Ha solar vignetting

[Dawson]

Using a 50mm Lunt, B600 blocking filter and ZWO585MC, in fact with any camera, is the vignetting at the edge of the FoV caused primarily by the blocking filter? Even when the Sun is positioned in the centre of the FoV, equidistant from the vignetting, there is an even illumination of the disc, even when the seeing is perfect and there are no clouds. Again, is this in part due to the B600 blocking filter? Would the B1200 improve this? I’m hoping a video uploads but I’ve been fighting with the website from my phone for half an hour so now lost the will to try other options 🙂

Thanks.

[Callum Potter]

Hi James,

I don’t have direct experience as I have a B600 on my Lunt 60 – but the B600 is recommended for visual use, and the B1200 for imaging.

Quite an expensive upgrade as an experiment…

Hopefully someone will be able to advise better.

Callum

[Ron Morley]

Hi James, I have a 50mm Lunt with B600 which I use for solar imaging. It is a bit fiddly to use but not that bad. Lunt did advise that the LS50 was more for visual while the LS60 was best for imaging – but much more expensive. My initial problem was Newton Ring type banding with my Altair GPCAM2 130 Mono. This was reduced by using a tilt adapter. But there was still some uneven lighting across the solar disk. Nearly all problems disappeared when I put my large Altair 24M on the small Lunt. It looked ungainly but there were no rings, vignetting or uneven light that couldn’t be controlled. No need for a tilt adapter. I have a new ZWO ASI585MC but haven’t tried it on the Lunt. As you will have found the LS50 helical focuser and etalon adjuster are not fine adjustment controls – mine is on a camera tripod which is a bit wobbly – but practice makes adjustment manageable. I’ve noted with the larger chip on the 24M (it’s one of the models that uses the IMX571) that there seems to be better areas than others to position the solar image. Again trial and error. But I’m delighted with the LS50, the B600 and the images it produces. I’ve used a 5x Powermate too (with the 130) – which looked ridiculous on the scope – but it focused – and produced respectable edge prominence images. Ron

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