Is There Any Ha In This Pic?

[Spacehead]

All, I splashed out on a new 1300d canon and had it astromodded (cheapastrophotography site - as recommended a lot on here).

So I have been taking pics of the region around Deneb - in particular the pelican nebula.  Whilst my shot is slightly low - the beak and head should 100% definitely be in the frame.

I have stacked about 40 mins of exposures at ISO 400 and 1 min each.  I really would have expected to see at least a smidging of Ha, but no - nothing.
It could be my processing skills need honing (well - actually learning).
But I was wondering - could someone download this and see if there is any hint of Ha in it for me - just so I know I am on the right track?
Or would absolutely zero Ha be expected through a 200p on a modded 1300d at 400 iso for 1 min?

http://www.serlimited-uk.co.uk/space/anyha.jpg

 

 

 

[wimvb]

You need to save images as raw files. Jpeg is just 8 bit/colour. Raw files are 12 or 14 bit, and holdm ore infornation. In order to see the Ha, you'll also need to stretch your images, in photoshop, or a similar program.

Do you have a copy of 'Making every Photon count'? Check it out on the FLO site.

[StargeezerTim]

I had a quick play but there is no HA there... I'm not actually convinced you have the right location. I attach an image of it and the stars in your image don't match up with the stars in my image, but I may be wrong.

As Wim said, do use raw images when capturing and save the stacked image as a tiff. I would expect to see a richer image than you have, it may an issue with stacking... post the process you used to stack and someone may well be able to help. 

Hope this helps, Tim. 

[Oddsocks]

Plate solving the image puts you right on target, overlaid your image frame in the Sky X and it shows where the camera was pointing and is added below with the white box indicating your FOV.

Is the frame you posted a single frame converted to jpg or the result of the stacked images? Were you collecting in RAW format or just JPG's?

Zooming into your image shows the stars in the central part of the frame appear to occupy two distinct positions which is a sign of backlash in the RA drive, the fact that the two positions are so well defined makes me think that the image you posted is just a single frame and not a stack of 40 but without more information about how you acquired the image, in which format, guided or unguided etc that it is impossible to make an informed prognosis of this particular issue.

In your posted image the brightest star is 57 Cygni (HIP103089) which at mag 4.7 should be appearing quite a bit brighter than it is but we don't know where you are and if from your location the Pelican is quite low then atmospheric extinction may be the reason you have recorded so little. There is a slight reddening of the frame where the Pelican should appear and if I were to make a guess I would say this is an image taken at low elevation and is the main reason the result is rather poor.

If you are not guiding then it is important to set up and use PEC correction on the mount so that you can expose for longer. Even with the astro modification only the red pixels will respond to Ha so only 25% of the detector will record the Pelican and a one minute exposure is really a little too short. On a guided mount, or a mount that is well polar aligned, is using PEC and is slightly unbalanced in RA to reduce backlash then longer exposures will reveal more (provided the target is high enough in the sky).

William.

[StargeezerTim]

42 minutes ago, Oddsocks said:

Plate solving the image puts you right on target, overlaid your image frame in the Sky X and it shows where the camera was pointing and is added below with the white box indicating your FOV.

William.

I'm very happy to be proven wrong. From the post it shows you are spot on in terms of framing.

I think it would help, as said, if you provide further info on how you collected the data. I also noticed the reddening around the star. I have had the same effect with thin high cloud in the past and i do wonder if that was also an issue.

I doubt it is anything to do with the camera...

[pete_l]

Since I happened to be in the area <g> I took a shot at this.
The first image is a 60s exposure through my ED80 + modded 1100d at ISO400.

The second is the same 60s but at ISO 6400. Both shot as JPG and no processing / stretching. Straight from the camera

 

[Oddsocks]

6 hours ago, StargeezerTim said:

 I also noticed the reddening around the star. I have had the same effect with thin high cloud in the past and i do wonder if that was also an issue.

I doubt it is anything to do with the camera...

The slight nebulosity appearing around 57 Cygni in the OP's image hints at high cloud, or dew forming on the optics.........

[Spacehead]

Ok, it looks like I have a couple of things to look at here in the main.

1.  Position - yes I was happy with that, although the pelican would be a bit low in the frame, I was confident about the area (took me over an hour to find lol).

