I just took two pictures of a coin using all of the same settings on my camera yet one was 200kb and the other was 50kb. How can that be? The larger one, I think the auto focus worked with the camera closer to the coin and I had to back up quite a bit for the picture of the reverse. I have it on the highest mega pixels, adjusted the white balance, set it on macro... Reason I ask is because some pictures, after they are posted let you zoom in and others won't. The only difference I notice is because of the kb's. I'm puzzled :computer:
You are asking 2 different questions. As stated already, for question 1 the size of the pic will vary depending on the distance from the camera to the coin - or the zoom you use. For question 2 - the reason you can zoom in on some pics is because of the size of the pic - or the kb as you metioned. The forum has a setting that only allows a certain size pic to be visible so that users don't have to scroll side to side to see the pic. If the pic fits within that limit you will see it full size in the thread. If the pic is larger than that limit, then you will have to click on it to blow it up to full size.
Questions back at you. What type of camera are you using? Are you sure you didn't accidently change a setting between pictures? What distance were you from the subject? Was you camera set on an Auto mode?
Another possibility. Certain image formats do file compression when saved. BUT they don't uncompress to the original file size. When the initial compression was performed a lot of stuff was just thrown away never to be seen again. The most familiar format that does this is jpeg. The amount of compression is a function of how complex the image is. Large areas that are uniform (or close to it) in color compress well. Complex images don't.
