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Equipment Discussions >> Reflectors

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azure1961p
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Reged: 01/17/09

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Re: The Most Beautiful Planetary Images In The World new [Re: Jeff Morgan]
      #6046028 - 08/25/13 09:30 PM

Quote:

Quote:

Well, that makes sense. In general "more processed" means sharper detail and better contrast. That's exactly how it should be - the image through a high-quality, larger aperture reflector should appear "more processed" because to the eye it will have more detail and more contrast simply due to the larger aperture.




I would buy the "more detailed" inasmuch as increased aperture will resolve smaller features to the limit of the atmosphere.

But more contrast? Let me play Devil's Advocate here. The Newtonian throws twice as much light into the first diffraction ring compared to a refractor (14% vs. 7%). Since the image of a planet is a series of overlapping diffraction rings transferring more light (signal) from the Airy Disk to the diffraction rings (noise) and then spreading that over the image should produce more less contrast (compared to the refractor), not more contrast.

While I own both types, I consider myself a Reflector person so I have to remain hopeful. But I'm not seeing how more aperture alone can create more contrast than is already inherent in the object itself. Indeed, reading Suiter and Clark it appears that the "best" telescope is the one that removes the least amount of inherent contrast.





An interesting point Jeff. A refractor, even a smaller aperture than a large reflector with a 25% CO will deliver higher contrast though less angular resolution, while the reflector makes up for this by the sheer size of the image its able to produce hence present details and contrasts invisible to eye or CCD of the smaller scale image made by the refractor.

Pete


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: The Most Beautiful Planetary Images In The World new [Re: azure1961p]
      #6046081 - 08/25/13 10:04 PM

Adding image scale at your eyepiece doesn't add contrast. The more power you use on a planet, the less contrast you will see. There is an optimal power to work at with any scope as far as observed peak contrast goes. I've observed at 500X with 20 f/4.3 Zambuto and the contrast on planets was certainly less than at 350X. Details might gain at higher power if seeing permits but contrast will surely wash out.

Quote:

Quote:

Quote:

Well, that makes sense. In general "more processed" means sharper detail and better contrast. That's exactly how it should be - the image through a high-quality, larger aperture reflector should appear "more processed" because to the eye it will have more detail and more contrast simply due to the larger aperture.




I would buy the "more detailed" inasmuch as increased aperture will resolve smaller features to the limit of the atmosphere.

But more contrast? Let me play Devil's Advocate here. The Newtonian throws twice as much light into the first diffraction ring compared to a refractor (14% vs. 7%). Since the image of a planet is a series of overlapping diffraction rings transferring more light (signal) from the Airy Disk to the diffraction rings (noise) and then spreading that over the image should produce more less contrast (compared to the refractor), not more contrast.

While I own both types, I consider myself a Reflector person so I have to remain hopeful. But I'm not seeing how more aperture alone can create more contrast than is already inherent in the object itself. Indeed, reading Suiter and Clark it appears that the "best" telescope is the one that removes the least amount of inherent contrast.





An interesting point Jeff. A refractor, even a smaller aperture than a large reflector with a 25% CO will deliver higher contrast though less angular resolution, while the reflector makes up for this by the sheer size of the image its able to produce hence present details and contrasts invisible to eye or CCD of the smaller scale image made by the refractor.

Pete




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Sarkikos
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Re: The Most Beautiful Planetary Images In The World new [Re: Peter Natscher]
      #6046182 - 08/25/13 11:23 PM

Peter,

Quote:

Adding image scale at your eyepiece doesn't add contrast. The more power you use on a planet, the less contrast you will see. There is an optimal power to work at with any scope as far as observed peak contrast goes. I've observed at 500X with 20 f/4.3 Zambuto and the contrast on planets was certainly less than at 350X. Details might gain at higher power if seeing permits but contrast will surely wash out.




I have to admit that this agrees with my experience also, but at smaller apertures - 10" and below.

Mike


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Cotts
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Reged: 10/10/05

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Re: The Most Beautiful Planetary Images In The World new [Re: Peter Natscher]
      #6046205 - 08/25/13 11:42 PM

Oooops! A brain cramp. Of course the Cass has three passes through the tube. Not sure what I was thinking....

I still like my MakCass, though.

Dave


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Jeff Morgan
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Re: The Most Beautiful Planetary Images In The World new [Re: Peter Natscher]
      #6046238 - 08/26/13 12:05 AM

Quote:

Who are the players these days for building non-fancy mounts for large observing scopes? I mean, mounts that have purely sidereal, maybe lunar, tracking with clutch friction control and hand pad directional controls. Old school mounts.





