Simple Experiment. Find a bookshelf full of books in a well lit area (such as a library or bookstore.) Find a seat about 10 feet away facing the bookshelf. Hold out your right hand in a fist with your thumb pointing out little less than a foot from your face just outside your peripheral vision. Now focus on the bookshelf and slowly move your thumb into view. Try to focus through the edge of your thumb onto the books without focusing on your thumb. You'll notice a blurry edge around your thumb, try not to let that distract you. If you do it just right, you'll notice the books 'squeeze' together and become sharper to your view. If you focus around the edge of your thumb you'll notice straight lines bend around your thumb in a distance. You can do this with any object in a distance, but a book shelf seems to do well because of the vertical lines. The 'focus' effect can be observed even more clearly by putting your finger and thumb into a squeezing position without touching each other and looking through that small seam between - the closer your finger and thumb come the more sharper objects at a distance become. If you wear glasses or contacts - take them off/out and this effect can be observed even more drastically. Is this 'warping' effect caused by gravitation lensing or is this some other effect?