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What is the most usable power you've used?

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#1 stratocaster

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Posted 23 September 2020 - 02:46 AM

I just got done looking at Mars tonight.  My best views ever.

 

I have a 10" dob with Zambuto mirror and an upgraded secondary.

 

I started at about 90x and kept bumping the power up.  Surprisingly, the views continued to look pretty good during those moments of steady seeing.

 

Next thing I know I've got my 7mm Pentax and I'm at about 180x.  Still looks pretty decent.  Maria features are easily discerned and defined.  In goes the 5mm Pentax at 250x.  Still good.

 

I barlow the 7mm at 357x.  This starts to look like the limit.  But I try the barlow on the 5mm anyway, just to see.  500x was still usable, but overall the barlowed 7mm gave the best views.

 

I don't think I've been able to come close to using these types of powers before, so I thought I'd ask what the most usable power is that you've experienced and maybe how often you've been able to achieve that.


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#2 Bean614

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Posted 23 September 2020 - 03:26 AM

"I just got done looking at Mars tonight.  My best views ever."...??? 

Gee, I guess it would have been nice if we had any idea where you lived.

I just got done looking at Mars tonight.  My best views ever.

 

I have a 10" dob with Zambuto mirror and an upgraded secondary.

 

I started at about 90x and kept bumping the power up.  Surprisingly, the views continued to look pretty good during those moments of steady seeing.

 

Next thing I know I've got my 7mm Pentax and I'm at about 180x.  Still looks pretty decent.  Maria features are easily discerned and defined.  In goes the 5mm Pentax at 250x.  Still good.

 

I barlow the 7mm at 357x.  This starts to look like the limit.  But I try the barlow on the 5mm anyway, just to see.  500x was still usable, but overall the barlowed 7mm gave the best views.

 

I don't think I've been able to come close to using these types of powers before, so I thought I'd ask what the most usable power is that you've experienced and maybe how often you've been able to achieve that.


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#3 havasman

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Posted 23 September 2020 - 03:32 AM

On Mars usually 210, 233, 262x or sometimes 168x. That with 16" f4.49.



#4 TOMDEY

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Posted 23 September 2020 - 05:24 AM

Theoretically, it should be proportional to aperture --- but, for me, in practice... it's aperture-invariant >>>

 

a very modest/conservative 250x !

on superb nights, a still-modest 350x.

 

Rather astonishingly, this is true for my 4-inch F/5 Televue Genesis APO Refractor, my 16-inch Binoscope, my 17.5, 29, and 36-inch Dobsonians, and my 12.5-inch Astrola. I always wind up hovering around 250x, for most of the observing session... and feeling that I am getting the most combined resolution and field that the sky, my eyes, and my scopes have to offer.

 

>My favorite targets are remote little galaxies, but I also do clusters, planets, planetaries, and multiple stars

>My visual acuity is 20/10 each and both eye

>My pupils don't get very big anymore

>My skies are country dark and the seeing is rather superior

>I'm quite experienced visual use

 

The above experience (untold thousands and thousands of hours at the eyepiece singleton or paired) convinces me that TeleVue's consul regrading 350x max is really very realistic.

 

I know that many people boast vastly higher max mags, most often using cute skinny little scopes... with thread-thin 100μm exit pupils, and all. But, I just don't see it, either theoretically or in practice. Results may vary, but Mother Nature should be in on the conversation. It might be that failing eyesight also pushes most geriatrics to absurdly high magnifications? With miniscule exit pupil, your diminished native acuity drops out of the equation.   Tom


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#5 TOMDEY

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Posted 23 September 2020 - 05:31 AM

Related cartoon here >>>    Tom

Attached Thumbnails

  • 18 80b pupils vs aperture at 140x.jpg

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#6 Redbetter

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Posted 23 September 2020 - 05:43 AM

On Mars the highest useful power for detail I have employed has been 714x one night with the 20".  I was mostly using 500x that night and sketching.  That was 2003 in East Texas.  I had other excellent nights there when everything was still.  I frequently had the 8" SCT topped out at ~310x for planetary there and the seeing was very steady.  I have never had a night like that out here.

