First Solar attempt

[jnp]

I made myself a neutral filter with Baader film and had a go at solar imaging for the first time, using a 90mm DIY refractor with a F10 lens.

It was interesting to see the boiling effect for the first time and its quite civilised doing this at daytime, but I am a bit underwhelmed with the photos, I know we are at a solar minimum, but just two sunspot clusters?

I tried lots of shots at varying shutter speeds (ISO 100 with a Canon 1000D), but could not see any prominances etc. I can get reasonable Deep Sky images, but seem to be at a loss for Solar imaging. Any pointers as to where I am going wrong, or is it that you can't do that much with a DIY white light filter? Even playing with tone curves fails to show much more detail.

DSS refused to stack my images so I have attached two clipped but unaltered shots. One is prime focus, the other was taken with a 2x barlow.

thanks

John

[Merlin66]

With a white light solar filter ( ie Baader film etc) this is as good as it gets!

With improved focus and stacking you should get a bit more surface detail but you won't get any Ha detail like prominences etc unless you spend $$$$$$ on a special filter ( SM60/BF10) or a PST.

[brianb]

Excellent images!

Incidentally the Sun has been so quiet recently that you're lucky to have anything at all visible on the disk in white light.

[legion48]

Nice images John.

Did you take them a few days ago? Yesterday the spots were quite near the limb.

[jnp]

I took the shots on New Years Day. Seems that I was lucky to have got anything at all if the spots are moving out of view.

This probably a really dumb question, but I assume the $$$$$$ Ha Solar filters go on the objective end. Would there be any mileage in using a while light filter at the objective end to reduce the intensity, plus a normal Ha filter (typically used for DSO) at the eyepiece end, to err..just pass Ha?

Anyway, I managed to stack about 15 shots using Registrax v5 and heres the result. I'd be intersted to know the correct way to stack Solar images as DSS seems to always need 'stars'?

thanks

John

[brianb]

Would there be any mileage in using a while light filter at the objective end to reduce the intensity, plus a normal Ha filter (typically used for DSO) at the eyepiece end, to err..just pass Ha?

No, the "tightest" Ha nebula filters have about 100 times as wide a bandwidth as a proper solar Ha filter. You need a bandwidth < 0.1nm to get good definition of the surface features. Not to mention the safety issues. 0.15 nm would show prominences but at 7nm you'd get far too much background light.

The proper solar filters are tunable, if you offset the tuning by 0.1nm or so you get a view which is essentially the same as the white light view. No surface details except spots if present, no prominences.

I'd be intersted to know the correct way to stack Solar images

Registax is happy to align & stack solar images ...

[jnp]

Brian,

Thanks for the concise and informative explanation about different types of Ha filter. Love your 5th Jan shots too.

cheers

John