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150mm f/5 newt owners

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#1 japaoletti

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Posted 29 October 2014 - 07:51 PM

I'm thinking of pulling the trigger on one of these. Most likely the Celestron Omni. I have no doubt the lower power wide field views should be very nice. Am wondering what kind of planetary views and powers you are getting out of yours?

Not much of a faint fuzzy guy myself , but do enjoy open clusters, luner and of course planets. Also what eps are you using for planetary viewing?  Might splurge for a TV nagler zoom otherwise probably plossls and orthos for me. Can't convince the CFO on the crazy priced ep's. (Yet)

Thanks

Jason



#2 Eric63

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Posted 29 October 2014 - 08:32 PM

Hi Jason

 

In my opinion, the 150F5 is one of the best all around scopes you can have.   It has great low power wide field views, it gives excellent high power views and there are lots of things a 6" will let you see (especially under a dark sky). I also find 6" a nice place to be for planetary viewing under typical seeing conditions.   The coma in the 150F5 is not bad at all and I don't find it bothersome.  For high power, I have taken mine to 280X on Saturn during great seeing once and the view was breathtaking.  It will compete easily with a C6 on lunar and planetary.  The C6 has a 37% CO and the 150F5 has a 33% CO so in theory the 150F5 is better (however I doubt many would be able to tell the difference between 33% and 37% under typical seeing conditions).  Also, both the Omni and the C6 have StarBright coatings, which help with brightness (my 150F5 does not have it).

 

I use a 2X barlow so that I can keep good eye relief at high power.  A good plossl  such at Televue would give you nice high power views but to be honest, I found that the supplied eyepieces were good for starters. I then took my time to research betters one.  I would therefore recommend a 2X barlow to start (assuming that your scope comes with 25mm and 10mm eyepieces).  I  now use an 11mm Televue plossl, a 10mm Televue Radian and an 8mm Hyperion for my high power work.  I don't often push it above 150X due to seeing conditions, but when the seeing is really good I do like to take it around 200X. When the seeing is great (which I have only experienced once) I will go towards 300X.

 

With 25mm, 10mm and 2X barlow you would have the following powers:

 

25mm = 30X

25mm -2X barlow = 60X

10mm = 75 X

10mm 2X barlow = 150X

 

I think that these are good to start with.  You may eventually want to get something like an 8mm or 7mm for days of better seeing conditions.

 

I use mine on both an AZ mount and an equatorial mount,  I like the AZ when star hopping but the EQ is better for tracking at high power. 

 

Eric


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#3 Eric63

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Posted 29 October 2014 - 08:39 PM

By the way, here is a trick for high power focusing with this scope.  No need for a two speed focuser :grin:

 

6557766-IMG_00000101.jpg

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#4 gene 4181

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Posted 29 October 2014 - 10:27 PM

my skywatcher 6in f5 came with a 17mm and 7.5 mm skywatcher plossls. the 7.5 plossl is a really decent planetary eyepiece. i compared it to my tv 8mm plossl, only place the tv exceeded it was on the moon, you could see a slight difference. the 7.5 and a tv 2x barlow gives 200.


Edited by gene 4181, 29 October 2014 - 11:03 PM.


#5 japaoletti

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Posted 29 October 2014 - 10:48 PM

Yeah planetary first. Although the others are close behind. I do have an equatorial mount so would just pick up the tube. I had an 8 inch dob back then but prefer to track at higher powers in the mount. Plus it would be easier for the kids.



#6 epenna

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Posted 29 October 2014 - 11:01 PM

I find that the secondary shadow in my F5 130mm is unpleasant in a 35mm eyepiece. 

 

I thought that I would have to go for a rich-field refractor to get those low power views.

 

But reading this thread, I am confused. Am I doing something wrong?

E


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#7 gene 4181

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Posted 29 October 2014 - 11:02 PM

well in that case, the kids and you having the mount, tracking, it'll be a nice scope to have.  if your young enough and your eyes are decent , i loved a 28mm -68 in this scope, now i'm using the 20mm -68, astigmatism reared its head, old eyes. but there's nothing like it cruising thru Cygnus to casseiopia. the really large open cluster's in northern. ophicus . i use all kind of eyepieces in this scope, plossls, ortho's and barlowed konigs and widefields, 82 variety.   i watched the transit of venus across the sun in this scope with my daughter, now she's all grown up. orion is selling a baader film sun filter for this scope, pops right on.



