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M101- work in progress


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Hi

This image of M101 and some friends was taken on 25th April using the ES 102 APO refractor.

A combination of 2, 3, 4 mins light frames. using AVX mount. Getting a little more confident with PHD2, min-mo's etc

Total duration 1 hour in total. Using unmodded Canon 450d camera at iso800. 

Stacked with DSS. And attempted processed which i need a lot of work :) on using photoshop. Cropped and  gradients etc. But i didnt want to loose other little fuzzm101-60mins02-dssinitialps02.thumb.png.cf411f00d5a6dd98b248c8ad9f96e8dd.pngies

Many questions but any improvements/ suggestions more then welcome

Thanks for looking

Dean

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Thanks. I did add bias and darks. Have to admit though i have being found out :) Darks may not have matched the 4 min exposure ones, and  temperature difference of around 5degrees. After so many cloudy nightsi was just happy to get going!  

Pleased to get guiding at what i think reasonable level. However the experts would disagree :) 

 

Dean

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same image reprocessed, but this time did not use darks frames, but lots bias frames flats. Not sure if a hours worth of light frames with a cls filter is enough to brimg out more colour? or is it my poor processing?m101-60mins-nodarkframes-dss01ps01.thumb.png.95540a1315fea86ba9ce9a1bad0ebfe5.png

Cheers

Dean

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That looks like a really nice image! :)

More data will help with the details, but i also recommend staying with 1 exposure length if possible. It will make processing and taking calibration frames easier. Only for very high dynamic range targets like M42 would you want different exposure times.

Speaking if colors - if you're stacking in DSS, there's an option to align RGB channels in stacked inage. I recommend to use this, especially with a CLS filter. Also, go to saturation tab and select +15 to +20 before you save.

Darks are best at same temp, but darks taken at a colder temp is usually better then no darks, as they will still help with hot pixels and sensor amp glow - just not as much as they could have at identical temp. Do not add any darks taken at a higher temp though, as this will actually remove data from your image. ISO and exposure length should  be identical to the light frame though.

I see you haven't taken flat frames though, and you really should. It will make the processing afterwards like night and day! I recommend not taking flats in daylight though, as the sunlight tend to creep in here and there and mess up the flats. Take then in the morning before the sun gets up, but after you can not see any signs of the brightest stars anymore. Or in the evening of course.

 

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33 minutes ago, gonzostar said:

same image reprocessed, but this time did not use darks frames, but lots bias frames flats. Not sure if a hours worth of light frames with a cls filter is enough to brimg out more colour? or is it my poor processing?

Cheers

Dean

There is some color in there, but i struggled to pull out any of it. Not quite sure why, as i would expect more color in there after 1 hour of data at F7.
I'm not the best at colors yet though, so others might have much more luck then me at this, but at least there is some color data in there. :)

m101-60mins-nodarkframes-dss01ps01.png.ed8fc9994dc531c96e268c8f7f579902.jpg

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14 hours ago, Jannis said:

That looks like a really nice image! :)

More data will help with the details, but i also recommend staying with 1 exposure length if possible. It will make processing and taking calibration frames easier. Only for very high dynamic range targets like M42 would you want different exposure times.

Speaking if colors - if you're stacking in DSS, there's an option to align RGB channels in stacked inage. I recommend to use this, especially with a CLS filter. Also, go to saturation tab and select +15 to +20 before you save.

Darks are best at same temp, but darks taken at a colder temp is usually better then no darks, as they will still help with hot pixels and sensor amp glow - just not as much as they could have at identical temp. Do not add any darks taken at a higher temp though, as this will actually remove data from your image. ISO and exposure length should  be identical to the light frame though.

I see you haven't taken flat frames though, and you really should. It will make the processing afterwards like night and day! I recommend not taking flats in daylight though, as the sunlight tend to creep in here and there and mess up the flats. Take then in the morning before the sun gets up, but after you can not see any signs of the brightest stars anymore. Or in the evening of course.

 

Thanks for your comments they are very helpful. Terms os exposure length i went for 3 minutes each. Some subs the guiding looked faily "good" so i i pushed for more time. Still experimenting with phd2. I do have a library of darks but not more then 3 minutes. Also have variations of temperatres, 0,5,10,15 degrees C. I have taken flat frames, honest :) Although i did take them in daylight with a white T-shirt pointing at a blue sky! away from the sun. But will try your technique

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14 hours ago, Jannis said:

There is some color in there, but i struggled to pull out any of it. Not quite sure why, as i would expect more color in there after 1 hour of data at F7.
I'm not the best at colors yet though, so others might have much more luck then me at this, but at least there is some color data in there. :)

m101-60mins-nodarkframes-dss01ps01.png.ed8fc9994dc531c96e268c8f7f579902.jpg

I see what you mean there is more colour to collect Thanks for trying:) The above image is PNG file. I will go back to the original stack TIFF files and aligning the channels better. I will also try the saturation to. I generally try not to do much processing in DSS. However will give a try? Also new to finding my way around PS. Did use gimp before

 

Dean

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14 hours ago, Davey-T said:

As mentioned stick to one sub length, the longest one you can confidently repeat, also try to get to grips with dithering, it really helps with DSLR images.

