Chroma 3nm or stick with baader

[Ken82]

I ordered a full set of baader narrowband filters some time ago which have been good. I do get halos with the oiii but reading around this appears normal. Just waiting for my SII to arrive as these are delayed for a while. I had initially wanted the narrower 4.5nm oiii but I’ve been told there is a long waiting time for these (possibly production issue)
 

In the mean time whilst I wait chroma have become available on the FLO website. I could potentially cancel the SII and look at getting the narrower 3nm or 5nm filters but is it worth it ? 
 

Has anyone experience with chroma filters ? Is it worth the narrower bandpass ? Would the oiii get rid of the halos ? I’m imaging from a fairly light polluted area bortle 6??? With refractor at f5 

thanks 

[tooth_dr]

@Jkulin I think John uses these and really likes them 

[Gina]

I have no experience of Chroma filters but I can tell you that Astrodon 3nm filters are much better than their 5nm NB filters at reducing star size and killing moonlight.  I know because I have both and never regret forking out for the 3nm filters.  They make all the difference to narrow band imaging.

Edited March 7, 2020 by Gina

[david_taurus83]

No experience with either of these top end filters but reading other reports the Chroma are regarded to be as good as the Astrodons.

[kirkster501]

7 minutes ago, Gina said:

I have no experience of Chroma filters but I can tell you that Astrodon 3nm filters are much better than their 5nm NB filters at reducing star size and killing moonlight.  I know because I have both and never regret forking out for the 3nm filters.  They make all the difference to narrow band imaging.

Yep, agreed about the Astrodon 3nm.  Moonlight hardly bothers them at all.  Be prepared to shell out some serious coin for Astrodon and Chroma.

[Jkulin]

57 minutes ago, Ken82 said:

I do get halos with the oiii but reading around this appears normal

Hi Ken,

Halos are not normal, it is is sign of a batch fault. If your filters are doing that then send them back with proof. Baader are usually quite conscientious and if presented with proof will replace them, one of my very good friends knows the owner and was given some to try, when he demonstrated that there were halos they were exchanged without any question, I have also heard from others about halos and advised them to do the same.

With regards to Chroma, they used to make them for Astrodon (Allegedly), they are blindingly exceptional filters, I use the 2" unmounted and the difference it has made to my imaging is unbelievably, NB or Broadband, I don't seem to get anywhere near the problems that others do.

I do hear that the new owners of Astrodon are not brilliant customer service wise, perhaps they are a bit complacent with their reputation!

Chromas are about 2/3rd's of the price of Astrodon, usually in stock and buy them direct as you will save money.

HTH

[Gina]

That's interesting.  If I find I want any more filters I'll try Chroma.

[kirkster501]

I have been extremely pleased with both sets of my Astrodons.  Their ability is far in excess of my own.

[ollypenrice]

People I trust say there is no disadvantage with the Chromas and they are cheaper (or, at least, less expensive!) so I'll be trying their OIII, I think.

Olly

[Jkulin]

Interestingly @ollypenrice all of my LRGB and NB are parfocal, so I only ever focus with the LUM, saves a hell of a lot of time focusing and the filters are bi directional, it does not matter which way they are mounted.

[don4l]

I am very happy with my Chroma filters.

They may seem a bit expensive, but they have upgraded the performance of my camera and scope.  I didn't really understand this properly until I saw the first 10m Ha sub appear on my laptop screen.

[Ken82]

Thanks for the feedback everyone ! I will have a further look into the cause of the halo in the oiii filter and let you know. I think I’m going to cancel my baader SII filter order for now. 

A friend has posted this to me, although they have no direct experience with the chroma filters they have based the comments on what’s written on the FLO website - 

 

Narrower band will result in better SNR as it will cut away more of the LP.

At some point you need to be careful about speed of the system, as light coming at an angle will have its effective wavelength "shifted" with respect to filter. It is not only related to speed of the beam but also to focal length of the scope and so called instrument angles - how large illuminated circle vs focal length of the scope.

Chroma 3nm Ha filters are apparently designed for:

"Filters designed for use with CCD and for f/4.0 or slower"

So that is fine, but there is spec that I don't particularly like:

Transmitted wavefront better than 0.25 waves/inch

This means that quality of filter is "guaranteed" to be 1/4 wave - and not over whole aperture of 1.25" filter. 1/4 wave optics is considered borderline usable, so called diffraction limited, but in practice people see difference between it and 1/6 or 1/7 optics.

And all of that at a cost of 500e. I don't know, I'm skeptical about it. I would rather use Baader Ha filter 7nm that is x4 less expensive but tried and tested to work well than something new and very expensive

 

[Gina]

Anyone know what the corresponding Astrodon figures are?  IOW are the Chroma filters of lower specification?  I use my Astrodons at f2.5 upwards.  I'm assuming they are including CMOS sensors in their CCD.

[Adam J]

On 07/03/2020 at 16:04, ollypenrice said:

People I trust say there is no disadvantage with the Chromas and they are cheaper (or, at least, less expensive!) so I'll be trying their OIII, I think.

Olly

Odd thing is that Chroma 5nm are more expensive than AD 5nm....and actually very similar in price to their 3nm...very odd.

[Whirlwind]

On 08/03/2020 at 10:59, Gina said:

Anyone know what the corresponding Astrodon figures are?  IOW are the Chroma filters of lower specification?  I use my Astrodons at f2.5 upwards.  I'm assuming they are including CMOS sensors in their CCD.

Astrodon quote they are suitable down to F3.5 and are also 1/4 wave.  So no real difference on these ones.

https://astrodon.com/products/astrodon-narrowband-filters/

[Adam J]

Are Chroma filters better than Baader, yes significantly so for the 3nm versions. But should you upgrade? That is purely a question of how deep your pockets are.

Adam

[don4l]

I use the Chroma filters at F3.6, F5 and F8.  I haven't seen any evidence that their performance is impaired at 3.6.

[Gina]

What is the effect of using NB filters at very wide apertures?  I use Astrodon 3nm at f 2.5 and don't seem to have any problem.

[souls33k3r]

From what i understood was that the bandwidth could shift slightly and enough to go off band with the 3nm filters.

[Adam J]

6 hours ago, souls33k3r said:

From what i understood was that the bandwidth could shift slightly and enough to go off band with the 3nm filters.

yes but you will always get something as it only occurs for the steepest section of the light cone.

[souls33k3r]

But then is that "something" enough to be justifying the spend for a 3nm filter or better stick with a 5nm and get both Ha and NII transmissions which will happily go down to a faster Focal length? 

[Highburymark]

Not an imager but I use a Chroma 3nm ha filter for night vision astronomy - as does Gavstar, a regular contributor to this forum. It’s frankly incredible - a big step up from the 7nm Baader filter I used previously from my city centre location. 

[Gina]

I have a 5nm Ha filter as well as 3nm so I could see if the 5nm gives any more signal at f2.8.

[souls33k3r]

9 minutes ago, Gina said:

I have a 5nm Ha filter as well as 3nm so I could see if the 5nm gives any more signal at f2.8.

That would be super interesting to see Gina. 

[Gina]

Ideally, I would want 3nm Ha on one camera and 5nm on the other so that subs could be taken at the same time.  ATM I have both Ha filters and SII in the filter wheel and fixed 3nm OIII in the other imager but I could swap filters over and put one of the Ha filters in place of the OIII.