M31 help

[Carl M]

Hi,

Yesterday I was having a go at M31 and have been trying to process it as best as I can without clipping the data but it seems really washed out and lacking much detail in dust lanes. I'm happy with it but want to have another go at it and try and get more detail without the blown out core and washed out dust lanes.

132 x 15 sec lights at ISO1600

200P on CG5 with dual axis motors

Canon 1000D unmodded

It seems everytime I go for 30 sec lights there is strange movement on them not like trails from polar alignment but vibrations on the mount?

Any help and criticism is much appreciated

Cheers

Carl

[BEYOND EARTH]

Hey Carl M

I have not yet done any astrophotography "trying to save up for a nice set up", so Im not all that familiar with the technical stuff behind that. But I am very experienced with photoshop due to the fact that Im a graphic designer. With that said I though I could help you out a little. After further evaluating your image I saw you had more detail than you initially thought, you just needed to show it some love. So I went in and reduced the brightness "alot" then bumped up the contrast to get more detail in the dust lanes. Once that was done I went in and did some dodging and burning to get more detail out, and then fixed the natural colors that were in your photo. I did this all very fast and there is more detail within your image. If you have the original high resolution image which Im assuming you do, then you can get even more detail out due to the higher pixel count. I hope this helped in some way and if you have any questions let me know.

[rightguard]

i have a feeling you may need some longer subs. have you thought about guiding? tho having said that i think the cg5 is equivalent to an eq5 which doesnt have much capability for guiding.

[JohnnyD333]

I have a CG5 and you will need a guidescope for any long exposures. It works well once you have one, but without it the star trails are unavoidable Tracking will only get you so far, even on the best mounts. As for your image, M31 can be a real pain. Its so bright that you can easily blow out the core, losing those valuable dust lanes we look for. It made me realize that not all DSOs can be imaged the same. I always went for 300sec subs around ISO 800. M31 would always be washed out or the core would be blown out. So I started going with 1 minute, ISO 1600 subs, lots of them, and it has worked out better. It is best to experiment with your imaging, your image looks good but make some adjustments next time you go out and see what you can get. Good luck:)

[Carl M]

The good news is that I will be getting a HEQ5 in the near future and intend on guiding using an ST80 and QHY5,the problem with the longer than 15 sec subs was due to backlash and the scope not being balanced correctly, which I hope to correct next time it's clear (most likely next month ) I'm sure it's possible to get more than 15sec unguided even if the mount is at it's capacity. Probably won't be M31 next time though as its a pain to get the whole thing in the FOV due to 1200mm focal length Hopefully Triangulum

Cheers,

Carl

[JohnnyD333]

I think you can pull off a minute or two exposure if you polar align the mount really well. Guidescopes clear DEC backlash so you might want to try getting that before a whole new mount, but if you have the money why not.

[dph1nm]

This picture looks fine to me! The core is not blown out - if you readjust with curves you will find only a very few pixels in the middle are saturated. Longer subs will make this worse of course! The dust lanes can be enhanced with unsharp masking - M31 is a very good candidate for this.

Flats are also very important for M31, as it is such a large target.

NigelM

[Carl M]

Thanks Nigel, the unsharp mask worked an absolute treat. I think I have got some more detail in the dust lanes now using an unsharp mask and tweaked curves a little bit more.

[JimStan]

The "focus" looks better, but DON'T lose the brightness contour in the core, which looks a little more steller in your first attempt !

Great picture, however. Do you plan on making a mosaic of the area ? It would be a fantastic effort !

Jim S

[studdedsole]

Hi Carl, Had a crack with a median filter and gaussian blur to generate a layer which is subtracted from the original to reduce the milky outer regions. Then masked the central region to maintain the core and sharpened the dust lanes. Could do lots more with the original uncompressed data

Tony

[studdedsole]

Carl, Another shot and with a bit more care there is some nice colour showing. You have some great data to play with. Hope you don't mind us all messing with it.

Tony

[Carl M]

I don't mind at all with people having a play, I'm uploading the original .tiff to dropbox now so you can have a go with the uncompressed version, didn't realise there is that much detail there. I'm such a photoshop newbie I might try that Jim would be a pretty cool thing to do since I have not caught M110 in the frame

[rightguard]

strange how u havnt captured m110 in the frame?? i took this with a 200p and a 400d no barlow or modding.

*edit* - nothign special, single sub ~45s exp, played with in gimp. the point was to show the scale of things im getting with my setup - only difference i can see is that you havew a 1000d? different chip size maybe??? this was prime focus through the 200.

**2nd edit* - my image is upside down compared to yours, ie your image has clipped m110 out. still, you have a greater magx than me

[Carl M]

I think M110 is above andromeda in my case rightguard and I also cropped the image a tad to make andromeda the whole frame. Here is the original .tif file http://dl.dropbox.com/u/47039370/andromeda%20original.tif

[studdedsole]

This is rightguards image rotated and cropped so the top right corner is roughly the same as Carls. M110 has been cropped off Carls image.

[rightguard]

strange how u havnt capured m110 tho. maybe was just outside of range? ie, the galaxy was perhaps too central in the scope to capture both? IDK, just guessing.

[studdedsole]

Carl - Do you have an unprocessed version of the original?

[Carl M]

Yes, I think I have got one unedited straight from DSS which I can upload. Im also stacking some old data along with the same data from this stack to see if any more detail will come out. Will it affect the image if some frames are ISO800 and some are 1600 being stacked together?

[studdedsole]

Yes, I think I have got one unedited straight from DSS which I can upload. Im also stacking some old data along with the same data from this stack to see if any more detail will come out. Will it affect the image if some frames are ISO800 and some are 1600 being stacked together?

Not sure if you can correct for different ISO in DSS. I use Nebulosity which allows you to match the histograms for each frame which helps to manage the differences in brightness.

[Carl M]

Here is the .tif which came straight out of DSS after stacking http://dl.dropbox.com/u/47039370/andromeda2.TIF