R1k

Jellyfish Nebula in HOO

- 4h 45 min integration over 2 nights

- Bortle 6 NW England

- Feedback welcomed 

Equipment

- Skywatcher HEQ5-pro (Rowan Belt Mod)

- Canon 800d (modded)

- TS Optics Photoline 80mm Triplet

- TS Optics 0.79x focal reducer/field flattener

- ZWO ASI-120MM-mini guide camera

- Skywatcher Evoguide 50ED guidescope

- 2 inch mounted Optolong L-eNhance

Acquisition

- Sharpcap polar alignment, ASCOM guiding/dithering with PHD2

- APT image acquisition

- Lights - 36 x 300s, ISO1600 and 15 x 420s, ISO800 (4h 45 min)

- Darks - 8 + 20

- Bias - 40 + 40

- Flats – 40 + 40

Processing

- Raw images stacked and calibrated in APP using the algorithms Ha-OIII extract Ha and Ha-OIII extract OIII.

- Mono images combined in APP using the HOO1 algorithm, OIII signal boosted by 2x

- Autostretched file saved as 16bit TIFF and run through Starnet++

- Selective contrast, saturation and stretching to nebula in starless image in Photoshop, denoise of background in this image using camera RAW filter

- Star mask on original combined/stretched image using select colour range – highlights tool

- Stars blended onto starless image

- Original combined and stretched image layered on at opacity 25% so that there was some signal in the dimmer stars

- Crop to preference

Just to update - thanks to all who helped. Scope has been sent to ES Reid in Cambridge today. 

15 minutes ago, TerryMcK said:

I've seen that before with one of my scopes. It turned out that the backfocus was a tad out and during the colder weather it was more noticeable. The scope itself was alright in my case.

Have you tried altering the shimming of your camera.

Thanks Terry - yes with the field flattener I tried 55mm and 62mm (7mm spacer) backfocus - same issue both ways.

issue also persisted without any flattener at all.

edit - using a modded Canon 800d (sensor set back 55mm)

And single frame from 3rd jan where things weren’t looking so bad. I’m really at a loss as to what’s gone wrong since 😔

And here is an image just from 3rd January where it was looking quite a bit better. I hadn’t done anything since then (to my knowledge at least) to cause the optics to become mis-collimated.

15 minutes ago, Waldemar said:

That is definitely no dew... Coma, probably caused by mis-collimation.
camera sensors do neither show such effects by temperature issues.

What did you do for 'unpinching' the optics?
To me it looks as if the triplet lens system is being taking out of it's housing and been put back in wrong...
Meaning not using the same positions of the lenses as in the original settings from the factory.

Thanks for the response. I loosened the retaining ring on the lens cell (which was EXTREMELY tight, jiggled it around a little and then finger tightened it. I’ve not adjusted anything else at all.

Below is an image of the whilst the optics were pinched a few weeks back 

Could it be due to sudden temperature change? I took the scope outside in the freezing temperatures directly from a warm room?.. 

Hi guys, having persistent issues with my TS optics 80mm triplet. Started when I received this (used) scope a few months back - pinched optics which have now been Un-pinched. Had a few nights where stars were looking reasonably good again.

went out last night and had very odd looking stars. Optics not pinched, no play in imaging train, no focuser tilt, persisted when field flattener taken out of the train and no dew whatsoever. 
 

Rotated the OTA and the shapes persisted in the current direction they’re in below.

Anyone seen this before (easier to see when zoomed)

Shot this target last night predominantly as a star test for the scope, fairly happy with the result although still some tilt somewhere in the imaging train to isolate. 

20 x 180s ISO200, 20 x darks, bias, flats

TS optics 80mm Triplet

0.79 x TS optics focal reducer

Rowan Belt modded HEQ5

Modded Canon 800d

On 02/01/2021 at 09:30, Ande said:

What mount did you use? For 5 minute exposures the starfield looks beautiful and sharp. I would be overjoyed with that image.

Thanks! Belt modded HEQ5

M81/82 and NGCs 3077, 2976, 2959, 2961

24/12/20

I like this image but I’m still struggling with odd stars, I think it’s collimation but could also be focuser tilt with my heavy DSLR hanging off it so scope will be heading back to TSO in the new year for a look.