#8 gene 4181

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Posted 29 October 2014 - 11:12 PM

epenna, sometimes i notice it when using the maximum exit pupil in a scope, but only really see it when racked out of focus. in focus it seems to disappear. you might be noticing it in brighter stars , fields or around the moon especially. my eyes don't open to a 7mm exit pupil any more. from my above post, I've backed down from a 28 to a 20 now. do you see it in a 25 mm eyepiece? unfortunately , this does happen in a reflector, go too big in a refractor, it just cuts off some of the apeture

Edited by gene 4181, 29 October 2014 - 11:17 PM.


#9 BoldAxis1967

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Posted 30 October 2014 - 05:04 AM

The Omni150 Newtonian with the CG4 was my first telescope.  I have found this to be a great scope.  It is still my favorite.  Easy to set up, quick cool down during the cold weather months.  It gives wide field of views and at the same time is surprisingly impressive on planetary and lunar viewing. And, it is great on open clusters.

 

At some point you will probably want a decent eyepiece around the 13 to 16mm range that has 70 to 80 degree field of view.  This will give you nice wide views of open clusters.  Take a look at the used market for Explore Scientific EPs.

 

I made out just fine for 6 months to a year with EPs that were under $100 and enjoyed the views immensely.  And, it is probably wiser to spend the money on a Rigel Quickfinder (Telrad is too large & heavy for this scope), a chair and a collimating tool.  

 

L.


Edited by BoldAxis1967, 30 October 2014 - 07:31 AM.


#10 izar187

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Posted 30 October 2014 - 12:02 PM

I use a Telrad on mine, and it works great.

But I already had the Telrad, so simply picked up another base for this ota.

 

My 150mm f5 came with a long eye relief straight through 6x30 finder.

It actually worked great too.

Particularly in suburban/urban viewing situations, where it's very large 6x fov revealed many more faint field stars than no power finders can.

This is sometimes very helpful for finding stuff.

 

Another vote for 200x with this type of scope, and more.

There are many multi element, well corrected, easy to look through ep's available these day's to get you there.

And barlow/ep combos too, as mentioned.

 

These ota's weight in around 10 lbs, so they are pretty easy to mount alt-az too.

They have a rather small range of focuser positions when alt-az mounted, so the ep is very easy to reach with one seat height position, for me. 

Small enough to sit upright in my cars, so easy take on road trips, like vacations, business, etc.

 

Mine is an older 1.25" focuser model, and I most often take it out under local rural sky.

I'm a bit better dark adapted there, so a garden variety 32mm plossl is usually my low power 2 degree widest field choice.  

But the scope does do well on planets too.

 

It's not like a long focus 6" achromat, nor an apo.

Nor is it an 8" scope.

 

But it is clearly able to out resolve smaller aperture scopes on planetary detail.


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#11 japaoletti

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Posted 30 October 2014 - 05:59 PM

Thanks for the replies eveyone. I have a few eps from back then, but had a longer fl scope so will have to change some things up. Still have a TV barlow so have a decent start.


Edited by japaoletti, 30 October 2014 - 06:02 PM.


#12 epenna

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Posted 30 October 2014 - 06:40 PM

Dear Gene, 

 

I will put the it back on the tripod, and work my way down from a 35mm until I no longer notice the secondary shadow, and report back. 

 

I guess my confusion had to do with the idea that an F5 reflector would give me a very wide field... But it turns out that the secondary shadow is limiting factor.

 

So if one wants the widest field possible, aperture notwithstanding, then an F5 refractor is the way to go, as I could throw a 35mm eyepiece on it with no problem?

 

Thanks, 

E
 



#13 japaoletti

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Posted 30 October 2014 - 07:20 PM

E, you are working with an exit pupil bigger than your own pupil. From what I understand most pupils only dilate to 7mm and as we age they get smaller. Not sure of your age, but your pupil is most likely around 5mm. So you would need most likely a 25 to maybe 30 mm ep at most.  Thats why you're seeing the secondary shadow. Yes you can do that with a refractor (no secondary) but you won't be using the refractors full aperture. 

I like at least 50x minimum. A 35 mm ep only gives you about 20x which you may enjoy, but to me not much difference than binoculars.

Try a roughly 25 mm widefield that gives you roughly the same fov as your 35mm. You'll love it.



#14 Eric63

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Posted 30 October 2014 - 07:34 PM

I use a 2", 32mm 70degree EP in mine without any problems.  

