Question about RAW versus JPG in PowerShotS50

BradfordBenn

Howdy-

Hopefully I posted this one in the right area. I am trying to figure out why when I shoot RAW on my Canon PowerShotS50 the exposure time is longer (shutter speed is slower) than when I shoot JPG in the same location and lighting and etc.

I thought that the only difference between the two modes was how the data was stored. I read the destructions and it did not explain the difference.

Any comments?

Thanks

rustic

RAW vs JPEG shouldn't have any effect on shutter speed... are you shooting in a different mode when you use RAW (Manual vs AV or TV)?

I could see it taking longer to write the image to memory maybe, but that wouldn't change the shutter speed...

Do you know that the actual shutter speed is different? Have you checked the EXIF?

colourbox

rustic wrote:

I could see it taking longer to write the image to memory maybe, but that wouldn't change the shutter speed...

I think that might be it. Raw files are much larger than JPEG, and the S50 is getting on in years (I use an S60), so it's no speed demon compared to today's. Definitely check the EXIF...I bet the shutter speed is no different and it's just a write speed issue.

BradfordBenn

I think they are the same
http://bradfordbenn.smugmug.com/gallery/3289034#182561943 and http://bradfordbenn.smugmug.com/gallery/3289034#182562639

I opened them up in Lightroom to take a look also and well I could not really tell any difference except for the metering average. Which I guess could make a difference, but yup the times were way different. So maybe my question is, how do I set it so that the metering is the same in both modes?

ziggy53

BradfordBenn wrote:

I think they are the same
http://bradfordbenn.smugmug.com/gallery/3289034#182561943 and http://bradfordbenn.smugmug.com/gallery/3289034#182562639

I opened them up in Lightroom to take a look also and well I could not really tell any difference except for the metering average. Which I guess could make a difference, but yup the times were way different. So maybe my question is, how do I set it so that the metering is the same in both modes?

Brad,

The camera modes are completely different. If you didn't change them, then the camera did when you chose RAW format. I bolded the pertinant areas:

---

http://bradfordbenn.smugmug.com/photos/182561943-O.jpg
Exif Sub IFD

* Exposure Time (1 / Shutter Speed) = 8/10 second = 0.80000 second
* Lens F-Number/F-Stop = 28/10 = F2.80
* Exposure Program = normal program (2)
* ISO Speed Ratings = 50
* Exif Version = 0221
* Original Date/Time = 2007:06:29 04:38:32
* Digitization Date/Time = 2007:06:29 04:38:32
* Shutter Speed Value (APEX) = 321928/1000000
Shutter Speed (Exposure Time) = 1/1.25 second
* Aperture Value (APEX) = 2970854/1000000
Aperture = F2.80
* Exposure Bias (EV) = 0/1 = 0.00
* Max Aperture Value (APEX) = 309375/100000 = 3.09
Max Aperture = F2.92
* Metering Mode = center weighted average (2)
* Flash = Flash fired
* Focal Length = 71/10 mm = 7.10 mm

===============================================

http://bradfordbenn.smugmug.com/photos/182562639-O.jpg
Exif Sub IFD

* Exposure Time (1 / Shutter Speed) = 1/60 second = 0.01667 second
* Lens F-Number/F-Stop = 28/10 = F2.80
* Exif Version = 0220
* Original Date/Time = 2007:06:29 04:38:54
* Digitization Date/Time = 2007:06:29 04:38:54
* Shutter Speed Value (APEX) = 5906891/1000000
Shutter Speed (Exposure Time) = 1/60.00 second
* Aperture Value (APEX) = 2970854/1000000
Aperture = F2.80
* Exposure Bias (EV) = 0/3 = 0.00
* Max Aperture Value (APEX) = 95/32 = 2.97
Max Aperture = F2.80
* Metering Mode = pattern / multi-segment (5)
* Flash = Flash fired, auto mode
* Focal Length = 227/32 mm = 7.09 mm
* Focal Plane X-Resolution = 2592000/283 = 9159.01
* Focal Plane Y-Resolution = 1944000/212 = 9169.81
* Focal Plane X/Y-Resolution Unit = inch (2)
* Image Sensing Method = one-chip color area sensor (2)
* Image Source = digital still camera (DSC)
* Custom Rendered = normal process (0)
* Exposure Mode = auto exposure (0)
* White Balance = auto (0)
* Digital Zoom Ratio = 2592/2592 = 1.00
* Scene Capture Type = standard (0)

colourbox

If the S50 works like my S60, then the scientific way to test this is not by turning the mode dial, but by keeping the camera in P mode and changing only the Raw or JPEG format setting in the Function menu. If you turn the dial between P and any other mode, the camera may change more settings than just the output format.

BradfordBenn

Thanks for the info. I will try just leaving it in "P" mode and shooting JPG and RAW. I was not clear on that after reading the handy desturctions (page 74) it is not real obvious.

Hopefully the request of a new camera will come soon... how many days until the holidays?