Equipment:
- Skywatcher HEQ5-pro (Rowan Belt Mod)
- Canon 800d (modded)
- TS Optics Photoline 80mm Triplet 
- TS Optics 0.79x focal reducer/field flattener
- ZWO ASI-120MM-mini guide camera
- Skywatcher Evoguide 50ED guidescope
- 2 inch mounted Optolong L-Pro

Acquisition:
- Sharpcap polar alignment, ASCOM guiding/dithering with PHD2
- APT image acquisition
- Lights - 40 x 180s and 40 x 90s, ISO800 (180 minutes)
- Darks - 40
- Bias - 30
- Flats - 30

Processing:
- Raw files stacked in APP using algorithm adaptive airy disc 
- light pollution, background calibration and star colour calibration in APP
- stretch of data with star mask in PS
- saturation and vibrance 
- Topaz denoise

Hi all, loosening the retaining ring on the lens cell completely sorted this. I am still sending back to TS optics as I think it requires a little collimation (colour correction not as great as I expected!)

Thanks for all the help

Rik

1 hour ago, Ken82 said:

Check this out, looks similar to an issue I had -

Can you post separate R G B subs ?

Ken

Cheers Ken - read the whole thread and was sad to hear you returned the scope!

Will post the R G and B channels tomorrow - using an OSC DSLR. 

Thanks

Rik

1 hour ago, vlaiv said:

I don't think this is chromatic aberration in the image.

I think it is some sort of dispersion. Either atmospheric dispersion, or what is more likely - something to do with FF/FR and tilt.

From what I'm seeing - blue is shifted downwards and red is shifted upwards in these star images (blue is not halo around whole star).

Also, note bottom corner stars:

Other corners are fine except for opposite corner that is the worst offender in dispersion effect (at least it seems so to my eye):

I don't think this is due to scope, but it could be due to collimation of the scope. Maybe best thing to do would be to take a series of test images:

- star cluster high in the sky so you avoid any atmospheric dispersion

- with FF/FR removed - and examine center of the field - to see what the stars look like.

- aiming near zenith will also minimize seeing. Atmospheric seeing impacts blue wavelengths more then red (as they are shorter), and often blue is slightly more blurred than red and green channel due to this.

If you still have this RGB separation without FF/FR - then it might be issue with collimation or something. If you don't have it without FF/FR - then look into FF/FR connection. Do you have threaded connection or you use 2" clamping. I had issue with 2" clamping mechanism and this scope FF/FR combination.

It would shift - and one day I would have good images and next day - astigmatic stars in corners.

Massive thanks for the detailed reply

I have uploaded:

- a single raw image of the doulbe cluster in perseus (right up at the zenith) with the FF/FR installed

- a single JPG image of Vega (sorry no Raw for this) of Vega in the centre of the screen showing the same colour separation) without the FF/FR attached. 

TS optics seem to think this is a collimation issue. 

Thanks again

Light_0009_ISO200_150s__18C.CR2

Hi guys, recently picked up a used TS optics 80mm FPL53 triplet. I have come from a SW evostar 80ED doublet. 

I am slightly disappointed with the colour correction with the scope, I am using the dedicated 0.79x FF/FR and a canon 800d at 61mm back spacing (as per manufacturer recommendation). I expected stars totally free of CA but instead find that bright white stars are surrounded by a small rim of blue CA (see autostretched single 150s frame of M45 attached as an example.) 

Would you guys say that this is acceptable CA for this scope or should I be right in being disappointed? I am considering sending the scope to TS optics who have agreed to look at it. 

Thanks

Rik 

Light_0028_ISO200_150s_19C-St.tiff

Hi guys, I have recently taken delivery of a used TS optics Photoline 80mm triplet which got its first light last night. It was shipped carefully packaged from Cyprus to the UK.

It quickly became apparent that my stars were misshapen, but in a consistent manner. I excluded the following problems - tilt, focuser misalignment, back spacing. 
 

A quick read revealed this was likely to be pinched optics, and indeed when I took the lens cell out, the retaining ring was incredibly tight. I have since loosened the ring and finger tightened it as per recommendations on other threads. Unfortunately I was unable to re-test as the clouds (and rain!) rolled in.

Would any of you experienced folk have a look at these images (one is just a tight crop of the other) to determine whether the misshapen stars appear to be consistent with the problem of pinched optics?

Thanks,

Rik

Thanks for the suggestions all, very helpful!

Hi guys, after some constructive feedback if possible on this one. This is data from September which I have re-processed in PS now that I am more familiar with the use of star/layer masks (still very much a beginner). I have used the Ha and Oiii extract algorithms in APP and recombined as HOO in APP before moving across to PS for further processing. Acquisition details below. I have also recently sold my SW ED80 and have replaced this with a TS optics photoline 80mm Triplet (f6) + 0.79x TS optics reducer, if anyone else is also using this scope I'd be keen to hear about your experiences!

