Reading mode: Light Dark

G7 ghosting (no bash!)

Go to last post
D

Dave O.

Active member
Messages
70
Reaction score
0
Location
PT
Hi there.

First of all, sorry to bring this subject up again... :(

I reported about a ghosting artifact on the G7 some days ago, referring to the "tunnel of doom" picture from DCRP's review. Some thought it was a too rare occurence, and others even mentioned this was just due to sharpening or subject movement. However, in the meanwhile I have bought the G7 and now I'm also getting this artifact on some pictures everytime there is a strong contrast between a very bright object (normally if the edge is overexposed), and some very dark background. This is getting me a bit worried.

I've investigated this a bit more and found out that this is visible in a lot more photos than I previously thought (see some examples below). I don't see this (at least is not obvious?) on other canon compacts' photos, including the A710IS. I think (but I'm not sure) that this artifact won't be visible in small prints, but I can see it clearly even at 50% on the screen. Also, I find it more obvious than, for example, the purple fringing on the S3IS, simply because the artifact is lighter and thicker.

I would like your honest opinion on this -
1. Do you think this could be considered a serious problem for some photos?
2. Is there any way to avoid it? (guess not...?)

3. If I want to do a large print of a photo that has this artifact, do you think this could be fixed (more or less) with some photo editing (like in Photoshop, or whatever)?

Again, I'm really sorry to be asking about this again, as nobody seems to be bothered by this problem(?) but me. I don't know if it's because nobody thinks this is a real problem or if nobody really noticed. Looking at the Leica M8 problems, I guess maybe I'm just being too much of a perfeccionist :). Anyway, I was just wanting some good advice to reassure me not to return the camera, as I'm very satisfied with everything else about it...

Here are some examples of the effect I'm talking about. On some pictures you can compare similar ones taken with other cameras, if you're not sure this only happens on the G7.

1. http://www.dcresource.com/reviews/canon/powershot_g7-review/IMG_0019.JPG

The "tunnel of doom" picture I've mentioned before. The effect is visible on several places, especially on right of overexposed areas, like on the right side of the columns and to the right of the woman on the center (I think the ghosting is always to the right).

2. http://img2.dpreview.com/gallery/canon_g7_samples/originals/img_0598_sj.jpg

There are several places where you can spot the artifact. The most obvious ones are over the left woman's chest, and on the second woman from the left, on the right side of her hat.

3. http://www.dcresource.com/reviews/canon/powershot_g7-review/IMG_0015.JPG

On the right of the "piramid shaped" building (sorry, don't know the name). The contrast is not so high as on other photos, but the effect can be seen even at 50%.

4. http://www.dcresource.com/reviews/canon/powershot_g7-review/IMG_0010.JPG

On the right side of the two columns that are in contrast with a dark background (the 4 columns on the center: the 2nd and 4th columns). This example is not as obvious, as the contrast is not so high, but it's there.

5. http://www.dcresource.com/reviews/canon/powershot_g7-review/nightshot.jpg

On the top of the building, on the right of the white bright objects (flags, etc.). I've taken some long exposure (5 sec.) nightshots with my G7 and got the same problem, only more noticeable (brighter and bigger objects on top of buildings).

So what do you think? Your comments and advice are welcome!

Dave.

PS - Sorry for the huge post.
 
Wow, a bit harsh reaction... :-(

Really sorry if I offended you in anyway, it wasn't my intention at all.

If I understood correctly, you're just being ironic by saying that I'm being too picky? It's ok, I just want some opinions on this. You find the "problem" I mentioned irrelevant, is that it? If I wanted to return my camera I'd already done it. I don't. I've already taken some very good pictures with the camera, and I'm enjoying it a lot. I just want to make sure this little artifact is a big deal on normal prints (don't have much time left to confirm this, If I return the camera), as I found it on more photos of mine that I though it would appear. Also, I have a feeling that if I really want to make a big print out of a photo that has this artifact somewhere, it could be minimized with some editing work and wanted to confirm this.