2.  Redness in the picture.

3.  RAW / JPG

So number 2 - the redness.
This is of some concern to me, because on the same evening I also took the star cloud (shown below) at the other end of Cygnus, here is the jpg.  It is 1 min ISO 400, no stacking or processing - straight off the cam.

At a glance, it doesnt look bad really.  So I stacked that single pic with DSS and dropped some GB but upped the R.  Here is the result of the above pic stacked alone and with the red pulled over.
I have just screen dumped the DSS adjustment screen so you can see my values.

As you can see - the image goes darker towards the edges.

My own theories and thoughts include.

a... I just collimated my scope - and now that it is spot on, the same thing that causes me to require a coma corrector to correct the stars around the edges is also causing a reduction in light capture around the edges?  To back this up, on my old camera (unmodded 400d) the "bright area" of all frames was offset way left and the darkness in the image was all on the right.  Whilst the top if the frame above seems lighter than the bottom, its far better than it was and I dont really want to make more collimation adjustments as everything looks bang on.
b... There are less stars round the edges of the field???? (I doubt it though).
c... My camera is duff (but its brand new).
d... Mist on the mirror - I did check the mirror a few times during the evening and whilst the whole scope was wet on the outside (it was very high humidity that night) the mirror "appeared" clear to the naked eye.

The image above was on the same night, although at least an hour earlier than my Pelican area shot.  

I want to draw your attention though if I may to the following image - one of my Starfield alongside a Pelican area shot (below)
Both of these were taken same night, different area, 1 minute, ISO 400 - and yet look at the background colour!  One is brown and the other is black.  Its as though the sensitivity changed - but the info on the images says nope - both iso 400 1min.

I wonder if the above offers anything which I could be advised upon?

3.  RAW / JPG.

I have taken raw pictures on this night aswell.  My camera was set to RAW + L.
On my camera, the files list under XP as the panel on the left, then when I have copied them to C:, they show as the panel on the right (below).

My confusion here is that when they get copied over, they are renamed as IMG_1234(21) for example, it seems XP isnt handling the RAW very well or something - this is why I didnt upload a RAW - because I havent established yet exactly what the heck they are since they are all showing as JPG and each file in each pair is the same size - I was thinking the RAW should be bigger?

So are these JPG files because the have  a .jpg extension?  or are they still RAW?  Being a programmer - I can't tell you how much this kind of unspecific crud fudge infuriates me - the file naming I mean.

Here is one of the renamed with a numbered (XY) bracket on the end - I am assuming these are the RAW in the RAW + L?  - but realistically I am afraid I have no dam idea.

Ive renamed it on the host - I dont like having stupidly named files (spaces and brackets) - but here it is.

 

So - I am at a loss really both on my RAW learning and also my HA experiments and also whether my cam is ok - I think my best bet is to just take some at 1600 (and higher) ISO and see what happens.
Also try different exposure times - say 1 min, 1.30secs, 2min - just to see really whether or not there is anything at all there.

A couple of other notes incase anything jumps out.
I track only - I have no laptop or guiding yet.
It was not a crisp night - but nor was it visibly cloudy - perhaps a tiny tiny bit hazy up there.
My next shots will have slightly (maybe) better Polar Alignment - so I may get longer exposures.

Dunno what else I can say really.  Any advice appreciated.

Cheers All.








 

[VilleM]

You have mist in the air / moisture in the optical train. I platesolved your image, pelican nebula is in the center of the image so lets rule out wrong position. What I would suggest is go for easier target at first, for example M31. DSLR and H-alpha dont mix usually. Simply because Ha emission is blocked in the filters between light and sensor. M31 is large, easy to find, and visible in the pictures with your exposure times even without post-processing or stacking.

Almost every camera has sensitivity range that stops at ISO 1600. Yes, your camera can go for iso X thats so much hinger. But its actually image taken with ISO 1600 and then camera simply increases brightness by X amount. This destroys faint signal aswell, so I wouldnt go above ISO 1600. If target is really bright I would lower to ISO 400-800. Always avoid using values that are not doubled from ISO100, like ISO 125 for the same reason. Its photo taken with ISO 100 and brightened in software X amount. So use ISO 100, 200, 400, 800, or 1600. And once you decide what sensitivity youre using dont change it between shots unless you want to do two diffrent images (or HDR).

