mode since the sensor is updated twice as fast.

I agree about the printers, monitors and such, but I don't think an autofocus routine (and hence the EX1 backfocus routine) really needs a good Siemens chart to do its thing.

The Siemens "focus bullet" chart is great for the human eye to see perfect focus (especially in an optical system) because it "snaps" into focus nicely. But does the EX1, which looks for contrasty edges, really need this? The very sharpest parts of the Siemens chart occupy such a small area of the frame that I doubt the camera even acknowledges them for its focus routine (especially at full wide at 3 meters, A4 sized chart).

When I first got the instructions (from a Sony dealer in Canada) for doing the Auto FB adjustment, no mention was specifically made of a Siemens chart - just a backfocus chart of some undefined sort (perhaps Sony has a proprietary one?). Anyway, a large chart with smaller features at the center and larger features at the edges would seem to be the best thing. A room sized Siemens chart might fit the bill.

I haven't tried this, but I bet some crisp black tape on a white background would work just as well or better than the Siemens focus bullet. A clean tape edge has a very high "resolution" (the sharp transition between black and white) as far as autofocus is concerned. For my next Auto FB, I'll put a focus bullet in the middle and some larger, crisp black features around it.

And I'm sure a plasma will work fine as well. Regardless of its resolution for displaying a Siemens chart, there's probably enough there for the camera to focus on - the pixels themselves in closeup and the edges of the screen at full wide.

Hi Eric,

True, I've asked myself the same questions (and you're probably right). But I don't know the inner workings of the FB ajust function. Adam Wilt was adamant about using a siemens star target and I believe it is just good practice. For all I know it detects interferance from the chart.

Somewhere there exisits a Sony directive on how the FB Adjust rig/setup needs to be. I'd love to have that clarity.

Until then I just stick to what I know to work, regardless of camera and lens.

George/

P.S. Steven, as the 'scene' is static I don't think the mode matters and the routine may just override anything anyways.

That's true Eric, the auto FB doesn't neccesarily benefit from the added resolution. I've had very good luck doing the adjustment off of a piece of letterhead with printed text on it taped to a blank wall. All that the autofocus does is look for edge contrast, and I'm guessing because of the nature of the CMOS sensors it only looks in the horizontal direction (just like the Peaking function).

I don't know if it would actually work with the auto function, but this is the chart we normally use to judge sharpness:http://www.ascmag.com/store/product....cat=333&page=1

I think what Sony is using must be something like the Digiprime backfocus tool. it is essentially a backlit siemens star behind an optical element. It works very well.

I was thinking this, too - and it makes me wonder if the Siemens star (or the chart you linked to) with contrasty edges radiating in all directions, might actually make the FB adjustment less accurate. In any case, I doubt that the multi-angular image is helpful at all, except to us humans. Might be worth trying some vertical black tape lines on the wall.

It would be great to see the exact technique that Sony recommends (will there ever be a service manual published for this camera?), though if it's the same technique their service department has been using on our cameras, perhaps it's not all that effective...

I'm pretty sure they use something not unlike the zeiss digiprime back focus tube. It was once described by a sony tech that they need a jig to make the adjustment, and this would be the easiest and most consistent way to do it.

-Sean

For me, Gerald's method improved my backfocus with ND1 filter on dramatically. So I'll take the chance in this thread to say: thank you Gerald (and others who have contributed!)
I have an important shoot, and I would not be able to send my camera back to Sony now.

The backfocus adjustement was really easy, and I'm a real noob at these things, but it worked. I have an even older firmware: 1.02.

Just to update you that I decided to go on with the adjustment (using the plasma displaying the Siemens star chart), and it worked.

Not saing it's perfectly sharp in all ND positions, but it's close.

Will have to do until the firmware update (whenever it happens).

Thanks Gerald for making us less scared off by the procedure involved!

After very careful examination (using my new 50" plasma - the 24" LCD I used before was simply too small!), I must admit that my adjustment has NOT been quite successful, after all :(

Before, the ND2 setting was the softest. Now, it's almost fine; the ND1 is tad sharp, but unfortunately ND off got worse. Much worse, I am afraid.