Old School is exactly right. No one makes them today, anyone wanting a Schaefer has to watch the Classifieds or place Wanted ads. Like many other out of production items one must have patience and a long view. Or fork out the extra $4-$8K for a modern mount that adds lots of nice amenities that will make your life easier but are not strictly necessary.

Since Cost usually a major factor in the decision to go Newtonian I was pointing out the Old School mounts will get the job done on a budget compared to a top-of-the-line modern imaging mount. There are certainly lots of them out there collecting dust in basements and attics and they could last several lifetimes. (I don't think you would say that about todays micro-electronic controlled mounts, or the cheaper stuff coming from China.)

But you definitely need to be the right buyer.


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Jeff Morgan
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Re: The Most Beautiful Planetary Images In The World new [Re: Starman1]
      #6046246 - 08/26/13 12:11 AM

Quote:

If you just want tracking, build a dob with an equatorial table. Simple, consumes little power, adjustable speed, and weighs tons less than an EQ mount. Transportable in a car in a 12-16" size, low center of gravity, much lower eyepiece height, stiffer, and the advantages just keep on coming.




Yep, all those advantages. Equatorial is only a serous player when talking about a permanently mounted Newtonian. And even then ....


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clintwhitman
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Reged: 01/01/07

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Re: The Most Beautiful Planetary Images In The World new [Re: Jeff Morgan]
      #6046353 - 08/26/13 02:45 AM Attachment (19 downloads)

Has anyone here priced out any Aluminum plate lately? I need 4 pieces 10" X 12" X 1/4" 6061 material $47 each!! 6 years ago they were $23 each.
Its no wonder Americans can't build any value based large mounts.
Ed Built Some nice ones!


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obin robinson
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Reged: 10/25/12

Loc: League City, TX
Re: The Most Beautiful Planetary Images In The World new [Re: clintwhitman]
      #6046519 - 08/26/13 08:01 AM

Quote:

Has anyone here priced out any Aluminum plate lately? I need 4 pieces 10" X 12" X 1/4" 6061 material $47 each!! 6 years ago they were $23 each.
Its no wonder Americans can't build any value based large mounts.
Ed Built Some nice ones!




Not just the cost of materials but the cost of machining as well. Look at how many metalsmiths and machinists have retired or passed away with nobody to take on the art form. Remember when high schools used to all have lathes, mills, drill presses, chop saws, brakes, band saws, english wheels, and paint booths? Now they have computer labs where kids can learn about Hollywood movie stars while they play the latest app on their smartphones.

I can't tell you how many younger (born in 1990 or later) people I've met in the military that say their high school had NO shop class. The first time they are operating a machine tool is when they join the military. They tell me their household growing up had nothing more complex than an electric screwdriver and a flashlight. On the other hand everyone had a smartphone, tablet computer, and mp3 player. When I toured NASA a year ago I mentioned the same concern. They even said that they had to hire guys out of retirement to do certain jobs because they couldn't find anyone younger with the skill sets. This is NASA I'm talking about. If they can't find the new talent then something tells me is isn't there.

Two years ago an Admiral came to speak to our squadron. A sailor in the crowd asked him why Grumman doesn't just build more C-2 aircraft rather than refurbishing the well worn out old ones. The Admiral said that when he asked Grumman about this they said "we can't build aircraft like that anymore. All the guys with those skills have retired years ago. We don't have the ability to make new products of that quality level." There is no reason why Grumman, the Admiral, or anyone else would be making this up. This highlights a serious lack of advanced skills our country has.

So it's no wonder that there aren't as many massive equatorial mounts available as there were in the 1950s-1970s. There aren't as many people around with the knowledge and skill to build one.

obin


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Starman1
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Reged: 06/24/03

Loc: Los Angeles
Re: The Most Beautiful Planetary Images In The World new [Re: obin robinson]
      #6046964 - 08/26/13 12:53 PM

Obin,
While you do have some valid points, I have been keeping track of the availability of mounts in the market for the last 20 years or so, and there has never been a time when so many high end mounts were available.
There are some beautiful, heavy-capacity, mounts from Italy, Germany, Canada, the US, Korea, Taiwan, China, Japan, and I am sure I am forgetting some of them.
If you want a mount for a 50 lb OTA, you have a choice of many many brands--more than in the '50s and '60s. For a 200# OTA you still have many choices. It's just that you cannot expect to be able to get one for a small amount of money. The PlaneWave Ascension mount is an example of machining work that exceeds anything available in the '50s, '60s, or '70s.
It's expensive, but knowing how much work goes into it, the mount is selling for very little more than the cost of materials and labor.
We have mounts available that can handle 1000 lb OTAs today that weren't even thought of by engineers 50 years ago.
No, while I do agree with you about a dearth of good machinists and the tragedy of a lack of education in that regard, I don't agree about mounts at all. We have more mounts available to us that any of us even dreamed about 30 years ago, let alone 50.
Where I observe, there is usually a fairly good crowd, and I have regularly seen EQ mounts from 15 different companies at a time. That wasn't true 35 years ago.


