Sh2-115 + 116 First light with Esprit 100 and a warning

[gorann]

Last weekend I had my first session with my new Esprit 100 and my new ASI1600MM pro. I used a Baader 7nm Ha filter and aimed at Sh2-115 and got the small Sh2-116 as a bonus. Less of a bonus was that I hade oval stars in the corners. I then remeber that FLO had told me that the flattener to chip distance in the Esprit 150 manual was slightly wrong. When I now checked the distance given for the Esprit 100 flattener on the FLO site (55 mm) I realize that this is quite a bit from the 63 mm stated in the Esprit 100 manual from SW (which I should not have trusted). So mystery probably solved and easily fixed by removing 8 mm of T2 extenders. What I cannot understand is why SW cannot get these distances right in their manuals (no new priniting needed as they are available as pdf on their site).

So, I had to crop quite a bit in the corners and still fix the worst stars in PS. Also the seeing was not the best. This is 53 x 5 min lights, so a bit over 4 hours. Stacked in PI  (and 35 x 5 min darks subtracted as Master dark) and processed in PS.

C & S most welcome!

[toxic]

very nice indded looks great

[gorann]

7 hours ago, toxic said:

very nice indded looks great

Thanks a lot Chris!

[wimvb]

Yes, that's a very nice catch. Will you add colour? (If the weather gods are in your fovour, that is.)

[gorann]

Thanks Wim. I have a version where I added colour from the Esprit 150 with ASI071MC pro to this Ha data. No other chance to add colour soon due to travel and the moon:

[wornish]

17 hours ago, gorann said:

Last weekend I had my first session with my new Esprit 100 and my new ASI1600MM pro. I used a Baader 7nm Ha filter and aimed at Sh2-115 and got the small Sh2-116 as a bonus. Less of a bonus was that I hade oval stars in the corners. I then remeber that FLO had told me that the flattener to chip distance in the Esprit 150 manual was slightly wrong. When I now checked the distance given for the Esprit 100 flattener on the FLO site (55 mm) I realize that this is quite a bit from the 63 mm stated in the Esprit 100 manual from SW (which I should not have trusted). So mystery probably solved and easily fixed by removing 8 mm of T2 extenders. What I cannot understand is why SW cannot get these distances right in their manuals (no new priniting needed as they are available as pdf on their site).

So, I had to crop quite a bit in the corners and still fix the worst stars in PS. Also the seeing was not the best. This is 53 x 5 min lights, so a bit over 4 hours. Stacked in PI  (and 35 x 5 min darks subtracted as Master dark) and processed in PS.

C & S most welcome!

 

I got the Esprit 100 with dedicated flattener two years ago and recently added the ASI1600MM pro camera and EFW7.  I have the camera sensor set at 63mm from the flattener and everything works great. 

The printed Esprit manual clearly states 63mm back focus, I read that as distance to sensor.   No one as ever raised this issue before in many years to my knowledge.

Is the figure FLO are quoting the distance to the camera mating surface face,  I have looked at another vendors site and they are quoting 52.5 mm to the camera face.   Many CCDs have different sensor to face depths so that needs watching.

 I think the sensor on the ASI 1600MM pro is 6.5mm from the face.  

An error of this size would be all over the forums surely?

 

By the way great capture.

[gorann]

2 hours ago, wornish said:

I got the Esprit 100 with dedicated flattener two years ago and recently added the ASI1600MM pro camera and EFW7.  I have the camera sensor set at 63mm from the flattener and everything works great. 

The printed Esprit manual clearly states 63mm back focus, I read that as distance to sensor.   No one as ever raised this issue before in many years to my knowledge.

Is the figure FLO are quoting the distance to the camera mating surface face,  I have looked at another vendors site and they are quoting 52.5 mm to the camera face.   Many CCDs have different sensor to face depths so that needs watching.

 I think the sensor on the ASI 1600MM pro is 6.5mm from the face.  

An error of this size would be all over the forums surely?

 

By the way great capture.

Thanks Dave!

On the FLO web site it says "The spacing for dedicated CCD imaging cameras is 55 mm from mating surface (69.8 mm from centre of rear element)"  so I can only assume that they mean from the mating surface of the flattener to the chip (and the rear element is the last lens in the flattener). They cannot mean the "cameras mating surface" as you suggest since that differs between camera models. The same distance is given as 63 mm in the SW manual. I used the 63 mm distance (or rather 63.5 mm which was the closest I could get, with filter wheel and T2 rings giving 56 mm and a further 7.5 mm inside the ASI1600). And got quite oval stars in the corners and perfect ones in the centre, which suggest an error in distance. I cannot believe that the 0.5 mm would have such an effect.