Yes, I guess this can be considered a bit of "buyers remorse syndrome" or something ;). I just wanted some "down to earth" commentaries on this.

Anyway, thanks for your opinion. No offense intended, really.

Dave.
 
No I just feel that you have found something that you notice and want fixed. And since no one on this forum can do anythig about it.I am just cutting to the chase and saying it is time to get Canon involved. I understand how you must feel been there before not with Canon. So I am just giving you the quick advice I feel is needed to get this thing resolved. Again Good Luck.
Ivan
 
Thanks, I did. And I remember your comment about the printing of the "tunnel" picture. I know I'm repeating an already discussed subject, but I've found some photos of mine where the effect is more visible, like the one on the 2nd example I mentioned, and I wanted to know if there is anything that can be done to avoid that artifact (a filter...?) or if you think that it could be minimized with some photo editing, should I decide to make a large print or a crop.

Dave.
 
Thanks for your answer. So in your opinion, there's not much to do about the ghosting artifact, right? You're right about involving Canon, that would be the right thing to do, but somehow I don't think they'd listen to me. From what I read, most people didn't care about this (and maybe they're right and I'm wrong, I should add), so I think my (single) opinion won't make any difference.

Again, thanks for your advice.

Dave.
 
Well it's your camera not thers so what really matters is if you want it resolved. Canon should take a look at it since you would be sending it to them for their advice. If they say it's nothing you have not lost anything but the cost of the shipping. If they say it's not covered under their normal warranty policy they should advise the cost of fixing it. Then again they may just replace to camera. Have you tried calling the people you bought the camera from?
 
I see the ghosts you refer to, and not similar ones on samples for some other cameras.

Since you find them in the tests samples at two web sites, and with your own camera, it sounds like you should return the camera and buy a different model if these artifacts trouble you. It is not just one or two units.

I don't own a G7, and with an SD700IS and S3 IS (plus a couple of DSLRs), it would be hard to justify .. though I admire the design. If I did, those artifacts might or might not bother me.

Apparently other owners are not seeing them in their shots. Maybe it relates to too high a sharpness setting in the camera. Almost looks like some sort of chroma "ringing".

Phil
 
I think this falls under the heading "compromise" -- as in small sensor, many pixels compromise.

Since the effect is related to strong overexposures, there are techniques to deal with it. None of your example pics are the type of image one would want to print at poster, or even 12x18 inch, size. Even with DSLRs, some exposures require HDR treatments. That is, combining multiple images taken using different exposures to battle limited Dynamic Range. If you should happen to capture a moment that contains this effect that you want to enlarge to poster size, you will just have to do some post processing.

People sometimes forget that if you want to capture a technically excellent image, the best DSLRs are the EASIEST tools to use and the P&S cameras are the HARDEST. That's why the pros spend all that money on top end cameras.

I hope some other G7 owners (I'm not one of those) will try some experiments and let you know if this is a common effect. Best wishes.

--
Bitplayer

To err is human, to post-process -- divine.
 
Hi Dave O,

I saw that flaw on G7 samples and I thought I would not spend the G7 price to put up with that !

It is related to the lens, the internal ho mirror and the Sony 10mP sensor.

the Sony 1/1.8 sensor often gives a pinky cast, and it really should have been sorted.

My A640 can behave similarly, but I thought it acceptable for the lower price camera.

Having said all that, I honestly believe that PTL would CA correction would render it near invisible........ as long as you take photos with sharpness at -2, so that the additional abberations to not recieve additional JPG artifacts before PTlens is left to do its work.

At least the PTlens download is free to try on 10 pics, and even the it is only $15. Check out the example for CA correction, it should do the same to the red ghosting.

http://www.epaperpress.com/ptlens/
 
PC Wheeler said:
I see the ghosts you refer to, and not similar ones on samples for
some other cameras.

