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Custom Scientific Dielectric Johnson V Bandwidth

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mlyttelton
Custom Scientific Dielectric Johnson V Bandwidth

Having been practising for some time with imaging RGB filters, I now want to buy a set of Johnson Cousins filters (BVRI). Unfortunately there is currently a considerable delay in availability of Astrodon filters which would have been my first choice.

I am therefore considering the Custom Scientific dielectric set which they market as well as the glass filter Bessells.

I note that the V filter bandwidth is quite different to the standard Johnson V. See the attached graph of bandwidth which shows a very square V bandwidth from approx 4700 - 5700 Angstroms. AAVSO defines Johnson V as extending well up to 6200, as seen in the Astrodon filter. 

Is this an issue? Should I wait for the Astrodons which may be 3 months +?

Thanks 

Matthew Lyttelton

 

Bikeman
Bikeman's picture
I would not recommend those

I would not recommend those filters, for the reasons you mentioned. I've never seen filters that look like this beeing marketet as Johnson/Cousins filters?!

Are filters from Baader-Planetarium an alternative for you?

I just checked at a German online shop and they also have delivery delays, but are supposed to ship  by mid March. That is for 1.25" filters, tho.

CS

HB

mlyttelton
Baader V are currently

Baader V are currently unavailable. I had also decided against Baader because the V filter has been noted in previous AAVSO posts to extend furtherinto the red, to the extent that v magnitudes are being significantly affected by H alpha emission. 

Your response confirms my doubts about the Custom Scientific. I will wait for the Astrodons to become available. 
 

matthew

spp
spp's picture
Baader V filters

Matthew,

Could you please point me to the AAVSO forum discussion about this filter.

Phil

mlyttelton
Phil

Phil

see the thread on Nova del 2013  https://www.aavso.org/nova-del-2013-photometry #51 and following. 
matthew

spp
spp's picture
Nova del 2013 discussion

Thanks Matthew.  That whole discussion is interesting.

Does anyone have any information about whether the "red tail" in the Baader V filter has been fixed?

Phil

JBD
JBD's picture
HI

HI
It looks more like Sloan photometric filters

JBD

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