 

With my son's 10" f/5 Zhumell the best night I have had with it for planetary in the backyard here, I was using 357x with a 2x Barlowed 7T1 Nagler.  I was briefly able to employ 417x that night with it on Jupiter, but the seeing slipped back a notch after a few minutes.  I don't know if the scope had anything more to offer because I didn't have the seeing to go further.  

 

I am not really into excessive power on planets, including with refractors.  Somewhere around 50x/inch is usually the sweet spot for my eye on the better nights here with good refractors.  When I go higher for detail it is typically to confirm separation at some scale, not to see anything additional.

 

With the 20" I use higher powers at times to provide separation for stellar objects (moons, supernovae in galaxies) and some other things where I am primarily looking for some separation or to examine the diffraction pattern.  On a good night here I started to feel certain I was seeing M87's jet at 417x and confirmed at 500 and 625x.  I use up to about 1,000x for very tight double stars, manually tracking, but there I am just hoping to get a few firm flashes of the spurious disks in the best moments.  I go into the 500 to 700's at times to tease out Uranus' inner moons.  Ditto for Mars.


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#7 Tony Flanders

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Posted 23 September 2020 - 07:12 AM

I mostly use 227X on my 12.5-inch Dob, for deep-sky and planetary observing alike. But on good nights, I can get quite glorious planetary images at 315X. Once or twice, the seeing has been good enough for me to deploy 554X. But that is extremely rare in the northeastern U.S.

 

If I lived in California or Florida, I suspect I would use 400X or more quite often.


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#8 Jon Isaacs

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Posted 23 September 2020 - 07:47 AM

I mostly use 227X on my 12.5-inch Dob, for deep-sky and planetary observing alike. But on good nights, I can get quite glorious planetary images at 315X. Once or twice, the seeing has been good enough for me to deploy 554X. But that is extremely rare in the northeastern U.S.

 

If I lived in California or Florida, I suspect I would use 400X or more quite often.

 

:waytogo:

 

The optimal magnification depends on the equipment, the preparation of the equipment, the seeing as well as the observer.

 

With my 10 inch Dob, I use 410x on the planets, double that for close double stars.

 

Jon


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#9 oldmanrick

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Posted 23 September 2020 - 10:32 AM

Either 129X or 187X pairs in my APM 150 BT, depending on seeing, transparency, and my eyes that night.

 

Rick 



#10 Dave Mitsky

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Posted 23 September 2020 - 10:56 AM

Years ago at the Winter Star Party in the Florida Keys I viewed Mars at over 900x through a telescope belonging to someone else.  Of course, that was under the WSP's superb seeing, which is the stuff of legends.

 

I usually use a high magnification of 324x when observing the Red Planet with the 17" f/15 classical Cassegrain at the Naylor Observatory.  On Sunday night, I pushed the power up to 432x but that was a bit of overkill.  I've used over 600x with that scope when viewing the Moon.

I've seen several high-surface planetary nebulae at magnifications of over 1000x through large truss-tube Dobs with premium primary mirrors.


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#11 JMW

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Posted 23 September 2020 - 11:06 AM

I was able to enjoy Saturn at 523 power while doing public outreach using a Naglar 3.5mm with a Paracorr SIPS in a my Webster D14 with f/4.3 14.5 inch Zambuto mirror. That was the only time I have been able to have a stable view at that magnification. It was a very mild August evening in the city of Sparks where temperatures were holding steady. Saturn was well placed and many people enjoyed the view that night. I had the ServoCAT engaged to track on Saturn. I have speed control using PWM on three 120mm Noctua fans behind the mirror. The fans are running slow enough once cooled down so no vibration can be seen. If I turn the fans off the view gets softer within a few minutes. I run them full blast before the start of viewing. 

 

Most of the time I stay below 250 power because of unsteady air flowing over the Sierra Nevada crest. I am very happy for the rare 305 power with my Ethos 6mm.


Edited by JMW, 23 September 2020 - 11:10 AM.


#12 Kent10

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Posted 23 September 2020 - 11:56 AM

It all depends on the seeing for sure.  I have been looking at Mars each night usually starting at 400X and then going down to 320 or 267 if necessary.  But I usually wait for the seeing to stabilize even briefly at 400.  Three nights ago the seeing was holding steady so I went to 533X and for the 1st time noticed the irregular shape of the South Polar Cap.  I don't have a lot of experience with Mars so this was my 1st time but it was just there and obvious to see.  Lots of fine detail on the planet too.  But my floaters were really annoying at this power.  I had to flick them away constantly.

