Optolong narrowband filter choice for my OSC camera, nebula imaging.

[LaurenceT]

I've almost completed my equipment for a lightweight and low cost setup for widefield DSO imaging. Essentially it's an Evoguide 50ED with field flattener and a ZWO ASI533mc Pro on an AZ GTI mount in EQ mode. I also have an Astrokaken bracket, guide scope and guide camera. I'll be running it on Stellarmate OS on a cooled Raspberry Pi. I'm now faced with the choice for a narrowband filter for emission nebulae.

I've narrowed it down to either an Optolong L-Enhance or an L-Extreme. I'm allegedly under bortle 5  skies in Camberley, Surrey although it doesn't seem very different to the bortle 6/7 skies where my children live in West London/Surrey borders. I'm not too concerned about the price differential but I've heard that focussing can be tricky with the L-Extreme if I go to darker skies. I'd be grateful for any comments or experiences.

[adyj1]

I am a fairly new owner of an l-enhance and have had no problem focusing by hand and autofocuser in my (theoretically) bortle 4/5 back garden.

Coincidentally, I also have the ASI533MC Pro which I was running on an AZ-Gti while I was messing with my main mount... 

If you don't laugh at my processing I'll show you a work in progress; 😉 

(5min subs, 1h50m total integration, although this was on my EQ5)

Edited March 3, 2022 by adyj1

[LaurenceT]

Thanks for that, I've just discovered that I can't use filters with the Skywatcher field flattener so that's going back to FLO, I've had a buy the Starizona FF which apparently takes filters. So far it's been 2 steps forward and 1 step back with this setup. I don't think anyone would laugh at your processing.

[Budgie1]

If you're using the 11mm adaptor on the front of the ASI533, you should have or can buy a 1.25" filter holder to go inside the adaptor ring. This will take the 1.25" L-eNhanse or L-eXtreme filter and enable you to use the SW field flattener. 

[LaurenceT]

14 minutes ago, Budgie1 said:

If you're using the 11mm adaptor on the front of the ASI533, you should have or can buy a 1.25" filter holder to go inside the adaptor ring. This will take the 1.25" L-eNhanse or L-eXtreme filter and enable you to use the SW field flattener. 

Thanks for that information, oddly FLO didn't suggest that fix.

[LaurenceT]

2 hours ago, Budgie1 said:

If you're using the 11mm adaptor on the front of the ASI533, you should have or can buy a 1.25" filter holder to go inside the adaptor ring. This will take the 1.25" L-eNhanse or L-eXtreme filter and enable you to use the SW field flattener. 

Update: I contacted FLO and they updated their advice and I've ordered the filter holder and cancelled my order for the Starizona FF! Thanks once again @Budgie1 

[adyj1]

4 hours ago, Budgie1 said:

If you're using the 11mm adaptor on the front of the ASI533, you should have or can buy a 1.25" filter holder to go inside the adaptor ring. This will take the 1.25" L-eNhanse or L-eXtreme filter and enable you to use the SW field flattener. 

This.

I got my 533 from the forum, and it luckily came with all the orginal accessories, which included the filter holder @Budgie1 is on about. (I also have a UV/IR filter for when the L-enhance isn't necessary, so ended up getting a cheap filter wheel to avoid having to do clumsy filter changes in the dark...)

[adyj1]

8 hours ago, adyj1 said:

If you don't laugh at my processing I'll show you a work in progress; 😉 

 

 

Not sure what has happened, but my nebulosity was a lot redder when I finished Affinitying it. I'll see if I can repost the original when I get home.

[LaurenceT]

57 minutes ago, adyj1 said:

 

Not sure what has happened, but my nebulosity was a lot redder when I finished Affinitying it. I'll see if I can repost the original when I get home.

I'd like to see that.

[adyj1]

Yous asked for it 😉

[adyj1]

So red, in fact, that I can't be sure that this isn't my 6.5nm HA filter - d'oh! (damn that manual filter wheel!)

Sorry

 

Edit: The thing I learned today was that if the stars are white, it wasn't taken with a single-band HA filter - so this is definitely the L-enhance. However I do have some other exposures labelled with the wrong filter name 😞

Edited March 4, 2022 by adyj1

[LaurenceT]

6 hours ago, Budgie1 said:

If you're using the 11mm adaptor on the front of the ASI533, you should have or can buy a 1.25" filter holder to go inside the adaptor ring. This will take the 1.25" L-eNhanse or L-eXtreme filter and enable you to use the SW field flattener. 

I don't think I'm going to need an 11mm adapter, FLO have said this:

either this or the ZWO version should enable you to add the filter inside the M42 T thread built into the camera. It would also be very close to the window of the camera to keep any vignetting to a minimum.
I'm getting a bit confused lol.

[adyj1]

I think you probably do - it's the bit that screws onto the very front of the camera. Here's the diagram from the zwo web page explaining how their different adaptors make up the standard 55mm back Focus, and you can see the 11 mm tube attached to the camera.

