Magnum

if you look at the pass bands of the filter they only let in 2 or 3 narrow bands which don't include any UV or IR so they both are effectively have UV?IR blocking built in, but it could be in the OIII band which is blue. However I dont get them if I use these filters on my other scopes and I dont get them if I use any other filter with the samyang, I only get them using the dual narrowband filters and samyang together with the OSC camera, that include all 3 that ive tried L enhance, L extreme & Tri band. ive added some more examples to my last reply for interest.

I believe its specific wavelength stars the very red carbon stars.

Here is one I took with the L Enhance, 533mc & sayang lens @ f2.8, when I first took this I was convinced id discovered something, but since then I get them pop up all the time LOL. I also found an image with same framing as mine taken with the identical setup and the identical ring on the same star, if you zoom around the full image there are some much fainter ones on several other stars. As I Said before its only on Red stars. Ive attached some example below from several images, as you can see the pop up randomly, not dependent on brightness at all.

ive found another one in the Original posters image, im 90% sure this is the same filter phenomenon I get with my triband and L enhance filters, every image I take with them has 1 0r 2 sometimes half a dozen of them, and yes they show in every sub. And yes they are always close around the star, its nothing like a typical halo, I believe its a spectral interference effect between the filter and glass, due to these new filter trying to pass 2 or 3 lines at the same time. Lee

No it’s just an artefact I get when using any dual narrowband filters in combination with the Samyang lens, on a handful of red stars. the first time I saw one last year I thought it was a planetary nebula too, and sent to the BAA as if never seen that type of halo before, then I found an image taken of the same area with the exact same setup on the other side of the world and that image had the same ring on the same star. Pretty much every image I take using the Tri Band or L enhance will produce have 1 or 2 stars with the same ring, and they are always red stars and usually dim ones.

Ive had it on only 1 star sometimes, but it will always be a red star, what filter are you using? lee

Captured this wide field centred on Gamma Cygni last night, I almost didn't go out then made up my mind at 12, so waisted about 3 hours of imaging time, anyway still managed to get 2 hours and enough to produce a smooth image. So this is 25 x 5 mins with my ZWO ASI533MC OSC cmos camera Gain100 Offset20 + Altair Triband filter & the excellent Samyang 135mm f2 lens set @ f2.4, mounted on the EQ8. Guided, Captured, stacked & stretched in MaximDL, slightly processed in Photoshop, No Calibration frames.

Are you using a dual narrowband filter? I get rings on some red stars with mine when using Altair tri band or L enhance combined with my samyang lens have a look on my image here both on the garnet star then also on a fainter red star near top left

Nice, what Bortle sky are you imaging from? and any filter?

Nice first light Olly, You might be interested in my latest 2 dual narrowband images with my 533 the little brother to the 2600, now ive developed a decent work flow im very happy with the results, ive changed a couple of steps since the data I sent you on Orion. Using the either the Altair Triband or Optolong L Enhance In comparison to real narrowband imaging with mono, I find OSC with dual band filters give a totally different look, its more like broadband image with some ha data added, as the stars don't get suppressed hardly at all, I did try a L Extreme, but I didnt like that as I found I then lost the range of colours in the targets ( ie the reds were all 1 shade ) as well as loosing the yellow stars. I actually really like the effect of having a fairy dust multitude of stars at same time as the Ha, and for me its not going to replace real narrowband, I have a triple rig now so im producing full colour with the 533 triband setup, then if I want to isolate the ha and suppress stars I shoot pure HA mono images with either of the other 2 scopes as I still love mono images. Only thing id watch with the dual narrowband filters is halos, you need to get the filter as close to the sensor as possible when using fast optics, especially with my samyang f2 lens but only on some red stars. Lee

If I can get away without flats then I do, which is usually doable on anything but galactic IFN as long as I keep everything perfectly dust free. Im sticking to my standard longer CCD sub lengths with the cmos, I tried loads of short ones but then I find the image needs stretching a lot more, plus stacking takes too long for me if I have more than 50 subs, I guess im too impatient LOL

I took this image of the Elephant Trunk IC1396 3 weeks ago but forgot to post until now. This is 43 x 5 mins with my ZWO ASI533MC camera + Altair Triband filter and the Samyang 135mm f2 lens @ f2.4. Guided, captured stacked and stretched in MaximDL, processed in Photoshop, no calibration frames as that's how I roll 😛 P.S. Yes I know there is an odd ring Halo around the Garnet star, but its an unavoidable artefact on specific colour red stars when using the samyang 135 with Dual Narrowband filters, ive experienced it with the L Enhance, L Extreme and now the Altair Triband. It pops up randomly on specific wavelength red stars and is not related to their brightness. It doesn't bother me at all but thought id point it out before I get comments about it hahahhaahahha, most of the time the red stars are so dim it doesn't really show. Lee

