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 Post subject: Re: Astrophotography...
PostPosted: Tue, 10-04-18, 9:09 GMT 
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fenerit wrote:
I would suggest also a shot to the nearby galaxy NGC 4631 (Whale galaxy) still in Canes Venatici and NGC 4565 (Needle galaxy) in Coma, they are good subjects for your equipment.

I'll put them on my observation list ;)
Apparent magnitude of 10.42 (NGC 4565) is a bit of a challenge with my exposure times though. But I'm trying to get a used EQ-6, which should allow for longer exposures with less rejects.

fenerit wrote:
A good 2x Barlow linse maybe could be your next acquisition, inserted between the coma corrector and the camera it does extend the focal lenght of the scope and you will go closer.

I thought about this, but I was not sure if it wouldn't simply enlarge the image (or reduce the FOV), without actually helping to get more details? I felt that I was already oversampling the resolution provided by the 6" with the APS-C camera sensor...
Do you have a link to some good Barlow?
Depending on the costs, it could be better to invest in a larger scope - but that's for the more distant future.


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 Post subject: Re: Astrophotography...
PostPosted: Tue, 10-04-18, 22:23 GMT 
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schreiberste wrote:
Apparent magnitude of 10.42 (NGC 4565) is a bit of a challenge with my exposure times though. But I'm trying to get a used EQ-6, which should allow for longer exposures with less rejects.

NGC 4565 has about the same magnitude of NGC 3628 (fainter Leo Triplet's component) but it is more luminous by far (read: its surface brightness), so it is possible you get lots of good samples. Of course with a better mount will be easier.

schreiberste wrote:
I thought about this, but I was not sure if it wouldn't simply enlarge the image (or reduce the FOV), without actually helping to get more details? I felt that I was already oversampling the resolution provided by the 6" with the APS-C camera sensor...
Do you have a link to some good Barlow?
Depending on the costs, it could be better to invest in a larger scope - but that's for the more distant future.

There are two kinds of Barlow lenses:
1) classic Barlow
2) telecentric Barlow
with some subtilety optical differences, the preminent is the number of the lenses' group. You can find some explanations here. Their prices are in range 150-250€ for 2inch quality 2x focal extenders.

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 Post subject: Re: Astrophotography...
PostPosted: Tue, 10-04-18, 23:14 GMT 
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About NGC 4565, you can compare the image below with that of NGC 3628 shown in the first page of this thread. NGC 3628 was 20x120sec. luminance, binning 2x2: 40min. total. Below is 3x10min. luminance, binning 2x2: 30min. total. Because you got a stunning image of NGC 3628, I do not see why you can't get also this beautiful galaxy. With averted vision this galaxy does stretch the spiral "tips" very apparently gaining brightness.
Attachment:
Ngc4565.jpg
Ngc4565.jpg [ 277.78 KiB | Viewed 993 times ]

3x10min. luminance, binning 2x2, some miscollimation

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 Post subject: Re: Astrophotography...
PostPosted: Wed, 11-04-18, 6:35 GMT 
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OK, now NGC 4565 moved up a bit on my todo-list ;)
But I'll have another go at M101 before, which should be far easier in any case!


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 Post subject: Re: Astrophotography...
PostPosted: Wed, 11-04-18, 9:39 GMT 
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schreiberste wrote:
OK, now NGC 4565 moved up a bit on my todo-list ;)
But I'll have another go at M101 before, which should be far easier in any case!

M101 is a very low surface brightness galaxy; visually, I don't like it too much, faint spiral arms and seeing dependent. Good catch!

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 Post subject: Re: Astrophotography...
PostPosted: Mon, 23-04-18, 10:37 GMT 
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These are the results of 2 nights of last week, around 10 hours of photographing M101.
Again, less than 2 hours usable - I stacked 222 images of 30 seconds each. It's still my best result for M101 so far.
The wide-field shows the original field of view with only a bit of cropping of the borders.


Attachments:
File comment: M101 Pinwheel crop
M101_Pinwheel-2018-04_(222x30s)_crop.jpg
M101_Pinwheel-2018-04_(222x30s)_crop.jpg [ 471.22 KiB | Viewed 899 times ]
File comment: M101 Pinwheel wide-field
M101_Pinwheel-2018-04_(222x30s).jpg
M101_Pinwheel-2018-04_(222x30s).jpg [ 1.9 MiB | Viewed 899 times ]
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 Post subject: Re: Astrophotography...
PostPosted: Tue, 24-04-18, 12:18 GMT 
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Hi,

Steffen, I am increasingly surprised by the good quality of your shots, given the simplicity and modest size of your Optics! Also the colors are pretty good.

Just for fun, here is celestia.Sci's imaging of M 101 (North is up)
[click on image by all means!]
Attachment:
Screenshot_20180424_112426.png
Screenshot_20180424_112426.png [ 379.51 KiB | Viewed 877 times ]

Near the bottom left you can also spot the Sc spiral NGC 5474. Note that the computer calculates the expected colors from the catalog's B-V color value. For B - V <~ 0.5 the galaxy looks mainly bluish while for >~ 0.7 it turns increasingly yellow-brownish. You can also see the quite frequent pink Hα regions...

