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4.5 inch reflector is there a great one?

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#26 steve t

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Posted 30 May 2018 - 08:16 AM

Very, very nice!

Thanks CharlieB.

I need to take a new photo to see if I can get rid of the annoying sideways picture



#27 Bomber Bob

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Posted 30 May 2018 - 09:47 AM

This one is a great 4" scope.  Optica b/c (Astro Optical) LN4-E.

 

Charlie, been meaning to ask:  Is there a lever / knob to disengage the motor from the polar axis gear (so the slo-mo can be used)??

 

I didn't see a way to make that mod on the Monolux mount without causing permanent changes...



#28 CharlieB

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Posted 30 May 2018 - 07:08 PM

This one is a great 4" scope.  Optica b/c (Astro Optical) LN4-E.

 

Charlie, been meaning to ask:  Is there a lever / knob to disengage the motor from the polar axis gear (so the slo-mo can be used)??

 

I didn't see a way to make that mod on the Monolux mount without causing permanent changes...

Yes, there is a clutch.  This photo shows it, although the focus is not great.  Turn the clutch clockwise to lock it and CCW to release it for manual use of the RA mechanism.  It's a compression fitting.

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#29 PaulEK

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Posted 31 May 2018 - 12:20 AM

NO. And why would you grind a 4.5" mirror when you can buy a 6" F/8 for $300, or an 8" for less than $500? 

Well, first, for some of us (me!) $300 is a significant amount of cash; $500 much more so*. So significant, that there is no way I can justify spending it on a telescope, especially another telescope.

 

Second, what's to guarantee that either the $300 6" or $500 8" are any good, either? There are expensive dogs out there, ready to bay at, but not necessarily provide good looks at, the moon.

 

Finally, some of us (me, again!) like making things, especially when we know that what we make will be (or, at least can be) excellent. I don't have the skills or knowledge to make my own mirror, but I'd really like to try one day.

 

* Not to jump on you, but too many times, an 'acceptable' price for a particular person posting in a thread, is presented as acceptable to everyone.


Edited by PaulEK, 31 May 2018 - 12:23 AM.

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#30 Littlegreenman

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Posted 31 May 2018 - 02:25 AM

Thanks CharlieB.

I need to take a new photo to see if I can get rid of the annoying sideways picture

Is this what you want?

Nice dog.

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#31 rmollise

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Posted 31 May 2018 - 05:46 AM

Hi,  I see tons of 4.5 inch reflectors for sale on craigs list.

I bought a newer one that was a orion mini dob, and I am really happy with it.

 

Since I am so happy with the format, I was wondering if there is a "premium" version of this scope.

What about a celestron/vixen model?  Would that mirror be just a little better?

I have seen some long 4.5's that have a 1000mm f.l.  Would that put up a sharper image than my 900mm?

Did any manufacturer ever parabolize one of these mirrors?

 

I have read mixed reviews about the red tasco's,  If I read between the lines, there were probably different sources, or

some sloppy QA, so some are good and others not so good.

 

Thanks for any help.

 

VT

 

That depends. The pre-Halley Tascos were not bad at all. Yes, the primary was spherical, but at the focal ratio used that was acceptable. As time went on, the scopes began to come out of China and were cheapened to the point where they were pretty much useless. My thoughts on the 4.5s?  http://uncle-rods.bl...good-tasco.html


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#32 Bomber Bob

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Posted 31 May 2018 - 06:09 AM

Yes, there is a clutch.

 

Thanks, Charlie!  If I had any machining skills, I bet I could make a copy of that bracket.

 

My thoughts on the 4.5s?  http://uncle-rods.bl...good-tasco.html

 

Rod, thanks for the link -- and the excellent article!



#33 terraclarke

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Posted 31 May 2018 - 06:56 AM

That depends. The pre-Halley Tascos were not bad at all. Yes, the primary was spherical, but at the focal ratio used that was acceptable. As time went on, the scopes began to come out of China and were cheapened to the point where they were pretty much useless. My thoughts on the 4.5s?  http://uncle-rods.bl...good-tasco.html

I love reading your blogs Unk! They are always as enjoyable and cleverly funny as they are informative!



#34 steve t

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Posted 31 May 2018 - 07:58 AM

Is this what you want?

Nice dog.

Thanks Littlegreenman and thanks for the compliment on the dog.  

Steve T 



#35 apfever

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Posted 31 May 2018 - 08:36 AM

NO. And why would you grind a 4.5" mirror when you can buy a 6" F/8 for $300, or an 8" for less than $500?

An excellent 6" F8 can be found for Much less than 300.
An excellent 8" can be found for Much less than 500.
 