Before another attempt, I'd like to ask those who fully succeded to tell me:

- did you engage the ND filters in any special sequence?
- did you leave the back focus menu for changing ND?
- after engaging a given ND setting, did you zoom in fully and focussed to your chart before executing the adjustment procedure?
- do you think I should repeat it for all 3 ND settings, or just the one that I really need to improve (ND off)?
- any other consideration that I didn't mention?

Thanks in advance!

I´m sorry to hear that!

I started with ND2 and worked down to ND OFF
No I didn´t

Yes I did!

Yes I would do that.

Thanks Gerald,

I don't quite get your last response - is it that you would repeat the procedure for all three, or just the one offending ND setting?

I wouldn't like to spoil the other two!

Piotr,i did the same as Gerald did in the above post.
Nd off the ND1 then ND 2 though.

Paul.

Ups, sorry!
I would do it for all three once again.
I did it a couple of times as well.

Hope it works for you.

regards,
Gerald

Thanks Gerald!

One more question to all dealing with the back focus problem/adjustment:

The usual way of checking the back focus is of course zooming in-focussing-zooming out and checking the focus. As I said, after my first adjustment it's now OK with ND 1 or 2 on, but not with ND off.

However, I am observing another thing which I am not sure about: when I am in focus having say ND2 on, and switch to ND1, I'm loosing the focus slightly, and have to re-focus (the same can happen when going e.g. from ND off to ND1/ND2, etc.) Now: is this normal, or is it another way of back focus manifesting itself?

I haven't tested it thoroughly enough to unambiguously tell wheter this is due to the DOF change due to the aperture change at ND filter switching, but I guess it is possible... Any opinions?

If you are making the stop compensation Piotr, you should gain more depth when going from ND 2 to ND1. It could easily be that the camera is now compensating for each filter independently, but not matching to each other. If you put the camera on a tripod pointing at something like a siemens star at a specific distance (doesn't really matter what) and measure the distance from the witness mark on the side of the body, do the focus marks in full manual mode match that? If they are significantly off, that is a good indication of a back focus problem.

-Sean

Sean,

Roughly speaking, the distances do match. However, this is not a conclusive indicator, as every tenth of a millimeter matters, and my measurements are really just approximations!

Also, I'm aware that opening up the iris to compensate for ND decreases, and closing down - increases DOF. The examples I have given of changing ND's and loosing focus are not based on "scientific" observations; I just want to know if everybody else can sometimes observe loosing focus when in Auto Iris mode and changing ND filters...

The thing is that while this could be explained without necessarily blaming back focus, I didn't experience it with my previous camera (the V1E) - but than agian, it had much deeper DOF being 1/4".

Taping out the lens doesn't have to be accurate to the millimeter, since the marks on the lens aren't that precise anyway. As long as the lens doesn't say 15 feet instead of 3, there isn't a big problem. I've never noticed losing focus while switching from a heavier ND to a lighter one, only the other way around as the DOF shrinks. It could easily be a software problem that is solved by the new firmware. In theory, the ND filters should be the same thickness, in which case they wouldn't affect the back focus, but perhaps the calibration is off for one of them, or the filters are slightly different. At this point I'd believe either one.

-Sean

Unfortunately, I am loosing some (long distance) focus when in full wide, the ND is switched from 1 to off - which of course denies the DOF change explanation.

Whether this is a software problem, I really don't know - I will be repeating the back focus adjustment procedure. I am not optimisticc however, as there is no apparent logic behind this behaviour.

SONY, please give us some white paper explanation about it - what is adjustable by the procedure in the menu, and what needs the firmware update!

One thing that obviously cannot be fixed by a fw update is this stupid ND switch,, which either stick half-way, or goes by the middle (ND1) postion to easily...

Who has read the procedure for backfocus adjustment for the Z7U? (Hint)

George/

How do you mean - anything we should know?

Please don't make me waiting :)

I just googled it,
It's got automatic backfocus adjustment !!

Maybe the same as firmware V1.05 for the EX1,ie automatically compensating for switching between ND filters.

Paul.

I too had back focus issues with the EX1. I performed the in-camera back focus routines (using single / multiple charts). I also did Gerald's excellent sounding procedure (adjust using each ND setting). I even tried adjusting using a high contrast brick wall (suggested elsewhere).

All to no avail.