 

Eric



#15 skfboiler1

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Posted 30 October 2014 - 08:14 PM

The sweet spot as far magnification with my 150, f/5 Orion Astroview 6 is around 188x under most conditions.  This is with my 8mm Orion Stratus eyepiece and the 2x Barlow.  The Stratus eyepieces have very good eye relief at 20mm.  Under good conditions I can see the Cassini division in the rings of Saturn and good detail with Jupiter.  I tried 234x magnification one time and it was a bit blurry.  


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#16 CollinofAlabama

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Posted 30 October 2014 - 09:15 PM

Exit pupil overshoot creates different results for different people.  There is absolutely no way to generalize it.  For me, exit pupils above 6mm are extremely uncomfortable.  Exit pupil, roughly, is the eyepiece focal length divided by the F/ratio of the scope.  For me, in this scope, I'd say a 28mm ep would be the maximum size I could tolerate, and then only under a dark sky.  In an urban environment, I'd be limited to 1.25" ep's due to exit pupil issues.  But everyone is different, and what would work for the OP is unknown.

 

I've thought a lot about this type scope.  I'm worried about the 2" focuser.   First, it's frustrating how unserious manufacturers consider the small newtonian market.  Even a 2" focuser should at least be a single speed Crayford in any F/5 reflector.  Dual speed would be better, but single speed would approach reasonableness.  But a rack and pinion?  Not the right way to do it, and part of my reluctance.  Also, tho, there's the point of it.  I mean, if a 28mm ep would yield a dark spot (noticeable secondary obstruction), gosh, why bother? The TFOV of this scope with only a 1.25" ep, like the Pan 24/ES 24mm 68*, is 2.1*.  That's not half bad at all.  OTOH, it's just over 2.5* with a 28mm 68* ep.  Now that's a rocking big TFOV.  Still wouldn't frame all of the Veil, but you'd have a good understanding of that big, bad boy with this combo (assuming it would work for you, secondary obstruction not visible, of course).  Makes the decision problematic.  Also, I like the idea of an 8" F/6 dob, personally, but the 150F5 is definitely more grab and go.  Good luck



#17 gene 4181

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Posted 30 October 2014 - 11:46 PM

collin, the focuser is a single speed crayford. epenna, your right a refractor at f5 will give you a wider field ultimately,

Edited by gene 4181, 31 October 2014 - 12:10 AM.


#18 gene 4181

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Posted 30 October 2014 - 11:59 PM

Dear Gene, 
 
I will put the it back on the tripod, and work my way down from a 35mm until I no longer notice the secondary shadow, and report back. 
 
I guess my confusion had to do with the idea that an F5 reflector would give me a very wide field... But it turns out that the secondary shadow is limiting factor.
 
So if one wants the widest field possible, aperture notwithstanding, then an F5 refractor is the way to go, as I could throw a 35mm eyepiece on it with no problem?
 
Thanks, 

E

if you want the widest fov, yes a refractor is it. I would look at the Antares 80mm f6 refractor from Canada, great reviews, not too expensive, less than 200 and a 2in focuser standard. there was a thread about it in refractors just last week E.

#19 CollinofAlabama

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Posted 31 October 2014 - 01:20 AM

Gene,

 

I agree, somewhat, about the 80mm F/6 refractory & TFOV.  Would be fantastic, but the OP did stress planetary viewing as a principle concern, and I'd bet the C150XLT would best the little achro, especially on Jupiter.

 

I hope you're right about the C150XLT and the 2" Crayford. Celestron sure is being quiet about it.  High Point Scientific specifically told me their $200 OTA had a 1.25" focuser, and the specs all over the web say 1.25" focuser.  Perhaps this is Celestron being stupid?  Sure hope so.  But OPT, B&H Photo, and others list the focuser as 1.25".  I realize people have gotten them with single speed 2" Crayfords in the past, but there's nothing to indicate to me those people weren't just lucky, and that if you opened up a new box and it had a 1.25" focuser, you'd have no legal recourse regarding returns.  "Cause I read it on Cloudy Nights" doesn't sound very convincing in a court of law.


Edited by CollinofAlabama, 01 November 2014 - 05:01 PM.


#20 epenna

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Posted 31 October 2014 - 01:54 AM

Hey all...

 

Thanks for the advice.

 

My F5 130mm has a 1.25" focuser, so I would have to upgrade to a 2" in order to use a wide-field eyepiece that would compare with a 35mm plossl's tfov at shorter focal lengths.... 

 

But then I would have to be sure that the diagonal is big enough to illuminate it, etc...

 

In any case, I didn't mean to take the thread away from to the OP's intention, but I am not sure what the point of a 6" F5 would be if not for wide fields. If you're after good high-mag performance, why not use the standard F9? I know it is less portable, etc, but not by that much at a 6" aperture. 