I also have an Esprit 150 and there I was told by FLO that the distance (mating survace of flattener to chip) should be 98 mm (as on their net site) and not 96 mm as stated in the SW manual. They told me straight out that it was an error in the SW manual.

I attach an image showing the stars in the corners before cropping, star fixing and further processing.

I will post what FLO says about it (I sent them the question late Friday so I guess I have an answer early next week).

[gorann]

PS. Just to check that the oval stars were not a stacking error in PI, I now looked at one of the subs, and they are clearly there, as seen in this crop from a corner. It cannot be guiding error since the oval stars are only in the corners and in different directions in each corner. It really looks very much like a probelm with flattener distance.

[wornish]

I asked FLO directly why the difference between their number 55mm and Skywatchers 63mm

Here is the reply they sent this morning.

 

" The spacing is 55mm when the included 8mm spacer is fitted to the flattener - this gives an M48 thread and the perfect spacing for a DSLR.

Without this spacer fitted the back focus is 63mm but you would need to attach to the M63 thread.

If you are getting good results already then I wouldn’t be concerned - often people have to adjust the spacing by a few mm using spacers to get optimal results so the quoted figures are not 100%. You may also find that a larger full frame chip would be more demanding of spacing to get the stars just right in the corners.

Hope that helps.

Kindest regards,

Grant "

 

It's just basically where you measure from the flattener itself or the 63-48mm converter that is included with it.  Mystery solved.

[Jkulin]

I have checked this with @RayD the 63mm back focus is if you are not using the field flattener adapter, the 55mm relates to the shoulder of the field flattener adapter, it is a little confusing but it works perfectly if you make those distances.

[gorann]

Thank you both! I check my distances carefully nex time. Does anyone know how much I should add or subtract with a Baader NB filter in the system?

[RayD]

Yes as John rightly says, the distance is 55mm if you are using the supplied adaptor, which most people will be as it provides the M48 thread.  You should add 0.6mm to this for Baader filters, so set the physical spacing at 55.6mm and you should be close.  You may need to fettle a little to get it spot on with a larger sensor, but you shouldn't be far out with this.

The confusion comes because the US version I don't believe is supplied with the adaptor, so the spacing of 63mm in the manual is actually correct, but we have the adaptor and factor this in to get the the 55mm.

[gorann]

5 hours ago, RayD said:

Yes as John rightly says, the distance is 55mm if you are using the supplied adaptor, which most people will be as it provides the M48 thread.  You should add 0.6mm to this for Baader filters, so set the physical spacing at 55.6mm and you should be close.  You may need to fettle a little to get it spot on with a larger sensor, but you shouldn't be far out with this.

The confusion comes because the US version I don't believe is supplied with the adaptor, so the spacing of 63mm in the manual is actually correct, but we have the adaptor and factor this in to get the the 55mm.

So now my confusion now is that I had 63.5 mm including the 8 mm adaptor from the actual focuser to the chip  (55.5 from the adaptor to the chip) which should be spot on if I take into account that I have a Baader filter inside (if the efect of the Baadre filter is that I need to slightly increase the flattener to chip distance). I guess I just have to start playing with T2 rings to see what happens. Fortunately I have a lot of different rings laying around.

[RayD]

24 minutes ago, gorann said:

So now my confusion now is that I had 63.5 mm including the 8 mm adaptor from the actual focuser to the chip  (55.5 from the adaptor to the chip) which should be spot on if I take into account that I have a Baader filter inside (if the efect of the Baadre filter is that I need to slightly increase the flattener to chip distance). I guess I just have to start playing with T2 rings to see what happens. Fortunately I have a lot of different rings lying around.

Yes you may need to have a play as there can be some variation.  I would check your distances, all from the mating surface of the adaptor, and just play with the spacing.  I would start by adding a little to get to 55.8 and see how that changes things.

[Rodd]

Well, well.....it seems that the Lord of Stars can have issues with the beastly things himself!  (I refer to the big blue one in the colored version).   Looks good though.  Did you use allot of noise control in teh Ha image?  I see that seeing was not great--That might explain it.  

