Rate my back focus

[TiffsAndAstro]

15 hours ago, ollypenrice said:

I think your backfocus is fine but what on earth is causing that blue supernova at the edge with its black counter-shadow? Ouch!

Noooo....

None of the excellent imagers who have worked here shoot flats per filter and per focus.  Some shoot flats per filter and some use L flats for all, but I've never known anyone try to replicate individual filter focus when shooting that filter's flats. Enough is enough in this game.

Olly

Supernova and other dust calibrated out with new flats. I think it was due to where a blob of dust was but wasn't so that spot is brightened up a lot in the stack?

Edited July 3 by TiffsAndAstro

[TiffsAndAstro]

quick histrogram view/stretch  post new flats

 

 

[tomato]

2 hours ago, Stuart1971 said:

I really don’t get how just using L flats can work, surely any dust or vignetting from the other filters will still show and ruin the image…🤔

I just don’t see any change in the dust mote pattern from one filter to another, and I have looked closely. If I take the camera off and put it it back then yes, it is retake flats time. I guess the optical theory experts on here might be able to tell us how far a particle has to be from the sensor before it’s shadow becomes invisible on the image. F ratio also plays a part as I don’t see any dust bunnies with the RASA or SY135, only vignetting or stray light issues.

[900SL]

The Veil is swamped in broadband, in my experience. It's one of those targets that benefit from dual narrowband. 

[TiffsAndAstro]

7 minutes ago, 900SL said:

The Veil is swamped in broadband, in my experience. It's one of those targets that benefit from dual narrowband. 

Was just a 15 mins test compared to a previous version with my dslr.

One, possibly two dual NB filters are on my list

[Elp]

34 minutes ago, tomato said:

I just don’t see any change in the dust mote pattern from one filter to another, and I have looked closely. If I take the camera off and put it it back then yes, it is retake flats time. I guess the optical theory experts on here might be able to tell us how far a particle has to be from the sensor before it’s shadow becomes invisible on the image. F ratio also plays a part as I don’t see any dust bunnies with the RASA or SY135, only vignetting or stray light issues.

I think it's worth when mentioning these things what your setup is like physically.

This was one of the issues I had with my 30 hour project previously mentioned. It was spread out over three months, some r, g, b sessions were unusable because of bad flats causing a pattern to stay on the image, no way were one set of flats for the four filters going to fix this. This was using the same refractor with a manual single filter drawer, setup and breakdown every time, so in this case I'd think flats every time were essential, even though they didn't work at the time (I've since developed the diffusion of the light source since). I could never get to the bottom of what really caused the issue, could of been the filters themselves or immediate location due to LP I always struggle with RGB here.

You're right about f2 though, not a dust mote to be seen in the flats but I do see the shadow of the secondary slightly in the middle with the C6+HS, more so when doing lum or OSC RGB.

[Elp]

11 minutes ago, TiffsAndAstro said:

One, possibly two dual NB filters are on my list

The sooner you do this you'll be laughing when doing emission nebula.

[TiffsAndAstro]

19 minutes ago, Elp said:

The sooner you do this you'll be laughing when doing emission nebula.

yeah ive looked a other's images but i genuinely like broadband images. probably change my opinion a lot when i get a nb filter. still will be tempting to add the Ha into rbg images though. but ill have the option anyway.

[Elp]

8 minutes ago, TiffsAndAstro said:

yeah ive looked a other's images but i genuinely like broadband images. probably change my opinion a lot when i get a nb filter. still will be tempting to add the Ha into rbg images though. but ill have the option anyway.

Don't misinterpret that a ha/o3 OSC narrowband filter changes the target colour, at least I don't think you have. Ha still registers on the red and o3 on the green/blue so you're still getting natural colour, they simply block out background LP which is not in the allowable bandpass so the signal jumps out of the background as it were, vs not using a filter at all. Stars do loose their natural colour...

See example here:

https://stargazerslounge.com/topic/401548-i-feel-the-need-the-need-for-speed-hyperstar-rasa-any-fast-f-ratio-telescope-imaging-thread/?do=findComment&comment=4388847

 

...but this is easily remedied with an hour or so of UV/IR or lum OSC imaging, then combining with a starless version of the OSC narrowband data.

Edited July 3 by Elp

[TiffsAndAstro]

1 hour ago, Elp said:

Don't misinterpret that a ha/o3 OSC narrowband filter changes the target colour, at least I don't think you have. Ha still registers on the red and o3 on the green/blue so you're still getting natural colour, they simply block out background LP which is not in the allowable bandpass so the signal jumps out of the background as it were, vs not using a filter at all. Stars do loose their natural colour...

See example here:

https://stargazerslounge.com/topic/401548-i-feel-the-need-the-need-for-speed-hyperstar-rasa-any-fast-f-ratio-telescope-imaging-thread/?do=findComment&comment=4388847

 

...but this is easily remedied with an hour or so of UV/IR or lum OSC imaging, then combining with a starless version of the OSC narrowband data.

Need to have a think about this, sorry. My plan for NB data was to extract Ha and composite it with grb or to use Ha and Oiii and replace stars with rbh stars if nessecery.  Or possibly some more nuts possibilities I've been thinking about,  Which others probably already have and there's a reason I don't see images doing what Im thinking about.

