#1  
Old 09-11-2018, 03:42 PM
Merlin66's Avatar
Merlin66 (Ken)
Registered User

Merlin66 is offline
 
Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,904
Bi wavelength filter!

https://www.cyclopsoptics.com/astron...d-filter-48mm/

Appears to give good filtering and suppression of background lighting.
Would need an OSC camera to separate and process the OIII and Ha images.
Reply With Quote
  #2  
Old 10-11-2018, 02:12 PM
Lognic04's Avatar
Lognic04 (Logan)
Registered User

Lognic04 is offline
 
Join Date: Mar 2016
Location: Melbourne, VIC
Posts: 889
You'll find it's just a rebranded UHC filter:
Attached Thumbnails
Click for full-size image (astronomik_uhc_trans.png)
76.3 KB31 views
Reply With Quote
  #3  
Old 10-11-2018, 02:22 PM
Merlin66's Avatar
Merlin66 (Ken)
Registered User

Merlin66 is offline
 
Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,904
Logan,
The tight transmission curves at OIII and Ha shows it's much more than an UHC filter.
Attached Thumbnails
Click for full-size image (duonarrowband-spectrum-2-en.jpg)
158.4 KB26 views
Reply With Quote
  #4  
Old 10-11-2018, 08:52 PM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by Merlin66 View Post
Logan,
The tight transmission curves at OIII and Ha shows it's much more than an UHC filter.
Yes the peaks are much tighter in bandwidth on the dual narrowband filter compared with the UHC filter. Some time ago I had the idea of using a UHC filter in this way with a DSLR and using the BLUE channel for OIII, and RED channel for Ha. For a dark sky (no light pollution) one could even use the GREEN channel with either the dual narrowband or UHC filter. I had made a comparison of these together with a Nikon D800 sensor response. I will look for the comparison and post it here later.

Best
JA
Reply With Quote
  #5  
Old 04-03-2019, 02:36 PM
gb44 (Glenn)
Registered User

gb44 is offline
 
Join Date: Jul 2012
Location: Gold Coast
Posts: 273
Possibly best filter for DSLR

Ken
Can you give us an update on this filter?
Did you buy it?

Cheers
GlennB
Reply With Quote
  #6  
Old 04-03-2019, 02:47 PM
Merlin66's Avatar
Merlin66 (Ken)
Registered User

Merlin66 is offline
 
Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,904
Glenn,
No, I didn't buy this filter.
I only do spectroscopy, so it wouldn't be of much help to me.

I see over on SGL that there are some members starting to use bi wavelength filters....early days.
Reply With Quote
  #7  
Old 04-03-2019, 02:48 PM
gb44 (Glenn)
Registered User

gb44 is offline
 
Join Date: Jul 2012
Location: Gold Coast
Posts: 273
Ok thanks.

I also found this $300 filter.
https://www.cyclopsoptics.com/filter...pectra-filter/

GlennB
Reply With Quote
  #8  
Old 04-03-2019, 03:35 PM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by JA View Post
I had made a comparison of these together with a Nikon D800 sensor response. I will look for the comparison and post it here later.

Best
JA
Here is that comparison of the UHC filter & Dual Narrowband filter against the Nikon D800 spectral response. The curves are aligned by eye at 400 and 700nm.

As is evident the peaks are much tighter in bandwidth on the dual narrowband filter (Bandwidth = ~15nm OIII & ~18nm Ha [even less if the D800 response were to be included) compared with the UHC filter(Bandwidth = ~50nm OIII & ~28nm Ha [with D800 response included - brown line line on top graph]). At a fraction of the cost, or perhaps something that one might already have, I would give it a try in the same way as the dual narrowband filter is used on colour cameras, for "narrowish" - band imaging or of course stick to "normal" colour imaging with it to remove some light pollution.

Best
JA
Attached Thumbnails
Click for full-size image (UHC v Dual Narrowband + D800 Response.jpg)
101.4 KB26 views

Last edited by JA; 04-03-2019 at 03:50 PM.
Reply With Quote
  #9  
Old 04-03-2019, 03:43 PM
Merlin66's Avatar
Merlin66 (Ken)
Registered User

Merlin66 is offline
 
Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,904
JA, et al,
I think Glenn was hoping to see some actual AP images with the bi-wavelength filter.....
Reply With Quote
  #10  
Old 04-03-2019, 04:03 PM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by Merlin66 View Post
JA, et al,
I think Glenn was hoping to see some actual AP images with the bi-wavelength filter.....
Hi K,
He didn't mention wanting to see images otherwise I would have pointed him to the sample images in your original link. Image number 5 in particular is an excellent demonstration of a difference, purportedly of the effect with and without the filter.