I am curious what your scope can make of this beautiful interacting galaxy group NGC 5679 (aka ARP 274) in Virgo!? The group is pretty far away from us (121 Mpc).
[click on image by all means!]
Attachment:
Screenshot_20180424_135302.png
Screenshot_20180424_135302.png [ 442.71 KiB | Viewed 877 times ]


Note that the toolbuttons are colored bright blue if the button was enabled (one of the grids, here equatorial).

Cheers,
Fridger

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 Post subject: Re: Astrophotography...
PostPosted: Tue, 24-04-18, 14:25 GMT 
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t00fri wrote:
Steffen, I am increasingly surprised by the good quality of your shots, given the simplicity and modest size of your Optics! Also the colors are pretty good.

Just for fun, here is celestia.Sci's imaging of M 101 (North is up)

Thank you!
The celestia.Sci rendering is excellent, of course, given that this is all automatic just from catalog data!
t00fri wrote:
I am curious what your scope can make of this beautiful interacting galaxy group NGC 5679 (aka ARP 274) in Virgo!? The group is pretty far away from us (121 Mpc).

I'm afraid this beautiful group is out of my reach. With sizes below 1' and app. magnitude of 14.5 and 16 they are too small and dim. M101 is much larger (28′.8 × 26′.9) and brighter (7.86 mag) in comparison! And still, I struggled to get a good image!
For comparison: in my M101 wide-field image you can see NGC 5422 in the upper right corner, which is 3,9′ × 0,7′ and 11.9 mag (visually).

Steffen


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 Post subject: Re: Astrophotography...
PostPosted: Tue, 24-04-18, 16:13 GMT 
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Steffen,

NGC 5422 and also NGC 5473 were both visible in the original celestia.Sci screenshot.
After all, the whole official NGC/IC catalog of 10937 DSOs is visible (
Let's see where they are: North is now tilted to the right on this shot and M 101 is down to the left. You will also notice that I switched on the labelling:

[Click on image by all means!]
Attachment:
Screenshot_20180424_175118.png
Screenshot_20180424_175118.png [ 260.95 KiB | Viewed 868 times ]

Can you see the sideways S0 galaxy as well as the elliptic E2 galaxy NGC 5473 ( fairly close to the top of the field?
Here is a close-up of NGC 5422.

[Click on image by all means!]
Attachment:
Screenshot_20180424_175246.png
Screenshot_20180424_175246.png [ 183.47 KiB | Viewed 868 times ]


Cheers,
Fridger

PS: Did you see Selden's reminder of today??
viewtopic.php?f=2&t=931

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 Post subject: Re: Astrophotography...
PostPosted: Tue, 24-04-18, 16:17 GMT 
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Indeed you get stunning images of DSOs! 8) 8) 8) Good images with you equipment are possible just with a fundamental knowledge of the astrophotography methods. Go ahead!

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 Post subject: Re: Astrophotography...
PostPosted: Tue, 08-05-18, 7:32 GMT 
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As fenerit suggested, I tried my luck with NGC 4565.
Well, I really struggled to get something good. I'm not sure if it was because of the bit of wind, but after 3 nights of taking photos I still had a single digit number of images without recognizable shaking and jitter. One of the nights I also slightly missed the perfect focus I think. So I stacked a lot of frames that I would have just deleted otherwise. Therefore details are not as good as I would like them to be, and I couldn't seem to get the colors right. I think, the star colors are way off, and I was not able to repair this in post processing.

Steffen


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File comment: NGC 4565 - The Needle Galaxy
NGC4565-Needle_2018-05_(220x30s)_dt.jpg
NGC4565-Needle_2018-05_(220x30s)_dt.jpg [ 2.75 MiB | Viewed 765 times ]
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 Post subject: Re: Astrophotography...
PostPosted: Tue, 08-05-18, 9:30 GMT 
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That's an amazing shot nonetheless! As you can see, with your equipment you are not confined to the Messier objects only and just the mount can prevent better stacks. For resolution details, that is matter of aperture scope; for magnification the focal extender can bring you closer.

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 Post subject: Re: Astrophotography...
PostPosted: Tue, 08-05-18, 13:18 GMT 
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I also think this is an excellent shot!

Cheers,
Fridger

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 Post subject: Re: Astrophotography...
PostPosted: Tue, 08-05-18, 13:27 GMT 
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Thank you :)


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 Post subject: Re: Astrophotography...
PostPosted: Tue, 08-05-18, 16:30 GMT 
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Few precisations about the Barlow/focal extenders for astrophotography: don't buy it before try it, and moreover don't buy it before you got a better mount. Unfortunately this "hobby" is expensive and buying an accessory to play with for then to be disappointed, is not the case. If you know someone at your local club who has such an accessory to loan, should be advisable.

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