O111 halo issues...

[ollypenrice]

Hi, a guest using a 314L/Altair Astro 115 F7 and Baader NB filters found that his 0111 was giving severe haloes, though the other filters were fine. I lent him my Baader 0111 which was no different and my Astronomik which gave haloes about half as bright but still not acceptable. The haloes are assymetrical and always in the same orientation with the star across the chip. They are all in the same wheel so if there is a tilt it should be universal, or could it be the position of the filter in the wheel if the whole wheel is slightly tilted?

Any other ideas?

Olly

[Davey-T]

Hi Olly

I have 314L, Revelation 100mm ref and Baader nb filters . I have always had haloes around stars in O111 narrow band images using two different wheels .

Never thought much about it and had to process them out. Though at least they are symetrical.

Davey-T

[Spikey]

Here's a single un-calibrated sub of a 20 min OIII exposure with the Baader OIII 1.25" filter taken with a Atik16HR. I've only experienced haloes with Ha (Astronomik filter) not OIII.

[ollypenrice]

Yes, what's odd about this is that the Baader which has been fine in two of my scopes was not fine in that of the guest, so something must happen in certain optical trains to cause it. But what, Holmes??

Olly

[Spikey]

It's going to be the old swap around with known good kit to see if it follows the wheel or the scope I reckon

[Davey-T]

Here's a pic taken with Baader nb filters O111 blue haloes round stars

Davey-T

[NickK]

What focal ratio is the scope? If it's too fast then it could be playing a part in it.

[ollypenrice]

What focal ratio is the scope? If it's too fast then it could be playing a part in it.

No, that's one of the odd bits, Nick. The guest's scope was F7 and I've used my O111 filters down to F5.3 without difficulty.

Olly