An 8" dob style is in the 200 range for the bargain find, both national scale and local Midwest. These would go fast in good shape but they show up regularly several times a year, and are easy enough to snag without chronic watching.  An 8" GEM mount (Meade 826 example) is in the 300 range in good ready to use condition, and the Meade 826 in particular is known to have typically nice optics from the 'In House' era.
 
The 6" F8 is mostly already in a GEM configuration. The RV-6 and Edmund 6" on grey GEM are two of the most popular, and rarely touted to be worth 300.
Celestron C6 on Polaris will crop well over 200, and the Celestron SP-C6 on the Super Polaris GEM should get around 300 to 350 with the good parts (brass instead of plastic on some gears).

All of the above named brand scopes tend to have good optics. I honestly am not interested in DPAC, picky star test, optical bench test, and such on 4.5" and 6" mirrors - as long as there aren't KNOWN issues with quality. I'm good with simple viewing to see if the optics are up to par (experience). You pay the price if you have to have tested known quality in this size aperture, either by high end manufacturer, or high end retailer such as CO. 7 that checks just about everything before releasing to a customer.

A front room display telescope can take something like a $100+ RV-6 and turn it into well over $200 with the restoration/refurbish. This is a great deal for some one looking for both display and function. Those that do these restorations are in it for the passion and not a living. Just one day on a refurbish for mechanical function, cleaning, collimation, etc. just won't make a $100-$200 classic (RV-6 or 6" Edmund) worth 3 or 4 hundred because you value your time at that.
The difference between convenience and ergonomics on a 4.5" and 6" is not much, even for a small person. The step to an 8" can start to show some handling reconsiderations.
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#36 SteveGR

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Posted 31 May 2018 - 10:41 AM

 The best is  a 4" Fecker Celestar from the 50's. They show up from time to time on Ebay and here for sale. Here is  a picture of the one I restored.

 

                        - Dave 

 

attachicon.gif 4celestar.jpg

That's a sharp looking scope. smile.gif



#37 Littlegreenman

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Posted 31 May 2018 - 10:59 AM

The difference between convenience and ergonomics on a 4.5" and 6" is not much, even for a small person. The step to an 8" can start to show some handling reconsiderations.

I disagree on the point I edited to bold above.

I agree that the performance, light grasp, and off-the-shelf quality of a 6" Newtonian are better than a 4.5 f/8 class Newtonian.

But the smaller scope for me is very easy to set up, move around, and use. For me and I would guess a large portion of the population setting up the smaller scope requires very little effort. If the set up includes a GEM such as a Vixen Polaris or Super Polaris mount, that would be heavier and does require a little lifting. Many 4.5 newts were matched with a smaller EQ mount, although those mounts are not as steady. Ironically, sometimes the smaller mount requires more effort because they are not quite up to supporting the weight of the tube.

 

A 6" f/8 is a heavier, longer scope. For me, even a 6" f/5 requires effort at lifting the weight to set up, take down, move around, etc. A 6" f/5 or F/8 would also require at least a Polaris class mount.

The difference between 4.5" and 6" class of scopes is relevant if the user wants a faster and easier set up either some of the time, or simply does not want or cannot deal with the heavier scope all of time. (Hmm. Read that sentence a second time).

If I had a situation where I could wheel out something like a Cave 6"f/8, that would be the better choice. But like many, I do not have that luxury, and portability and the effort of setting up and taking down are major factors.

 

LGM

PS If you bench press 200 lbs this probably irrelevant to you.


Edited by Littlegreenman, 31 May 2018 - 01:18 PM.

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#38 apfever

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Posted 31 May 2018 - 06:50 PM

I could do the 200 lbs press before the fall a couple of months ago.
I don't think that affected my opinion. A 6" could proportionately double the weight of 4/5" in the same production line, like the Edmund DSC and SSC.
However, the total difference in weight is small with small scopes, and extra counterweight and so on. If such fine lines are pertinent to a viewer, then a star party and some hands on is always an overly GOOD idea. And fun, and social, and sometimes that unexpected bolide like RMSS a few years ago.

#39 steve t

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Posted 01 June 2018 - 10:15 AM

Now that I've got a better handle on posting pictures 😁 For fun I've attached a photo of my 4" F/8.5 (5" OD tube) in front of the  6" F/8 (7" OD tube). Fully assembled i would guess the weight of the 4" is about 1/3 the 6", but need to get them on a bathroom scale to be sure.  

 

Edit: I was a little off on my estimate,  the total weight of the 4" is about 40 pounds and the 6" is about 80 pounds. 

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Edited by steve t, 01 June 2018 - 10:30 AM.

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#40 terraclarke

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Posted 01 June 2018 - 01:05 PM

That’s a beautiful double star!