 

I use these powers and higher on double stars all the time.  On Jupiter generally I haven't been higher than 400X.  Saturn I like to start at 400X because I am trying to see the Encke Division and I don't think I have a chance at lower power.  Might never see it but I enjoy trying and I think I "might" have seen it very fleetingly.  I only had the seeing once this season to get some good views at about 500X.  A few days ago, I decided to enjoy Saturn as a whole rather than looking for detail so I was using 133X and it was so beautiful.  With the moon, I also generally start at 400X and try higher if the seeing allows.  I will use lower powers to get an overall picture of areas on the moon or the complete moon in the FOV.  But I use higher power more often because I enjoy the challenge of trying to see certain features.


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#13 stratocaster

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Posted 23 September 2020 - 12:02 PM

"I just got done looking at Mars tonight.  My best views ever."...??? 

Gee, I guess it would have been nice if we had any idea where you lived.

That would be Las Vegas, NV.  The smoke from California was temporarily blown elsewhere.



#14 TOMDEY

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Posted 23 September 2020 - 01:41 PM

I just realized the obvious answer... like a Gestalt epiphany... 1x    Tom


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#15 Andrekp

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Posted 23 September 2020 - 02:13 PM

There is no answer to this question.  It’s like asking what the best food is.


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#16 sg6

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Posted 23 September 2020 - 02:29 PM

Question, or wording, is I suspect a bit wrong. Should it be:

What is the highest usable power you have used?

 

Most usable is generally low, 60x to 80x. The highest usable is different. "Most" in this case has 2 options for its meaning. Most as in often or Most as in biggest.

 

Mine is either 125x for Saturn or 183x on something or other.

May have been higher without me knowing but not on my equipment. Makes me wonder what I was viewing Neptune or Uranus at a year ago. Know the scope, no idea of the eyepiece.


Edited by sg6, 23 September 2020 - 02:32 PM.


#17 TOMDEY

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Posted 23 September 2020 - 02:34 PM

There is no answer to this question.  It’s like asking what the best food is.

Good point; it's a personal thing! For me, it's 500x, a one-pound bag of classic Fritos, a pint of onion dip, and three cans of the cheapest beer.    Tom, rural Springwater, NY


Edited by TOMDEY, 23 September 2020 - 02:34 PM.

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#18 Redbetter

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Posted 23 September 2020 - 03:39 PM

 

If I lived in California or Florida, I suspect I would use 400X or more quite often.

 

If you lived along the coast/or coastal range in California perhaps.  Inland?  Not so much.  Seeing in the valley is mostly poor, typically only getting good at times only in shoulder months when the humidity is higher and the temps moderate.  Even at elevation in the Sierra, finding a spot with decent seeing is tricky. 

 

I had better seeing in Missouri, Georgia, and Texas than I have ever had here, even at my best spots in the mountains.   The combination of the long central valley and ranges on either side seems to be rather disruptive to inland viewing.  Arid conditions with large diurnal temperature changes contribute to problems with seeing, especially when combined with topography that sets up problematic wind patterns.

 

There are times when the seeing is good at elevation here, but this tends to be in the early evening hours when the air is at equilibrium, neither rising nor falling down slope.  At the first gentle brush of down slope breeze, things begin to deteriorate.  At many sites the breeze will accelerate throughout the night.  By the time it is settling before dawn I am already packed and headed home or in the tent.

 

As you might guess, having seeing that is only at its "best" in the early evening is not optimal for planets.  Why?  Because at those time Mars/Jupiter/Saturn are either low in the sky or well away from their most favorable distances near opposition.  Locals who turn in/leave dark sites early are somewhat oblivious to this defect.  



#19 GeneT

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Posted 23 September 2020 - 04:29 PM

This depends on the size of the objective lens and seeing. I prefer to explain your question this way:

between 10X and 30X per inch with 20X per inch most often used because I can normally go there even in bad seeing. When seeing is good, I like to crank magnification up to between 30X and 40X per inch, particularly for planetary viewing. Splitting double stars--up to 50X to 60X per inch for close pairs, and if the seeing will take that much juice. 


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#20 TOMDEY

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Posted 23 September 2020 - 07:43 PM

"What is the most usable power you've used?"

