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Ode to the C4-R

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#1 waskeyc

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Posted 04 May 2010 - 07:47 AM

I'm just amazed at the things I can see with my 4" achromat that I bought on clearance in 2007.

Friday night, April 30, I took advantage of the low humidity, clear sky, and hour between the end of twilight and moonrise. My goal was to come up with some sort of threshold for what I could expect to see with my telescope in terms of limiting magnitude or surface brightness. I used the Free Mag 7 star charts, available here to make a list of 48 galaxies in the Virgo cluster to look for. I planned to denote which of the 48 galaxies on my list I could see and which I couldn't, in order to come up with a limit. The galaxies ranged in magnitude from 8.4 to 11.9, with only two dimmer than 11.5. I live in rural Virginia and the brightest part of my sky is above a Walmart 3 miles away.

I ended up identifying 26 different galaxies down to magnitude 11.1 (5 total magnitude 11.0 and fainter), and didn't miss a single one that I hunted for in the time allowed. Once the moon rose, the sky got brighter and I called it a night, otherwise I think I might have been able to identify every galaxy on the list.

Do others have similar experience hunting the deep sky with small telescopes?

#2 TomN

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Posted 04 May 2010 - 08:31 AM

Chris, Shhhhhhhhhhh.....don't tell anyone. Folks think they have to spend mega bucks $$$ to see this stuff..... :lol:

#3 waskeyc

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Posted 04 May 2010 - 09:04 AM

To see, no. To see well, the verdict is still out.

I honestly didn't expect to see as many galaxies as I did, but on the other hand, I was able to see very little detail. The edge-on galaxies usually had obvious shape, but I'm not positive I was able to detect the dark area of M64, and I certainly didn't see any spiral arms, halos, or other internal structure in any of the others. Then again, most astrophotos of the Virgo cluster members don't show much of that either.

I'm still stoked that I was able to see them at all, and I'm amazed at what I can see almost every time I get my $250 telescope out. (plus another $400 in eyepieces and drive motor)

#4 Clive Gibbons

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Posted 04 May 2010 - 09:10 AM

Skies in my backyard are pretty bright. Not good enough to see much beyond the brighter DSO's.
But a 4" refractor will pick out very faint stars, if the magnification is cranked up and the air isn't too turbulent.
I've detected stars down to ~ 13.5 mag. under those conditions.

#5 WillCarney

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Posted 04 May 2010 - 09:25 AM

Refractors can be nice to use. I used a 4" Celestron refractor to do my entire Lunar Observers program from the Astronomical League. Worked really well on the Moon. Any of the Messier objects will be visible. Heck I spotted all of the Messier items with my 15x70's so you can with a 4" refractor. Especially under good skies.

William

#6 skyward_eyes

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Posted 04 May 2010 - 10:10 AM

A friend of mine did nearly the entire Hershal 400 in one night with a 4" refractor (TeleVue 101). He got 388 of them using a Go To mount but the fact that he used a 4" scope was impressive.

#7 RAKing

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Posted 04 May 2010 - 12:05 PM

When I was growing up, a 4 inch refractor was my "dream scope" and I still have my trusty Celestron 4 inch achro. I've done most of the Messier list with it and even though I prefer my 5 inch Tak, I still bring out "Old Faithful" a few times a year.

Under dark skies, it does a great job. :cool:

Cheers,

Ron

#8 waskeyc

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Posted 04 May 2010 - 12:08 PM

...But a 4" refractor will pick out very faint stars, if the magnification is cranked up and the air isn't too turbulent.
I've detected stars down to ~ 13.5 mag. under those conditions.


Magnitude 13.5, that's amazing! I wonder what the naked eye limiting magnitude would have to be to do that?

#9 Clive Gibbons

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Posted 04 May 2010 - 12:16 PM

...But a 4" refractor will pick out very faint stars, if the magnification is cranked up and the air isn't too turbulent.
I've detected stars down to ~ 13.5 mag. under those conditions.


Magnitude 13.5, that's amazing! I wonder what the naked eye limiting magnitude would have to be to do that?


Naked eye limit from my yard is around 4.5 to 5.
By pushing the magnification high, so that the sky background appears dim in the eyepiece, you don't need really dark naked eye conditions, to see faint stars thru the scope.

However, under better conditions and with keener eyes, someone could likely discern stars fainter than mag. 14 in a 4" refractor.

#10 Jon Isaacs

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Posted 04 May 2010 - 12:30 PM

A friend of mine did nearly the entire Hershal 400 in one night with a 4" refractor (TeleVue 101). He got 388 of them using a Go To mount but the fact that he used a 4" scope was impressive.


