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Help needed with stacking and stuff

Triskellion

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Triskellion

Triskellion

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Not really a quick question here but i have been out trying to get some decent pics again and again i seem to come back with the same old thing. I took a few pics of the old fav Orion last night and then have been trying to stack them and stuff. Now this is what i get from single frame:

image.jpg

This was a 30s exposure at 1600ISO using a canon 350d. I took several of these (about 10) at this setting and 800ISO with some different times thrown in.

I then tried to stack using registax but it doesnt seem to make the pic look any better. In fact it looks worse to me all grainy but no more detail:

image.jpg

Then i used a different stacker called rot and stack (freeware somewhere of the net and this came out:

image.jpg

Ok i know i know it looks pretty terrible but look at all the detail which is there. How am i not getting that out of registax? Anyone know of a good tutorial i can follow cos im doing everything ive read i should and its just not working. I only used jpg files as it was just a quick look see and i always forget to switch to raw. The mount is alt az so i cant take too long exposures and need to rotate the images as well as stack. The rot and stack thing does this well and give me lots of nice detail but always seem to have this effect of overcooking it a bit.

Andy

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daz

daz

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Registax can't cope with the rotation, at least I'm fairly sure it doesn't - even with the multi-point in v4.

Using JPG's is never going to give you good results anyway - the data is just too compressed, and there is no way to get it back. The reason for the over-exposure is because the stacking is probably doing a average-add or something similar. I would drop the ISO to 400 and switch to RAW and try again

I'm try to do the same sort of experiments myself, and I'll post up my results as soon as I can.

HTH

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Triskellion

Triskellion

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Cheers for the advice guys i had a look at those programs and they do look good just dont really want to spend any more money at moment. I will try again with the raw files and shorter exposures/ lower ISO etc and see how i get on with those at the next available clear night. Just dont see why when i stack in registax it never seems to do anything. as you can see from the last pic there is defe a lot of info there but i can never get regi to bring it out. Not sure if the other program i used handles raw files so you see my dilema.

Andy

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daz

daz

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Deep Sky Stacker handles RAW files, Registax doesn't. Don't know about Registar. ImagesPlus also does.

If your software doesn't, convert the RAW's top 16-bit TIFF files. Not as a good as RAW, but heaps and heaps better than JPG's :D

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Triskellion

Triskellion

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The problem i have is i need to derotate the images too. The software i was using (rot and stack) does this very well but will only handle jpeg or png files. Never heard of png. i thought i could derotate using the multipoint stacking on the latest registax but it doesnt seem to be the case. looks like i need to buy more software or a wedge.... or maybe a new scope....if only eh

Andy

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Triskellion

Triskellion

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To be honest i cant for the life of me remember where i got it from. Think it was one of these links to free astro software somebody posted on a forum somwhere somtime if you know what i mean. i probably have a link on my home computer but cant find one here. I have a zipped copy i would be happy to email to you if you wanted. its only a very small program which is in no way advanced or anything and like i said only seem to handle jpeg but it has somehow given me the best results ive had so far if a little grainy and over processed looking. Let me know your email if you want me to send a copy if not il try to dig out the link when i get home.

Andy

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Triskellion

Triskellion

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Sorry guys im really strugglin here, i dont have the link and cant remember where i got it. Tried to email it to Philip earlier but got stopped by the fun police at work. Its a 6mb file zipped and my work email strips any exe files apparently. Cant send with my personal as it only allows 2mb attachements (its web based email) all i can think to do is send each file in the zipped folder seperately using my home email. il try doing that to Philip later and if it works then il take your email CC and send it to you too. I may have to do it a bit later though as it will take some time and it a clear sky out there at moment so i wanna have another go with the raws and lower ISO etc. il keep you posted. incidently if you know of another way i can get the files to you let me know. Maybe it can be posted on this site somehow?

Andy

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MartinB

MartinB

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Andy, your rot and stack software looks like it is doing a "sum" combine. This adds the pixel values of each of the stacked images together and so brightens the combined image. This is ok in some situations however you would be better using "average" combine for images of the same exposure and ISO. This calculates the average pixel value from the stacked images and doesn't cause brightening but increases signal to noise ratio so that you can stretch the image much more. If you have a set of subs using 1600 and another using 800 combine the 2 groups of subs seperately using average combine then combine the 2 combined images using sum. That's assuming the software gives you these choices.

