Cannot reproduce 7d ghosting issue

Started Oct 28, 2009 | Discussions
Jay Bean Veteran Member • Posts: 3,661
Cannot reproduce 7d ghosting issue

I tried yesterday afternoon to reproduce the ghosting issue with my 7D without any success. I shot 8fps of a moving high contrast dark object against the clear blue sky with a long telephoto both in JPEG and RAW. I couldn't find any ghosting even after supper exaggerating the levels in Photoshop. So either (a) there is some specific configuration that causes the issue or (b) not all units have the issue.

(I upgraded to 1.0.9 last week so sorry, I can't try the same test with 1.0.7)

loafer Senior Member • Posts: 1,403
send it back

must be defective - either that or user error.

Karl Gnter Wnsch Forum Pro • Posts: 11,408
Re: Cannot reproduce 7d ghosting issue

Jay Bean wrote:

I tried yesterday afternoon to reproduce the ghosting issue with my 7D without any success.

Do you need the effect?

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jrarsenault Senior Member • Posts: 1,149
Re: Cannot reproduce 7d ghosting issue

Actually I'm glad that you couldn't reproduce it. Thanks for the effort though.

Jay Bean wrote:

I tried yesterday afternoon to reproduce the ghosting issue with my 7D without any success. I shot 8fps of a moving high contrast dark object against the clear blue sky with a long telephoto both in JPEG and RAW. I couldn't find any ghosting even after supper exaggerating the levels in Photoshop. So either (a) there is some specific configuration that causes the issue or (b) not all units have the issue.

(I upgraded to 1.0.9 last week so sorry, I can't try the same test with 1.0.7)

Julio Veteran Member • Posts: 4,886
or, c)...

Jay Bean wrote:

So either (a) there is some specific configuration that causes the issue or (b) not all units have the issue.

... c) the units that have it only show the problem occasionally. I don't think anyone has reproduced this at will.
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DRG Veteran Member • Posts: 5,217
Re: Cannot reproduce 7d ghosting issue

The only way I can think of that this phenomenon can occur is if the sensor reset signal isn't being asserted long enough for a few sensors that skew toward the slow side due to higher-than-nominal resistance (in terms of how long it takes to reset the pixel). There may be residual signal remaining on some sensors after the reset signal is removed and a new exposure begins.

David

loafer Senior Member • Posts: 1,403
seriously...

Possibly the 'ghosting' is useful in video - so maybe it is a feature of the sensor. Total speculation.

ohyva Veteran Member • Posts: 6,342
Re: Cannot reproduce 7d ghosting issue

DRG wrote:

The only way I can think of that this phenomenon can occur is if the sensor reset signal isn't being asserted long enough for a few sensors that skew toward the slow side due to higher-than-nominal resistance (in terms of how long it takes to reset the pixel). There may be residual signal remaining on some sensors after the reset signal is removed and a new exposure begins.

I thought the same.

And this can explain why some people get this and some not - some sensor can empty their sensels a bit faster than others.

RobertoAvanzi Senior Member • Posts: 1,003
Re: send it back

loafer wrote:

must be defective - either that or user error.

LOL!

Roberto

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OP Jay Bean Veteran Member • Posts: 3,661
Found It!!!

Went back to the photos I took yesterday, this time in LR, and started really aggressively playing around with the sliders & tone curve.

I found "the ghost"

It's really difficult to make it appear and even when it shows up, it's very very faint (nothing like what I've seen posted online). It only shows up very faintly when the sliders are pushed to where you can see tonal separation at the very very bottom end of the shadows, e.g., the ghost seems to only be of dark objects not of bright or even mid-tone objects.

Once I figured out how to view it, I look for it in RAW files and it's there also. This means it's not an artifact of the Digic JPEG processing or in-camera JPEG enhancements, nor is it an artifact of the in camera RAW to JPEG conversion. It's down at the sensor level as many have surmised.

Here's where my LR sliders were to see it in my shot. You can see the extreme it took to make it show up:

EXP: +2.57
REC: 0
FILL: +100
BLACKS: +86
BRIGHT: +150
CONTRAST: +55
CLARITY: -100
VIB: +100
SAT: 0
HIGHLIGHTS: -100
LIGHTS: -100
DARKS: +100
SHADOWS: +100
POINT CURVE: Strong Contrast

Jay Bean wrote:

I tried yesterday afternoon to reproduce the ghosting issue with my 7D without any success. I shot 8fps of a moving high contrast dark object against the clear blue sky with a long telephoto both in JPEG and RAW. I couldn't find any ghosting even after supper exaggerating the levels in Photoshop. So either (a) there is some specific configuration that causes the issue or (b) not all units have the issue.

(I upgraded to 1.0.9 last week so sorry, I can't try the same test with 1.0.7)

mailman88
mailman88 Veteran Member • Posts: 5,764
Re: Try again halloween night...

...the ghost will be out for sure. Sorry I had to do it...its the season!

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