Not red all your link yet, but I like you NB M16. I would want to add some of the Ha NB data into it, but not as a luminance channel (if I [removed word] this with my gear) I'd also want to not waste the leftover oIii but I guess  simply blending both images doesn't look good.

Edited July 3 by TiffsAndAstro

[TiffsAndAstro]

2 hours ago, 900SL said:

The Veil is swamped in broadband, in my experience. It's one of those targets that benefit from dual narrowband. 

It'll be a while until I get a filter. Though I might had said that about a camera.

Veil is probably my next target but broadband all July if I get 10 hours I'll move on to target #2

Hoping to use little darkness atm to iron out things like tube slop and/or tilt.

[AstroMuni]

Siril suggests that you may have some tilt.

[TiffsAndAstro]

16 minutes ago, AstroMuni said:

Siril suggests that you may have some tilt.

I don't disagree, but how do you distinguish tilt from tube slop? I think I have both but not certain. I don't want to start messing with tilt screws if it's focus tube slop

Also could imperfect back focus impact this? If all the other items in my optical train are accurate I need another 0.3.mm back focus to account for filter 

 

[AstroMuni]

11 minutes ago, TiffsAndAstro said:

but how do you distinguish tilt from tube slop?

The only way you could determine that is by comparing images in various positions of the scope really. If the tilt keeps altering you know its being caused by slop.

[TiffsAndAstro]

24 minutes ago, AstroMuni said:

The only way you could determine that is by comparing images in various positions of the scope really. If the tilt keeps altering you know its being caused by slop.

Cool Ty. Single subs are ok? Will try this asap

M101 straight up ish. Veil is lower to east. I can do west near meridian easily when  I do phd2 calibration

Edited July 3 by TiffsAndAstro

[Elp]

1 hour ago, TiffsAndAstro said:

I would want to add some of the Ha NB data into it, but not as a luminance channel (if I [removed word] this with my gear) I'd also want to not waste the leftover oIii but I guess  simply blending both images doesn't look good.

Don't get what you're trying to achieve. With a typical dual ha/o3 OSC filter you're already capturing ha in colour. If you extract the ha what will you do with it in addition?

[TiffsAndAstro]

12 minutes ago, Elp said:

Don't get what you're trying to achieve. With a typical dual ha/o3 OSC filter you're already capturing ha in colour. If you extract the ha what will you do with it in addition?

Was going to try using the Ha as luminance in lrgb composite

[Elp]

4 minutes ago, TiffsAndAstro said:

Was going to try using the Ha as luminance in lrgb composite

I've done that, but the ha was captured with a mono camera. Not sure if it makes a difference if you're duplicating that data already present in the image.

[TiffsAndAstro]

1 hour ago, Elp said:

I've done that, but the ha was captured with a mono camera. Not sure if it makes a difference if you're duplicating that data already present in the image.

I've seen one video and looked ok. At least once I get data I can try the options.

[900SL]

21 hours ago, Elp said:

The sooner you do this you'll be laughing when doing emission nebula.

I remember the first time I tried the veil in OSC dual narrowband, it blew my mind

Here's a progression over a couple of years, from DSLR broadband, 533 OSC broadband 135mm, and 533 OSC decent scope and IDAS NBZ DNB (only 90 minutes!)

[TiffsAndAstro]

5 minutes ago, 900SL said:

I remember the first time I tried the veil in OSC dual narrowband, it blew my mind

Here's a progression over a couple of years, from DSLR broadband, 533 OSC broadband 135mm, and 533 OSC decent scope and IDAS NBZ DNB (only 90 minutes!)

I almost can't believe that last image only took 90 minutes.

NB filters are on my list. Maybe I should avoid it in broadband until then....no clear nights makes it an easy decision

also that last shot almost doesn't look like NB as you have what looks like a wide spectrum of colours in it, which I really like a lot 

Edited July 4 by TiffsAndAstro

[900SL]

2 hours ago, TiffsAndAstro said:

I almost can't believe that last image only took 90 minutes.

NB filters are on my list. Maybe I should avoid it in broadband until then....no clear nights makes it an easy decision

also that last shot almost doesn't look like NB as you have what looks like a wide spectrum of colours in it, which I really like a lot 

It was b7 helsinki too, but great seeing and looking out to sea. I think 90mm at f4.6 reducer, so pretty fast

[TiffsAndAstro]

11 minutes ago, 900SL said:

It was b7 helsinki too, but great seeing and looking out to sea. I think 90mm at f4.6 reducer, so pretty fast

I'm bortle6 72mm and 5.8 so probably works out similar though I'm not looking out to sea  maybe slightly in my favour as 1 bottle is 4 times ?

Edited July 4 by TiffsAndAstro

[Elp]

3 hours ago, 900SL said:

NBZ

Did you get the coloured stars with the NBZ at the same time or did you do some sort of colour correction separate from the nebula? I would of thought they were imaged separately due to NB filters not allowing true coloured stars.

Edited July 4 by Elp

[900SL]

1 hour ago, Elp said:

Did you get the coloured stars with the NBZ at the same time or did you do some sort of colour correction separate from the nebula? I would of thought they were imaged separately due to NB filters not allowing true coloured stars.

I got the stars from the NBZ from memory. I'll check my files, I keep everything I may have separated them and played around with colour tints. I should really keep notes when processing, but most of it is improv