Equipment:

- Skywatcher HEQ5-pro (Rowan Belt Mod)

- Canon 800d (modded)

- Skywatcher Evostar 80ED

- Altair Lightwave 0.8x focal reducer/field flattener

- ZWO ASI-120MM-mini guide camera - SW 9x50 finderscope

- 2 inch mounted Optolong L-eNhance

Acquisition:

- Sharpcap polar alignment, ST4 autoguiding with PHD2

- Manual acquisition using intervalometer

- Lights - 20 x 360s (2 hours)

- Darks – 20

- Bias – 30

- Flats - 30

Thanks

Rik

Unusual target but in a nice position from Northern skies at present. Shot in the early hours of the morning on 22/11/20

Constructive feedback appreciated.

Equipment:
- Skywatcher HEQ5-pro (Rowan Belt Mod)
- Skywatcher Evostar 80ED
- Canon 800d (modded)
- Altair Lightwave 0.8x focal reducer/field flattener
- ZWO ASI-120MM-mini guide camera - SW 9x50 finderscope
- 2 inch mounted Optolong L-Pro

Acquisition:
- Sharpcap polar alignment, APT acquisition, autoguiding/dithering with PHD2
- Lights - 10 x 150s and 38 x 90s at ISO200 (1 hour 22 minutes)
- Darks – 5 x 150s and 10 x 90s
- Bias - 20
- Flats – 20

16 hours ago, ollypenrice said:

Sure. This is Photoshop. We'll assume the Ha is co-registered to be an exact fit on the RGB image.

1) Select and copy the Ha (CtrlA CtrlC).

2) Make the RGB active and split the channels. Minimize green and blue for a tidy screen.

3) Paste the Ha onto the red channel (CtrlV.)

4) In the Layers dialogue box change the blend mode from Normal to Lighten. (Now the Ha top layer will only be added to the lower red layer where the Ha is lighter.)  If the Ha isn't doing much you can stretch it further right here in situ over the red. I tend to use Curves for any extra stretch so I can pin the background Ha value where it is. We don't want to lighten the background sky because that will end up reddening it.

5) Flatten (CtrlE) the Ha onto the red.

6) Merge channels. Choose RGB mode and put the now modified R in red, the G in green and the B in blue, of course.

7) If the HaRGB looks overdone in Ha you can paste it onto the original RGB and vary the opacity to have as much or as little Ha as you like.

Ask again if any of that's unclear.

Olly

Thanks Olly, this is very very helpful. Appreciate the help (as always!)

On 27/02/2019 at 14:38, ollypenrice said:

Firstly I would only add star colour to a NB image which was aiming to approximate natural nebular colour in the first place, probably HOO.

Rather than try to 'fill in' the star colour on the HOO you could use Photoshop like this:

1) Process the RGB, the Ha and the OIII and align them to fit each other. In processing the RGB concentrate on the stars, keeping them small and colourful and don't worry about the nebula which will be coming from the NB layers.

2) Add Ha to red in blend mode lighten, making sure your Ha stars are smaller and fainter than your red stars. (Use multiple iterations of a star reduction routine like Noel's actions or whatever on the NB layers.) save three copies of this. Call this Ha to red.

3) Add OIII to green in blend mode lighten in one of the copies and call it OIII to green.

4) Add OIII to blue in blend mode lighten in another copy and call it OIII to blue.

5) Make a three-layer stack like this:

OIII to blue

OIII to green

Ha to red.

Now you can choose opacities for the top two layers which give you the most natural nebular colour. Your RGB star colour should be unaffected.  As you can see, this method does not work by replacing star colour so it gives a more natural look, yet the NB contribution to the nebulosity is the same.

Olly

 

 

Sorry to bump an old thread.

olly - could you kindly explain what you mean by adding Ha to red in step 2?

Do you mean splitting the RGB channels and adding the monochrome Ha data to the red channel?

54 minutes ago, ollypenrice said:

 

How long your short subs should be is very kit-dependent. For my own M42 efforts ( https://www.astrobin.com/380941/?nc=user and https://www.astrobin.com/321869/?image_list_page=2&nc=&nce= )  I used 11 seconds for the Trapezium stars and 50 seconds for the Trapezium region, then 15 minutes for the outlying parts. That's using cooled monochrome CCD.

When assessing a sub length look at what is saturated (burned to white) in the linear sub. Anything saturated is saturated for good. You can do nothing with it.

For how to blend different exposure lengths you cannot beat this method: https://www.astropix.com/html/j_digit/laymask.html

Regarding the filter (which I've never used) my understanding is this: it will block wavelengths other than Ha, OIII and H Beta. In order, those wavelengths lie roughly in the red, the green and the blue. So will they approximate to RGB? No.  Although H Beta is blue, it is emitted by much the same gasses as are shining in Ha so it will only add rather faint blue signal to what is already there in the Ha. The OIII line lies right on the blue-green border so that, too, will pass a small amount of the longer wavelength blue. But neither the H Beta nor the OIII will pass the bulk of the signal from blue reflection nebulosity. Quite a lot of the Running Man feature is made up of broadband blue, so the filter is stopping it.

