SilverAstro

1 hour ago, Nigel G said:

The little box in the bottom left of one is a copy paste mistake,  I only noticed after I had closed startools

No worries Nige, I only mentioned the little box as an aid in identifying (with Ian's help) which picture I was not seeing, all sorted now = a fault with my browser which will have to be replaced ! 

Thanks Ian,

the plot thickens, it is Nige's 1st one  PSX_20160709_031747.jpg.8ba22b25002c6d8aaf4f284fb7c5ffd6.jpg  that has gone AWOL, I can see it if I revert to Firefox but for some reason yet to be determined K-Meleon ( based on Firefox) cannot see it and even worse did not put up a blank icon to signify I wonder what else it has been not showing me 

I think a trip to K-Meleon site is on the cards !

11 minutes ago, The Admiral said:

Really?

  yep really now I am seriously worried, what is going on, the top one is pale, the middle one is orange-ish with a "Paint" dialog wee box lower left and the bottom one is pale yellow with ummm yellow-green in the spiral, but the sun is creeping up on my monitor , how strange

These are the 3 part URLs

PSX_20160718_215237.jpg.c1dce7c6219f4a10aea5dda143a7306e.jpg
PSX_20160718_215704.jpg.10c2840ba70cc6f89d9f1f9aa2615d6c.jpg
PSX_20160719_121341.jpg.d8d0b5fd53451753223adbe6c4ccbfeb.jpg

which am I missing, is it also a jpg or something else that my browser is rejecting ?

What if I re-quote it all , how many remain ? :--

3 hours ago, Nigel G said:

I stand corrected,  after processing all 4 M31 images I find a little more detail as more subs are added.  Few, I thought I was running out of room for improvement. 

The 4 images . No1  = 40 x 45s during quite poor seeing.  No2 = 120 x 30s during good seeing and low light pollution . No3 = 120 x 30s plus 40 x 45s during full moon. No4 = everything 120 x 30s + 80 × 45s . 

There is a small difference between them , a bit more detail on the outer spirals, I find M31 a difficult dso to process. 

I get a lot of noise to deal with even after stacking  200 subs. I think this is due to the camera and sensor limits rather than the scope.

Nige.

3 hours ago, Nigel G said:

 unmodded.

Oh ! I am amazed, I thort you had a modded one, , , and isnt the NA mostly Ha emission ? so you are not lacking for much,

mummble mummbl, think I'll forget all this stuff about measuring the response of various and just go buyme a 1200d like wot my chum Nige has

2 hours ago, Nigel G said:

The 4 images . No1  = 40 x 45s during quite poor seeing.  No2 = 120 x 30s during good seeing and low light pollution . No3 = 120 x 30s plus 40 x 45s during full moon. No4 = everything 120 x 30s + 80 × 45s .

Luvverly stuff, but am I going blind - I can only see 3

9 minutes ago, The Admiral said:

My mind has turned to means other than astro! How dare you sir you could get Black-balled for that or  Ha-balled

but at least different cameras could be compared. We would have to make sure that each camera owner bought the same LEDs ? and not all will be happy with the electricals etc perhaps ? 

But I like it so far, good laterals !

4 hours ago, Stub Mandrel said:

What about the Dumbbell M27?

Unmodified Canon 10D -  30 second exposures at ASA1600 in 2015:

Modified Canon 450D -  30 second exposures at ASA1600 in 2015

OK, not the same camera and my processing is better than it was, but same scope, same place and the first picture was done on 5 May the second on 5 July so much less favourable conditions...

 

Perfect example of the sort of embryo that was in my mind, thanks SM, 2 cameras from the same source brill ! Do you still have the frames as they came out of the cameras so you can do the same (or lack of !) processing on them both ?

Just by way of example of how I thought a protocol might develop here is what I was thinking we might do in IRIS, it has a slice tool to take a histogram across an image,  first I reduced them to b&w to compare levels, we could discuss how to compare colour amplitudes in a colour image later(?)