Hi:

Your mention of the Herschel 400 reminded me of Jay Reynolds Freeman. He is probably best known for completing the Herschel 400 with his 55mm Vixen Refractor "Big Red." (No GOTO... of course) The other night I was viewing some faint Galaxies with my NP-101 but Jay raised the bar...

Comments on the Herschel 400

Jay Reynolds Freeman Astronomy Pages

Jon

#11 jrbarnett

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Posted 04 May 2010 - 12:54 PM

I concur that 4" refractors are under-appreciated as DSO instruments.

Y'know you're getting old when you have a "story" illustrating almost every premise posted on CN. :lol:

My first (and optically one of my best) 4" refractor was a Vixen f/9.8 102mm achromat; likely the predecessor of the C4R design. I was in law school, living in a flea-bag studio apartment in Santa Clara. One of my classmates had an apartment across the courtyard from mine, and got the astronomy bug after looking through my scope and borrowing his cousin's 3.5" Questar for a couple of months. He purchased a Coulter Odyssey 13.1" Dob. He transported it in a mid-80s Civic hatchback. That, in itself, was miraculous to behold. I had never looked through such a large scope, so we arranged a semi-dark outing after hours at Rancho San Antonio park.

Gemini was high over head by the time we had both scopes set up and cooled down. The first thing that struck me was how many stars were visible in the 13.1" when aimed at a nondescript piece of sky, and also how grey rather than black the sky background was compared to the 4-incher.

Eventually both scopes were aimed at M35. It was glorious in both scopes, but much, much brighter and denser in the 13.1" than the 4". Moving to NCG 2158, we were both quite surprised with the results. While the cluster was brighter in the 13.1", the 4-incher showed considerable resolution (only just shy) compared to the larger scope. So much so that my buddy was wondering whether there was anything "wrong" with his big Dob.

I don't think anything was wrong with the Dob, but rather that there was something very, very right with the Vixen. Specifically, an extremely high quality, 4" unobstructed scope puts most of the light from a target where it belongs. Larger scopes of poorer figure and obstructed design may gather more light, but also may not put all of the extra light where it belongs in the image. Scatter, whether due to central obstruction or rough optics, reduces contrast even if aperture-driven-brightness remains intact.

A 4" refractor will reward the patient user and serves as an excellent general-purpose scope. It's not just for planets anymore. :grin:

- Jim

#12 Doug76

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Posted 04 May 2010 - 06:13 PM

I'm just amazed at the things I can see with my 4" achromat.


As am I with my 4" f/13.
You could could change the title to "Ode to the C6R" and the result would be just as pleasing.
Long achro's are my favorites.

#13 MorningStar1969

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Posted 05 May 2010 - 12:53 AM

The C4R was the scope that got me back into this awesome hobby. I remember the Celestron SPC102 with a pricetag or around $1800 being my dream scope. The C4R alwazed amazed me for how sharp and clear it was for the new pricetag.

#14 astroneil

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Posted 05 May 2010 - 05:54 AM

Chris:

Long live the 4" refractor!!

Hard to go wrong with these all-round performers.

Best wishes,

Neil.

#15 Sarkikos

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Posted 05 May 2010 - 10:06 AM

Chris,

The C4-R was my reintroduction to astronomy after nearly 35 years absence. (My first scope was a 4.25" Edmund reflector.) I also bought my C4-R on clearance for about $250 back in 2007. It was my main scope for about a year until I really started my period of scope buying, all of them on sale or used at a good price.

The C4-R is an f9.8 achromat, so the false color is not too bad. I enjoyed this scope immensely for the bright planets, the Moon, and double stars. I did see many of the Messiers, but I never completed the entire list until I bought my larger Newts. I have a red zone sky at home, so some of the low surface brightness Messiers are difficult to see here even in my 10" Newt. But the views of Mars, Saturn and Jupiter are not really that much better in my 8" or 10" Newts than in my C4-R, unless the seeing is unusually steady, which is not at all usual here in the NE. However, IMHO, the view of the Moon through a binoviewer in a 10" Newt cannot be beat by a 4" refractor.

In all honesty, although many DSOs can be seen in the C4-R, now I always use my bigger Newts for the faint fuzzies. A bigger aperture is just better for that purpose. (One exception may be open star clusters. A wide-field, sharp edge-to-edge view of an OC through a 4" refractor is a thing of beauty.) I never take the C4-R to a dark site. I always bring the 10" Newt. In fact, the C4-R has been resting in the back corner of my closet for nearly two years now. I was thinking of selling it, but after the praises lauded upon it in this thread, I might take it back out again for old time's sake. One bad thing, though, is that I'm a star hopper and a reversed image makes star hopping more difficult. And 2" prism diagonals are soooo expensive.