Max your exposure time for individual subs. Longer the better in this case. Also, I would stay away from DeepSkyStacker. I havent got anything great out of it, I dont know is it just user problem or bug but I always end up with weird artefacts. When you stretch images dont assume the colour of it and stretch individual channel, instead stretch whole image. There is light coming in to G and B channels too. Not H-alpha, but none of these so called "H-alpha" regions are 100% Ha light. Keep in mind theyre best visible in that part of spectrum, but DSLR sensor might still record signal that looks more like purple than red.

Good luck!

[Oddsocks]

2 hours ago, Spacehead said:

a... I just collimated my scope - and now that it is spot on, the same thing that causes me to require a coma corrector to correct the stars around the edges is also causing a reduction in light capture around the edges?  To back this up, on my old camera (unmodded 400d) the "bright area" of all frames was offset way left and the darkness in the image was all on the right.  Whilst the top if the frame above seems lighter than the bottom, its far better than it was and I dont really want to make more collimation adjustments as everything looks bang on.
b... There are less stars round the edges of the field???? (I doubt it though).
c... My camera is duff (but its brand new).
d... Mist on the mirror - I did check the mirror a few times during the evening and whilst the whole scope was wet on the outside (it was very high humidity that night) the mirror "appeared" clear to the naked eye.

a ) The light reduction around the edges is normal in all optical systems and is called vignetting. When a scope is perfectly collimated the brightest part of the image will be dead centre while the corners, top bottom and both sides will show equal darkening when using a camera with a square detector, with a DSLR that uses an oblong detector then the sides will show greater darkening than top and bottom. The bigger the detector then the more apparent the darkening due to vignetting becomes. In post processing you add frames called flats which are just images containing nothing other than the distribution of a homogenous light field across the detector and the image processing program does some magic with the flat field image and reads the amount of darkening. The program then uses this information to brighten the actual star image in the corners and your image is then said to be calibrated and will appear the same brightness across the full frame.

b ) Answer above applies

c ) The camera is most likely fine.

d ) This seems most likely the reason for the poor images, in a Newtonian reflector the first part of the optical chain that suffers dewing is the secondary and you can't really see that when looking down the tube unless you shine a torch inside the telescope and look for the reflection of the secondary. Looking in this way you should be able to see right back to the camera shutter if the optics are free of dew. In very cold or humid conditions it is not unusual to have dew forming on the coma corrector, again you should be able to see this when shining a light inside the telescope and looking for the reflection back from the secondary.

2 hours ago, Spacehead said:

My confusion here is that when they get copied over, they are renamed as IMG_1234(21) for example, it seems XP isnt handling the RAW very well or something - this is why I didnt upload a RAW - because I havent established yet exactly what the heck they are since they are all showing as JPG and each file in each pair is the same size - I was thinking the RAW should be bigger?

So are these JPG files because the have  a .jpg extension?  or are they still RAW?  Being a programmer - I can't tell you how much this kind of unspecific crud fudge infuriates me - the file naming I mean.

Windows Xp can not display a raw camera file directly. Canon use the file extension .cr2 as their naming convention and to handle a raw .cr2 file you need image processing software that can read it. For instance, Photoshop, or the image processing software that is supplied with the camera package. The free stacking software DSS can read raw .cr2 files and most astronomy image processing software can read raw files. but Windows Xp can not read these natively.

Unfortunately you have cut off the most interesting part of the Windows Xp file contents picture because when Windows Xp thinks it is looking at a folder of jpg's it will display only jpg images and hide any files it does not recognise, you have to open the camera's image folder in Windows Explorer and use the dropdown tab at the bottom of the folder window to show "All Files". It should show both the jpg's and .cr2 files separately.

I seem to remember there is also a setting in Windows under the "view" menu that allows Windows to hide any file extension it does not recognise and you have to choose to make Windows Xp show file extensions it does not know what to do with, it's been a few years since I have used Xp and my memory is a bit rusty here but I am sure there is a setting that has to be made if you want to view unknown files in Windows Explorer, hopefully someone still using Xp can answer this if you can't find it yourself.

I have found using the supplied Canon software to directly read the image folder of a USB tethered camera sometimes a little quirky and often file numbering and image duplication seems to occur, I much prefer to remove the memory card from the camera and plug it into a USB card reader, then file numbering and file size reporting in the explorer window seems more reliable.

