The down sampling process it's definitely bad in these cases:
- If you're unaware of it.
- If you're aware of it but don't know how to circumvent it.
- If email is the only vehicle you use to transfer photos from the phone to your PC.
Points two is what this post is about and point three is where problem gets worse for people like me who have not got any iTunes-compliant PC to connect the iPhone to.
The iPhone 3G S shots photos at the decent resolution of 2048x1536 px² (don't know whether that's optical or not) which gives you photos of approximately 17x13 cm² at 300 dpi² or 34x26 cm² at 150 dpi² (the minimum output resolution you should use depends on the characteristics of the sampling technology used to shoot it). If you want to bring your photos to your PCs for further editing or printing you can rely on an email or an USB connection to a PC which correctly recognizes your phone. I tested Solaris Nevada up to build 116 and the iPhone is not recognized: that game's over for me right now.
When you enter the camera roll, you can select multiple photos and send them via email, amongst other thing, by using the Share button shown in the following screenshot.
That's a fast path but that's when the down sampling takes place! If you want to send your photos at full resolution you should make your selection, copy and paste them into a new email and send it. Copy and paste does not modify the copied data and your email will contain your original photos.