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Which filter next OIII or SII?

Steve789

By Steve789
in Imaging - Discussion

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Steve789

Steve789

Posted
Posted

I'm sure this is a common question so I apologies if its been asked before.

I already have an astronomic 12nm Ha filter and have enough money in the piggy bank to get another narrowband filter but I'm not sure which to go for. If you had to make the choice between OIII or SII which would it be (and why?).

Eventually I'd like to have all three Ha, SII and OIII but funds won't stretch that far yet.

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Dave In Vermont

Dave In Vermont

Posted
Posted

How about one of these:

http://www.telescope.com/Astrophotography/Astrophotography-Filters/Orion-125-Dark-Frame-Imaging-Filter/pc/-1/c/4/sc/63/p/113382.uts

If that's too rich for your blood - get the OIII. Most would agree that Astronomic is the one to aim for. I have the Baader entry though. It works great!

Dave

ps - My first suggestion may be a joke..... :icon_mrgreen:

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wuthton

wuthton

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Ah, but it would be rude point out someone's lack of artistic appreciation... so I couldn't possibly. :evil: Anyway, it would be off topic :grin:

ChrisH

Off topic?

It's in the forum's finest traditions that no astronomy thread is complete without a discussion about Spanish goatherds or Monty Python's fish slapping dance.

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johnrt

johnrt

Posted
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Wow is that really a thing? "For when a lens cap on the end of your scope just won't do" ?? :huh::rolleyes::grin:

In all seriousness I would steer clear of the Astronomik OIII as it is prone to halo on bright stars, I had one which was terrible, had it swapped free of charge, it was much better but still not great. I'm afraid Astrodon got my money when it came to the crunch.

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Steve789

Steve789

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Thanks for the advice johnrt. Unfortunately it's come a couple of days too late as I received my new astronomik 12nm OIII filter today in the post ! I went for the astronomik just because I have an astronomik Ha filter and their website claimed they would be parfocal (I'll believe it when I see it).

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IanL

IanL

Posted
Posted

Wow is that really a thing? "For when a lens cap on the end of your scope just won't do" ?? :huh::rolleyes::grin:

Well in theory, it would be very useful for remote control imaging assuming you have a spare slot in the filter wheel, as it saves the airfare each time you need some darks (or more realistically getting one's backside off the sofa and in to the garden).  In practice light leakage in the filter wheel might limit its usefulness, and to be honest once you have a library of darks, how often are you going to redo them? 

Now if you advertised it as a filter wheel blank, you could see how it would be useful in keeping dust off the sensor/optical window without having to use an expensive filter as sacrificial cannon fodder.

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ChrisLX200

ChrisLX200

Posted
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Well in theory, it would be very useful for remote control imaging assuming you have a spare slot in the filter wheel, as it saves the airfare each time you need some darks (or more realistically getting one's backside off the sofa and in to the garden).  In practice light leakage in the filter wheel might limit its usefulness, and to be honest once you have a library of darks, how often are you going to redo them? 

Now if you advertised it as a filter wheel blank, you could see how it would be useful in keeping dust off the sensor/optical window without having to use an expensive filter as sacrificial cannon fodder.

I got one of those, but I can't remember where it came from, I have a feeling it was included with the filterwheel? Yes it is useful for darks, I use it in addition to a lens cap in case either it or the focuser has a small light leak.

ChrisH

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ollypenrice

ollypenrice

Posted
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Of course the OP might like to know that adjustable filters are available. They can select any narrowband wavelength down to fractions of a nanometre both well inside and outside of the visual spectrum. How useful is that? However, a 4 inch focuser won't be big enough...

NTT%20VLT%20INTERFEROMETRIC%20NB%20DETEC

This one was under construction when I visited it (and, swoon, touched it at Marseille Centre for Astrophysics. It's destined for use on the VLT and, later, the OWLT.

Come on Don Goldman, get copying!

:grin: lly

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MartinB

MartinB

Posted
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Thanks for the advice johnrt. Unfortunately it's come a couple of days too late as I received my new astronomik 12nm OIII filter today in the post ! I went for the astronomik just because I have an astronomik Ha filter and their website claimed they would be parfocal (I'll believe it when I see it).

Don't worry Steve, you have made the right choice. I have used Astronomic filters a fair bit and only one ever produced halos (a 2" Ha). They went through a phase of really suffering with this problem. If you do get them don't hesitate to send it back. It is pretty important for your filters to be par focal.

Bringing back some controversy - distinguishing a 3mm astrodon Ha from a 12mm astronomic Ha using calibrated and matched images is about as easy as telling a Puligny Montrachet from from a Chassagne Montrachet. It can be done with practice if you ever really feel the need and have the money to spare!

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DaveS

DaveS

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True, but a 12 nm Astronomik won't enable you to separate Ha from [NII], you'll get them blurging on top of each other.

Of course, you may not *want* to separate Ha from [NII], but it's nice to be able to do so, and you can always combine the subs later.

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ollypenrice

ollypenrice

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The mark of a good salesman is to make people desire things they never realised they needed!

...or fear things they had never previously feared until the salesman brandished the antidote! Remember 'Night starvation?'  The cure was Horlicks or Ovaltine or something. Here in France it's cholesterol that is to be feared now that we have things rich in Omega Three.  Being a good consumer means learning to be afraid of everything for which a cure is miraculously available.

Oh no, I may be suffering Nitrogen Contamination in my Ha layer.  :eek:  The stress is killing me, pass me a kilo of omega three!! Eek, but then again I could have Nitrogen Starvation through using a 3 Nan.... I'm dithering - but at least that's good for the signal to noise....

Olly

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