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First light(s) for my 300mm Orion Optics UK Dobson
Introduction
It has been quite a while since you heard from me but finally I managed to find some time to give you an update on the performance of my new telescope, the 300mm Dobson from Orion Optics UK. I have been using it on several nights during the last few months and in this article you find a summary of the results of these more or less short observing sessions.


The equipment I used with the 300mm f 5.3 Dob:

Eyepieces
1. 32mm Plossl (50x, afov 50 deg, tfov 60', eyerelief 22mm, exit pupil 6, and Dioptrx 1.0)
2. 12mm Nagler Type 4 (133x, afov 82 deg, tfov 37', eyerelief 17mm, exit pupil 2,25)
3. 7 mm Pentax XW (229x, afov 70 deg, tfov 18', eyerelief 20mm, exit pupil 1,3)
4. 5 mm Vixen Lanthanum (320x, afov 50 deg, tfov 9.4', eyerelief 20mm, exit pupil 0,9)

Filters
Lumicon UHC and OIII

Overall impressions
After the first 5 to 10 observing sessions in my light-polluted suburban backyard (limiting magnitude 4.5 to 5.3), there is one thing that is very clear to me: aperture really can make the difference. When I was observing with Jo, a fellow observer who also got the Orion Optics UK 300mm very recently, we both agreed that the views with the 300mm on a less than average night are better than with our 200mm telescopes on the best night ever. Not only the amount of detail you see in many deepsky objects is simply amazing, the bigger scopes also make it possible to observe a lot of objects that were more or less invisible in the 8-inch telescopes we've looked through. I have been told many times that buying a telescope with a larger aperture is of little or no use if you live in the suburbs. Well, maybe that is through for one class of objects, the fainter galaxies, but for all the other objects I have been looking at during the last few months (including the big bright galaxies) the story is very different. They all look better, brighter, more detailed and some of them even show some colour!

I also am convinced that for visual observing, this is the system for me. It is very quick to set up, and following objects by hand is very easy with this scope. If you have the balance right, you can follow objects without a problem, even with magnifications up to 457x (I've tested this with a 3.5mm Pentax XW eyepiece I borrowed from a fellow observer). Also switching eyepieces at higher magnifications isn't a big Issue, if your eyepieces have a large apparent field of view (68 to 82 degrees). With my Vixen LV eyepieces, which have an apparent FOV of 50 or even 42 degrees, the objects rush out of view at higher magnifications. All in all I can say that this will definitely be my most used telescope for deepsky observing.

Open clusters
I have observed a large number of open clusters, M35 and NGC 2158, M36, M37, M38, M48, M67, the double cluster, NGC 7789, NGC 2301, NGC 457, M103, and many more. They all looked brighter, showed more fainter stars and simply looked beautiful, a real pleasure to just look at and enjoy the views! I also tested the Dob by hopping along 20 not so bright clusters in Cassiopeia, which I had observed with the 8-inch in the last few years. I remember that with the 8-inch most of them where very difficult to detect from my magnitude 5 backyard, but with the 300mm dob they all were visible on first sight. Other fainter / smaller clusters like NGC 1907 (near M38) and NGC 2158 (near M35) where resolved into many pinpoint stars. All the very small or faint clusters, which my TAL 200K simply did not show, were no problem for this telescope. The eyepiece I liked most for the clusters where two I borrowed from fellow observers, the 22mm and the 24mm Panoptic from Televue. I probably will replace the 32mm Plossl by the 22mm Panoptic (about the same field of view, but much higher magnification and excellent exit-pupil of 4mm).

Planetary nebulae
I was in for a big surprise! I only looked at a few planetary nebulae but I will never forget my first look at the Blue Snowball (NGC 7662). This planetary is really blue! I never saw any colour in my 8-inch telescope when observing deepsky objects, but in the 300mm, bang! The colour was best with the 24mm Panoptic I borrowed, but in the 12mm Nagler and the 7mm Pentax the colour was also very easy to see. Last Sunday night I observed NGC 6210 in Hercules. This planetary was also strikingly blue in my 7mm Pentax and 12mm Nagler. I also tried the UHC and OIII filters. NGC 6210 became brighter, but the colour disappeared. I liked the view without the filters best. Then I visited another planetary last night, M 97 in Ursa Major. I was surprised that I could see it at all from my suburban backyard! I had never seen it before with the 8-inch, except one time when I was in Austria at 1800 meters I did see it with the TAL 200K. And what can I say, well with the UHC filter M 97 was very easy to see, a very big planetary, better than I ever seen it before, even better than at the star-party in Austria, which is at a higher altitude and has a much better seeing transparency. I tried to detect some details (the eyes of the owl), but I could not see them. However, I am convinced that I will see them from a dark sky-observing site. So what can I say about the planetary nebulae I've seen with this telescope? They all where brighter, much easier to see, and some of them even showed some colour.

