A question about Baader OIII filter

[lensman57]

Hi,

I have managed to purchase a used OIII filter in mint condition, however as I concluded a test last night I noticed that there was considerable focus shift between this filter and Baader Ha filter, also some stars seem to have a large halo around them. The imaging conditions were as everyone has now experinced during these hot summer evenings, hazy skies with alot of moisture. Is the halo normal or is something wrong?

Many thanks and Regards for your help.

A.G

[sloz1664]

I would cross reference with other filters I have and see if there is halo's showing in some form on them. hopefully it's only the atmospheric conditions.

cheers

Steve

[ollypenrice]

I'd just check that you have the CCD OIII filter and not the visual one. I find that at F5 the Ha and OIII are exactly parfocal so I suspect that you may not have the imaging filter there. It's marked CCD on the outer rim.

Olly

[lensman57]

I'd just check that you have the CCD OIII filter and not the visual one. I find that at F5 the Ha and OIII are exactly parfocal so I suspect that you may not have the imaging filter there. It's marked CCD on the outer rim.

Olly

Good afternoon Olly and Steve,

You are indeed correct, it does not state that it is a CCD one, so that explains it all. Well , it was £40.00 wasted. May I ask if there is any merit in using a multi band filter such as Hutech IDAS NBN filter? It is supposed to pass all the good stuff through, Ha, HB, Oiii and block out other wavelengths.

Regards,

A.G

[ollypenrice]

Good afternoon Olly and Steve,

You are indeed correct, it does not state that it is a CCD one, so that explains it all. Well , it was £40.00 wasted. May I ask if there is any merit in using a multi band filter such as Hutech IDAS NBN filter? It is supposed to pass all the good stuff through, Ha, HB, Oiii and block out other wavelengths.

Regards,

A.G

You should easily get your £40 back. This is an outstandingly good visual filter, essential on the Veil and many other objects. It is one of my standard bag of tricks when doing visual astronomy and I couldn't be without it. If you wish to sell it then I'd be happy to offer this endorsement via PM or whatever. I paid more than £40 for mine!!

Olly

[lensman57]

You should easily get your £40 back. This is an outstandingly good visual filter, essential on the Veil and many other objects. It is one of my standard bag of tricks when doing visual astronomy and I couldn't be without it. If you wish to sell it then I'd be happy to offer this endorsement via PM or whatever. I paid more than £40 for mine!!

Olly

Good evening Olly,

Thanks for your reply sir, I don't do much visual as all my scopes are between 80 and 127mm. I may put it up for sale and put it towards a ccd one, it is only a 1.25" one so I need to top it up by another £35.00. So much to learn and so few clear nights.

Regards,

A.G