Since you find them in the tests samples at two web sites, and with
your own camera, it sounds like you should return the camera and
buy a different model if these artifacts trouble you. It is not
just one or two units.
Click to expand...
No, you're right, it's not. I've just tested a friend's new G7. It has the exact same ghosting artifacts, which proves it's the same for all G7's.
PC Wheeler said:
I don't own a G7, and with an SD700IS and S3 IS (plus a couple of
DSLRs), it would be hard to justify .. though I admire the design.
If I did, those artifacts might or might not bother me.
Click to expand...
I'm still trying to decide if this bothers me to the point of returning the camera or not. I'm going to make some small sized prints (most of my pics will be printed in the "standard" small size...), to see how it looks. I'm expecting it not to be visible at all. If it's not, I'll consider to keep the camera, as I'm satisfied will all the rest: build quality, IQ (except for the ghosting, of course), lens sharpness including corners, speed, even ISO performance (cleans up nicely with post processing, especially if shot with low sharpness), size, weight, controls, macro mode (very good)...

For big prints (which will happen rarely), the ghosting won't be in most photos for start (only happens in some special conditions), and for the ones that have it, I guess some PP (even some more "manual" PP work) could take care of it. As this will happen rarely, I guess it's more acceptable. I just have to see how this comes out in real prints, especially "normal" (small) sized prints.

It's just a shame that a supposedly top-of-the-line compact camera from Canon can have such a flaw when all their other lower priced cameras don't (although they have their own limitations, of course). It's more absurd because I think this could probably been solved with some lens coating or whatever, as this seems to be caused by internal lens reflexes.

Of course, I also mentioned the Leica M8 "thing", which, when you put it into perspective, is even more outrageous (5k camera...).
PC Wheeler said:
Apparently other owners are not seeing them in their shots.
Click to expand...
The ghosting is only very evident on some photos. It's there on other photos, like the examples I mentioned, but it's more subtle. Of course, when you know what to look for, you'll see it more easily.
PC Wheeler said:
Maybe
it relates to too high a sharpness setting in the camera. Almost
looks like some sort of chroma "ringing".
Click to expand...
Lowering sharpness makes it perhaps a tiny bit less visible, but not by much, really. I have some photos (long exposure night shots) where you can even see 2 ghost images (one more faint than the other - multiple reflexions?)... Also, this is not the same as CA, or red fringes (the G7 has it, but it's not the same effect). I've tried different zoom and apperture values, but it doesn't seem to make much of a difference.
PC Wheeler said:
Phil
Click to expand...
Thanks for your comments, Phil!

Dave.
 
The problem doesn't seem to be severe enough to warrant sending the camera back.

Adjustments in PhotoShop can get rid of a lot of the problem, maybe all.

--
Warren
 
Warren73 said:
The problem doesn't seem to be severe enough to warrant sending the
camera back.

Adjustments in PhotoShop can get rid of a lot of the problem, maybe
all.

--
Warren
Click to expand...
Hi, Warren! I think you're right, as I'm getting to the same conclusion.

I printed some photos today (small size: 10x15cm), including the examples I posted and one of my long exposure night photos where the ghosting can be seen. The result? Well, on most photos I can barely see the problem and I only see it because I know where to look. On others, I can't see it at all. However, on the night shot it's clearly visible, unfortunately. Not something horrible, but it's evidently a (small) double image.

However, I also printed some other photos I took with the camera, and I must say they all looked excelent, with excelent IQ... Moreover, contrary to some opinions, I enjoy the handling of the camera in my hand (different from an A series or SLR, but not bad after you learn how to hold it), and I really like how easy it can fit in my pocket to take it anywhere. The size and weight is a good compromise. The LCD is also very very good even with bright sunlight, much better than, for example, a Canon A camera. It doesn't have a swivel LCD, but to compensate this the LCD can be seen from very narrow angles - not the exact same thing, but it helps a bit. All cameras have some compromises, including IQ (there's other things I don't like on other cameras). It's a pitty Canon didn't address this issue properly, with so much marketing bull* about the special lens coating on the G7 that eliminates ghosting, etc., only to find out that it's (probably) the only Canon compact that has this kind of ghosting... The irony of it...

