If anyone is interested in checking it before purchasing or comparing it with their own, these are the transmission curves in linear and logarithmic scales tested on my filter.
Optolong L-Ultimate 2" transmission curve test
If anyone is interested in checking it before purchasing or comparing it with their own, these are the transmission curves in linear and logarithmic scales tested on my filter.
That's very interesting, thank you!
I use the l-enhance currently and have been pleased with the results but I have read that the Ultimate offers a good upgrade (albeit at a cost) I'd be interested to hear your thoughts. Thanks David
Not OP, but I use the L-Ultimate myself. I’m very happy with it’s performance. I almost never see any halos. Recently I was imaging the area around Deneb and this is how the halo looks at 480s. With such a bright star, I think this is pretty good. The green and blue channels are where the halo’s at - the red channel shows little to no halo.
📷 image.png
The transmission curves Matteo posted are a little concerning, since L-Ultimate is supposed to have a 3nm bandwidth, while their measurements show a 4nm bandwidth, which could indicate poor quality control. Pixinsight’s filter curves measure the bandwidth at 3nm though.
Compared to the L-enhance, this filter will give much better images (more contrast, less unwanted signal), due to much tighter bandwidth. I think you’d be hard pressed to find a cheaper dualband filter that performs comparably to L-Ultimate.
Helpful Engaging
David Carr · Aug 18, 2025 at 08:51 AM
I use the l-enhance currently and have been pleased with the results but I have read that the Ultimate offers a good upgrade (albeit at a cost) I'd be interested to hear your thoughts. Thanks David
In Bortle 7 Austin, Texas, I used the L-enhance and switched to the L-Ultimate. Contrast is significantly better with the L-Ultimate which translates to less imaging time for the same S/N. Halos seem to be a bit better as well. I’m very pleased with the switch. However, if you live under darker skies, I’d expect the advantage to be less.
Well written Helpful Concise
Thanks Rob. Bortle 4/5 here but I’ve ordered one and should be here any day. Thanks for your reply
My test report of the Canon EF 300mm f/4 L IS USM for astrophotography
I am by far not an expert, but, hoping to do something nice for the community, I am submitting a report that would have helped me tremendously when choosing a lens for deep-sky astrophotography. I still think even a good doublet refractor is the way ...
Test report includes transmission curves data relevant to filter testing discussion.
Over correcting flats with fix
Howdy all. I've been rather bummed with the quality of my images for the last 9 months. I have data collected for two projects that I never finished due to the poor quality. Recently I discovered that my flats were over correcting my LRGB images ...
Flat correction issues affect image quality from filter and optical testing.