Canon quality issue

[david_hirst]

Every now and then images taken with my 5D have what i can only decribe as a

stocking filter look to them.

This affects the image that it renders it useless. By kooking at an image it

just looks as though as a stocking was placed over the lens for effect, but it

has not.. Anyone any ideas.

 

I will put an image in my port for you to have a look at

 

Dave<div></div>

[awindsor]

Two possibilities that I can think of:

 

1) RF interference. This can be caused by an external source or by the lens motor (though typically this appears only in AI Focus or AI Servo mode and at high sensitivities).

 

2) Underexposure. The pattern you get I see in the shadows some of my high sensitivity shots. It is possible to get the same pattern (apparently related to the structure of the sensor) at ISO 100 by underexposing and then increasing the exposure in a RAW converter.

 

Was this shot taken in RAW ? Did you use a RAW converter that performs automatic correction (ACR for example) ?

[david_hirst]

Yes i always shoot in raw!

 

And i used adobe raw converter

Dave

[digitmstr]

Actually. a stocking over the lens would produces a totally different effect :)

 

It looks like a RAW conversion problem to me caused by the sofware or plugin you used.

[awindsor]

Adobe camera RAW has the option of automatically correcting exposure. Ensure that this option is off or look at the file in one of the Canon RAW converters. If the file is very underexposed then that is your problem.

 

If you shot with a filter on the lens then try removing the filter. Every now and then there are unusual effects produced by UV filters (including banding).

[rainer_t]

David,

 

my guess for this picture is ... underexposure, and massive EV correction in the raw-conversion. (That's what brings up the noise).

 

The EXIFs say: 50iso, 1/125sec, f/22, no flash.

 

A quick calculation ... 1/125sec (7EV) f/22 (9EV) 50iso (1EV)

so the exposure is for 7+9+1 = 17EV ... (a sunny day is about 15EV.)

 

Eventually, you used a studio flash, that is not recognised by

the camera? (But still ... 17EV is a lot).

 

Rainer

[ed_baumeister]

Underexposure yields highly variable results in digital, in my experience with the Canon 10-D and 1D Mark II. Try converting from raw with Canon's DPP v. 2x. Obviously, the system knows more than I do about underexposure, but DPP seems to deal with it best.

[leicaglow]

It looks more to me like you're shooting at a high ISO and the image has a lot of noise in it.

[awindsor]

Michael,

 

The shot is ISO 50.

 

David,

 

Out of interest why shoot at ISO 50 ? ISO 50 is a special option and comes at the cost of reduced dynamic range. If you just want to maximize quality then ISO 100 is a better bet.

[KenPapai]

Ranier and Alistair answered your question. It's technique NOT the 5D.

 

It's obvious you underexposed. You know f/22 is not really all that optimal for portraits (depending on your lens its optimal sharpness may be achieved between f/8 and f/11). And 1/125 for a *sitting* portrait? Just use MLU and the 2 second timer countdown.

 

Why not shoot much wider open with ISO 100, say 1/60 and f/4 ?

[david_hirst]

Ed was right

 

Thanks

The problem was sorted on looking at acr i switched of auto everything and sorted it myself, and hey presto the noise like grain has gone.

 

Thanks for the imput guys

 

Dave