Mike

#16 MorningStar1969

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Posted 05 May 2010 - 11:17 AM

Hey Mike if you ever wish to sell it, please message me.
Thanks and clear skies.

#17 waskeyc

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Posted 05 May 2010 - 01:38 PM

...Moving to NCG 2158, we were both quite surprised with the results. While the cluster was brighter in the 13.1", the 4-incher showed considerable resolution (only just shy) compared to the larger scope. So much so that my buddy was wondering whether there was anything "wrong" with his big Dob.


I have been to a few star parties with larger scopes, including a C14, and I've had similar experiences. Although I've never consciously tried to compare different objects at the same magnification, then same exit pupil size, etc., I've always come away from the star parties thinking to myself, "The view in my telescope is not that different from that of all of those other, larger ones."

#18 Sarkikos

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Posted 05 May 2010 - 02:00 PM

MorningStar1969,

That was not my intent in posting to this thread, but I will seriously think about it.

By the way, my C4-R is on a CG4 mount with dual drives, a ScopeStuff saddle, and vibration-free wooden legs. I'm just saying... :grin:

Mike

#19 John Kocijanski

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Posted 05 May 2010 - 04:14 PM

Do others have similar experience hunting the deep sky with small telescopes?


Absolutely. I really enjoy my C102 f/10 when I take it out. The last time I had it out was in March. Here is my DSO hit list for that evening. I'll have to make sure it is the next scope I get out.

Double Cluster
M36
M37
M38
NGC 1907
M45
M1
NGC 1647
M35
NGC 2264
NGC 2392
M78
NGC 1981
M42
M43
M41
M50
M46
M47
NGC 2438
M48
M44
M67
M105
NGC 3371
M95
M96
M65
M66
NGC 2903
M63
M94
M106
M108
M97

#20 Jacques

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Posted 06 May 2010 - 08:05 AM

Same feeling here :) It was my first and still most used scope (not surprising really as this includes those quick spins when cool down time and observing time are the limiting factors). Anyway, this humble 4-incher takes the credits for getting me hooked on DSO from the first night on. I still love using it for deep sky viewing and hunting down ngc galaxies at the aperture limit. It does very nicely on planets and doubles too. It sure is a fun scope.

#21 CharlieB

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Posted 06 May 2010 - 09:40 AM

I use mine all the time, and when it's stopped down (using the built-in aperture mask) to a 50mm f/20, it throws up some incredibly sharp, nearly color-free views. It works well with many mounts and is easy to collimate well. It is one of my most useful scopes for all-around usage and one of those I'll keep forever.

#22 BillP

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Posted 06 May 2010 - 10:10 AM

To see, no. To see well, the verdict is still out.


What does seeing a faint fuzzy "well" mean (presumably with a larger aperture instrument)? Does it mean it's slightly less faint, is it just a larger faint thing, or does it go from it being a faint thing with adverted vision to being able to say that it is clearly faint and fuzzy with direct vision, or is it being able to say that one can see some faint fuzzy dark things inside the faint fuzzy thing?? :rofl5:

What one really needs to see faint fuzzies satisfyingly (i.e., less faintness with larger extent of fuzziness) isn't larger instruments, but more along the line of dark skies. Not something for the faint-hearted these clearly fuzzy things :imawake:

#23 Sarkikos

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Posted 06 May 2010 - 10:44 AM

I must admit the Orion Nebula looked very good in the C4-R, but it's absolutely superb in my fully-flocked 10" Newt, even here in a red zone. Nothing beats aperture for DSO, whether you're observing bright Messiers or much fainter fuzzies. As I said, the only exception may be open clusters, especially the bigger brighter ones, in a moderate-sized refractor ... say, a C4-R.

Mike

#24 Sarkikos

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Posted 06 May 2010 - 10:51 AM

Bill,

What one really needs to see faint fuzzies satisfyingly (i.e., less faintness with larger extent of fuzziness) isn't larger instruments, but more along the line of dark skies.


I agree and disagree. What one really needs is dark skies AND larger instruments.

But as I say, there may be exceptions - for instance, open star clusters, the Veil, the North America Nebula, the Helix and possibly some other DSOs, through moderate-sized refractors, e.g., a C4-R (or even an ST80 in the case of the Veil and NA).

Not something for the faint-hearted these clearly fuzzy things :imawake:


Agreed.

Mike

#25 John Kocijanski

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Posted 06 May 2010 - 03:14 PM

I'm just amazed at the things I can see with my 4" achromat


You inspired me to take mine out last night. I had a nice time hunting down galaxies Virgo, Coma Berenices, and Ursa Major. :cool:






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