I'd try the filter thus: Shoot and process a full spectrum RGB without it. Shoot and process a version with the filter, such as you already have. Apply the NB version over the full spectrum one in Photoshop's Blend Mode Lighten. That way the NB image will only brighten those parts where it has allowed you to find more signal. Where the RGB image has more blue, it should be unaffected by the top layer. (Warning, I haven't tried this. Normally I split my RGB channels and add Ha to red and OIII to green and blue in blend mode lighten. You might have to split channels in both your RGB and NB images and do it as I do but it might work done 'all in one.' I don't know.)

Olly

 

Thanks for this Olly, totally makes sense. I will try this entire technique (RGB with various sub lengths, blended and the NB layer on top) in the coming months when I get to have a bit more time on the nebula. Very much appreciate you making the effort to explain this in great detail, have certainly learned a few things that I’ll be able to move to other projects/targets too.

By the way, your M42 on Astrobin has totally blown my socks off, wow! 🤯

1 hour ago, Rustang said:

You have some lovely detail there, the cores fairly well handled. To me though the colors a bit to much on the red/pink front, its making it a little difficult to look at! but that's my own personal view. There's some noise/texture that's really present, might be slightly over stretched!? Cracking though mate, you must be pleased, Orion's always a winner. 👍

23 minutes ago, ollypenrice said:

It's good, but I'll make constructive comments.

To control the core on M42 you really will need short subs. It's one of very few objects for which this is essential. The whole Trapezium region is saturated here.

For me there is green where there ought to be blue. What's showing as green here is not OIII emission but reflection nebulosity. Your OSC camera without the filter would have shown this. What is your filter bringing to the table?

Olly

thanks both for the very helpful comments, I agree it is overstretched and probably a bit oversaturated.

Olly - Many thanks again, this type of feedback is exactly what I am after. how short should the subs be for the core? We talking 30s and less? As for the filter, I’m fairly new to the hobby, so assumed that any object with emission nebulosity would benefit from a NB filter. I will have a bash without a filter and see how it compares. 

 

thanks again both!

Very much enjoyed shooting this for the first time ever last night, keen to receive feedback as always

--

Technical details:

Equipment:

- Skywatcher HEQ5-pro (Rowan Belt Mod)

- Canon 800d (modded)

- Skywatcher Evostar 80ED

- Altair Lightwave 0.8x focal reducer/field flattener

- ZWO ASI-120MM-mini guide camera - SW 9x50 finderscope

- 2 inch mounted Optolong L-eNhance

Acquisition:

- Sharpcap polar alignment, ST4 autoguiding with PHD2

- Manual acquisition using intervalometer

- Lights – 15 x 180s (45 minutes)

- Darks – 25

- Bias – 30

- Flats - 30

Processing:

- Stacked and calibrated in APP using HA and OIII extract algorithms

- Monochrome images combined in PS CS6 (HOO Palette)

- Crop to area of interest

- Levels/curve stretch

- Unstretched core blended carefully onto stretched image so that it was less blown-out

- Contrast enhancement and denoise

- Slight desaturation of brightest stars (they appear too blue with the L-eNhance filter)

1 hour ago, vlaiv said:

Just because something is rendered brighter on the screen does not mean it has more signal!

ISO setting is just multiplication factor.

You used same scope and same exposure time and same camera for both of these two images. Images received same number of photons - same signal.

If you have say 100 photons and you use multiplication factor of 8 in one instance and get ADU value of 800 and multiplication factor of 2 in second case and get ADU value of 200, does that mean that somehow signal got stronger?

That is simply brilliant - all one needs is single exposure and the we just multiply with very large number and get very strong signal! No need to spend hour sand hours under the sky!

However, that is not the case. It is not numerical value that we assign to signal that is important - it is signal to noise ratio and that one is fixed to number of photons we captured. SNR is equal for both images (at least that part coming from photons).

Why the recommendation to use ISO200 then? It has to do with other noise sources, particularly read noise. ISO200 is probably "sweet spot" - as ISO gets larger read noise gets smaller (good thing) and so does full well capacity (not good thing). ISO200 is likely to be the best balance of the two - giving lowest read noise for highest full well capacity.

In the end - when you stack your images, it is highly unlikely that you'll be able to tell the difference between the two - ISO200 and ISO800 as resulting noise difference is so small and can only be measured and not perceived by eye. Shoot which ever way is more convenient to you.

Thanks so much for your very detailed and excellent explanation. Appreciate the help