Solar Photography

Most of my recent observing has been at the eyepiece rather than the webcam, but a few crisp winter mornings and some new equipment has tempted me back to photography. The target this time is the Sun, armed with my trusty Phillips SPC900 and my newest piece of kit - a Lunt LS60 solar telescope. I've become fairly proficient with the SPC900 when taking pictures of the Moon, so how hard can it be to take pictures of the Sun? The short answer is 'harder'. Before I get onto my list of problems, here's my first attempt:

It's not a complete disaster but clearly could be a lot better! So what makes taking pictures of the Sun more difficult than taking pictures of the Moon?

1. It's sunny. Sitting with a laptop underneath the Moon is not a problem - set the brightness to a minimum and the picture is clear and easy to focus. Sitting with a laptop underneath the Sun means an umbrella, a towel over the head, a reflecting screen with every last speck of dirt magnified, and a picture that is still a bit washed out. I definitely need a better set-up to keep things darker around the laptop.

2. Focusing. It is much easier to focus upon features on the Moon - the field of view is typically crater sized and it is easy enough to get most things in focus. No such luxury with the Sun where different features are best seen at completely different focal settings. When a sunspot is looking sharp, a nearby prominence is barely even visible. Get the prominence in focus and the sunspot has disappeared.

3. Exposure. Getting the right webcam settings for the Moon is fairly easy - simply increase the exposure rate and decrease the gain. For the Sun things are a little more complicated. The picture above is mostly over-exposed but it's not easy to find suitable settings for both the disk and the limb. This was made even more difficult by not being able to clearly see the laptop screen.

None of these problems is insurmountable but I need to be much better organised. All in all, more practice is needed.

Southern Lunar Crater Field

After far too long without an update, I've finally got some new pictures to upload. Unfortunately they aren't that good! The last eighteen months have consisted of a year of not being able to fit in much observing and then six months of pretty dismal weather. Even on the clear nights the observing conditions have been mostly bad.

This picture of part of the dense southern crater field illustrates my point:

 

At the top-left is the familiar sight of Clavius, and the cluster of craters in the centre of the picture are Gruemberger, Moretus, Curtius and Cysatus. The dark crater looming from the lower edge is Newton, somewhat tucked away for such a big name.

The air turbulence made it impossible to achieve good focus and a fuzzy image was the best I could produce. Furthermore, having to stay at low magnification resulted in my over-exposing the right-hand-side of the image.

P.S. If the picture looks really bad it could be Blogger playing up. First I found out it doesn't work with IE11, then some of my previously uploaded images went missing, and then all my new images appeared distorted. It seems to be ok at the moment but I wrote this post 2 months ago!

Plato

Moving north here is a nice wide angle shot of Plato and its surroundings:

A close-up really shows the rugged terrain and the shadows cast across the crater floor:

Displaying this alongside a previous image of a waxing Moon gives a good feel for the undulations on both sides of the crater rim.

Tycho

Here's another pair of pictures of one of the Moon's more prominent craters - this time Tycho. My previous attempt at this target is here and is a little blurry. These are better but still a bit off.

Clavius and Maginus are the two larger craters towards the bottom right. As this close-up shows, Tycho isn't the most spectacular of craters.

However it does give a good feel for the depth of the crater, particularly when compared to the length of shadow in Sasserides to the north

Copernicus

And now a close-up of Copernicus, which I'm posting second because I'm rather pleased with this one:

Really this should be rotated about 90 degrees anti-clockwise but for some reason it looks better this way up. This is undoubtedly one of my best pictures so far - it is sharp, detailed and has a good amount of shadow. My only previous close-up attempt at Copernicus was hampered by hazy skies but this picture would have improved any of my earlier efforts.

Eratosthenes

Following on from the previous post, here is a closer look at Eratosthenes:

I'm fairly pleased with this picture but I think I could have achieved slightly sharper focus. Nevertheless, it is a big improvement on my previous attempt with the 2x Barlow.

Copernicus and Eratosthenes

Another couple of old favourites but whereas I'd previously always photographed them individually this time I've got them in the same shot.

They're a good distance from the terminator and this highlights the detail without swamping them in shadow. I have a couple of close-ups that will follow shortly.