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NGC5775 etc and a quick M13.


ollypenrice

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All this done with the new Mesu/Atik 460 in the old TEC 140. I'm having to learn how to work with the new camera. It's not as easy as I'd expected! (Old dogs, new tricks... :icon_mrgreen:)

This one is from Virgo and shows the spindle galaxy NGC5775 apparently interacting with the spiral NGC5774. It's interesting to take a close look at the spiral which seems to have a spiral arm drawn off in a direction opposite to its natural one. There are other interesting galaxies in there, including what looks like a ring, PGC53081. This is crop, the targets being on the tiny side!

L 16x15 minutes, colours 12x10 each.

NGC5775%20FINAL%20WEB.jpg

And then M13, just 9x5 minutes per colour.

M13%209X5%20web-X3.jpg

Olly

 

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I like M13 - I think it's come out well and after completing M3 earlier, I will be tackling this one on the next full moon :) I've looked long and hard at the stars in the first shot and I can't help feeling that some of them (not all) are rather off colour with something of the magenta about them..... I think that's what I've settled on as I've looked at it for some while trying to work out what it's saying to me.

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Very nice Olly.  The background sky seems much darker in the galaxy picture (on my iPad anyway).  Could it be that it is that the crop is allowing us to see some magenta at the edges of the brighter stars?  

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1 hour ago, swag72 said:

I like M13 - I think it's come out well and after completing M3 earlier, I will be tackling this one on the next full moon :) I've looked long and hard at the stars in the first shot and I can't help feeling that some of them (not all) are rather off colour with something of the magenta about them..... I think that's what I've settled on as I've looked at it for some while trying to work out what it's saying to me.

 

58 minutes ago, gnomus said:

Very nice Olly.  The background sky seems much darker in the galaxy picture (on my iPad anyway).  Could it be that it is that the crop is allowing us to see some magenta at the edges of the brighter stars?  

The stars are certainly off. This applies to both images. The problem is to learn why this is so.

In the galaxy image I tried colour channel aligning in AstroArt (not great this time), then in Registar (which is normally infallible) and finally in Registar followed by AstroArt. In all cases the tricolour alignment was off, giving stars with different colours either side. The blue channel is also questionable in terms of focus/bloat. I used the radial blur trick to 'mix' the star colours but I don't intend to spend the rest of my life bodging like that!

I am 2mm too close to the flattener with this camera. Adding 2mm is rather tricky but I'll look into it. (Suggestions welcome!)  Then there is an established debate over the compatibility of the TEC140 with the Sony chip in the blue channel. Not much I can do about that, though doing one colour at once in its own focus might be a help.

I appreciate the feedback and, though I didn't say so in my original post, I know that these images don't meet the house standard! I'm getting on OK with the 460 in luminance but not in colour. I dare say it will be good in NB as well but we'll have to see.

Olly

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Just now, gnomus said:

I knew it couldn't be that easy.  I believe FLO can make custom extension tubes/adapters.  

Yes, thanks. Something may already exist 'out there' and I have about two cubic metres of discarded bits which might, perhaps, include the necessary!

I think our high res future may lie with the 11000 and the Meade ACF...

Olly

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I'm interested in your thoughts on the 2mm spacing..... If the spacing is out then it normally manifests itself in corner elongation in whatever direction....... But surely if this were the case all colours would be elongated equally? Why do you think that the spacing may be affecting your overall colour?

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26 minutes ago, swag72 said:

I'm interested in your thoughts on the 2mm spacing..... If the spacing is out then it normally manifests itself in corner elongation in whatever direction....... But surely if this were the case all colours would be elongated equally? Why do you think that the spacing may be affecting your overall colour?

I'm not sure that it is, but I've learned that system errors don't always play neatly by the book. Basically I'm getting lousy stars out of this rig (which is rather hard because I think I'm OK at stars!) and one thing that's happening is colour assymetry within the stars. If the spacing is wrong it might possibly be 'more wrong' in blue than in red, creating increasing mismatches in colour alignment off axis.

On the other (and more pessimistic) hand it might be that the Sony chip catches out the colour correction of the TEC. The TEC is better colour corrected with the flattener than without it (I know this for sure from experience) so maybe if I had the right spacing I'd get the better colour correction and better stars. I do need to try it. It isn't a big deal, anyway. I could always hit a target in the 11 meg for colour then shoot a high res L layer in the 460.

Hey, the second Mesu is singing like a canary. I'm still a happy bunny.

Olly

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1 minute ago, swag72 said:

It will be interesting to see if the spacing does indeed solve the colour issue. At least you have a backup plan and I have been looking forward to seeing the Meade and 11000 together :) 

Well, it's about time, I'll give you that!!!!

:icon_mrgreen:lly

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18 hours ago, ollypenrice said:

10 inch, the original version illegally marketed as a Ritchey Chrétien.

Olly

That will be interesting to watch, I look forward to learning from your experience, I have a 12 inch F8, ACF.  I have no problem maintaining focus, but the details are just not as sharp as with my refractor, have only done a couple of serious images with it so far

Mark

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On 27/04/2017 at 20:11, swag72 said:

I'm interested in your thoughts on the 2mm spacing..... If the spacing is out then it normally manifests itself in corner elongation in whatever direction....... But surely if this were the case all colours would be elongated equally? Why do you think that the spacing may be affecting your overall colour?