Captured this image of the Heart and Soul nebulae a couple of weeks ago on 16th August but forgot to post on here, 26 x 5 mins with my ZWO ASI533MC camera Gain100 Offset20, + Altair Triband filter & the Samyang 135mm lens @ f2.4. Guided, captured, stacked and stretched in MaximDL, processed in Photoshop. No calibration frames. Really pleased with the image as Ive finally found a good workflow the ASI533 cmos, it has required quite a change compared to my normal longstanding workflow with my mono CCD's, now feel a lot happier with the purchase. I still dont think CMOS is any better than CCD in contrary to popular opinion ( I own both ), but this latest gen has closed the gap to where I feel they are almost equal. Lee

Thanks Olly, it reached max altitude of 15 degrees on the last sub so yes pretty darn low. I normally dont like to image below 40 degrees, but it came out surprisingly well considering.

Had a quick go on M20 the Trifid nebula last night, this is very tricky for me froim the uk as its so low, which means im shooting through tyhe thickest and most turbulent part of the atmosphere, causing the detail to get smeared and the stars to become very bloated. So have been struggling to process it for several hours the stars were particularly stubborn and not still not great but that's as small as I can get them without artefacts. Only 15 x 3 mins with my ASI533mc camera and the Meade127 F7.5 Triplet refractor. No calibration frames Lee

So that’s where they stored the Arc of the covenent at the end of raider of the lost Arc😜 😜

M16 Pillars Of Creation/Eagle Nebula. Meade 127 F7.5 Triplet refractor & Atik460EX mono CCD, 15 x 5 min subs in Ha. This target is always pretty low from the uk, last nights data was captured between 16 & 25 degrees above the horizon, so difficult to match the clarity of images taken from lower latitudes but came out better than I expected. Lee

The difference between the D1 and D3 was minimal anyway, The D3 is the latest greatest one for LED pollution which is constantly replacing sodium, so probably the best one to have going forward. Many thanks for doping the tests Lee

I've just had a look at the single subs in both APP and MaximDL. APP has an autostretch like Pix Insight and also a neutralise background checkbox, if I leave that unchecked then the colours vary hugely, but with it checked they all become similar except for the gradients and vignetting differences, the D1 has the least vignetting and gradients, next is the D3, then P3 and finally no filter is the worst. So id say with whatever makes up the majority of your local LP I think the D1 is performing best, however you said that the conditions were worse on the night you used the D3, so maybe you can try that again, I would take a single sub with each filter on the same night just to eliminate the conditions as a variable. I prefer to evaluate filters with just single subs rather than stacks of several hours purely because then they can be taken all within 10 mins and identical conditions.

Wow thanks for being the ginny pig and doing this test Lee, they are so close aren't they! I think No filter looks the worse and Possibly D1 looks to be picking the Ha jets on M82 the best. but as you say the conditions weren't favourable to the D3. Id be interested in seeing a single sub from each to see which has the least noise in the background like you did at the top of the thread but including the D3. Maybe you could also upload a single raw fits file for each filter in dropbox or something, so I could try and compare in MaximDL. Lee

great image Peter.

Its all relative 😜 Well, lets see. The first law of thermodynamics, also known as Law of Conservation of Energy, states that energy can neither be created nor destroyed; energy can only be transferred or changed from one form to another. 🥸 so using a focal reducer or barlow cant increase the number of photons entering the scope, but can either concentrate them into a smaller area or spread them out when they reach the sensor 🤪. I dont know if thats right but it sounded good in my head, so id say the aperture increaser will win.

I think what olly means is, if you reduce green the image will become more magenta, if you reducer magenta it will become more green as they are on the same colour axis so are affect each other. Lee

Completely missed this challenge until 2 days after the closing date lol 😭 oh well maybe next time

Hi Lee, Ive also been testing filters and on same target, but my goal was to see which one picks up the faint IFN in the background. So far I've used my standard UV/IR filter, my Idas P2, the Astronomik CLS ccd, though none of these are designed with LED lights in mind. I see you went for the P3 but they also released a D3 at the same time specifically designed for LED LP. By the specs the new D3 would seam better as like the previous D2 it has a cut out for the brightest LED peak. Maybe you could ask to swap it for the D3? I would like to try one myself but they are too expensive to just buy on a Wim, I know FLO have the 30 day return policy but I only just retired another filter I was testing and its not really fair to them to keep buying things just to test. Maybe as you've already bought the P3 it would make more sense to see if they would let you exchange for the D3 to add to your existing tests ? https://www.firstlightoptics.com/idas-filters/idas-lps-d3-light-pollution-filter.html Lee P.S. im also a Lee P, P for Phillips what's your P for LOL