Best
JA
Reply With Quote
  #11  
Old 04-03-2019, 06:28 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
I got the STC Duo from Cyclops a few weeks ago. Using it on an asi071 OSC.

http://www.iceinspace.com.au/forum/s...d.php?t=173501
http://www.iceinspace.com.au/forum/s...d.php?t=173374

Processed as an OSC image. Need long subs as the two bands are narrow (10nm). Need 10min subs with the filter -compared to 1.5min with just a uv/ir filter. I'm still capturing lights for these images.
Reply With Quote
  #12  
Old 04-03-2019, 06:39 PM
Merlin66's Avatar
Merlin66 (Ken)
Registered User

Merlin66 is offline
 
Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,904
Chris,
How does the SCT bi-filter compare with the smaller bi- wavelength version??
Reply With Quote
  #13  
Old 04-03-2019, 07:12 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
What's the other one you are talking about Ken? I got this one

STC Astro Duo-Narrowband Filter (48mm / 2")
https://www.cyclopsoptics.com/astron...filter-48mm-2/

Sorry, I get confused easily ...
Reply With Quote
  #14  
Old 04-03-2019, 07:41 PM
Merlin66's Avatar
Merlin66 (Ken)
Registered User

Merlin66 is offline
 
Join Date: Oct 2005
Location: Junortoun Vic
Posts: 8,904
Chris,
The term SCT threw me....
There are also bi and tri wavelength filters designed as full aperture SCT filters.
Reply With Quote
  #15  
Old 04-03-2019, 08:34 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
Oops. Yes STC filter. This is the best comparison I have of using the Duo filter, on the Tarantula.

First is 2.7 hours of 90sec lights with UV/IR filter.
Second is 2.8 hours of 6min lights with STC Duo narrow band-filter.

Ignore the difference in resolution - as the first image is binned 2x2, the second isn't.

Edit: the first shot is at f5.9 and the second with the duo is f5.0.
Attached Thumbnails
Click for full-size image (NGC2070_L_integration_DBE-6-final-bin2_2.jpg)
171.7 KB42 views
Click for full-size image (NGC2070_integration_2019_02_12_DBE-4_final.jpg)
217.9 KB44 views

Last edited by ChrisV; 05-03-2019 at 08:09 AM.
Reply With Quote
  #16  
Old 05-03-2019, 10:09 AM
sil's Avatar
sil (Steve)
Not even a speck of dust

sil is offline
 
Join Date: Jun 2012
Location: Canberra
Posts: 1,474
Interesting thread. I was wondering about this filter too as I use the UHC one currently. For me I dont think I can us the bi-wave, though this thread has me thinking, especially seeing the wavelength graph comparisons that I should look at stripping my OSC subs and try processing as Ha Si filtered data and see what i get.
Reply With Quote
  #17  
Old 05-03-2019, 10:20 AM
JA
.....

JA is offline
 
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,945
Quote:
Originally Posted by sil View Post
Interesting thread. I was wondering about this filter too as I use the UHC one currently. For me I dont think I can us the bi-wave, though this thread has me thinking, especially seeing the wavelength graph comparisons that I should look at stripping my OSC subs and try processing as Ha Si filtered data and see what i get.
I would definitely try that as the OIII & Ha bands are typically "only" about 2 to 3 times wider with the UHC filter if we also take in to account the camera's Ha response. It would be great to see such.

Best
JA
Reply With Quote
  #18  
Old 05-03-2019, 01:21 PM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
Quote:
Originally Posted by Merlin66 View Post
Logan,
The tight transmission curves at OIII and Ha shows it's much more than an UHC filter.
Correct. That's why the stars don't bloat after 700nm.
Reply With Quote
  #19  
Old 05-03-2019, 04:13 PM
ChrisV's Avatar
ChrisV (Chris)
Registered User

ChrisV is offline
 
Join Date: Aug 2015
Location: Sydney
Posts: 1,737
Before getting the duo filter I used a UHC filter a fair bit. The duo is a very different beast due to the much narrower bandpass as others have mentioned. I'm guessing but think I'd need subs at least 5x longer to get background levels equivalent to those with the UHC filter. Might do a comparison on a dud night.
Reply With Quote
  #20  
Old 05-03-2019, 04:58 PM
glend (Glen)
Registered User

glend is offline
 
Join Date: Jun 2013
Location: Lake Macquarie
Posts: 7,033
Chris the STC Duo certainly looks like a mono layered narrowband result. Good investment. I would be tempted to try it with my Nikon (when night's get cooler).
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 07:48 PM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Testar
Advertisement