Canon G7 - blurry photos

Hi, has anyone experienced problems with blurry photos when shooting at f8 with the Canon G7? I have been using a tripod to eliminate camera shake but the photos are still blurry. Does anyone know why this might be?

tph567 wrote in post #3958696
Hi, has anyone experienced problems with blurry photos when shooting at f8 with the Canon G7? I have been using a tripod to eliminate camera shake but the photos are still blurry. Does anyone know why this might be?

When Using a Tripod make sure to turn OFF the IS (Anti-Shake).

Believe it or not but that adds slight Vibrations when camera is well grounded.

Please post a sample. We can only guess otherwise, as there are several types of "blur". F/8 is pretty small for a P&S, so I suspect subject motion blur, but we'll have to see.

f/8 could also be due diffraction effects. Pls post a sample.

J

I'd second the tip about turning off the image stabaliser. On a tripod, that stabaliser can really induce some blur

f/8 is too small an aperture for a small-sensor camera - so you will get unsharpness induced by diffraction.

Read more about it here:
D60's ( APS-C )sensor is too small to stop down below f/11?

OK, just kidding. The thread is actually a bit long.

Take a look at this explanationand this review: http://www.dcresource.​com/reviews/sony/dsc_v​3-review/
and scroll down until you see the two pictures of the church clock, one taken @ f/8, the other @ f/4.

On my G2, the 'optimal' aperture was somewhere between f/4 and f/5.6.

Best regards,
Andy

You don't have to read my "Franken-thread". Let me see if I can condense it down for you with numbers that are applicable to the PowerShot G7.

The G7's sensor is so small (at 5.32 x 7.18 mm) that it suffers an enlargement factor of 35.4x when making an 8x10-inch print from a nominal crop, and an enlargement factor of 50.8x when making a 10.8 x 14.4-inch print - the size you'll get at an unresampled image resolution of 254 dpi using all 9.98 Megapixels (2736 x 3638 pixels).

Problem: The greater the enlargement factor the more vulnerable your final print will be to suffering visible degredation caused by diffraction.

At the 35.4x enlargement factor required to produce an 8x10-inch print from the G7 sensor (nominal crop), you can not stop down below f/4.2 without inhbibiting a desired print resolution of 5 lp/mm.

At the 50.8x enlargement factor required to produce a 10.8 x 14.4-inch print from the G7 sensor, you can not stop down below f/2.9 without inhibiting a desired print resolution of 5 lp/mm.

IF your goal is to support the communication of subject detail to the final print at a desired resolution of 5 lp/mm, you pretty much have to shoot wide open with the G7 at all times - confining yourself to a single combination of aperture and shutter speed for any combination of available light and chosen ISO setting. If only the G7 were equipped with a faster lens... It has a variable maximum aperture that ranges from f/2.8 to f/4.8, so if you're shooting wide open at the camera's shortest focal length, f/2.8 will not induce diffraction sufficient to inhibit a desired print resolution of 5 lp/mm at any enlargement factor up to that suffered near a 10.8 x 14.4-inch print. But if you're shooting wide open at the camera's longest focal length, where you're forced to work at f/4.8, you can not maintain a goal of retaining subject detail to a resolution of 5 lp/mm in prints larger than 8x10-inch.

In my sample calculations, I've specified 5 lp/mm as the desired print resolution and I've used two different enlargement factors, but the amount of subject detail you hope to retain in the final print might be lower or even higher than the figure I've chosen arbitrarily for the sake of discussion and, similarly, only you can anticipate what size prints you hope to make. So don't pay attention to anyone who flatly says, "You can't stop down below f/whatever with that camera because of diffraction," unless they qualify that statement (as I always do) by telling you at what combination of enlargement factor and desired print resolution that diffraction-limit f-Number applies. Even if they determine the f-Number empirically, through testing, rather than relying on the very dependable Rayleigh Criterion, they should qualify their results by at least communicating the enlargement factor and viewing distance at which they drew their conclusion.

Most people with healthy vision can appreciate the difference between a 2 lp/mm and 4 lp/mm at a viewing distance of 10 inches. A print that can communicate 4 lp/mm worth of subject detail would usually be described as "sharp" by most people, but some can appreciate increased resolutions as high as 8 lp/mm at a viewing distance of 10 inches.

The thing to understand here is that there is no one f-Number at which a given camera will begin to suffer visible diffraction. There are three variables which determine the f-Number at which degradation caused by diffraction begins to inhibit a desired print resolution: The viewing distance, the desired print resolution, and the enlargement factor.

Here's a formula for calculating the f-Number (N), at which diffraction will begin to impact an image at a specified combination of desired print resolution for a 10-inch viewing distance (in lp/mm), enlargement factor, and anticipated viewing distance (inches):

N = anticipated viewing distance / desired print resolution for a 10-inch viewing distance / enlargement factor / 0.0135383

If you prefer to always assume someone may view your prints as closely as 10 inches, you can use this formula:

N = 1 / desired print resolution for a 10-inch viewing distance / enlargement factor / 0.00135383

Note: The two versions of the formula have different constants (a 10x difference).

I recommend you select a desired print resolution no lower than 4 lp/mm and no higher than 8 lp/mm. (4 lp/mm requires an unresampled image file resolution of 200 dpi. 6 lp/mm requires 300 dpi. 8 lp/mm requires 400 dpi.)

Enlargement factor can be calculated by dividing the width of the print by the width of the sensor using the same units. Sensor dimensions can be obtained at at DPReview's Learn / Glossary > Camera System > Sensor Sizes page.

http://www.dpreview.co​m/... .../?/Glossary/Camera_​System/sensor_sizes_01​.htm

Mike Davis

http://www.AccessZ.com

try tripod + Self timer

Hi guys,

Thank's for the information above, it was very instructive.

I have a similar problem but different problem.

Some time ago I travelled by airplane and I made a HUGE mistake of dispatching my camera in one of my bags. So when I took if from the bag the lens got a heavy condensation. Then I made the second mistake of turning it on BEFORE the condensation was totally dismissed. I tried to take some pictures from that day on and they become blurred no matter what I try.

I disassembled the camera and tried to clean up the CCD and the back of the cristal which protects it. No result so ever. So right now I am planing to change the whole lens.

This post is my last try. Anyone have a suggestion what it may be and what could I do to fix it? I have heard from other G7 users that the picture can be blurred in some parts but no solution for them.

Did I messed up with CCD? Or other part? I am afraid to buy the new lens and the problem is in other part...

Thank you.

Send to Canon for service?

Canon service in my country (Brazil) has denied to accept the camera. Actually they say there isn´t parts anymore for this model. So it would not worthy the cost of shipping it to them.
I have done some research over Internet and I found out someone with a similar problem. He'd related that it is caused by a dealignment of the IS component at lens. The only additional information is that maybe possible to realign, but is quite tricky.
Canon telephone suport said they do not disassemble the lens because it is impossible to realign.
I am considering buy a new camera...