[LaurenceT]

Got it now, many thanks for taking the time to do that.

[adyj1]

And to try to make up for my schoolboy error, here's a single 5-min exposure DEFINITELY WITH THE L-ENHANCE, with only stretching to bring the stars out - no other processing whatsoever so you can see the 'raw' focusing. I have no problem focusing with it... 

 

edit: damn, that's big... 

Edited March 3, 2022 by adyj1

[LaurenceT]

Thanks for that, impressive for a single sub. It wasn't the L-enhance that someone had trouble focusing with it was the L-extreme.

For my purposes I think that I will go for the L-enhance despite what Cuiv has to say about it 😆

[Richard_]

Bit late to the party, but like @adyj1 I also shoot under Bortle 5 skies with my ASI533, however, I use the l-extreme filter instead as I wanted the slightly tighter bandpass. As by coincidence I have an image of the Heart Nebula with a total of 4.5hrs integration time, see below. 

It's not fair to directly compare to the other image presented in this thread due to difference in total time and processing technique so I wouldn't use it as a "l-enhance" vs "l-extreme" comparison. 

The one downside to this filter is the halos produced from bright stars. I don't have any final images at hand to illustrate this but I did see this effect on the bright star present in IC 1396 Elephant's Trunk nebula and also one near NGC 7000 North American nebula.  Apparently, these halos are much less pronounced or not visible when using the l-enhance filter. In all honesty, it doesn't really matter which filter you go for as you'll get much better results than shooting without one so I'm sure you'll really enjoy using the l-enhance 😊

[Richard_]

Oh and to answer your original question regarding focusing, it works OK with the L-eXtreme in my Bortle 5 skies!

I've used autofocus [AF] routines using my ASI Air Pro [AAP] (with ZWO EAF) and NINA (with ZWO EAF and more recently the PrimaLuceLab Sesto Senso). Using the default ASI533MC settings (Gain=100, Offset=70) I am able to execute the focusing routine with 10s exposures with standard 1x1 binning. If the star field is dim in the area you are shooting, you can always increase exposure time or set binning to 2x2 for the star detection.

Below are examples of recent AF routines using both UV-IR (Fig.1) and L-eXtreme (Fig.2) filters in NINA (v2.0.0.2045 Beta) using the PLL Sesto Senso autofocuser. As you can see, the regular routine with UV-IR filter takes about 2 minutes with 5s exposures whilist the L-eXtreme takes about 3 minutes with 10s exposures.

I don't have any experience with the Stellarmate OS, but if the AF routine is similar to the ASI Air Pro software, then the only issue you may run into is star detection for autofocus routine. With my AAP, it could take up to 1 minute for it to detect a suitable star to use for the AF routine. Sometimes I would have to stop, adjust the exposure time and/or bin to 2x2 and re-run. It appears that NINA works much better in terms of star detection and running the routine with standard 1x1 binning and 10s exposures works perfectly fine everytime.

Hope this helps!

Fig.1 - UV-IR Autofocus routine (2min 15s)

Fig.2 - L-eXtreme autofocus routine (3min 4s)

[LaurenceT]

Thank you for that very detailed reply.

[900SL]

Also look at the IDAS NBZ duoband filter, no star bloat

[Stuart1971]

I use NINA with default autofocus settings and with a QHY268c camera and recently bought the L-Extreme filter, it focuses perfectly well, and just as quick and easy as with my LP filter, and this was just under 2 hours of 2 min subs of the heart through bortle 5-6 skies…

 

Edited March 7, 2022 by Stuart1971

[alacant]

On 03/03/2022 at 09:00, LaurenceT said:

low cost setup

Hi

Unless you're after strict scientific accuracy, there is a good alternative.

We tried the optolong offerings and found we got similar results using a €30 UHC. 

Similar effects. Different marketing. And yes, you can split colours and do HOO stuff too. As with optolongs however, the UHC still blocks most of the spectrum, so there's no free lunch; you still need long exposures to get anywhere near.

Worth considering?

Cheers and HTH

 

Edited March 7, 2022 by alacant

[Stuart1971]

30 minutes ago, alacant said:

Hi

Unless you're after strict scientific accuracy, there is a good alternative.

We tried the optolong offerings and found we got similar results using a €30 UHC. 

Similar effects. Different marketing. And yes, you can split colours and do HOO stuff too. As with optolongs however, the UHC still blocks most of the spectrum, so there's no free lunch; you still need long exposures to get anywhere near.

Worth considering?

Cheers and HTH

 

Hmmmmm, long exposures I don’t think so, this is L-extreme, 2 min subs x 30, so 1 hour, from bortle 6, don’t think the UHC would give this detail in 1 hour….sorry to disagree….🤔🤔

 

[LaurenceT]

After much consideration and re-reading the posts in  this thread I bought the L-Enhance filter this morning. When it arrives my lightweight and relatively low  cost DSO imaging setup will be complete. 

My thanks to all those who contributed to this thread.