Blue Halos - Trius 814 + Esprit 80 Pro Refractor + Altinak

[Midnight_lightning]

Hi, I have found some similar posts but not found the answer I need so I hope you will bear with me. 

I have been using the above equipment for a while without issue for LRGB HA SII OIII (Baader) images but last night went for B33 and Altinak, in particular, has come out very bloated on the Blue stack - see images (Note the combined image has no calibration - just a quick stretch in star tools). I guess previous targets didn't have such bright stars in them.

Any suggestions for how to overcome this issue?

An IR/UV cut filter has been suggested and my scope takes a 2" filter somewhere in front of the filter wheel, is this the way forward, if so any suggestion on brand/specificaytion - I see different makes cover different bandwidths?

Are there any known issues with these filters, it would mean that it also gets used in conjunction with all my other filters including NB? I'm a bit worried about losing nebulosity etc.

I don't like adding more glass into the imaging train but I'm thinking I may not have any other option - or does someone produce an LRGB set with an IR/UV cut already built into the Blue filter?

Thanks

Jon

 

 

[oldannie]

Not sure whether this is relevant to your issue Jon but I had a problem with halos around eta Geminorium when imaging the Jellyfish nebula using Ha.  I was told  that one halo was probably off the CCD window, the faint outer one from the rear element of the scope whilst the middle one was probably off the filter!  I could try using a soft edged mask to tone it down a bit but all in all was probably stuck with it!  I use 2" Baader filters the Ha being 7nm.  As far as I am aware  if I used a narrower bandwidth I would get slightly more contrast, smaller stars so more moonlight and light pollution tolerant . but would pay a lot more and I assume maybe less likely to be parfocal.   Probably entirely irrelevant to your issue!!  

I think we've met on another forum!

Annie

 

 

[Midnight_lightning]

Hi Annie, great to hear from you, its been a while

I'm still trying to reach a conclusion on the issue I have but I suspect it is different to the one you outline. The problem only happens with the Blue filter and I think a cut filter would probably help but different makes operate at different wave lengths (e.g. from 380 or 400) and I'm not sure what I need - my other filters are Baader.

I'm also keen to find out what issues a Cut filter may add, for example you mention reflections and every new bit of glass is a potential source. 

All the best

Jon