L-Enhance filter help

[Desmond 13]

Hi,

I recently spent my Xmas money on an L-Enhance filter as I have seen amazing results with this filter.

I took it for a test run on the Y Cas Nebula last night (not the best night, but when is?)

I managed to get around 43 mins of time.

I normally shoot 1 min exposures with my 1000D modified camera but I thought I'd go for 90 seconds as the filter would reduce brightness? (any thoughts on exposure times here would be great)

The results were not as great as I was hoping for - see below.

O over stretched it just to see if I had captured the 'ghost'. He's there, but it turns out really grainy and not the nice subtle wispy nebula that I see from other folks.

So my questions are:

- is this a tricky nebula target?

- What exposure times should I run? 

- Is 43 mins way too little for this (or any) target?

- any other advice???

Setup is:

Canon 1000D - modified

L-Enhance filter

Skywatcher 72ED Telescope

Skywatcher AzGTI mount (AZ mode at the moment until I can get polar alignment working with SharpCap)

Any thoughts, hints, tips greatly appreciated!

Thanks in advance!

 

 

[smashing 126]

Fantastic effort well done.

I think you need longer subs although I'm sure someone here with more knowledge will help you more.

Edited December 31, 2020 by smashing

[blinky 447]

Yeah looks like you need longer exposures - long time since I've used a DSLR but I would have thought exposures in the 5mins plus would be what you are aiming for.  What confuses me is that you said the mount is in Az mode until you can polar align, I would have expected to see star trailing at 90 second exposure length...

[rnobleeddy 116]

I use a similar filter + DSLR. I'd suggest

- longer exposures - if your mount can manage it, as long as possible, with 300s tending to be typical (this was explained to me well by another member recently, but it's likely that at 1 minute exposures, the read noise of the camera is the dominating factor in your noise)

- more total exposure time - I don't see good results (usually) until I've got 2 hours of data, obviously that's somewhat target dependent

- trying again when the moon isn't at 100% - even with a narrow band filter, the moon has a big impact

[TerryMcK 1,057]

It's a faint object so you need much more time on it. You have stretched a lot of sensor noise.

Try 3 minute subs although I'm not familiar with that mount. I think from the description it is an alt azimuth so you will get field rotation and it is therefore very limited for long exposure deep space work.

[Desmond 13]

2 hours ago, blinky said:

Yeah looks like you need longer exposures - long time since I've used a DSLR but I would have thought exposures in the 5mins plus would be what you are aiming for.  What confuses me is that you said the mount is in Az mode until you can polar align, I would have expected to see star trailing at 90 second exposure length...

I have had trailing at some elevations, but if the scope is fairly high, it seems to cope for 90 seconds  - but EQ mode is the future

[Desmond 13]

2 hours ago, TerryMcK said:

It's a faint object so you need much more time on it. You have stretched a lot of sensor noise.

Try 3 minute subs although I'm not familiar with that mount. I think from the description it is an alt azimuth so you will get field rotation and it is therefore very limited for long exposure deep space work.

Great - thanks for the insight - I'll get this going in EQ mode for my next assignment

[Desmond 13]

2 hours ago, rnobleeddy said:

I use a similar filter + DSLR. I'd suggest

- longer exposures - if your mount can manage it, as long as possible, with 300s tending to be typical (this was explained to me well by another member recently, but it's likely that at 1 minute exposures, the read noise of the camera is the dominating factor in your noise)

- more total exposure time - I don't see good results (usually) until I've got 2 hours of data, obviously that's somewhat target dependent

- trying again when the moon isn't at 100% - even with a narrow band filter, the moon has a big impact

Great - thanks for the info - much appreciated. Lots to improve on
I'll try and get this mount going in EQ mode (failed a few times but I know now what I did wrong). Then I hope to get longer exposure times going. I think 90 seconds is about as much as I can do in AZ mode.
Yep - bright Moon, eager beaver to test things out!

[Desmond 13]

2 hours ago, TerryMcK said:

It's a faint object so you need much more time on it. You have stretched a lot of sensor noise.

Try 3 minute subs although I'm not familiar with that mount. I think from the description it is an alt azimuth so you will get field rotation and it is therefore very limited for long exposure deep space work.

Ahh so I did pick a difficult one regards target being faint. I got much better results on the North American Nebula without a filter a few nights back so I was expecting that and a lot more from this one. 

Never assume

This was my filterless North American Nebula effort:

[alacant 4,212]

3 hours ago, Desmond said:

Y Cas Nebula

Hi

Nice effort.

My advice would be to not use the filter. Un filtered will record the nebulae and stars with much better colour and the former will stand forward more. 

Cheers and HTH

[Desmond 13]

Just now, alacant said:

Hi

Nice effort.

My advice would be to not use the filter. Un filtered will record the nebulae and stars with much better colour and the former will stand forward more. 

Cheers and HTH

I will give that a go for comparison. Good idea.
Just wondering why I spent all that on a filer in that case!
When would a filter be preferable then, given I'm in a Bortle 4 area?

Thanks for the help - much appreciated!

[rnobleeddy 116]

8 minutes ago, Desmond said:

I will give that a go for comparison. Good idea.
Just wondering why I spent all that on a filer in that case!
When would a filter be preferable then, given I'm in a Bortle 4 area?

Thanks for the help - much appreciated!

If time allows, a comparison would be interesting!

Generally, the dual/tri band filters are best suited for emission nebula. They tend to be marketed with photos of the veil nebula and I've found that target works exceptionally well using them. Unfortunately, it's now a little low in the sky.

On other targets, for example the North America nebula, I've found I get a much cleaner image with the filter, but that it's hard to get anything other than red color, as I imagine the Ha signal is dominating. I'm going to have another go at processing some of the data, but for now, I've only been really pleased with the veil. 

That said, I don't see a lot of OSC images that do show nebula in glorious color - my guess is that it's just so much easier to produce pretty images with a mono setup.

 

Edited December 31, 2020 by rnobleeddy

[alacant 4,212]

32 minutes ago, rnobleeddy said:

so much easier to produce pretty images with a mono setup

I think things are changing though. 

Have a look at the Optolong l-extreme for example.

Cheers

Edited December 31, 2020 by alacant

[alacant 4,212]

42 minutes ago, Desmond said:

I'm in a Bortle 4 area

Not sure what effect you are looking for with a filter, but I think with a reasonably dark sky, most targets will look better un-filtered.

I found the l-enhance gave much the same effect as the -sensibly priced- UHC. Both need around 4x the exposure to grab the same amount of light.

The y-cass ghosts will certainly be recorded better without.

Cheers

 

[rnobleeddy 116]

31 minutes ago, alacant said:

I think things are changing though. 

Have a look at the Optolong l-extreme for example.

Cheers

If you use one of these, do you have a link to some example images? I use a similar STC filter and I'd like to know if I'm getting results that are comparable to others?

[Xsubmariner 190]

Hi Desmond,

I also have the L-Extreme filter and from my experience believe it is excellent for imaging with a colour camera when there is moon present (light noise swamps signal). I would definitely increase your exposure time when using the filter, remember you are effectively conducting narrow band imaging with a colour camera. Here is an image taken with my QHY163C with L-E filter on a 75% moon night. It is the combination of only 13 x 10 min exposures taken when clouds allowed.  Remember that your mount/guiding limitations will have to be adhered to, no point having more signal if your stars are bloated or misshapen due to poor guiding. 

[alacant 4,212]

2 hours ago, rnobleeddy said:

link to some example images

I've not had hands on yet but try here.

Cheers