Adreneline

9 minutes ago, Clarkey said:

I hope my 1600MM pro keeps going then. I'm not sure there is a 'modern' mono equivalent with a similarly sized sensor.

Exactly my concern - I've invested significantly in 1.25" filters  

1 minute ago, DaveS said:

I may have left too much green in the image when I was taking it out as I wanted to avoid sending it too red. I may have another go.

It's a difficult balancing act between removing green cast and not reducing green too much such that it throws off the RGB histogram balance.

This is your original with histogram...

... and after applying SCNR ....

The peaks are now slightly better aligned and the relative differences have been reduced and the balance has been improved.

2 minutes ago, DaveS said:

I thought the Flats would have taken care of that.

Tricky things flats! I've had lots of fun and games (Not!) taking flats that do the job properly and actually produce a flat image.

4 minutes ago, DaveS said:

I ran NoiseX but kept the level to 60% as I didn't want the background to go too "plasticky".

I was trying to reduce this - which I suspect is jpg artefacts rather than anything else:

26 minutes ago, DaveS said:

any advice will be welcome.

Ah, the captivating Bubble - it's a real challenge!

This is all down to personal taste but this is what I achieved:

Looking at your image there appears to be some back ground gradient - like vignetting - which is not helping to achieve a flat background.

I applied ABE to try to flatten it best I can and then super-stretched the mask so you can see the problem.

I used SCNR 90% to reduce the green cast. I also inverted the image and used SCNR 100% to remove the magenta.

I used an L mask to reduce the noise (and I am bound to have lost some detail as this is a jpg) and I also carried out a tiny bit of sharpening to try to ameliorate the noise reduction.

I created a second L mask and boosted the gold and the blue a little.

Colours are all down to personal taste and I am not a fan of green or magenta but quite understand some members like to retain the green Hubble'esque look.

I hope this is of interest.

42 minutes ago, ovrcome said:

I will try these settings tonight! 

It can be tempting to use a large Coarse step size but I would be cautious and start 'small' and increase gradually to ensure you get sufficient change in HFD for the process to work and generate the 'U' curve. As I said it all comes down to your particular gear ratio. My belt system is approximately 20:1 - I think. With my Fine step of 13 I can barely see the focus ring move - with the Coarse step of 26 I can clearly see a small movement.

If you set 'Reverse' the routine should (hopefully) initially drive the focuser away from the 'infinity' point - toward '10' or '5', and then step back gradually to go through the minimum point.

Good luck.

1 hour ago, ovrcome said:

when I try to use autofocus, the automatic out and in focusing hits infinity and causes my gear to skip and I simply cannot autofocus.

Sorry to hear you are having problems. Frustrating!

Have you tried setting the Reverse option?

I measured the Backlash on my system accurately and chose my Fine and Coarse based on the backlash figure; as I understand it the Backlash is not used in the Autofocus routine. As you have a different gearing arrangement I assume you need to use different Fine and Coarse figures.

Fingers crossed this helps.

2 hours ago, Elp said:

Have you tested the 85mm?

No, not yet. Have you?

2 hours ago, aleixandrus said:

For now, as I say before, I think this is 'well enough' and I think I deserve some fun just imaging without dealing with technicalities.

Sounds like a good plan!

You have been very thorough in your investigations and preparation. In my case I base the focus position for my lens purely on the result from using the Canon 6D, which when focused at infinity (or for sharp stars and perfect BM pattern) is right in the middle of the base of the 'L' - what is good for the 6D will be good for my ASI camera - or that was my thinking.

I have now switched my ASI183MM for my ASI1600MM - (I still get one dodgy corner so it is not the sensor!) - and I am going to try using my ASI183MM with my f1.4 Samyang 85mm manual lens. As it turns out the f.o.v. for the SY1600 combination is almost identical to the SY85 combination - what luck! I've ordered the M48 adapter so once that arrives I shall have all sorts of fun trying to establish the correct spacing all over again - joy!

