Telescope Reviews: Solar Imaging

Two questions for you on this one - what kind of focal reducer are we talking about here (what reduction factor), and when you try to focus does it get better when the focuser is all the way out, all the way in or does it never come to focus either way? You'll need to check this on a distant object, like a radio tower or an astronomical subject.

If it's trending towards focus when fully racked out, this is the simplest fix - you need an extension tube. If you have a barlow with a removable lens this usually works well.

If it's trending toward focus when fully racked in then it's a bit problematic. If it seems like it is close but not quite focused then you may be able to move the primary mirror slightly toward the front of the scope by turning the spring loaded collimation screws to shift it forward and then re-collimating. However, you have to be careful to leave enough travel on the screws to still perform a collimation, and this will only net you a small change. I wouldn't recommend trying this unless you're really pretty close to focus.

If it never comes close to focus then either the distance between the reducer lens and the imaging sensor is incorrect or the reducer is not designed for your telescope.

You do need to have a reasonable polar alignment on the SVP to keep the Sun from drifting out of the image. This drift is going to happen pretty quick if you don't.

If you have a chance it would be best to set up and get a good polar alignment either before sunrise on the day you're doing this or the night before. You can mark the tripod's position on the ground with tape (or some other way that will last until you need it) and carry the mount in and out fully assembled (the scope doesn't need to be on it when you carry it). That would work well.

Otherwise you're left with making an educated "guess". Get a good polar alignment at some time before the event - making sure that the base of the tripod is level. Lock down the altitude adjustment well before taking the mount apart. On the day of the event, set up your tripod, making sure to get it levelled well. Using a compass (adjusted for magnetic deviation), set the azimuth as close to north as you can get it. You should be able to get within a degree of the pole if you do this carefully, and this should definitely minimize the number of corrections you'll need to make.

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"He's dead, Jim - I'll get his wallet, you get his tricorder." - Leonard "Bones" McCoy

Weston CSC: