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I recently scored a great deal on facebook marketplace and bought Skywatcher Skymax 180 mm Maksutov-Cassegrain Telescope (f/15) with EQ6R-pro mount. I understand that long focal length telescopes are more suitable for planetary imaging. However, as I am tight on budget, I would like to use the same scope for deep-sky astrophotography. I have Canon Rebel T5 DSLR camera that I am using for taking images. Without autoguiding and a decent polar alignment, I can get ~30 seconds long shots without any star trailing, but that's not sufficient for imaging objects like M51. I would like to be able to integrate longer, say few minutes, thus would like to purchase an autoguider. Here are some specific questions I have.
1). The telescope comes with an 8 x 50 straight-through finder. If I were to use it as a guidescope, what type of image integration time can I expect? Has anyone done autoguiding for f/15 scope with an 8x50 or other finderscopes?
2). If the integration time will be an issue with the 8x50 finder scope, I am open to purchasing an off-axis-guider. However, considering the narrow field-of-view of Mak-180 telescope, I am concerned about not having enough photons from guidestar for autoguiding. For instance, with my DSLR camera, I need to integrate 20-30 seconds to see the nearby stars in M51. What type of OAG and camera would I need to autoguide with my scope? Are there affordable cameras (~$200) that would do the job for me? Would ASI120MM Mini Monochrome (~$150) do the job? What about OAG?
I plan to use phd2 software for autoguiding rather than relying on the build-in guide port on the mount. Instead of integrating for hours, I am planning to do DSS stacking of few mintues long multiple shots, hopefully this will put less strict requirements on the autoguider.
In case this information is relevant: with my current setup, I have no issue pointing my scope to a desired deep-sky object, track the object within the field-of-view of my DSLR camera for hours using the mechnical tracking of the EQ6 mount. For instance following is a single raw image of Ring nebula taken with 30 seconds shot. But it is not enough for generating high-quality images.
Thank you in advance for your help.
Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).
Night Vision: PVS-14 with Photonis 4g INTENS.
Eyepiece: Plossl 55mm (f2 x38).
In spring 2019 I created a Sky Safari observing list of 214 highest brightness galaxies in the night sky above.
I have observed 134 of the 214 (the others have not been well placed over my garden when I have been outside).
In my first pass through these 134 galaxies, they were graded 0-3 (where 3 means "clear spiral arms" and 0 means "nothing to see here!")
I have now completed a second pass through the grade 2 and grade 3 galaxies. This has resulted in some movement between bands based on my now greater experience and having a better idea of what I expect to see.
My latest graded lists contain 38 grade 3 galaxies and 30 grade 2 galaxies (when combined this gives a list of the best galaxies to view when using military night vision technology combined with a low power eyepiece (using the TeleVue PVS-14 adapter).
[Note that lower power eyepieces give the best spiral arm results as they “increase the effective focal ratio” of the telescope/night vision system which really helps increase the detail seen at the eyepiece.]
As we are still in galaxy season 2020, now seemed a good time to re-publish my findings so others have the opportunity to observe some of these fantastic galaxies before they become “unavailable” for another 10 months…
Grade 3 galaxies (the best of the best).
M51 M61 M64 M65 M66 M81 M90 M91 M94 M95 M96 M99 M100 M101 M106 M109 NGC891 NGC2403 NGC2903 NGC3184 NGC3628 NGC3631 NGC3726 NGC3893 NGC3953 NGC4051 NGC4216 NGC4274 NGC4449 NGC4559 NGC4565 NGC4618 NGC4725 NGC5248 NGC5371 NGC5746 NGC5907 NGC6946
Grade 2 galaxies (good but the arms are not quite there…)
M82 M88 M98 M104 NGC2537 NGC2768 NGC3294 NGC3344 NGC3373 NGC3596 NGC3646 NGC3675 NGC3718 NGC3729 NGC3813 NGC3938 NGC4013 NGC4214 NGC4293 NGC4389 NGC4490 NGC4517 NGC4535 NGC4625 NGC4762 NGC5005 NGC5364 NGC5383 NGC5775 NGC6015 Hopefully someone will find this useful information, next time they plan a galaxy observing session...
Note that my dobsonian uses an Astrodevices Nexus unit which I control using Sky Safari. Here are my exported observing lists (which you can import into your Sky Safari app should you wish to do so?)
Grade 3 Galaxies.skylist
Grade 2 Galaxies.skylist
1. email them to your phone/ipad,
2. read the email on your mobile device and after clicking on the attachment, you should be offered the chance to “send to Sky Safari” by your email app…
3.Sky Safari will open and give a message “Observing List Created”.