Clear skies and thanks for the interesting write-up - and photos!

Adrian

1 hour ago, MonsterMagnet said:

there is no real concensus whether 4GB RAM is actually required.

I have an 11" iPad Pro 64 gb which apparently has 8 gb of RAM - ASIair Sky Atlas runs without problems.

I have a 128gb iPhone 11 which apparently has 4gb of RAM - ASIair Sky Atlas runs without problems.

I also have a 'cast-me-down' 7" iPad mini 32 gb which apparently has 4 gb of RAM - ASIair Sky Atlas won't run at all!

Make of that what you will. Maybe the old iPad mini uses its internal RAM differently to the newer 11" iPhone 11.

HTH with your deliberations.

Good to see you back Brendan.

I really like the way you've processed the dark stuff and the sense of depth you've achieved across the whole image - I particularly like the bottom centre to right corner - it just draws you in.

Adrian

3 minutes ago, Adreneline said:

To illustrate the point I decided to swap my ASI183MM for my ASI1600MM on the Samyang last night

This was a single 300s Ha frame from last night to check image train alignment - I am pretty pleased with this:

... and the result of stacking 10 frames in APP:

.. all cut short by the early arrival of clouds!

Adrian

1 hour ago, Albut said:

I find adding shims or increasing the distance makes it worse with my samyang 135mm.

This is very frustrating for you - it can be a very frustrating lens to set up and I can only hope your lens is not defective.

To illustrate the point I decided to swap my ASI183MM for my ASI1600MM on the Samyang last night. I made the not unreasonable assumption that the sensor position would be the same on both lenses so I just took the 183 off and screwed the 1600 on to the EFW. My preview image was very out of focus - blobby stars! I found I could not achieve focus at all - I was getting close but the lens was up against the end-stop. I decided to remove the 0.5mm spacer between the EFW and the camera (used purely to get the orientation of the sensor so it was orthogonal to the Vixen bar - in 'landscape'). Removing the 0.5mm spacer allowed me to achieve focus but with the focus mark approx 3mm before the 'L'. After much messing around in the dark at midnight I finally achieved focus with 0.3mm of spacing - the lens focussed on L, Ha, OIII and SII all within the confines of the 'L'. I can but assume the sensor position on the 183 is different to the 1600, i.e. the back-focus is not 6.5mm - I assume it 6.7mm. I read somewhere that ZWO state the sensor is positioned to with ±0.5mm - that is a lot when used with the Samyang 135mm (and have seen the same quoted on CN). I suppose the back-focus could be anywhere between 6.00 and 7.00 mm - again a huge range when trying to set up the Samyang.

I can only suggest to persevere but bear in mind the 44mm figure is purely a starting point that will be affected by filter thickness and sensor position. The gap between my ASI1600MM camera front face and lens end plate is 38.73mm, so the spacing is (38.73+6.5) = 45.23 (±0.5mm cos' I don't really know where the sensor is!). Finding the right spacing for your setup is based purely on trial and error and a range of 1mm for the sensor position is a real challenge for the Samyang. (I also read somewhere that 'top-end' dslr manufacturers place the sensor to within ±0.01mm of the flange plate interface with the lens).

Sorry I cannot be of more help.

Good luck!

Adrian

19 hours ago, emyliano2000 said:

I hope you like it.

I do like it! Personally I prefer the colours to be less vibrant but that said the structure and detail is very revealing - especially this bit:

Never mind "the fingers of God" ..... spooky!

Adrian

29 minutes ago, iwols said:

if you could share your steps that would be great

I'll PM you later rather than add to this thread  

25 minutes ago, carastro said:

If you remove the green you have nothing to convert to yellow

Hi Carole

SCNR is Subtractive Chromatic Noise Reduction (SCNR) - it is designed to perform noise reduction and in particular to remove colour casts.

There's still plenty of green left in the image as per the histogram:

Without SCNR (and inverted SCNR) the histogram for the image is ...

