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6footgeek

Galaxy imager with light pollution

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Posted (edited)

Hey everyone!

Im looking for ideas and or suggestions for a new telescope. I have been imaging a little while and have become a little bit obsessed with galaxy's. The maths just blows my mind and they are really interesting to process. 

I have a 72ed on a heq5 Pro with a canon 450d (unmodified) I have paired this with a ZWO asi120mm with the ZWO mini guidescope for guiding.Everything is working well (yay for ASCOM) and I’m enjoying spending the limited summer darkness playing with plate solving and tweaking the guiding. Oh and I also have a skywatcher 150p that I’ve never used in anger but I just bought it for last years star party (the rainy one so it never got used)

Im looking for something that will get these galaxies a bit closer - obviously the 450d with a 72ed results in a massive fov and I fully intend to keep that scope but I have some questions around which kind of telescope to get for imagining galaxies from my bortle 6 back garden!

I understand from using fov calculators that changing the camera can also result in bigger objects but would like suggestions for either just a telescope or a telescope / camera combo or indeed, just a camera change! I’m not averse to the idea of narrowband imaging either in case that helps.

Thanks in advance as always

 

Edited by 6footgeek

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Narrowband won't help with galaxies as they are broad band targets.

Cooled camera will certainly help with all sorts of imaging - if you have the budget, then cooled mono astro camera is the way to go - then you can do narrow band imaging if you get proper filters for that.

As for scope, well, you want to match it to your camera. Something about 700-800mm FL will be a good choice to start with. If you like simplicity of refractors and have the budget for it - get one that is 130mm F/7 with matching reducer / corrector to bring it down to focal length of about 700mm. This is however rather expensive proposition, especially if you plan for camera as well.

6" F/5 newtonian is another good option - just get good coma corrector for it. 8" F/4 newtonian is again good instrument, but will pose quite a few challenges - collimation and focusing are especially tricky at that speed. Any sensor tilt will also show quickly.

You can go with something more exotic - like RC type scope, either 6" or 8" but processing is a bit different when taking images with such scopes - they are rather long focal length, about twice that what you need. You will likely need to bin your data x2 or even x3 depending on pixel size of your camera of choice.

Good, fast optics need not be expensive. How about Explore Scientific Comet hunter? It's Mak-Newtonian type of scope - no diffraction spikes (if you don't like those), fast optics at F/4.8, 730mm focal length ....

Do you have any sort of budget? Also, your preferences would be good to know so we can narrow the list down.

 

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The RC scopes out there are a bit hit and miss when it comes to collimation.

A edgehd 8 will likely fit your needs quite well and you can also do planetary nebulae as well.

I shoot only OSC you can see my galaxies etc here:

http://www.astrobin.com/users/gotak/

I am located at the edge of Toronto so LP while better than downtown is a constant problem. I use a LP filter to cut the sodium lights but locally more street lights are moving to LEDs which might be a problem.

There could be some use of narrowband for galaxies in the form of highlighting Ha regions but I find my cooled CMOS catches the Ha sufficiently well to show them up.

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Thats great thanks @vlaiv and @cotak

Vlaiv - Which mono to go for? I understand that the 1600mm is the one most people seem to be using. Any thoughts? I definitely want to go mono rather than OSC - just so that i can play with different things. Thanks for the models - that comet hunter looks very promising. Budget wise, this is a future planning type of post so as I have a setup thats more than good enough for now, I can just merrily chuck money into savings until I get to the price point required. That being said, I would prioritise a new camera over the telescope in terms of which one I bought first!

Cotak - The edgeHD 8 looks brilliant but i'm not sure i could jump to that prior to buying the camera. Noise is the bain of my life at the moment (even with aggressive 8px dithering) as my canon just seems to generate the stuff out of any situation :) Your galaxy pics are brilliant, exactly what I envision from this proposed setup so thanks for uploading them - im bookmarking them for inspiration. I do have a SkyTech CLS Canon EOS Clip in filter, but whilst it does an excellent job of suppressing light pollution (i can quite happily take 5 minute subs without skyglow taking over) I do have trouble processing any natural colour out of the image... I think that may well just be to a lack of skill on my post processing skills though. I saw some images with Ha regions in galaxies and I think it looks brilliant - good to hear that the cooled CMOS can bring out that detail too though.

 

Thanks!

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4 minutes ago, 6footgeek said:

Thats great thanks @vlaiv and @cotak

Vlaiv - Which mono to go for? I understand that the 1600mm is the one most people seem to be using. Any thoughts? I definitely want to go mono rather than OSC - just so that i can play with different things. Thanks for the models - that comet hunter looks very promising. Budget wise, this is a future planning type of post so as I have a setup thats more than good enough for now, I can just merrily chuck money into savings until I get to the price point required. That being said, I would prioritise a new camera over the telescope in terms of which one I bought first!

Cotak - The edgeHD 8 looks brilliant but i'm not sure i could jump to that prior to buying the camera. Noise is the bain of my life at the moment (even with aggressive 8px dithering) as my canon just seems to generate the stuff out of any situation :) Your galaxy pics are brilliant, exactly what I envision from this proposed setup so thanks for uploading them - im bookmarking them for inspiration. I do have a SkyTech CLS Canon EOS Clip in filter, but whilst it does an excellent job of suppressing light pollution (i can quite happily take 5 minute subs without skyglow taking over) I do have trouble processing any natural colour out of the image... I think that may well just be to a lack of skill on my post processing skills though. I saw some images with Ha regions in galaxies and I think it looks brilliant - good to hear that the cooled CMOS can bring out that detail too though.

 

Thanks!

I'm going to be somewhat biased here as I own ASI1600mm, and in my view, you can't go wrong with it.

It is a good camera, and it is certainly very affordable way to get into mono imaging. Depending on filter wheel used, you will be able to use 1.25" filters without much vignetting - this also keeps the price down.

Only alternative in budget department for mono cams that I can see is one based on 183 chip - but that is smaller sensor with smaller pixels. In CCD space - camera with similar specs to ASI1600 would be based on KAF8300 - and these tend to be at least 50% more expensive.

I think that ASI1600 + comet hunter would be a good match (I might even consider getting one myself at some point, not that I need it next to 4 scopes I already have, ah, man can dream .... :D ).

ASI1600 + 72ED is going to be very nice wide field setup - I have something similar TS80 that I use with my 1600.

 

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The color balance is quite easy to achieve with the right app, and in this case APP (astro pixel processor) was how I managed to get better colors out of my images. And it was as easy as drawing a few boxes to select stars to calibrated against and moving a few sliders to set the correct green v magenta balance.

As for noise, well each person's preference is different but I find it best not to dwell too long on it. Most of the time no one views the images at full size. If noise really bugs you I find printing really dials down your ability to see the noise :)

 

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