I've managed to add about 1.6 of the missing 2mm. We imaged M63, the Sunflower, last night and the luminance strikes me as very sharp. I also did some parfocality testing and, with this camera, there isn't any! The colours require individual focus, which wasn't the case with the 11 meg chip. Still, that's not a problem once I know about it. Blue came down to a decent FWHM after a bit of effort. So it looks promising.

I also found that darks do more harm than good, creating a lot of dark pixel noise. Bias as dark gives a significantly cleaner result.

7 hours ago, nucdoc said:

That will be interesting to watch, I look forward to learning from your experience, I have a 12 inch F8, ACF.  I have no problem maintaining focus, but the details are just not as sharp as with my refractor, have only done a couple of serious images with it so far

Mark

Yes, my idea is to decide which is best, big scope-big pixels or small scope-small pixels. Only one way to find out!

Olly

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1 hour ago, ollypenrice said:

Yes, my idea is to decide which is best, big scope-big pixels or small scope-small pixels. Only one way to find out!

 

There will be a lot of people watching this with interest..... myself included as I was wondering about a smaller pixel camera for the TMB.

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On 4/29/2017 at 06:12, ollypenrice said:

I've managed to add about 1.6 of the missing 2mm. We imaged M63, the Sunflower, last night and the luminance strikes me as very sharp. I also did some parfocality testing and, with this camera, there isn't any! The colours require individual focus, which wasn't the case with the 11 meg chip. Still, that's not a problem once I know about it. Blue came down to a decent FWHM after a bit of effort. So it looks promising.

I also found that darks do more harm than good, creating a lot of dark pixel noise. Bias as dark gives a significantly cleaner result.

Yes, my idea is to decide which is best, big scope-big pixels or small scope-small pixels. Only one way to find out!

Olly

Olly,

It almost seems worth having a precise part made.  A company here called Precise Parts of all things does just that.  I am having one made for the TOA.  Its not very expensive (30-40$ for an adapter).  I am sure they can make a 2mm spacer with whatever threads you want. Most scopes have a margin of error though on the sensor spacing--vignetting being the typical symptom as someone said.  But precise parts can get you precisely the right distance.  It normally takes 7-10 days.  Not sure about overseas--but they do that.

Rodd

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2 hours ago, Rodd said:

It almost seems worth having a precise part made.  A company here called Precise Parts of all things does just that.  I am having one made for the TOA.  Its not very expensive (30-40$ for an adapter).  I am sure they can make a 2mm spacer with whatever threads you want. Most scopes have a margin of error though on the sensor spacing--vignetting being the typical symptom as someone said.  But precise parts can get you precisely the right distance.  It normally takes 7-10 days.  Not sure about overseas--but they do that.

I looked at one of these when I needed a part ...... when you factor on postage to the EU as well as any Customs battle you may encounter, it worked out at well over $100 ........ I can recommend a couple of UK guys if you decide to get a part made Olly :) having had to get two made for the Tak as the quoted spacing wasn't working and so I had to get another one made up with a guess of how much spacing I wanted.

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16 minutes ago, swag72 said:

I looked at one of these when I needed a part ...... when you factor on postage to the EU as well as any Customs battle you may encounter, it worked out at well over $100 ........ I can recommend a couple of UK guys if you decide to get a part made Olly :) having had to get two made for the Tak as the quoted spacing wasn't working and so I had to get another one made up with a guess of how much spacing I wanted.

 

3 hours ago, Rodd said:

Olly,

It almost seems worth having a precise part made.  A company here called Precise Parts of all things does just that.  I am having one made for the TOA.  Its not very expensive (30-40$ for an adapter).  I am sure they can make a 2mm spacer with whatever threads you want. Most scopes have a margin of error though on the sensor spacing--vignetting being the typical symptom as someone said.  But precise parts can get you precisely the right distance.  It normally takes 7-10 days.  Not sure about overseas--but they do that.

Rodd

Thanks. I do have a PP adapter in the line already, in fact, but the delrin spacer I used to get within 0.4mm will, on this small chip, be good enough for government work!

Olly

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On 2017-04-29 at 12:12, ollypenrice said:

Yes, my idea is to decide which is best, big scope-big pixels or small scope-small pixels. Only one way to find out!

Olly

Wait a minute here. Aren't you advocating larger aperture ( = big scopes) anymore? :glasses9:

On 2017-04-29 at 13:14, swag72 said:

There will be a lot of people watching this with interest..... myself included as I was wondering about a smaller pixel camera for the TMB.

Yes, me for one. I'm looking into either the atik 460 or zwo asi 1600 for my step into rgb imaging, so this thread is very interesting.

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6 minutes ago, wimvb said:

Wait a minute here. Aren't you advocating larger aperture ( = big scopes) anymore? :glasses9:

Yes, me for one. I'm looking into either the atik 460 or zwo asi 1600 for my step into rgb imaging, so this thread is very interesting.

No, I'm all for big scopes if they work and you can afford them. I have the specific choice between TEC with small pixels or Meade ACF with big ones since I have that kit already. I'm not, alas, in the market for a higher quality larger scope. So the question is a partiular one, TEC/Atik 460 versus Meade/Atik 11000. I won't be testing the Meade for a while yet. I want to get the hang of the 460 first. (I don't expect the Meade to cover full frame but that's not a problem, I'll crop.)

Olly

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Interesting thread . . . as I too wonder about a small pixel CCD for my FLT132, eg 690.

Great pair of images Olly, I especially like the M13 with the detail and resolution to its core.

Working with the luminance data from Steve's 690 and his Esprit 120 for our collaboration on M63 certainly encourages me in my thinking.

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