You are correct though regarding  file sizes. Using RAW +L on the 1300D should give an uncompressed file size of 24Mb for the RAW .cr2 and 6.4mb for the jpg. I would suggest putting the prime lens on, clearing the memory card, then take some daytime shots using RAW +L then take out the memory card and pop it into a card reader, open the card in Windows Explorer, check "Show all Files" and you then should see a 6.4Mb jpg and a 24Mb .cr2 file, both will have the same number but different file extensions. You will be able to open the jpg in Windows and view it but the .cr2 can only be opened in DSS or Photoshop etc, or the Canon image processing software that came with the camera.

3 hours ago, Spacehead said:

I want to draw your attention though if I may to the following image - one of my Starfield alongside a Pelican area shot (below)
Both of these were taken same night, different area, 1 minute, ISO 400 - and yet look at the background colour!  One is brown and the other is black.  Its as though the sensitivity changed - but the info on the images says nope - both iso 400 1min.

The two images show the classic example of either high level cloud or dewing on the optics as noted earlier, the image on the left is crisp with no fuzziness around the brightest stars, the darker image on the right when stretched hard shows a halo of fuzziness around the bright stars, the fuzziness is either dewing or high cloud, both have the same broad effect though high cloud normally just removes details from the image while remaining the same brightness, which comes from background light pollution, while dewing on the optics both removes detail while simultaneously darkening the image because light is scattered inside the telescope before reaching the camera. You can be led astray a little here though if your local authority uses night time dimming of street lights as there will be a sudden drop in background sky brightness as the lights are dimmed and the programmed time. 

Given you are not guiding then just go for the longest exposures you can manage, 1600 ISO might be little high and introduce a bit too much noise, 800 ISO is a good comprise. Check in the camera what setting is currently used for the option "Long Exposure Noise Reduction" and take some astro images with it both switched on and off then compare the results. "Long Exposure Noise Reduction" when on, doubles the amount of time the camera needs to take and download the image (a 1 minute exposure takes approx 2 minutes 15 seconds to complete with Long Exposure Noise Reduction turned on) but the result is that noise in the final image is reduced and this may be beneficial at the higher ISO settings. When you become more proficient in astro imaging Long Exposure Noise reduction is usually disabled to speed up image acquisition and separate noise reduction frames called "darks" are taken at a latter time and used manually in the post processing software.

I think that covers all your questions raised.

If you want to read further then this book is often recommended and will explain things more clearly than bite sized chunks that you tend to be presented with using astro forums, the book was written by one of our forum moderators "Steppenwolf" and will get you advancing up the astro imaging ladder much faster than trying to work it out piecemeal.

https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

HTH.

 

[pete_l]

12 hours ago, Spacehead said:

So - I am at a loss really both on my RAW learning and also my HA experiments and also whether my cam is ok - I think my best bet is to just take some at 1600 (and higher) ISO and see what happens.

Also try different exposure times - say 1 min, 1.30secs, 2min - just to see really whether or not there is anything at all there.
 

Yes. The test image I took, above, with my modded 1100d (by the same person you got yours from) shows that at ISO400 and 60seconds there is no Hα apparent - no matter how much you stretch it. But go up to ISO6400 and a 60second exposure brings it out. Then if you stack lots of them, you reduce the noise and get a nice picture.

The red background in your images seems to me to be light pollution.

[StargeezerTim]

11 hours ago, pete_l said:

Yes. The test image I took, above, with my modded 1100d (by the same person you got yours from) shows that at ISO400 and 60seconds there is no Hα apparent - no matter how much you stretch it. But go up to ISO6400 and a 60second exposure brings it out. Then if you stack lots of them, you reduce the noise and get a nice picture.

The red background in your images seems to me to be light pollution.

You do get a red background with modded cameras. Its not normally a problem as DSS will sort out the colour balance when stacking. Otherwise you can sort it out during processing.

I'm sure you will capture plenty of HA when you get a clear night and bump the iso up a bit (i use 800 or 1600). It doesn't help either that we have no astro dark at the moment.

[Spacehead]

Ok - I have read and read and read!!!  Thanks folks.

So last night I got to set up for just a handful of pictures.  Yes - a handful, 11   before the clouds rolled in and piled high.  So I didn't have much chance to experiment with different settings.

Not to worry too much - progress has been made.

My polar alignment was good - I used my app to turn the RA until it matched on the scope and app then got the pole star bang in the middle of the small circle.
I ensured the main mirror and the secondary were clear of mist - it was a dryer night all up.
I had intended to do a whole range of ISO 400/800/1600 at 60sec and 90sec (just to test) but I just didn't get the skies.

