Filter guru's. I was hoping for your help and a bit of a shortcut. I have been doing mostly visual observing for some time now, or planetary imaging with my...
... Kevin I believe there's software that will do the calculations for you. You can image a G2V star then use the software to calculate the proper ratio. I...
I'm new but I don't see anyone else jumping in here so I'll give it my best. If anyone can make my answers better or if anyone sees an error, please jump...
Hi, I haven't been posting here much lately since getting involved in spectroscopy. I can currently do low resolution spectroscopy to better than ~15A...
the guy that used to say that 3nm is bad and 6nm is good is now selling something he calls 3nm and has no explanation why his position changed how about...
Hi, I have been doing some spectroscopy on ngc7009. I have seen references where there is significant NII emission from this planetary nebula, see: ...
All I can say is that you'd better calibrate exactly where the bandpasses of the filters are before attempting the workaround by using 2 Ha filters. Perhaps...
Being in a lucky location that I never needed to play with filters. Or at least never thought of bothering with it. I have been doing so reading as i look at...
Hi Joe, sky pollution filters are still made. Most every filter manufacturer has one available for sale. Narrowband filters address specific needs. A major...
Hi Joe, Yes, light pollution reduction filters are widely available and some work well for removing the type of light pollution which is created by many kinds...
Hi my NII filter workaround will have to wait. I just received the Custom Scientific 3nm Ha filter that I purchased on AstroMart. The filter looked physically...
Somehow I suspect that the problem may be with Custom Scientific quality control, rather than stability. Christian Buil also quotes a similar off-center...
Hi Samir, that's very interesting, thank you. I remember years ago that people were concerned about bandpass shifting in 10nm bandpass filters. Seems that...
Hi, after observing the out of spec Custom Scientific 3nm filter, I was concerned about my 2" Baader Ha filter. The last time I measured transmission of that...
Hi, I ran a few more Baader filters of mine through a precision spectrograph, +-0.06nm accurate. Four new 1000 data point files with filter curves have been ...
Richard: Tell us more about unstable filters ? I know that the V filter for measuring brightness for VSO degrades with time. I didn't think that dielectric...
Hi Larry, filter manufactures advertise their filter stability. Interference filters can be changed by moisture diffusion and temperature. See this for...
Hi, the Baader OIII imaging filter misses most of the 4959A line of OIII. The advertisements of the Baader Visual OIII filter touts capturing both the 4949A...
Hi, just to follow up on my 2" Baader Visual OIII testing, I measured the light leakage from 190 to 950nm. The chart can be seen in file folder Filter tests,...
Hi, I see a lot of HeII (4686A) in planetary nebula and I understand that HeII filters are used for finding Wolf-Rayet stars. Is there anybody here currently...
Hi Richard, very interesting! There's a lot of information on HeII in your images. Seems to be one of the last elements blown off the star. I'm going to get a...
I tried it on the crescent, and it has a Wolf Rayet star. I didn't see any action in the data but I may give it a half hour with high binning to try one more...
Hi Richard, one additional thought. What is the bandpass of your HeII filter? Gas maybe being expelled from the Wolf so fast that your narrow bandpass HeII...
Hi, I have tested the 1" Thorlabs 470nm 10nm (HeII) fitler. The chart can be seen in file folder Filter tests, file Thorlabs_HeII.xls. Notice that the filter...
two comments: these low cost filters are often designed for creating monochromatic light rather than for imaging. To be useful for imaging there is a substrate...
Having problems with message search?
Fill out this form to ensure your group is one of the first to be migrated to the new message search system.
