The inner circle must be a circle, not an oval. If you see an oval, change the aspect ratio of your monitor or video projector (from 4:3 to 16:9 or vice versa)
Adjust your device in order to distinguish all the shades of the grayscale. On a computer monitor it's easy to distinguish. On TV or video projectors, difference of shades can be difficult to appreciate at both ends of the grayscale (critical areas A-B and I-J). Adjust to see all the changes in tone if possible (usually decreasing contrast slightly and / or increasing or decreasing brightness)
IS YOUR DEVICE CROPPING THE IMAGE?:
There are six arrows towards the edges of the pattern, reaching the real limit of the image. If you can't see the complete arrowheads this means that your screen is not showing the whole picture. Some flat screens, video projectors and old TV's usually crop the frame. Look at the menu of your device to see if there is any option to display the whole image (sometimes called "under scan" option).
If it's useful for you, I would appreciate it if you give it a like and leave a comment. Thanks!