The main pics are a batch of 10 - taken with RAW + L - ISO 1600 - 60sec. 

I transferred to my other machine which is faster and running WIN 7.  I really want to avoid 8 or 10 TBH - but I will go up if I have to.
This machine has enabled me to get hold of both the RAW and JPG files for the set.  My JPGs are 6mb and my RAW are 26mb - so I have that sorted.
I have no flats/darks or bias - I am not fully sure about these yet (see below a bit later on).

So - here we have the JPG (I also have the RAW though) of one of the main 10 at iso 1600 and 60 seconds.  

In terms of the Ha capture, I am pleased with this, you can just about see it in this one shot.  The RAW (I should note) looks visually identical on the screen.

So - with the "confidence" in mind that I am actually capturing Ha at 1600 and 60 secs my plan is to get 100 frames and stack them and experiment with Registax 6 and also DSS.

Thats for the next clear night - in the meantime I have stacked these images.  There are a number of issues I have to overcome.

1.  DSS didn't stack CR2 correctly (known bug apparently) - downloaded the latest version, and now it does.
2.  Registax 6 does not read CR2 - downloaded IRFANVIEW to convert them to TIFF - but the TIFFS are all grey - I am stumped on that one.
3.  Darks Flats Bias - (as far as I am remembering this messy business) DSS does not accept JPG flats - and RS6 doesn't either - and I don't know whats happening with my TIFF conversions - so thats where I am up to on the Darks Flats Bias etc.  Basically - needing to take them, and then somehow convert them.

So I experimented with RS6 and DSS with what they would read (RS6 my JPGs only - DSS my JPGs and my CR2s).  The output is fairly similar from both systems - and looks as below.  (so 10 lights, no darks, no flat, no bias and "fiddling" with the stretching etc. as I learn).


So we can see the Pelican taking shape (the back of it and its "wing").
I raised the target in the frame a bit since my first shots last week.

Ok - so now I am at the point where I really do need to address this "glow" or "vignetting"?

1.  I need to somehow get rid of that glow as I feel its washing out my Ha - is this a sensible conclusion?
2.  I have PaintShop Pro X8 - but am not familiar with it yet.  Is there a simpler software available to sort out my glow?
3.  I have ordered from FLO the book "making every photon count" - as suggested - waiting for that.
4.  I am not too worried about my eggy out stars at this point (unless a coma corrector will also get shut of the glow?) - just concerned about this glow business, above, StargeezerTim said DSS would sort it out on stacking - but it actually enhanced it really.  Is there something I can focus my attention on in RS6 or DSS?  A specific setting somewhere which I am not seeing?
5.  Is there a way of getting hold of a PhotoShop CD?  I don't want to get this subscription thing really - although I will if I have to.

So thanks guys progress has been made.  Any comments on my new questions appreciated very much.












 

[pete_l]

Two things.

First of all, the Pelican is not a bright target, so it is easily washed out by the Moon which is getting fuller now.

Second, in the UK there is precious little true darkness at this time of year - though depending on the level of LP in your location, that may not be too much of an additional problem.

If I were you, I'd wait a few months until the nights start to have some true darkness AND when the Moon is not in the sky. Until then try some other targets, open clusters rather than faint nebs.

[StargeezerTim]

Progress is good! If you take your flats, bias and darks in raw, DSS reads and outputs the stacked file as a tiff

 I just have my camera on raw only, i never need the jpgs, saves confusion and disc space...

I reluctantly subscribed to PS but i have to say it has made all the difference to my processing. The"free" programmes are difficult to use i find..

Layers are great!

 

[newbie alert]

On 2017-6-4 at 13:21, Spacehead said:

 

With this image above,are you using a 2 inch or 1.25 nose cone to attach the DSLR to the scope...as looking at the image suggests you are..

If yes,dismiss this and use a t adapter as it looks like it's missing full illumination.. I use a 100d also modded from Juan, depending on the subject depends on what iso I use..for bright nebula such as m42 I like using iso 400,where as something dimmer I use higher iso,in poor conditions I also cut down the exposure times..and if there's high cloud resulting in just a pink frame it's time to pack up!












 

 

[Stub Mandrel]

You need more subs and you need flats to get rid of that vignetting.