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jjosefsen

Magnification for Venus and Mars?

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HI guys,

Just got my first sight of Venus and Mars through my scope.

Venus was a milky white disc no real detail, but still pretty cool!

Mars was a little bit of a letdown, just a small reddish dot.

Now the conditions were quite bad, windy and shaky and a streetlight shining almost straight down the scope and blinding me too.

What sort of magnification are you using for these two?

I was at 150x on my SW Explorer 150p with the EPs that came with the scope.

 

//Clear skies

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Detail on Venus is very tricky to see and very subtle at best. The planet is covered with thick clouds so what we see is the sunlight relfecting from them. Thats why it's bright.

Mars is a very long way from us at the moment. It's disk is only about 5 and a bit arc seconds in apparent diameter so needs lots of magnification to see any detail at all on it. When it is next at opposition (July 2018) Mars disk will be nearly 5x as big so much easier to view.

I can just see a few details on Mars using around 250x - 300x at the moment. With Venus I'm getting nice views at around the magnification that you are using - 150x and maybe a bit more at times.

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In general - as much as atmosphere and optics allow.

Both Mars and Venus are not easy targets. Venus is closer to the Sun which means that when it is the closest to us - we are looking at it's dark side. Also, because of this, you can view it either in the mornings or evenings - not during the night.

Mars on the other hand is small and best viewed when on same side of the Sun as Earth - this happens once every couple of years. So for these two targets, apart from general good preparation for planetary observation - scope cool down, good seeing, making sure there is not much impact from your surroundings (sources of heat / turbulence like houses, concrete pavements, brick walls, and such) - you need to pick the appropriate time to get the most out of observing session.

This of course does not mean that you can't observe and enjoy in doing so even now - just keep in mind that you need all of the above to get those best views ever ...

 

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Venus basically has no detail, it is effectively 100% cloud covered so all we see is the tops of the fuzzy cloud cover, so no detail.

MArs seems to need a good scope, and around 250x (oro more), clear skies, stable skies and a big proportion of luck. Presently Mars is considered too low - although it seems reasonably high at around 6:00pm, but it is getting further away. Next close meeting with Mars is next year when it is reckooned to still be a bit low, but better in 2020. However you will still need the scope+magnification+skies+luck.

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Thanks for the replies guys makes sense.

Im still blown away by the fact i just looked at another planet!! ?

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Generally speaking, lowish magnification is sufficient for Venus whereas Mars needs high. We were using a 16" SCT  at 500x on Venus and Mars today at 3.45pm, Mars was still a small dot!   :icon_biggrin:

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The first time you see Saturn you will say out loud "I can see its rings" I never forgot seeing this for the first time. No matter how many pictures I had seen of it, seeing with my own eyes was amazing. Then you got Andromeda to get you interested in deep sky objects. Welcome to a fascinating hobby.

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I'd be satisfied with just enough magnification on Mars to reveal it as a disk - in it's present distance. This would also be a bit of a balancing-act due to the brilliance of Venus. Too much magnification, and Venus would overwhelm Mars altogether.

Last Analysis: Play with it until it looks good to you, knowing Mars isn't really going to deliver it's details until 2018. Images of Mars now will make for an interesting contrast with one's taken in 2018 - and up until then too.

Dave

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A bit of letdown at 150x? I was amazed when looked at it at 100x ;).

You'll have to wait a bit to see some more of Mars as folks before me mentioned. But now you could wait a bit (or wake up early??) for Jupiter. I've seen it last night and even with my modest gear it completely blew my socks off ;). 4 moons and some colours were easily visible at 100x magnification ;).  And just before sunrise you may catch a glimpse of Saturn and Mercury too. Good luck with the hunt.

BTW, who bought new scope in Midlands?!? I can't remember seeing so much clouds over here...

Edited by Major
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Magnification has its limits, which are set both by the scope and the atmosphere. A magnification of 50X per inch of aperture is generally considered the limit. Magnifying above this limit will increase the image scale but won't resolve any more detail. Increasing the image scale by upping the magnification will only benefit the observer if the local seeing conditions allow the practical use of higher powers, which often they don't. When seeing conditions allow it, a high quality lens or mirror should be able to produce sharp images in excess of 100X per inch, however the resolution will not be any greater than at 50X per inch. Once the image of a planet becomes soft as the magnification increases, then really increasing the magnification any further will only make matters worse. It is preferable to have a smaller sharper image, requiring careful scrutiny, than a larger blurry disc where the detail is being disrupted  by the turbulent atmosphere, or residual internal heat within the scope itself. Ive often found that a power of 180X, or there abouts, is a good general power for lunar and planetary observing, irrespective of the aperture or design of scope. 

A few days ago i was observing Mars using a power of around 185X and noticed a small dark marking in the centre of its tiny disc. After a few minutes of observation it became evident that there were dark arms extending out from this central feature, so i made a rough sketch of what I saw. Then, only to confirm the accuracy of positioning, did I increase the power to 296X, and only then because the seeing allowed it. The high power view did confirm the accuracy of the lower power observation, but it did not resolve any finer detail.