Lots of people are using deep sky stacker with good results. It's free!

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Triskellion

Triskellion

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I have been trying to get my new lot of snaps to stack using deep sky stacker this morning but it just seems to get up to the point where it says stacking and then seizes. i did manage i think to get to the end once but then it just displayed a pic like the originals saying 1 frame???

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Triskellion

Triskellion

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6mb zipped its 7 files in total but i think the link that has been added above works ok so everyone should be able to get it via that now. i have been trying to get the stacking working again with the shots i took the other night but still dont seem to be able to get anywhere. tried deep sky stacker and got it working at last. i think it was an issue with my pc not having enough RAM as i used my work one and it worked ok That has 1gb ram mine has only 256 or somthing. Still though all i get out is a pic whihc looks exactly the same as one single frame or worse sometimes. Tried registax again too but that was even worse and wouldnt derotate either. Really frustrated as im sure ive got some very good info in the shots but i cant for the life of me get it out of them.

Andy

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MartinB

MartinB

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Here is my effort on your jpeg subs Andy. I used Maxim to do seperate combines of the 25 sec and the 30 sec subs using average combine. Then combined the 2 result images using a sum combine. Saved as a 16 bit tiff and transferred into photoshop. Did iterative levels and curves saving one image at an early stage to use for the core. After finishing the stretch I lassooed the core in the ealier image using a feather of 30 and pasted it into the brighter image.

Next I created a seperate star layer to protect the stars from changes made to the main image. I sharpened the brighter parts and blurred the dim parts. Applied a minimum filter to the star layer to make them a bit smaller and recombined everything. Finally made some small contrast adjustments.

There is a fair bit of detail in the image and the stars are great.

image.jpg

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Triskellion

Triskellion

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Martin

Many thanks for having a go with my subs. This is obviously the point where i am going wrong as i havent a clue what you are talking about when you say what you actually did. Feel i need to get a book or something to help me out with these bits. I have been trying to do this now for about 2 yrs using the old trial and error technique but so far only seem to have found the errors. Anyone suggets a good book? As you say there is obviously some good detail there and i thank you very much for taking the time to show it too me. if only i could get it all myself i would be a happy bunny. How did you guys all learn this stuff as it makes me look/feel silly not to be able to after all this time.

P.S dont suppose you could send me the full size version of what youve done as if you have no objections i wouldnt mind having it printed out as its the best pic ive taken to date. With acknowledgements to your work of course.

Andy

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MartinB

MartinB

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Andy, I didn't save the full size version (doh) but no problem to run through it again.

I have learnt just about everything I know about processing from a couple of books by a chap called Ron Wodaski - new ccdastronomy which covers everthing from choice of scope to processing details. This is ccd orientated and although covering the basics very well some of the stuff in there is very high powered. I have found that I have to go round in learning cycles. Learn a bit, practice then read again by which time the more complicated bits make sense.

http://www.newastro.com/newastro/default.asp

I recently bought his newer book Zone System for Astroimaging. This is a photoshop based book. It is very expensive for what it is but includes an excellent DVD and really does cover what you need to know.

An alternative approach is to buy ImagesPlus - this works especially well with Canon and Nikon DSLRs. It costs a little over £100 and includes 5 CDs which run through the whole of the software in great detail. As well as excellent image capture and calibration tools it has some very powerful processing tools which Mike Unsoeld runs through extremely well. It is possible to use ImagesPlus for all your image capture and processing. It will even control some DSLRs for capturing images. Having used both PS and ImagesPlus I find PS's layers capability makes it a more flexible option but for the price ImagesPlus is fantastic.

I am going to be adding some more primers to the imaging techniques section of the deep sky imaging board. Have a look through the one on histogram streching with levels and curves. There will soon be ones on creating a star layer, improving star appearnace, making selections, sharpening and blurring and use of layers. Will hopefully add these over the next 4 weeks if there is enough interest.

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