Celestron 9.25 at f6.3, SW EQ6R pro, Canon 550 D modded
The galaxy group Hickson 44 in Leo. This is based on 29 x 240 s, plus bias and flats.
Hickson 44 in Leo:
There are some other galaxies near by, some of which are names in this overlay from Astrometry.net:
Overlay from Astrometry, naming the other objects:
The main ones are NGC 3190, NGC 3185, NGC 3187 and NGC 3193. NGC 3190 has a well defined dust lane. NGC 3187 is a barred spiral galaxy with two arms. NGC 3193 is an elliptical galaxy.
The light captured by my camera last night left these galaxies just after the extinction event killed the dinosaurs on Earth.
From APOD: Galaxies, like stars, frequently form groups. A group of galaxies is a system containing more than two galaxies but less than the tens or hundreds typically found in a cluster of galaxies. A most notable example is the Local Group of Galaxies, which houses over 30 galaxies including our Milky Way, Andromeda, and the Magellanic Clouds. Pictured above is nearby compact group Hickson 44. This group is located about 60 million light-years away toward the constellation of Leo. Also known as the NGC 3190 Group, Hickson 44 contains several bright spiral galaxies and one bright elliptical galaxy on the upper right. The bright source on the upper left is a foreground star. Many galaxies in Hickson 44 and other compact groups are either slowly merging or gravitationally pulling each other apart.
This image is based on 19 x 300 s , plus flats and bias. It shows a LOT of galaxies, in a grouping called Abell 1367. In this image you are looking at part of one of the biggest structures in the Universe, the Great Wall.
The Leo Cluster (Abell 1367) is a galaxy cluster about 330 million light-years distant (z = 0.022) in the constellation Leo, with at least 70 major galaxies. The galaxy known as NGC 3842 is the brightest member of this cluster. Along with the Coma Cluster, it is one of the two major clusters comprising the Coma Supercluster, which in turn is part of the CfA2 Great Wall, which is hundreds of millions light years long and is one of the largest known structures in the universe.
The overlay from Astrometry gives some of the galaxies visible in the image.
By Joaquim Q
Hi, i..m on Stargazers Lounge for long time ago, but now i have a new scope at last!!! The scope is a Skywatcher classic200p dobsonian, and i received it just one month ago. I.m really happy with it. For now, i.m using the stock eyepieces that come with the scope, a 25mm and 10mm super plossl 52. Yesterday i was received a Celestron Omni barlow, and that expands my magnification range. I posted some pics with my set.
Congratulations to Stargazers lounge team, this is one of the best sites to learn about astronomy and equipment.
Besf regards to everybody
By LR Watanabe
For Deep-Sky AP of mostly galaxies (and nebulae), what'll give me the best results– a medium-weight 130 P-DS or a very lightweight wide-field WO Z61? I know the "best" telescope is one that doesn't just collect dust all day long, but I just can't figure it out. Supporting said telescope will be the SW HEQ5 PRO Synscan (with the Rowan Astronomy belt attached), which will be supported further by a autoguiding system, possibly a very lightweight CF 32mm refractor with a ZWO ASI 120mm Mini (Can't find the -S model in Japan). On the telescope'll be the Canon EOS 600D, quite a heavy beast IMO.
Instead of leaving it here, I'll say (just blurt out) everything I know about these seemingly-equal telescopes.
The 130 P-DS, clocking in at F/5, will produce fantastic photos of Nebulae and Galaxies alike, although its aperture will slightly limit the galaxies it'll see. It seems this telescope does particularly well when it comes to imaging M81 or M51, and Nebulae like the Rosette. Its price-performance ratio is basically unbeatable, as it's only 250$ over here in Japan and it cranks out fantastic images. The only addition I'll need will be a F/5 SW-issued Coma Corrector; however, I don't need to worry as I'll be getting one from me mum in a few week's time.
The William Optics Z61, which has a slightly higher F number of 5.9. It sports 2 lenses with FPL-53 elements in them, allowing for extremely high contrast images of nebulae like the Rosette, Orion, all that lot. I've previously asked a similar question, and I've been convinced by the answer that "I won't really be able to take images of galaxies other than M31, Andromeda, and M33, Triangulum. So why do I even have this as an option when I could just go with the cheaper 130 P-DS? Well because it's a wide field APO. Everything it supports, whether it be the design to the focuser, is just amazing, so much so I can't emphasise the emotion enough.
On Astrobin, I've checked out what kind of images these telescopes produce, and I encountered a problem– pretty much everyone was using everything but the 600D. They all used the fancy Mono-cooled CCDs like the ZWO ASI 1600MM Pro.