Mike

 

2017-01-15 14.07.11.jpg

Edited by mikeDnight
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17 hours ago, mikeDnight said:

A few days ago i was observing Mars using a power of around 185X and noticed a small dark marking in the centre of its tiny disc. Mike

Great drawing Mike! Wonderful to see people still sketching at the eyepiece :)

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A few days ago the atmosphere was steady enough to use a magnification of 340x with my 7" refractor on Venus. The cloud patterns are very subtle but it was possible to see some bands and slightly lighter areas at the poles that I recently learned are known as cusp caps. This observation was made around 3.30 pm in the twilight before the sun has fully set. With a planet as bright as Venus, twilight observations have the advantage of it being at a much higher elevation that after dark, so there's less of our atmosphere to look through :)

venus sketch showing caps.jpg

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I've been using 250x-350x on Mars quite a bit. The seeing where I observe is variable but if you persevere you "catch" the steady moments and thats when the detail "pops" :icon_biggrin:

Having great optics also helps a bit !

Great sketches chaps :icon_biggrin:

Edited by John
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10 hours ago, timwetherell said:

A few days ago the atmosphere was steady enough to use a magnification of 340x with my 7" refractor on Venus. The cloud patterns are very subtle but it was possible to see some bands and slightly lighter areas at the poles that I recently learned are known as cusp caps. This observation was made around 3.30 pm in the twilight before the sun has fully set. With a planet as bright as Venus, twilight observations have the advantage of it being at a much higher elevation that after dark, so there's less of our atmosphere to look through :)

venus sketch showing caps.jpg

Nice! Thats a gold tip.

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I got a really good look at Venus when she was in half phase on Saturday - I was also looking well before it got properly dark and thought then what a good view I had - at that time I didn't know why so thank you!

Edited by JOC
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On 15 January 2017 at 14:00, mikeDnight said:

Magnification has its limits, which are set both by the scope and the atmosphere. A magnification of 50X per inch of aperture is generally considered the limit. Magnifying above this limit will increase the image scale but won't resolve any more detail. Increasing the image scale by upping the magnification will only benefit the observer if the local seeing conditions allow the practical use of higher powers, which often they don't. When seeing conditions allow it, a high quality lens or mirror should be able to produce sharp images in excess of 100X per inch, however the resolution will not be any greater than at 50X per inch. Once the image of a planet becomes soft as the magnification increases, then really increasing the magnification any further will only make matters worse. It is preferable to have a smaller sharper image, requiring careful scrutiny, than a larger blurry disc where the detail is being disrupted  by the turbulent atmosphere, or residual internal heat within the scope itself. Ive often found that a power of 180X, or there abouts, is a good general power for lunar and planetary observing, irrespective of the aperture or design of scope. 

A few days ago i was observing Mars using a power of around 185X and noticed a small dark marking in the centre of its tiny disc. After a few minutes of observation it became evident that there were dark arms extending out from this central feature, so i made a rough sketch of what I saw. Then, only to confirm the accuracy of positioning, did I increase the power to 296X, and only then because the seeing allowed it. The high power view did confirm the accuracy of the lower power observation, but it did not resolve any finer detail.

Mike

 

2017-01-15 14.07.11.jpg

A beautiful sketch Mike. Complimented by a very classy script.

My handwriting is atrocious. I think was a GP in a previous life.

Edited by Swoop1
Meatware problem!
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11 hours ago, Swoop1 said:

A beautiful sketch Mike. Complimented by a very classy script.

I agree,  wouldn't mind having a lot through that notebook. ☺️

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7 hours ago, jjosefsen said:

I agree,  wouldn't mind having a lot through that notebook. ☺️

I've always sketched but in the early days I'd also include copious notes. Eventually I came to the conclusion that I would be the only sad person who'd ever read through them, and even I got bored out of my mind by them. I rarely make lengthy notes these days but prefer to make annotated sketches. A sketch can be interpreted and related to in seconds, and if it is an honest interpretation of the view through the eyepiece, can be very informative. My early sketches are laughable! :lol:

 

Mike :happy11:

 

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Funnily enough Mike I used to make lots of notes and now don't. If there's something of note about the way I saw something that will make me smile later I do note that but otherwise I try and let the sketch do the talking.

I am currently working my way from atrocious to starting to resemble reality and hope eventually to get closer to your efforts which are works of art, truly.

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22 hours ago, Moonshane said:

Funnily enough Mike I used to make lots of notes and now don't. If there's something of note about the way I saw something that will make me smile later I do note that but otherwise I try and let the sketch do the talking.

I am currently working my way from atrocious to starting to resemble reality and hope eventually to get closer to your efforts which are works of art, truly.

I've seen some of your observational sketches Shane and they are excellent!  :thumbsup:

Realism is good! :happy11:

Mike

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