Dave

Thanks Dave. I did intend to stick to 3 minute subs as i am getting still used to PHD2. However somehow got lucky and managed to push to 4 and a couple of 5 minute exposures. I have heard of dithering because Phd2 was telling my PA error was 13arc minutes. So every 10 minutes or so i kept slewing the scope back to M101.  Does this count as dithering?

Cheere#

Dean

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20 minutes ago, gonzostar said:

Thanks Dave. I did intend to stick to 3 minute subs as i am getting still used to PHD2. However somehow got lucky and managed to push to 4 and a couple of 5 minute exposures. I have heard of dithering because Phd2 was telling my PA error was 13arc minutes. So every 10 minutes or so i kept slewing the scope back to M101.  Does this count as dithering?

Cheere#

Dean

You need to dither in both directions, 12 / 15 pixels using DSLR,  if you use APT you can set it all up.

Dave

There's a good video on Y'tube by Tony Hallas, I'll have a search for it

https://www.youtube.com/watch?v=PZoCJBLAYEs

 

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I also do minimal DSS processing, I usually just stay with channel alignment and set saturation to +20.  Hope people don't mind me linking to another forum, but this thread describes exactly how i do it in DSS: https://www.cloudynights.com/topic/571430-qhy-163-c/
After this it's a lot easier to do the final processing in PS, and you also instantly see if your flat frames have worked as intended or not, so you won't get a surprise after a bit of processing.

I've not tried the t-shirt way for flats, but personally i found flats to work very well when taken in the morning or evening without anything covering the scope, having the scope pointed upwards to the most evenly lit part of the sky and shoot 30-200 frames. I've never been able to get correct flat frames during daytime (they ended up messing up more then they solved). 

For dithering they say you'll want a really good amount for a DSLR (compared to a mono with filters), if i remember good they recommend the image to bounce around at least 15-20 pixels. You need to move the image in both axis though. 

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Thanks Dave Will look on Youtube later. Cloudy night here this evening. With my PA 15-20pixcels looks kike np problem! :) Thanks for the link Jannis very helpfull.Used this to get image below then used PS

m101-solo-ps02.thumb.png.f0251f77d694e1890c9606340ee18b00.png The t-shirt and pointing to evenly lite parts of sky seemed to work. 

Anyway have just had another quick go at just M101 hopefully got a bit more colour detail

 

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That looks much better, just grab more data and it should turn out really nice! :)

As a side note, i also have the CLS CCD, and expected to be using is all the time (as i live in an orange zone), but it turned out i was very wrong. I found the CLS filter to not work very well for me at all when it comes to star color and galaxies. Star colors could only be recovered to some extent (as a lot of the yellow/orange star light color is blocked), and for galaxies it was easier to beat the light pollution by gathering more data. For emitting nebulosity it worked very well though, and also as an L filter for narrowband images it should be as good as ideal. It might be a different story with a modified DSLR though. Give it a try and compare. :)

PS, I see you have the Polemaster - for next to nothing you can convert and use it for imaging as well. All you need is these two items:  
http://www.ebay.com/itm/C-Mount-to-1-25inch-Video-Camera-Barrel-Ring-Lens-Adapter-for-AstronomyTelescope-/191814589650?hash=item2ca90a5cd2:g:-vAAAOSwAuZX5Jvd
http://www.ebay.com/itm/New-1-25-UV-IR-CUT-Block-Filter-Infra-Red-Filter-CCD-Camera-Interference-Track-/182083946035?hash=item2a650c8633
It might not be an ideal camera for imaging, but if you're on a tight budget and it's just laying around anyway it could be worth a go. It gave me a huge detail increase as to my DSLR images for brighter targets.
As an example of what the Polemaster did to my old DSLR images, here's my DSLR attempt form 2013  and here's how it looks when i used the Polemasters L data on it. Though my DSLR imaging and processing might have gotten better over the years also, i've never achieved anything close to that amount of details with just the DSLR.

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Cheers More data i know people go for 2hrs+. Hopefully as you mentioned getting more data the CLS clips. But as always hopefully plenty room for improvements.

Howver this filter seemed to work well for Trifid, Lagoon, Orion nebulas. Also got glimpses of veil nebula through it last year using this camera with the SCT. Iam looking to purchases a specialist astro camera in the near future though. However for me small steps!

I can try out these filters you have suggested and see if it improves my images. I do though live in a area where there is light pollution. Although i can see down to 3-4 magnitude stars on a good evening.

Iam very impressed with your images of M51 and what a big difference.  How long where your subs? This is certainly worth researching ang giving it ago. Which capture software did you use?

 

Thanks for sharing and lots of good tips

Dean

 

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The filter i linked to is just if you decide to image with the Polemaster. For the M51 i used 330x 1 min exposures at gain 30, F/5.  
I found Sharpcap to be the best for capturing with the Polemaster. Note the longest exposure appears to be  2 minutes. I also found it a good way to get used to mono imaging for almost no extra costs and to learn to capture and add L data. 

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