Iris did not allow me to do a screen capture of where I placed the slice so I added the green arrow later in the approx position , the slice on the left shows that the level in the Ha light region ( short green line ) is well below that in the right pic

(and as I type this Ian has added a right good idea !)

but let me not waste my cunning Iris plan :-

35 minutes ago, Stub Mandrel said:

What about the Dumbbell M27?

and my processing is better than it was

 

Good candidate (I think, but my knowledge of it is limited !!)

and that is the big problem, how to avoid processing distorting the ratio, it may look pretty but may not be quantifiable. Some way of doing it raw-ish would need to be defined

Very interesting folks, cant stop - due into the clutches of the NHS, will be back later to comment better

29 minutes ago, Nigel G said:

A good idea, certainly should gather some useful information,  something like orion neb although that's a few months off yet, 

30 minutes of subs  limit  ? Although light pollution in different areas could play a part in the result. Plus aperture.

Yes, Orion in the offing that is indeed why I am contemplating a new camera, be prepared, boyscouts etc initially for wide field.

Thanks for your suggestions. My initial thoughts are for a nebula in which the two regions are reasonably distinct ( not overlaid or jumbled up ! ) such that the reflection could be used as a broad spectrum reference level and the Ha signal amplitude compared to it. So aperture should affect them both equally ?(I think ?)

Light pollution hmmm yes good thinking that could be a bit of a nuisance (!) to quantify, especially if the pollution had strong emission near Ha (??) and it would rule out pollution filters I suppose - that could be a bit of a killer of the whole idea

A limit on subs, yes another problem area, if the sensor was differentially non-linear ? are they, I am rapidly getting outa my depth here !

1 hour ago, wxsatuser said:

I don't know of a definitive site that can tell exactly even approx would be a good start how each camera reacts to Ha.
If in doubt I would most likely take the modded approach

I can definately say the 6D and 7DMK2 see enough Ha that modding is not necessary
but it's down to personal taste in the end.

In the end I suppose I could buy one of each and try them ! Oh, hang on an idea is germinating, , , , "try them"  measure them !! Nige, Admiral, me and others I am sure like a good experiment soooo being as there are many owners of many models, mod and not mod, on the forum  can the collective come up with a standard model (standard target?) and standard method free of user bias to determine the %Ha  for each ?

Henceforth to be known as the loadsaHa challenge   " %Ha Challenge"

Edit PS is it a bit odd that Canon have different filters for different models ? For viz light cameras one would have thought that they would have determined an optimum cut-off and stuck to it through the range ??

EDIT 2 ) A. a reflection and emission nebula in close proximity, ie. a convenient field frame size

 B. stacking OK ? but no curves / gamma etc.

 C. ?

10 hours ago, wxsatuser said:

Modifying just makes nebulae more red and tends to hide all the other colours like blue and green.If a dslr can see 20 to 30% of Ha, thats more than enough, modifying should only be done to cameras that see next to nothing of Ha.

An example with an unmodded  6D at f/2.8 50mm 7 x 30sec exposures ISO 1600.
Not properly processed as it was just a test but you can see what I mean.

A very nice example, yes I see !

As I am trying to decide between a 1200d{mod or maybe not} , a 1300d{not}, or a 100d{not} but not got  a clue about their %Ha ! (and I dont think Curry's will be able to help ! ) where would be a good place to get this info ?

Apart from Nige's excellent work ,, another pic some time ago, I forget where, was of Barnard's Loop next Orion, and in mod/not mod comparison the loop was not visible at all without the mod, now I am kicking myself cos I did not note the make of that camera

Very good !     +1 for the first one, unreduced.

1 hour ago, Stub Mandrel said:

Not overly convinced there is an issue. Think of the overhung loads on a car wheel bearing which is of comparable size.

interesting that you should raise that - my first polar disc mount used a strut + wheel hub off a Ford Zodiac, amongst other bits and pieces !