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obin robinson
Carpal Tunnel
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Reged: 10/25/12

Loc: League City, TX
Re: The Most Beautiful Planetary Images In The World new [Re: Starman1]
      #6046995 - 08/26/13 01:18 PM

Don,

I'm sorry I should have said "aren't as many massive AMERICAN MADE equatorial mounts available" in my last sentence. I was responding also to the cost of aluminum and other metals being higher than they used to be. I agree that there's lots of awesome gear available today which was considered sci-fi even only 30 years ago. On the other hand it's sad to see the great American builders of the past go out of business. The other countries will pick up the slack with EQ mounts the same way they do with tube amps.

obin


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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

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Re: The Most Beautiful Planetary Images In The World new [Re: obin robinson]
      #6047033 - 08/26/13 01:45 PM

Quote:

Don,

I'm sorry I should have said "aren't as many massive AMERICAN MADE equatorial mounts available" in my last sentence. I was responding also to the cost of aluminum and other metals being higher than they used to be. I agree that there's lots of awesome gear available today which was considered sci-fi even only 30 years ago. On the other hand it's sad to see the great American builders of the past go out of business. The other countries will pick up the slack with EQ mounts the same way they do with tube amps.

obin




Except for:
PlaneWave
AstroPhysics
Losmandy
Parallax Instruments
Chronos Mounts
Mathis Instruments
Software Bisque Paramount mounts.

all American-made EQ mounts.

That's more brands than were available 30-40-50 years ago, and a lot more choices within brands.

It looks like we have a dichotomy between cheap mounts, where China has picked up the business, and higher-end, high-capacity, mounts, where American-made is still flying high, and with plenty of choices.


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: The Most Beautiful Planetary Images In The World [Re: Starman1]
      #6047070 - 08/26/13 02:13 PM

The Celestron SC killed the long-tube Newtonian and the dob revolution finished off the simple and big GEMs for these Newts. for us observers. It's now the new imaging revolution that has opened up the GEM market once again, but has forgotten us observers. Observers are a declining group! Imaging is more exciting to younger amateurs, and it's so easy to do. Astro-Physics, Celestron, Takahashi are more and more imaging companies and they will continue to build imaging scopes and mounts. That's where the market is.


Quote:

Obin,
While you do have some valid points, I have been keeping track of the availability of mounts in the market for the last 20 years or so, and there has never been a time when so many high end mounts were available.
There are some beautiful, heavy-capacity, mounts from Italy, Germany, Canada, the US, Korea, Taiwan, China, Japan, and I am sure I am forgetting some of them.
If you want a mount for a 50 lb OTA, you have a choice of many many brands--more than in the '50s and '60s. For a 200# OTA you still have many choices. It's just that you cannot expect to be able to get one for a small amount of money. The PlaneWave Ascension mount is an example of machining work that exceeds anything available in the '50s, '60s, or '70s.
It's expensive, but knowing how much work goes into it, the mount is selling for very little more than the cost of materials and labor.
We have mounts available that can handle 1000 lb OTAs today that weren't even thought of by engineers 50 years ago.
No, while I do agree with you about a dearth of good machinists and the tragedy of a lack of education in that regard, I don't agree about mounts at all. We have more mounts available to us that any of us even dreamed about 30 years ago, let alone 50.
Where I observe, there is usually a fairly good crowd, and I have regularly seen EQ mounts from 15 different companies at a time. That wasn't true 35 years ago.




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Astrojensen
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: The Most Beautiful Planetary Images In The World new [Re: Peter Natscher]
      #6047377 - 08/26/13 05:25 PM

It was never fun to use a newtonian on a GEM, that's what killed them. At least for most people. That and the weight.

A dobsonian of the same size is just infinitely more user friendly and will handle the magnifications most people use (50x - 300x) just fine.


Clear skies!
Thomas, Denmark


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obin robinson
Carpal Tunnel
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Reged: 10/25/12

Loc: League City, TX
Re: The Most Beautiful Planetary Images In The World new [Re: Starman1]
      #6047467 - 08/26/13 06:12 PM

Quote:

Except for:
PlaneWave
AstroPhysics
Losmandy
Parallax Instruments
Chronos Mounts
Mathis Instruments
Software Bisque Paramount mounts.

all American-made EQ mounts.

That's more brands than were available 30-40-50 years ago, and a lot more choices within brands.