I observed sharp focus at full tele - NOT at the wide setting (very soft). Also, it seemed that sharp focus would remain only for the last adjusted ND setting. It would loose some focus when switching modes - right after performing adjustment on the other setting! Also, the cam exhibited discernible lens vignetting (didn't exist prior to back focus adj).

So after being on the fence since getting cam in January (sn#102019 w/firmware 1.03), I frustratingly sent it back to Sony. I wrote a detailed letter highlighting these issues with this cam. Along with other notable issues I'd been dealing with, including:

-Iris ring locked on me twice in full manual (had to restart cam)
-Battery (BP-U30) draining when not in use (battery left on/cam is OFF)
-Faded lettering near the SEL/SET dial
-SEL/SET dial knob frequently not moving in expected direction
-Audio issues when using my Sennheisser K6 shotgun mic

After 1 1/2 wks - I have spoken to the engineer working on my cam. I thought I'd share some feedback with the community.

1. vignetting/back focus issue -> SONY needed to "re-align" the lens.

2. Battery drainage -> SONY has replaced a circuit board to fix this.

3. SEL/SET dial knob not working as expected - SONY updated firmware (1.05) fixes this.

4. Fading letters -> SONY is replacing the back panel. This incidentally is delaying the return of the cam. They are currently waiting for parts (eg. panel, buttons).

5. Audio issues -> SONY performed diagnostics and report no audio issues (hmnn!)


I hope this is helpful to anyone who is contemplating returning there unit to Sony. I will update once it has been returned to me.

-B

That scares me. My EX1 should be arriving in San Jose today or tomorrow and I have the same v1.03 as you. I also need the back panel replaced and if they hold up my repairs waiting for THAT stupid part, I'm gonna be pi**ed. And, I'm not sure if they are going to have to replace my lens or not, but I found crud inside the lens and you can see it here:

http://www.vimeo.com/1007825

Yes . . . bummer on the delay. I will be in Africa next week and hope to use the EX1. However, after expressing my concern, Sony has promised to get it back to me before then.

-B

Here's an interesting excerpt (post #33) from Diego Marcone discussing firmware 1.05

http://www.dvinfo.net/conf/showthrea...=121280&page=3


"Release of PMW-EX1 V1.05

Reaso/Purpose
Function improvment and bug fixes

Function added:
1) Improved operability of jog Dial
When operating the Jog dial, the cursor moves in the unintended direction on the menu.
The operability of Jog dial has been improved
2) Countermeasure against the flange-back shift when turning on the ND filter.
The accuracy of flange-back when turning on the ND has been enhanced.
3) Change of i.LINK Enable menu selection
To save the power, the i.LINK Enable can be salected in the HQ mode so that the HD-SDI can be turned off
When set to i.LINK in the HQ mode, the i. LINK output is not output while the SDI output is turned off."


-B

The Z7U has a similar Auto FB Ajust function to the EX1 and the procedure for doing a backfocus ajustment is clearly explained in the manual (pg 11).
It stands to reason that the procedure for the EX1 is very similar if not the same (I would have guessed ND Off, but Z7 FB auto adjust is ND1 on).

The Z7 routine also has a manual mode and it's not 'hidden' as you would expect to adjust BF with every lens change at least (more likely every location change).

My opinion is that Sony dropped the ball on the bacfocus adjustment on the EX1 and should update the firmware to move the FB Adjust out of the service menu. When you move the camera from (airconditioned) inside, to baking in the sun outside or if take it to the arctic or anything in between the lens will physically change and require (BF) adjustment.

The 1.05 FW fixes the correction for the ND filters. I am sure the firmware has only 1 lookup table (LUT) for the backfocus, so performing the adjustment for all three ND variants will likely result in inacurate values. As the firmware corrects for ND, doing the adustments with the ND switch in the wrong position will most likely result in worse backfocus.

I am not sure if the EX1 needs to be adjusted with ND Off or ND1 (as with the Z7). But this is easy to test.

If you have firmware before 1.05 my advice is to do an adjustment on location at the ND you're shooting at. This obviously limits you in changing ND between shots.

The FW 1.05 Technical Bulletin specifically states the fix for the backfocus from whch I deduce that every camera with lower FW has this problem to some extend.

George/