Emission nebula
There's only one emission nebula I observed, and that was M42( and M43 of course). What a beauty at all magnifications, and what a detail! I looked at M42 at least on 5 different nights. In the Trapezium the E component was always visible, and the F component could be detected on 4 out of 5 nights. But the most stunning area was the bright central part of the Orion nebula. The details where amazing, even without a filter. Now I finally know what the Frons, the Occiput, the Pons Schroeteri and Sinus Gentilii are (I will publish a separate article on this!). There are lots of other structures left to detect, but on the first few nights I simply sat and took in the wonderful views. This has definitely become my favourite winter object. My 8-inch TAL cannot compete with the 300mm Dob on M42 / M43, I am really looking forward to the next winter, when I hope to see the Orion Nebula from a dark sky site.

Globular clusters
Last Sunday night I observed three globular clusters, M13, M3 and M92. I can be very short: they where all resolved right to the core. These objects are simply 10 times better than in the 8-inch. At 133x and 229x M13 looked liked a giant propeller, with chains of stars running from the core across the cluster into the dark sky, creating different streams of stars with dark lanes between them. I want to take up deepsky sketching again, but I think that I skip M13 ☺
The amount of stars is just overwhelming. M3 and M92 where also beautiful to see and I am looking forward to observe a few more globular clusters this year. They really look much better in the 300mm. The 200mm Tal only could resolve M13, M3 and M15 right into the core on the nights with a good seeing, but most of the time the larger parts of the globular clusters stayed hazy. Not with this telescope!

Galaxies
And now for the galaxies. I only had a look on a few of the bigger galaxies. They also looked a lot better than through the 8-inch. M81 and M82 in Ursa Major were the first two galaxies I had a look at. In my 8-inch M81 looked like a small circle and M82 like a small elongated patch of light. In the 300mm M81 looks really huge, a big more or less round (a little oval) galaxy. M82 looks like a big cigar. It shows a lot of detail at 133x and at 229x. The elongated bar of light is broken in two or three places by dark lanes and I could detect two "brighter" areas. M65 and M66 were very easy, even on a night with a mediocre seeing and transparency. Last Sunday night I had a look at M51 and it's companion NGC 5195. Now through my 8-inch I only saw two more or less points of light, with a little haze around it and sometimes, from my backyard, I could not see them at all. Last Saturday, when the transparency was not so good (a lot of high clouds) I did see a little more than usual, but it still was a bit disappointing. Sunday night however, the sky was a lot clearer and there it was, M51 looked like a really big round smudge of light with a very bright core and some areas of uneven brightness detectable in its disk like structure. NGC 5195 was a lot smaller but also had a very bright core. I am sure that from a dark-sky site, M51 will reveal some of its spiral structure.

Well, that’s all for now. I hope we will have a lot of clear skies in the next few months, and I will keep you updated! If you have any questions on the scope, or want to react on this article, please feel free to do so.


Posted by Math on 04/18 at 08:54 AM
Deepsky log • (6) CommentsPermalink

I will visit you and have a good look through the eyepiece of your big new toy grin

Posted by  on  04/18  at  12:04 PM

You’re welcome, and don’t forget next tuesday. We have a meeting of our deepsky-group!

Posted by Math  on  04/18  at  02:02 PM

My new Orion Optics 8inch reflector is own its way to me.

How did you find the quality of the eyepieces that came with your telescope? mine apparently comes with a 10mm and 20mm

Cheers
Mike

Posted by  on  05/11  at  11:58 PM

Sorry for 20mm read 25mm Plossl

Posted by  on  05/12  at  12:08 AM

Hi Mike,

I have only used the 25mm which is OK, a normal quality good eyepiece. I didn’t use the 10mm because of its short eye-relief. I like to observe with long eye-relief eye-pieves like the Vixen Lanthanum, the Pentax XW or the Televue Radian. In the next few months I will publish an article about the eyepieces I am using with this telescope. So hop in every now and again.

Clear skies

Math

Posted by Math  on  05/12  at  08:53 AM

Thanks Math
Telescope being delivered tomorrow!

Posted by  on  05/13  at  05:33 AM

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