It looks like we have a dichotomy between cheap mounts, where China has picked up the business, and higher-end, high-capacity, mounts, where American-made is still flying high, and with plenty of choices.




True. You have a point there. I was thinking of the older companies like Edmund Scientific, Unitron, Optical Craftsmen, Cave, Criterion, Star Liner, Tinsley, etc. I suppose that for every of the old ones which are gone there is one to take their place.

obin


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: The Most Beautiful Planetary Images In The World new [Re: obin robinson]
      #6047481 - 08/26/13 06:26 PM

If Edmund Scientific, Unitron, Optical Craftsmen, Cave, Criterion, Star Liner, Tinsley, etc. were still making telescopes and GEMs today, they would be designing for and selling to imagers. That's the business today.

Quote:

Quote:

Except for:
PlaneWave
AstroPhysics
Losmandy
Parallax Instruments
Chronos Mounts
Mathis Instruments
Software Bisque Paramount mounts.

all American-made EQ mounts.

That's more brands than were available 30-40-50 years ago, and a lot more choices within brands.

It looks like we have a dichotomy between cheap mounts, where China has picked up the business, and higher-end, high-capacity, mounts, where American-made is still flying high, and with plenty of choices.




True. You have a point there. I was thinking of the older companies like Edmund Scientific, Unitron, Optical Craftsmen, Cave, Criterion, Star Liner, Tinsley, etc. I suppose that for every of the old ones which are gone there is one to take their place.

obin




Edited by Peter Natscher (08/26/13 06:29 PM)


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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: The Most Beautiful Planetary Images In The World new [Re: Astrojensen]
      #6047483 - 08/26/13 06:26 PM

Thomas,

Quote:

It was never fun to use a newtonian on a GEM, that's what killed them. At least for most people. That and the weight.

A dobsonian of the same size is just infinitely more user friendly and will handle the magnifications most people use (50x - 300x) just fine.




Here! Here! Agreed on all counts. Remember the unnatural motions of the GEM, especially if you wanted to locate an object toward the NCP? Remember the uncomfortable positions the focuser would get into for a Newt on a GEM? Not too fun. Then you'd have to make rotating rings. But I never did. I just moved all my Newts to Dobsonian or other alt-az mounts and never looked back.

However, a good Dob in the nudging hands of an experienced observer can easily handle magnifications of at least 600x - I know, because I have.


Mike


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: The Most Beautiful Planetary Images In The World new [Re: Sarkikos]
      #6047494 - 08/26/13 06:33 PM

Yeah, but you spend so much of your observing time moving and centering the object. I love the tracking and hand controller accuracy of my AP900 GEM mount while observing at 400X. It reminds me of the old days.

Quote:

Thomas,

Quote:

It was never fun to use a newtonian on a GEM, that's what killed them. At least for most people. That and the weight.

A dobsonian of the same size is just infinitely more user friendly and will handle the magnifications most people use (50x - 300x) just fine.




Here! Here! Agreed on all counts. Remember the unnatural motions of the GEM, especially if you wanted to locate an object toward the NCP? Remember the uncomfortable positions the focuser would get into for a Newt on a GEM? Not too fun. Then you'd have to make rotating rings. But I never did. I just moved all my Newts to Dobsonian or other alt-az mounts and never looked back.

However, a good Dob in the nudging hands of an experienced observer can easily handle magnifications of at least 600x - I know, because I have.


Mike




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Sarkikos
Postmaster
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: The Most Beautiful Planetary Images In The World new [Re: Peter Natscher]
      #6047535 - 08/26/13 06:59 PM

Nudging - like observing - becomes second nature with experience. The idea isn't to keep the planet centered. How could you do that without tracking? What you do is move the planet back to the EOF and observe it as it drifts across the FOV.

That said, I plan on having tracking incorporated into my next scope, about a 14" Newt. But it will be a Dob that tracks, not a GEM. I don't think I'll ever put a Newt on a GEM again.

Mike


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obin robinson
Carpal Tunnel
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Reged: 10/25/12

Loc: League City, TX
Re: The Most Beautiful Planetary Images In The World new [Re: Sarkikos]
      #6047536 - 08/26/13 07:05 PM

Quote:

I don't think I'll ever put a Newt on a GEM again.

Mike




That's fine because obviously you are an observer and not a photographer. I can't imagine putting a newt on anything BUT a GEM.

obin


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Mirzam
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Reged: 04/01/08

Loc: Lovettsville, VA
Re: The Most Beautiful Planetary Images In The World new [Re: obin robinson]
      #6047559 - 08/26/13 07:22 PM Attachment (20 downloads)

I put mine on a GEM. If it doesn't require a ladder it's not a real telescope.

JimC


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