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#41 mikeDnight

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Posted 01 June 2018 - 01:35 PM

 The best is  a 4" Fecker Celestar from the 50's. They show up from time to time on Ebay and here for sale. Here is  a picture of the one I restored.

 

                        - Dave 

 

attachicon.gif 4celestar.jpg

What a beautiful telescope Dave. It really shows a measure of pride both by the manufacturer and by you yourself.  Fantastic!

 

Back in 2004 a local astronomer loaned me a 4.5" F11 Newtonian to play with for the evening. At the time I was using a Vixen FL 102 apo, which was an amazing instrument. To my total amazement, the 4.5" reflector gave a noticeably more detailed view of the intricate and subtle fine rings within the Saturnian ring system than the 4" fluorite.  That was a lesson in humility! That 4.5" Newt' not only gave the refractor a run for its money, but it beat many larger reflectors on the field too, as far as definition was concerned. 

 

Mike


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#42 steve t

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Posted 01 June 2018 - 02:17 PM

That’s a beautiful double star!

Thanks Terra.

Steve T 



#43 grafton

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Posted 12 August 2019 - 09:07 AM

Perhaps 15 years ago I purchased a 4.5 inch f/8 primary and a .75 inch secondary mirror from e-copes.  I was interested in a small scope for observing the planets and had owned a 4.25 inch f/12 from Coulter decades ago that was excellent.

 

The .75 inch secondary is only a 16.7% obstruction of the primary and I made a 3 vain spider to hold it.

 

Visually the scope works great for its size and the surrounding sky is very dark when viewing Jupiter. This scope produces a fine image of Saturn at 300x.

 

Last night I dug this scope out of my closet and imaged Jupiter and Saturn when they were about 35 degrees altitude.

 

 

Jupiter and Io.

 

jup_4_5inch.jpg

 

 

 

sat_4_5inch.jpg

 

 

Ed in Houston

 


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#44 terraclarke

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Posted 12 August 2019 - 09:29 AM

Perhaps 15 years ago I purchased a 4.5 inch f/8 primary and a .75 inch secondary mirror from e-copes.  I was interested in a small scope for observing the planets and had owned a 4.25 inch f/12 from Coulter decades ago that was excellent.

 

The .75 inch secondary is only a 16.7% obstruction of the primary and I made a 3 vain spider to hold it.

 

Visually the scope works great for its size and the surrounding sky is very dark when viewing Jupiter. This scope produces a fine image of Saturn at 300x.

 

Last night I dug this scope out of my closet and imaged Jupiter and Saturn when they were about 35 degrees altitude.

 

 

Jupiter and Io.

 

attachicon.gif jup_4_5inch.jpg

 

 

 

attachicon.gif sat_4_5inch.jpg

 

 

Ed in Houston

Those are wonderful pictures! waytogo.gif waytogo.gif 

 

Thanks for sharing. :)



#45 bremms

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Posted 12 August 2019 - 11:01 AM

Have a 4.25" F6 Edmund mirror scope. it performs very well when properly collimated. Mirror even look good under DPAC, About 1/6 wave I would estimate, it is parabolic and smoother than I would have expected. Had a C130 Polaris (Vixen) that gave good images. Had an F12 Coulter mirror that was decidedly not great. A friend was going to refigure it, but may have used it as a trivet instead. (really)



#46 clamchip

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Posted 12 August 2019 - 05:25 PM

The Edmund Palomar Jr. and Deluxe Space Conqueror are great scopes.

The Pal Jr. came first in the 1950's, black tube 4-1/4" f/10.

In the sixties the tube became white and a name change to 'Deluxe Space Conqueror' with a 

few other minor changes but the inerds remained the same with the excellent UPCO primary.

Robert

 

IMG_8496.jpg


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#47 tim53

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Posted 13 August 2019 - 09:32 AM

...but that mount is utterly ridiculous!



#48 clamchip

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Posted 13 August 2019 - 09:56 AM

It's actually bigger in real life and works great.

Here it is the 1950's Pal Jr.

 

post-50896-0-22344300-1554734563.jpg

 

 


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#49 terraclarke

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Posted 13 August 2019 - 01:01 PM

How is the mount different from this one (my 1967 Edmund 5/8” shaft mount)?

 

(Other of course, than the Vixen clamp which is a recent modification.)

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#50 DAVIDG

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Posted 13 August 2019 - 01:18 PM

...but that mount is utterly ridiculous!

 Yep, it needs help. It is next on my project list to see what I can do to beef up mine so it does not have the shakes. Don't forget to check the quality of the diagonal as well. Almost every one of the two dozen that I have checked have been 1/2 wave or worse. That really hurts the performance of a clean 4.25" f/10 sphere. With a good diagonal they are a true 1/8 wave system which will give excellent images.

 

                 - Dave


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