Rodd

 

[gorann]

20 hours ago, Rodd said:

Well, well.....it seems that the Lord of Stars can have issues with the beastly things himself!  (I refer to the big blue one in the colored version).   Looks good though.  Did you use allot of noise control in teh Ha image?  I see that seeing was not great--That might explain it.  

Rodd

 

I was rather gentle on the NR. Seeing is probably the main course of the largish blue halo and not issues with the optics or camera. You can almost see how the light have been shattered in the atmosphere. I could suppress it more but then I kind of liked to have the blue contrasting against all the red in this image - just like some people like star spikes I guess.

[Rodd]

1 hour ago, gorann said:

I was rather gentle on the NR. Seeing is probably the main course of the largish blue halo and not issues with the optics or camera. You can almost see how the light have been shattered in the atmosphere. I could suppress it more but then I kind of liked to have the blue contrasting against all the red in this image - just like some people like star spikes I guess.

I guess its the seeing.  

Rodd

[ollypenrice]

I love the object and processing.

Regarding the confusion, it would be so much better to provide the information with annotated photographs, I think.

One of my information bugbears is finding out chip size. I want it in mm, per side and the diagonal. Why is this so difficult???

lly

[gorann]

20 hours ago, ollypenrice said:

I love the object and processing.

Regarding the confusion, it would be so much better to provide the information with annotated photographs, I think.

One of my information bugbears is finding out chip size. I want it in mm, per side and the diagonal. Why is this so difficult???

lly

Thanks Olly, much appreciated!

Yes, I spend much time finding out those details and find myself jumping between the vendor sites (FLO, OPT, TS....). Often the least information (and least updated) is on the manufacturers sites. In the current case I will just have to start experimenting with T2 rings (I have plenty by now) until the stars look OK, since they do not look OK right now with the "correct" spacing.

[wimvb]

Sometimes astrophotography is like plumbing. It's just that the connecting parts are made from anodised aluminium rather than copper, and are more expensive. And despite (or because of?) the tighter tolerances, they rarely fit anyway.

[gorann]

On 22/10/2018 at 18:19, Rodd said:

Well, well.....it seems that the Lord of Stars can have issues with the beastly things himself!  (I refer to the big blue one in the colored version).   Looks good though.  Did you use allot of noise control in teh Ha image?  I see that seeing was not great--That might explain it.  

Rodd

 

 

You may be right Rodd, so while I wait and wait and wait for clear skies, I (and the lord of stars) had a go at reducing the blue/magenta particularly around the main blue star, primarily by reducing magenta saturation:

[Rodd]

4 hours ago, gorann said:

 

You may be right Rodd, so while I wait and wait and wait for clear skies, I (and the lord of stars) had a go at reducing the blue/magenta particularly around the main blue star, primarily by reducing magenta saturation:

I think it looks better--kind of subtle

Rodd

[gorann]

No clear skies in sight so I have been chewing on this one, done a bit on the colours and found that it looks quite different when turned 90° (as often)

[Guest]

Looking at your first attempt on this Göran, I really like the cloud like effect produced by the composition - reminds me of a lazy Moon floating above the clouds ?

Aside from my preference for the composition in the first example - the colour of the star and blending with the nebulosity in your last is really quite impressive! That blue seems to radiate out into the picture - exceptional!

Also in your last image above - the colour balance is much improved and the background looks perfect - it wasn't working for me until I saw that - I really like both the monochrome and colour versions.

David

[gorann]

On 05/11/2018 at 08:35, David_L said:

Looking at your first attempt on this Göran, I really like the cloud like effect produced by the composition - reminds me of a lazy Moon floating above the clouds ?

Aside from my preference for the composition in the first example - the colour of the star and blending with the nebulosity in your last is really quite impressive! That blue seems to radiate out into the picture - exceptional!

Also in your last image above - the colour balance is much improved and the background looks perfect - it wasn't working for me until I saw that - I really like both the monochrome and colour versions.

David

Thanks a lot David!

I really fought with the transition between the background and the nebulosity as well as the red colour. Blending Ha into RGB sometimes work well but here I did not think I got it right until vesion 50 of the image, which is the last one posted here, so I am really pleased with your positive feedback.

Now I am left with the prolem of deciding which rotation is the best. It really looks different in each of the 90° rotations I have tried out.