To conclude, I tried some photo editing to see how difficult it was to manually correct the artifact and, as I expected, it was not difficult at all. Much easier than to correct some other problems like excessive CA or red fringing that sometimes affects lots of parts in an image. The fix completely eliminated the visibility of the artifact on all pictures I tried, so none of the pictures were ruined. This was the conclusion I needed. I won't be returning the camera. It's not perfect (the ghosting, the flash delay issue, some noise problems...), but for me it's still the best compact on sale NOW.

Thank you all for your patience. Happy holidays.

Dave.
 
Dave O. said:
To conclude, I tried some photo editing to see how difficult it was
to manually correct the artifact and, as I expected, it was not
difficult at all. Much easier than to correct some other problems
like excessive CA or red fringing that sometimes affects lots of
parts in an image. The fix completely eliminated the visibility of
the artifact on all pictures I tried, so none of the pictures were
ruined. This was the conclusion I needed. I won't be returning the
camera. It's not perfect (the ghosting, the flash delay issue, some
noise problems...), but for me it's still the best compact on sale
NOW.
Click to expand...
I'm glad to hear the G7 is working for you, Dave. Though I have an S3 IS and an SD700IS (not to mention 20D), there may be a G7 in my future. I handled one in a local store yesterday, and I liked it (too well!). I found the OVF to be very good (surprising, with the negative reviews) and accurate for composition .. the one in the SD700 is useless, but the EVF in the S3 works well.

Phil
 
PC Wheeler said:
Dave O. said:
To conclude, I tried some photo editing to see how difficult it was
to manually correct the artifact and, as I expected, it was not
difficult at all. Much easier than to correct some other problems
like excessive CA or red fringing that sometimes affects lots of
parts in an image. The fix completely eliminated the visibility of
the artifact on all pictures I tried, so none of the pictures were
ruined. This was the conclusion I needed. I won't be returning the
camera. It's not perfect (the ghosting, the flash delay issue, some
noise problems...), but for me it's still the best compact on sale
NOW.
Click to expand...
Click to expand...
What did you use to correct the images ?

I haven't had that many chance to shoot with my G7 yet and I keep hearing about problems but can't hardly find any in my pictures.
PC Wheeler said:
I'm glad to hear the G7 is working for you, Dave. Though I have an
S3 IS and an SD700IS (not to mention 20D), there may be a G7 in my
future. I handled one in a local store yesterday, and I liked it
(too well!). I found the OVF to be very good (surprising, with the
negative reviews) and accurate for composition .. the one in the
SD700 is useless, but the EVF in the S3 works well.

Phil
Click to expand...
The small differences between the S3 and G7 made me sell my S3, I do miss the 12x zoom and EVF :-(

The OVF on the G7 is not bad but I loose a big portion on top of the images, it doesn't seem that centered, also with the lens adapter, it is useless, half of the image is gone :-(

I'm going to start to look for external viewfinder.

All the small quirks of the G7 makes me love it more, you have to learn how it work like the old 35mm cameras :-)

--
Stephane
 
Dave O.

The more I thought about it and revisited your pictures, it seems that the problem is what the DPReview indicated was "Purple Fringing" which is noted in the review of the G7. They say "Purple fringing and some CA visible at wide end of zoom in some shots."

It seems worse where there are high contrast areas, with the "ghosting" or "purple fringing" occurring in lines between dark and light.

I haven't experimented, but wonder whether racking down the contrast setting when the scene is apparently going to produce these types of areas might help. Also, backing off the extreme wide end of zoom may help. After that, PhotoShop can do wonders, especially if you have CS2 and the Shadow/Highlight function.