But cars are not usually steered with arc second accuracy

38 minutes ago, The Admiral said:

It's a thought, but I can't help feeling that would be too easy! I wonder if the calculations would become unbounded, like dividing by zero!

Yes, exactly my worry hence my "Can regular eq mounts be sold to people living close to the north pole ?"

I know there are general solutions to handle it, eg. in the case of star sensors on spacecraft, but I cant remember how (that wasnt my prime responsibility ) nor if it is implemented in these softwares. We need an experimenter

Side line : another thing, I've never been happy with German equatorials, too wobbly perched on top of tripods with their bearings way too close together on the shafts for stability,  but if one of those shafts is turned vertical(ish) then maybe not so bad ?

17 minutes ago, The Admiral said:

I think EQ mounts only offer a limited range of latitude adjustment.

Mechanically that is certainly true, bent bolts and all ! But if the software is capable of handling the spherical coordinate shift to working vertically at the pole then there is no reason (?) for it not to work in London if it were de-wedged and told a little white lie ! (In other words it would need to pretend to be working at the centre of the earth, ie. only good for geocentric not topocentric coords. ( good for stars,dso etc, not nearby solar system )  I think !!

37 minutes ago, The Admiral said:

I hadn't realised that the Evo mount drive now included a worm gear,  I think so but best to check , my memory is not always reliable !

The beefy mounts I referred to can be used in both altazimuth and equatorial mode, so there wouldn't need to be any extra work involved. Yes, sorry, I was not clear, my brain cell had wandered to the other single purpose beefy but les expensive eq ones. I was also thinking that for the alt-az there seem to be two schools - those who swear that the mount needs to be carefully leveled and north pointed, and those who just plonk them down, so two software implementations ???perhaps,   maybe the go-to software in an eq may be the wrong sort and not tolerate a big tilt and plonk ! 

I think blue bloat reducing filters are available I believe,  hmm interesting, a blue cut filter presumably, so that would give a R+G image and then a B would need to be taken through a trueBlue filter and the two added in post proc. A lot of fiddling !

 

EDIT  Can regular eq mounts be sold to people living close to the north pole ? In which case one could be used in London with an appropriate tilt, the software would not know that you were lying when you said you were in Svalbaard or wherever ! Caveat, that will only work for geocentric coords, so the moon and close asteroids would not be tracked correctly (maybe not even the planets ? )

The Celestron SE mounts use spur gears, the Evolution mounts use (supposedly better) worm&wheel and was big in the publicity when they were introduced, I dont know what the Discovery uses ?? I suppose a big beefy eq could be de-wedged ! depends on how clever the software spherical trig is I suppose.

Does the jerkyness of the mount tracking mean that it is advantageous to use many short exposures, even in the East or West where 90sec could be done it may still be better to do 9 x 10sec say, and give DSS a better chance of using them ?

Blue star bloat in (who's was it ?) Achro,  wild idea = is there such a thing as a red & green pass filter ? a 2 position filter wheel with exposures made by red&green + blue.  Thus similar as the big long boys do R + G + B + luminance + whatever other channels they fancy   ok I'll get my coat

Nige - fingers and everyting xxed for your Mum, best wishes.

3 hours ago, The Admiral said:

Hmm, not sure I'd go along with that . It's still using an Alt-Az mount;

Hmmm I'm not sure I'd go along with myself either ! and I agree with Calli ( I am being very agreeable today, , even though I have just returned from the clutches of the NHS myself   ) that it is a bit ott for amateur alt-az, but from PMs with Nige I know he likes a mechanical challenge 

So, deffo in the experimental challenge category ! Thanks for the link to the software control, I expect Gina could do something with an arduino as well !

Just for curiosity (?!)  an alternative to the complex maths to follow the 'nodding' field rotation motion, that I read about somewhere ( sorry lost link) , is to use an off-axis guide to follow a rotating edge of field star.

