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please give advice on how to improve:)

garethmob

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garethmob

garethmob

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hello guys

well i really need some advice, and how ever honest it is i do really want to improve my photos (from taking,stackin, alligning, processing)

heres m31+32 i took last night

canon 300d 135mm lens, stopped down to 4 (1 stop)

its 20 photos with 6 darks each pic 1min long

garethmob-albums-pics-picture13688-m31-m32-stacked-135mm-cant-get-rid-gradient-though-how-ever-i-try-do-i-lose-too-much-detail.jpg

please be totally honest :)

(i'll include the origional file from my dropbox as soon as its uploaded)

gaz

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garethmob

garethmob

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ahhh thas the one key word i cant get right :) flats,........are they the same length as the lights......how many flats per lights would i need?

i dont have the cash for the numan boards and not very good DIY skills i do know some one who could fabricate somthing but the idea i would need help on :p

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steppenwolf

steppenwolf

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Flats are often neglected but they are possibly the most important of all the calibration frames. They are not taken at the same exposure length as the 'lights' but are taken so that they do not fully saturate the camera's sensor. I use an EL panel but there are other ways (including a laptop screen to emulate an EL panel) but a white 'T' shirt stretched over the front of your telescope and aimed at the twilight sky is a very effective way of doing it.

Set your 300D to Av mode and take a series of 20 images with the 'T' shirt in place and stack those to produce your 'master' Flat frame. The important thing to remember is to not touch the focus position of your lens between taking the 'lights' and taking the 'flats'.

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RikM

RikM

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More data and a load more darks would help. Flats would be good. You should aim for at least 30 of each to get the best result.

You have done well with this so far. I had a quick poke about with it using PS3 at work at lunch time and there is a load more you can pull out using the curves tool.

You could try and get rid of the gradient by duplicating the layer, applying a median filter to the new layer with a radius of 30pix, then clone stamp out the light patch left by the galaxy or use the spot healing tool with a big brush size to smooth it all out. Apply a Gaussian blur with a 50pix radius. Set the layer blend mode to difference and adjust the opacity to about 50%. This is a bit of a crude method, but is quick and can be quite effective.

Well done. It is great to see the Andromeda spiral in a nice widefield setting.

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Black Knight

Black Knight

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More data and a load more darks would help. Flats would be good. You should aim for at least 30 of each to get the best result.

You have done well with this so far. I had a quick poke about with it using PS3 at work at lunch time and there is a load more you can pull out using the curves tool.

You could try and get rid of the gradient by duplicating the layer, applying a median filter to the new layer with a radius of 30pix, then clone stamp out the light patch left by the galaxy or use the spot healing tool with a big brush size to smooth it all out. Apply a Gaussian blur with a 50pix radius. Set the layer blend mode to difference and adjust the opacity to about 50%. This is a bit of a crude method, but is quick and can be quite effective.

Well done. It is great to see the Andromeda spiral in a nice widefield setting.

I haven't reliably got the hang of removing gradients myself, so I shall give your tips a go.

Oh, and er, nice pic BTW! :) More data, flats and darks, sorted!

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garethmob

garethmob

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hehe im going to give your suggestion a go now rik..... if i get stuck looking for them in PS mind...... :) im using CS3 mac

@steppenwolf........ this is probally where i skipped the section in your book :p i thinks i gonna give it another really good read... what do you mean by twilight sky?

is there a limit to how long u can do an exposure for?

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RikM

RikM

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Nicely done. There is enough data to give the curves a bit of a shove to get the outer structure of the galaxy to pop out.

Here's a quick example.

I opened 'curves' Added a point low down to pin the sky background (hover over the background and press alt + left click to add a point), then added one to pin the galaxy core. Finally I added one for the outer spiral and used the arrow keys to raise the curve a bit. Finaly I added another point higher up (but still below the 'core' point and flattened it out a bit to control the blending from spiral to core.

Then I ran another 'false flat' routine like last time with the duplicate layes etc.

post-18573-133877669092_thumb.jpg

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RikM

RikM

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Looking at it again here, I would probably run HLVG on it. Hasta la vista Green. It is a free plug in for photoshop that would (I think) get rid of the colour gradient top centre, but I don't have it installed at work so can't have a fiddle with. Worth a try, nice plug in.

You have got a great capture there, I really wish I could get good data like that with that field of view. Keep at it :)

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