Warren
Dave O. said:
Hi there.

First of all, sorry to bring this subject up again... :(

I reported about a ghosting artifact on the G7 some days ago,
referring to the "tunnel of doom" picture from DCRP's review. Some
thought it was a too rare occurence, and others even mentioned this
was just due to sharpening or subject movement. However, in the
meanwhile I have bought the G7 and now I'm also getting this
artifact on some pictures everytime there is a strong contrast
between a very bright object (normally if the edge is overexposed),
and some very dark background. This is getting me a bit worried.

I've investigated this a bit more and found out that this is
visible in a lot more photos than I previously thought (see some
examples below). I don't see this (at least is not obvious?) on
other canon compacts' photos, including the A710IS. I think (but
I'm not sure) that this artifact won't be visible in small prints,
but I can see it clearly even at 50% on the screen. Also, I find it
more obvious than, for example, the purple fringing on the S3IS,
simply because the artifact is lighter and thicker.

I would like your honest opinion on this -
1. Do you think this could be considered a serious problem for some
photos?
2. Is there any way to avoid it? (guess not...?)
3. If I want to do a large print of a photo that has this artifact,
do you think this could be fixed (more or less) with some photo
editing (like in Photoshop, or whatever)?

Again, I'm really sorry to be asking about this again, as nobody
seems to be bothered by this problem(?) but me. I don't know if
it's because nobody thinks this is a real problem or if nobody
really noticed. Looking at the Leica M8 problems, I guess maybe I'm
just being too much of a perfeccionist :). Anyway, I was just
wanting some good advice to reassure me not to return the camera,
as I'm very satisfied with everything else about it...

Here are some examples of the effect I'm talking about. On some
pictures you can compare similar ones taken with other cameras, if
you're not sure this only happens on the G7.

1.
http://www.dcresource.com/reviews/canon/powershot_g7-review/IMG_0019.JPG
The "tunnel of doom" picture I've mentioned before. The effect is
visible on several places, especially on right of overexposed
areas, like on the right side of the columns and to the right of
the woman on the center (I think the ghosting is always to the
right).

2.
http://img2.dpreview.com/gallery/canon_g7_samples/originals/img_0598_sj.jpg
There are several places where you can spot the artifact. The most
obvious ones are over the left woman's chest, and on the second
woman from the left, on the right side of her hat.

3.
http://www.dcresource.com/reviews/canon/powershot_g7-review/IMG_0015.JPG
On the right of the "piramid shaped" building (sorry, don't know
the name). The contrast is not so high as on other photos, but the
effect can be seen even at 50%.

4.
http://www.dcresource.com/reviews/canon/powershot_g7-review/IMG_0010.JPG
On the right side of the two columns that are in contrast with a
dark background (the 4 columns on the center: the 2nd and 4th
columns). This example is not as obvious, as the contrast is not so
high, but it's there.

5. http://www.dcresource.com/reviews/canon/powershot_g7-review/nightshot.jpg
On the top of the building, on the right of the white bright
objects (flags, etc.). I've taken some long exposure (5 sec.)
nightshots with my G7 and got the same problem, only more
noticeable (brighter and bigger objects on top of buildings).

So what do you think? Your comments and advice are welcome!

Dave.

PS - Sorry for the huge post.
Click to expand...
--
Warren
 
Just a minor update on this…
Warren73 said:
Dave O.