Ok, back to reality sorry for the diversion > > >

echo Ian, and best wishes from me.

43 minutes ago, SilverAstro said:

knowing of your mechanical skills and expertise with a lathe, how about a Field Derotator ?

On second thoughts, a field derotator would probably disqualify for "No Eq" as it is just another means of compensating for the earth's polar motion, an eq mount by another name/philosophy !

1 hour ago, The Admiral said:

mirrors my own to some degree (no pun intended!).

The minute you said that I felt sure Nige would second the motion when we put this to the committee

3 hours ago, Nigel G said:

 room for improvement without costing hundreds and I'm on the hunt for improvement.

Ah yes I see, note that I have cut out "big", on the grounds that your results are already amazingly impressive !

So, mindful of your desires and knowing of your mechanical skills and expertise with a lathe, how about a Field Derotator ?

I fear I might have lost the plot here ( long day + some amber nectar!) -
but why do you want to downscale from your 150 reflector to a 130 reflector ? ( going to a refractor is a whole other kettle of fishes ! )
In an Alt-Az context duration of exposure, and number thereof, is the (main?) problem so 150 wins over 130 for photons captured. A secondary problem is the stability of the mount vs. size of scope but you have already proven that is OK for your 150.
Another prob might be the focuser (DS vs not DS) but again you have that sorted !
The 130P-DS (if it is like the 150P-DS) has the secondary closer to the primary for photography at prime focus, but you sorted that with your hacksaw.

Another prob is criticality of collimation at f5 of the fixed 150 vs the adjustable 130, but you sorted that by un-fixing the 150 !

So I am not seeing why you want to go down to a 130 ?

120 refractors are above my paygrade/competance

1 hour ago, Nigel G said:

or CA, need to research a bit.

CA = chromatic aberration, is what happens in the glass of a lens, like in a prism, and gives the colour fringing that Herzy describes. Does not happen on the aluminium surface of a reflector

an Achromat (achromatic) lens attempts to correct this CA for a limited selection of colours by using lens elements made of different refractive indexes.

an APO = apochromat (apochromatic) lens, corrects CA for a wider selection of colours by using even more lens elements of even fancier design and thus more expensive than an achromat.

The chromatic problems of lenses (refractors) are reduced when imaging through monochromatic filters with monochrome cameras.

hth

1 hour ago, Nigel G said:

Well after a tough night thinking about light speed and distances and trying to understand our Universe ☺ ( you'll know what I  mean if you saw last  night's post.) I dont remember you submitting a proposal to the committee to go and do some actual astronomy !!! would you believe whatever next

Quote

tracking and exposure needed is behond the capability of my mount ☺. Good thing is it only took a few minutes to work that out. Quicker than sorting out the big bang !

M 31 Andromida galaxy less that 13.7 billion light years away. Prove it

 nice one, glad we kept you awake long enough to catch the clear sky,(I thought it went quiet !!),  good start there and yes you deffo need the cut-down focus tube and no barlow for that one, it'll be good to watch how you get on with this target,

thanks for showing. (and the late night conversation !)

On 25/05/2016 at 11:28, Vox45 said:

There are also Linux distribution that were created specifically for astrophotography

That looks very interesting thank you, a Live one ,, nice introduction web site etc., only one small problem I dont think my internet is stable enough to take a 2.2G ( or thereabouts ) iso down in one go, nor my browser to recover from a drop.

Is there a reliable torrent of  it   DistroAstro3 anywhere anyone ?

On 26/05/2016 at 12:31, Gina said:

 I've used the GIMP in the past - must check up on latest version - have they upgraded to 64bit yet, for instance? 

Yes. There are 64bit versions (( windows builds, both portable and installable, of both Gimp2.8 (stable but only 8bits/ch) and the 2.9 (dev with 16bits/ch) The first place that comes to mind is at Partha's Place http://www.partha.com/ ))