 

E



#21 Eric63

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Posted 31 October 2014 - 06:48 AM

 

In any case, I didn't mean to take the thread away from to the OP's intention, but I am not sure what the point of a 6" F5 would be if not for wide fields. If you're after good high-mag performance, why not use the standard F9? I know it is less portable, etc, but not by that much at a 6" aperture. 

 

E

 

A 6”F9 would be a better planetary scope but as we all know, telescopes are compromises.   I prefer solar system viewing and I would love to get a large Mak-Cass, but I then think of how rarely I’d be able to push high magnification because of my poor seeing conditions, and of the winter cooling issues I’d have.  This is when the 6”F5 shows its strengths

.  

It’s light, very portable and can even be used for grab and go should one want to.  It cools fairly rapidly (I installed a fan behind mine to shorten cooling time) and it rides very nicely on either an ALT-AZ mount for casual sky viewing or an EQ mount for tracking.  With the legs extended on my AZ4, the EP is at the perfect height for standing and I can view without bending for a few hours (great for grab and go).

 

It can do wide field  (I can get just over 3 degrees with my 2” version) and can easily give great views up to 200X  (Yes other scopes would probably gives sharper views above 200X, but how often does one really get to go above that? In the past two and half years, I have only been able to do that once or twice).  But best of all, one can easily tweak it to make it even better.  I also flocked my tube to improve contrast, added a dew shield and lately I had the mirror refigured to 1/10 wave should I ever need to push high magnification on it.  Unfortunately I have not been able to test its limits yet.  But as I noted earlier, I did push 280X with the old mirror in perfect seeing (the only time I rxperienced that) and the image remained quite sharp (and it was the typical ¼ wave).

 

The CO is 33%, but that’s still better than most SCT and Maks. And let’s not forget how inexpensive it is.   Coma is not really a problem and if it is an add on can be used down the road (Paracorr).   My 6”F5 is used in all seasons while I rarely take my Mak out in winter.  It truly is a great little Jack of all Trades at a very reasonable price.

 

Eric


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#22 gene 4181

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Posted 31 October 2014 - 09:33 AM

I think the op is set on what he wants. I called highpoint, they're going to open up a box to check the focuser. they said they'd get back to me. about the refractor having the widest field, that was in response to epenna. and I hear your concern's Collin , get a scope with a 1.25 focuser. its a shame celestron and orion don't step up like skywatcher. you can get a 150 mak and a 180 mak newt in Canada, not here. a 127 mak from skywatcher Canada has a 2in vb, whether its completely usefull is another point of contention, but I've heard both sides of it. these scope are very good at what they provide, wide field and high power planetary, no color, just a touch of coma.

Edited by gene 4181, 31 October 2014 - 09:36 AM.


#23 labmand

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Posted 31 October 2014 - 10:46 AM

The 150mm f5 newt was a shocker for me, bought one mainly for the eq mount, so the ota

was not used for a while because of my reservations of a f5 at high powers, mainly dbl star

Observing but after using several f8-f16 long tubes, reflector and refractor, I read some reports

Here of how good these f5 newts really were, thanks for the reports guys, my f5 is really shockingly

Good for what I like to do. I've been using a mak lately to see what they have to offer but my little

F5 newt is going nowhere soon, it's a keeper for sure.



#24 epenna

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Posted 31 October 2014 - 11:47 AM

Dear Eric,

 

I do agree that the 130/150mm F5 is a very sweet and manageable size. 

 

After reading your post, I'm going to put some serious thought into upgrading to a 2" focuser. 

 

I really want an rft, and upgrading my Vixen would probably be cheaper than trying to buy a refractor of a smaller aperture.

 

Off to research secondary mirror sizes and filed illuminations...

E
 



#25 gene 4181

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Posted 31 October 2014 - 10:11 PM

I think the op is set on what he wants. I called highpoint, they're going to open up a box to check the focuser. they said they'd get back to me. about the refractor having the widest field, that was in response to epenna. and I hear your concern's Collin , get a scope with a 1.25 focuser. its a shame celestron and orion don't step up like skywatcher. you can get a 150 mak and a 180 mak newt in Canada, not here. a 127 mak from skywatcher Canada has a 2in vb, whether its completely usefull is another point of contention, but I've heard both sides of it. these scope are very good at what they provide, wide field and high power planetary, no color, just a touch of coma.

I received an e-mail from highpoint scientific, they opened a new Omni 150 and it did have the 2in crayford focuser. I talked to dave this a.m.


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