The more I thought about it and revisited your pictures, it seems
that the problem is what the DPReview indicated was "Purple
Fringing" which is noted in the review of the G7. They say "Purple
fringing and some CA visible at wide end of zoom in some shots."
Click to expand...
It may be, but I'm not 100% sure of it. See, the worst case of "ghosting" I saw was on one of my long exposure night shots, where there are two metal structures on top of two buildings. One is illuminated with white lights and the other with yellow lights. The ghost images are white and yellow, respectively, not purple, or blue, like typical CA's.
Warren73 said:
It seems worse where there are high contrast areas, with the
"ghosting" or "purple fringing" occurring in lines between dark and
light.
Click to expand...
Yes, and I think this is actually good, because I found out that when the ghosting is visible, that area has less detail (too dark), so it makes it (typically) easier to correct if needed.
Warren73 said:
I haven't experimented, but wonder whether racking down the
contrast setting when the scene is apparently going to produce
these types of areas might help. Also, backing off the extreme
wide end of zoom may help. After that, PhotoShop can do wonders,
especially if you have CS2 and the Shadow/Highlight function.
Click to expand...
I actually tried all zoom and aperture ranges and it didn’t (seem to) make a difference. Contrast has some (limited) effect, which is expected.

For anyone that’s still interested in this ghosting "issue", I must make a correction to a statement I made previously. I think I found out a similar problem of ghosting on other recent Canon compacts, namely the A630/640/710IS. I previously said that only the G7 seemed to have it, but now I think that’s not true. I don’t have access to other cameras myself, but I had here on my HD some pictures from the reviews of those other cameras, which I had downloaded when trying to decide on what camera to choose from. I looked more carefully at those pictures again, and I found some evidence of the same effect on some of the example photos. Now, I don’t know if it’s exactly the same or the same amount of the effect, but I do feel it’s similar if the conditions (light, scene, etc.) are identical (which doesn’t always happen in photo reviews, of course). I looked at some A620’s photos, just to compare, and I couldn’t find a picture with a similar ghosting artifact, just some mild red fringing, even boosting gamma, in order to make any trace of ghosting more easier to spot. Maybe this camera doesn’t have that problem. However, it could be just that it doesn’t appear on those photos.

If you’re curious, here’s one example of an A640 photo that appears to have the same issue:
http://www.steves-digicams.com/2006_reviews/a640/samples/img_0004.jpg

Look at the white railing (is this the correct name? I’m not English…), on the center above the stairs. If you saw my G7’s examples, you can see it’s pretty much the same. Someone who has an A640 had already mentioned that it also had the same thing, but I wrongly thought that person was mistaking it as (more typical) red fringing.

As for the rest, I’m still enjoying very much the G7! I hope the battery life improves a little bit after the first charges (I’ve only charged it 3 times), as it seems to go down pretty quickly - and I have IS set to "shot only" and continuous focus disabled also... By the way, the manual states 1h30min to charge the battery, however mine has taken 2h on all 3 times... I also like how quick the camera behaves, but it would be great if there was a firmware update that could improve trigger time when using the flash (even using the " " trick). I tried some indoor photos with a very active 2 year old, and although this isn’t the best camera for that scenario (DSLRs rule here), the flash delay wasn’t helping either... ;-) But I still managed to get some pretty good photos in the end!

Cheers,
Dave.
 
The photo you link has CA not ghosting.

There is blue edging related to sky, and red shift away from the lens centre which could be corrected with PTlens.

This photo looks fractionally overexposed and the camera sharpness needed to be reduced.
I run my A640 with exposure at -1/3, and sharpness at -2.

Maybe the same could be tried for G7 with same sensor.
 
I look through your example, some example from last year cameras and some of my photo and came to this conclusion : The is increase ghosting on the newer camera but less CA so you can pick your poison, to me I prefer ghosting to CA, it is less visible.

--
Stephane
 
You must log in or register to reply here.

Keyboard shortcuts

f
Forum
m
My threads
Mobile site
About
Editorial content
Cameras & Lenses
Community
All content, design, and layout are Copyright © 1998–2025 Digital Photography Review All Rights Reserved.
Reproduction in whole or part in any form or medium without specific written permission is prohibited.
When you use DPReview links to buy products, the site may earn a commission.
©GPS Media - Guides, Products, Services.
Back
Top