Before I start on this post I want to make it clear this not about aiming. Sighting and aiming are completely different subjects as far as I'm concerned.
Now, this will probably be my last thread I create on the fundamentals, as I believe I've covered the most important aspects in my previous fundamental threads, perhaps not in the correct order, but you can piece it all together
Sighting refers to seeing things in the clearest way possible for the individual. Every snooker coach I've had, with the exception of Nic Barrow have always said it doesn't matter how your vision is placed when sighting, as long as you keep it consistent. The brain is a powerful tool in pool and maybe they were right, the brain will teach the eyes over time what centre ball is and what straight is from a distorted view and override the eyes. But, and its a big but, the learning curve is hugely reduced if you can get the vision in the right place to start with. Why do years of retraining when a 5 minute 'test' can get your vision in the right place? Good question, Pidge, I hear you say. So, what is this test? Follow me....
Ah, the vision 'test'. I've mentioned it a few times on here already but I'll try and explain in as much detail as I can now. What you need is a pool table and some tape. Tape that's about half an inch or thinner is perfect. Now, what you need to do is stick the tape on the table bed, about 12 inches away from the rail. Bring the tape back towards the rail keeping it as straight as possible and place it under the rail, then up the cushion and along the rail again keeping it nice and straight. The tape should be staggered due to the height increase onto the rail from the baize. This step is the important part in showing you how you see a straight line as straight, and just as importantly where you are lined up on the cue ball is in fact where you are lined up. So, if it looks like you are hitting centre ball you are in fact lined up to strike centre ball. All you have to rely on then is the rest of your fundamentals. So, this line of tape....you will notice as you move around the table and move the head the line stops looking straight. You need to stand in a way that this line looks dead straight. This is how you will need to stand behind the shot at hand when using what ever aiming method you choose. If you need to line centre to centre for a straight in, you stand as though the line is from centre to centre. Centre to edge...exactly the same. Now, place your cue along this line, or a spar shaft. Make sure its perfectly aligned and do what ever it takes to keep it still. I personally tape an old shaft to the rail when showing people this. Now you need to get down as though you're about to shoot. Does the shaft look straight along the tape with the tip aimed at the end of the tape? If not you need to move your head until it does. When it does, stop, take in the new head over the cue position and this is how your head needs to be over the cue on all shots.
Its as simple as that. Its easy, cheap and quick to determine your new sighting position. For those who are sure their stroke is reliable but can't stop adding unintentional side spin to the cue ball....do this test. You might be surprised at how far off your sighting position may be. For those who think they suck at aiming, do this test. Your misses should reduce and stop being because of sighting errors, which narrows down why you miss so you can work on other aspects. Regardless of the system you use to aim, if any, all I've come across require your sighting position to be correct. That super awesome aiming system will get a lot more super awesome if you get your sighting position into the correct place.
Just remember, remove the tape from the table before the next guy comes to play. You don't want him to fix his sighting issues!
Now, this will probably be my last thread I create on the fundamentals, as I believe I've covered the most important aspects in my previous fundamental threads, perhaps not in the correct order, but you can piece it all together

Sighting refers to seeing things in the clearest way possible for the individual. Every snooker coach I've had, with the exception of Nic Barrow have always said it doesn't matter how your vision is placed when sighting, as long as you keep it consistent. The brain is a powerful tool in pool and maybe they were right, the brain will teach the eyes over time what centre ball is and what straight is from a distorted view and override the eyes. But, and its a big but, the learning curve is hugely reduced if you can get the vision in the right place to start with. Why do years of retraining when a 5 minute 'test' can get your vision in the right place? Good question, Pidge, I hear you say. So, what is this test? Follow me....
Ah, the vision 'test'. I've mentioned it a few times on here already but I'll try and explain in as much detail as I can now. What you need is a pool table and some tape. Tape that's about half an inch or thinner is perfect. Now, what you need to do is stick the tape on the table bed, about 12 inches away from the rail. Bring the tape back towards the rail keeping it as straight as possible and place it under the rail, then up the cushion and along the rail again keeping it nice and straight. The tape should be staggered due to the height increase onto the rail from the baize. This step is the important part in showing you how you see a straight line as straight, and just as importantly where you are lined up on the cue ball is in fact where you are lined up. So, if it looks like you are hitting centre ball you are in fact lined up to strike centre ball. All you have to rely on then is the rest of your fundamentals. So, this line of tape....you will notice as you move around the table and move the head the line stops looking straight. You need to stand in a way that this line looks dead straight. This is how you will need to stand behind the shot at hand when using what ever aiming method you choose. If you need to line centre to centre for a straight in, you stand as though the line is from centre to centre. Centre to edge...exactly the same. Now, place your cue along this line, or a spar shaft. Make sure its perfectly aligned and do what ever it takes to keep it still. I personally tape an old shaft to the rail when showing people this. Now you need to get down as though you're about to shoot. Does the shaft look straight along the tape with the tip aimed at the end of the tape? If not you need to move your head until it does. When it does, stop, take in the new head over the cue position and this is how your head needs to be over the cue on all shots.
Its as simple as that. Its easy, cheap and quick to determine your new sighting position. For those who are sure their stroke is reliable but can't stop adding unintentional side spin to the cue ball....do this test. You might be surprised at how far off your sighting position may be. For those who think they suck at aiming, do this test. Your misses should reduce and stop being because of sighting errors, which narrows down why you miss so you can work on other aspects. Regardless of the system you use to aim, if any, all I've come across require your sighting position to be correct. That super awesome aiming system will get a lot more super awesome if you get your sighting position into the correct place.
Just remember, remove the tape from the table before the next guy comes to play. You don't want him to fix his sighting issues!