... so it is pretty clear what SCNR has done - the main body of the histogram is largely unchanged.

I should have been more careful with my choice of words and said use SCNR "to remove the green (and magenta) colour cast".

Adrian

1 hour ago, iwols said:

anyone fancies showing me what i might be able to achieve

I do think it is better without the green BUT that is entirely personal taste.

I had a very quick go in PI with green and magenta removed but only minimal boost to blue and yellow/gold:

As with all these images colours are all down to personal preference.

If you wish I can let you know my steps in PI to achieve the above - I am sure with more time it could be better.

Thanks for sharing your masters - it's always fun to have a play with other peoples data.

Adrian

16 minutes ago, iwols said:

how do i do that in pi please

SCNR will remove the green from the image; some like to remove it all (1.0), some like to leave a trace (0.9). If you invert the image and apply SCNR at 1.0 it will remove the magenta which often occurs as star halos - again a matter of personal choice/preference. Once green is removed some like to boost the blue and the yellow/gold regions using ColourSaturation and/or CurvesTransformation.

Excellent Maurice - a very deft touch with the processing with great colour palette.

Looks like the Tak-ε is doing a great job for you with very nice stars all the way to the corners.

Adrian

6 hours ago, SAW said:

Here is a single 120s image all I have done is a EZ Soft Stretch in Pix.

Just eye-balling the image the stars on the right look 'bigger' to me than on the left of the image - that might suggest there is a bit of tilt from left-to-right - maybe?

Sadr taken mid-May, presented at 1:1 : 12 x 300s of S, H and O:

Just the edge stacking effects cropped reveals the stars look pretty good all the way to the corners:

Processed to tame Sadr and reveal the heart of Sh2-108

Don't you just love the Samyang 135  

This image is nothing much to write home about but I was keen to revisit Sadr and try to get a result where Sadr itself does not dominate this region of nebulosity.

This image is just 12 x 300s of S, H and O taken in nautical darkness and no Moon, taken on 23rd May.

Pre-processed in APP and post-processed entirely in PixInsight:

Presented at 1:1 with only minimal edge cropping so you can see the star shapes all the way to the edge:

I am pleased that even with the Samyang 135 mm I have been able to reveal the beautiful area of nebulosity at the centre of Sh2-108 that is so often obscured by Sadr itself, a star that is well separated from the Gamma Cygni nebula and plays no part in ionising the nebula.

Solved to reveal the main features:

Even in grey scale it presents well:

Thanks for looking.

Adrian

7 minutes ago, SAW said:

Where do I get 0.1 shims ?

Ebay.

10 hours ago, SAW said:

even just adding 1mm of spacing then through the focus back the other way where it was in focus before the L mark.

I'm not sure why you are not following the advice I gave you on the 28th May; you need to make incremental changes of 0.1 mm not 1 mm. 

13 minutes ago, aleixandrus said:

Those Astronomik filters are the "MaxFR" or the traditional ones?

They are just the standard version - not the MaxFR ones.

1 hour ago, aleixandrus said:

results seem not very promising...

I've recently imaged NGC7000 with my SY135+ASI183MM - 300s subs using Astronomik 6nm filters and this is a comparison for you with one single sub from each session:

Difficult to tell but you do seem to have a little less O and S compared with H (and with my filters).

My H and S focus in almost the same position - O is a little different but not that much.

I also image at ~f2.6 using a 49mm sdr - gain was 111 and temp was -20 degrees.

"This Samyang 135 is driving me crazy, specially due to bakcfocus and tilt problems, so adding one more issue is tempting me to sell it and buy a proper scope "

It took a while to get mine up and running properly and a lot of patience with assembling and disassembling to get spacing and tilt issues sorted - it was worth it in the end.

As for buying a proper scope - my experience of so-called 'proper scopes' has not been that great.

Adrian

4 hours ago, SAW said:

is this where I need my focus to be correctly spaced when using my 2600MM

Well in my opinion it would be. Good luck!