New Baader Filters

[FLO]

As a confessed Filter-Nut, I have many, many filters on my cases. Never had a problem with the Baader NB's. In fact Baader has another new H-a filter: H-alpha Interline camera 35nm. Available in both 1.25" and 2" format. I just got one in. 

It is good to hear you are pleased with your filters. The Baader 35nm arrived here in the UK back in 2008 and is intended for ultra-fast imaging setups. SteveL wrote a post detailing his experience of the filter: 

IC1805 Heart Nebula, with new Baader 35nm Ha filter

The Baader 7nm Ha will indeed work at very wide acceptance angles- I used the 2" filter on front of a 50mm F1.4 camera lens for this shot of Cygnus/Cephius

That will be because the filter was fitted to the front of your lens

The light only forms a cone when it exits the optic, then if the cone is unusually steep (fast telescopes) it can be a problem for some filters. 

HTH, 

Steve

[olivdeso]

up

Hi all,

-> Ha 3.5nm :  We have measured in lab (using a,n HP spectrophotometer) the new Baader Ha 3.5nm. I can confirm its FWHM is 3.5nm and is its percfectly centered on the Ha line. (sorry I don't have the graph yet)

-> OIII 8.5nm : we have measured an Baader OIII and a Hbeta and other filter.

FWHM detailed measurement: (we used a gaussian fit for FWHM calculation)

- the filter is perfectly in line with its specifications:

   - transimission 85% (86% claimed)

   - FWHM 7.9nm  (8.5nm claimed)

   - well centered on the 501nm line

   - in fact all the Baader filter we tested are perfectly in line with their specification, not even a nanometer difference...good job!

Comparison with some other OIII filters

- For visual use I have choosen the 1000 oaks, which transmits both the 496nm and 501nm lines at 95% and cheaper than the Lumicon.

-For photo use, the baader is more suitable with its narrower bandwidth, a real photo OIII filter which only transmits the 501nm and thus can provide a narrower bandwidth than the "visual" OIII like the lumicon, 1000oks and else that transmits both lines.

- The low cost skywacher have a wider bandwidth, but it still narrower than an UHC and is a real OIII which does not transmit the Hbeta line. It cans give good results under a moderate to low light polution condition.

Now the point which may explain star bloats :

you can see that none of the tested filters completly cut the Ir or Uv band. For visual use there is not any impact.

But for photo use, this may be a concern especially with refrators.

The baader is the best performer among the 3 tested : no leaks in UV, but there are still some small leaks in IR at 750nm, 850nm and 950/1050nm. 

This particular filter is about 5 years old, and this issue may have been solved or improved since, but with modern sensor used on refractor, these kind og leaks would obviously result in start bloating.

-> in case of star bloat, I would suggest the use of an Ir cut filter stacked onto the Baader OIII.

Olivier

[olivdeso]

p.s. where is the "edit" button?

[bilgebay]

Any updates on these filters anyone ?

[bilgebay]

I have just discovered that Andreas have been using these filters with success here --> http://www.astrobin.com/users/equinoxx/

Hope this helps...