 

Ohhh... we've been misinterpreting the question?!

 

Hydro, for sure. Nuclear might explode, Cold Fusion is a canard, Solar and wind are completely unreliable and kill birds, Coal is black, and Gas smells. So, Hydro it is!    Tom


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#21 areyoukiddingme

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Posted 23 September 2020 - 07:50 PM

Mars on the best nights recently is typically around 350x in my 8" F7. I can push higher, easily, but I don't see more and the planet scoots across the field more quickly than I'd like.

 

In my 12.5", I've found a similar sweet spot, but also enjoyed the views beyond 400x, including on Saturn.

 

But even on the best nights, Jupiter is generally at its best for me around 250x. 



#22 Arthur NY

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Posted 23 September 2020 - 07:56 PM

I'm fairly content with a 12mm in my 8" SCT. That's 170X and usually workable. On really good nights I can pull out the zoom and try for 10mm or 8mm, but not often. Maybe muggy summer nights with Jupiter high in the sky.



#23 Redbetter

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Posted 23 September 2020 - 08:31 PM

I'm fairly content with a 12mm in my 8" SCT. That's 170X and usually workable. On really good nights I can pull out the zoom and try for 10mm or 8mm, but not often. Maybe muggy summer nights with Jupiter high in the sky.

Yes, when referring to planets and magnification that is useful on the best nights, the elevation of the planet in the sky is a critical factor.   Somewhere above 45 degrees or so I don't notice a change, but below about 35 degrees planetary viewing takes a noticeable hit due to the seeing impact of the additional column of air.  That is without even considering atmospheric chromatic dispersion. 

 

Some areas have smoother air down to low angles in the sky, but here by the time the planets are in the upper or mid 20's the blurring is becoming general and severe. It correlates well with the twinkling at different elevations in the sky.


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#24 BillP

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Posted 23 September 2020 - 08:36 PM

When the seeing is steady, which I can usually find often enough, with my 10" was not unusual to push around 500x using a 5XO and 2x Barlow with a Baader Contrast Booster.  In the 4" Apo 200x I can use fairly often.  Coincidentally that is a 0.5mm exit pupil in each.  Smaller than that and start losing the low contrast features.


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#25 CrazyPanda

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Posted 23 September 2020 - 09:04 PM

I just got done looking at Mars tonight.  My best views ever.

 

I have a 10" dob with Zambuto mirror and an upgraded secondary.

 

I started at about 90x and kept bumping the power up.  Surprisingly, the views continued to look pretty good during those moments of steady seeing.

 

Next thing I know I've got my 7mm Pentax and I'm at about 180x.  Still looks pretty decent.  Maria features are easily discerned and defined.  In goes the 5mm Pentax at 250x.  Still good.

 

I barlow the 7mm at 357x.  This starts to look like the limit.  But I try the barlow on the 5mm anyway, just to see.  500x was still usable, but overall the barlowed 7mm gave the best views.

 

I don't think I've been able to come close to using these types of powers before, so I thought I'd ask what the most usable power is that you've experienced and maybe how often you've been able to achieve that.

One night about 2-3 years ago I had a once-in-a-lifetime view of the Moon through my 12" when the atmosphere was effectively not present. Zero scintillation. Literally none. Chucked my 3mm DeLite in for 508x and the only problem was the view was a bit dim due to the small 0.6mm exit pupil. Tack sharp otherwise. No movement what-so-ever. Literally felt like I was in orbit around the Moon. Very surreal experience.

 

Could have gone much higher with mags, and that mirror had a bad stig problem.

 

I didn't have a barlow handy and didn't want to run and grab one from my astro junk drawer due to fear of the seeing returning to its usual boiling pot of water state. So I just stayed at 508x on Clavius and soaked in ALL the little teeny tiny itsy bitsy craters that I've only ever seen in stacked images from big SCTs.

 

Doubt I'll have a night like that ever again in my area.

 

That being said, I regularly use mags over 1,100x on my 15" when observing planetary nebulae, even in bad seeing. The views aren't anywhere close to crisp, but the size lets me view the macro features with *direct* vision, and I see more detail than I would at lower magnifications with averted vision.


Edited by CrazyPanda, 23 September 2020 - 09:07 PM.



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