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Venus in Very Good Seeing.

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#26 David Gray

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Posted 27 March 2020 - 08:26 AM

Many Thanks Randolph, Ted and to everyone again.....Likes and all......smile.gif

 

Clear out so another Venus session shortly to resume those above-mentioned filter trials.

 

A bit of a milky sky: strong solar aureole extending out to the planet (still readily seen naked-eye tho'). 

 

Looking like I'll be further investigating those Neodymium combos....in particular with the blue filters,

which can be compromised by such a sky, but the Neo allowed their use previously......so seeing allowing...tongue2.gif..... 

 

https://www.cloudyni...-neo-surprise/ 

 

Cheers,

Dave.


Edited by David Gray, 27 March 2020 - 08:27 AM.


#27 stanislas-jean

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Posted 31 March 2020 - 04:31 AM

Hi,

Your 26th march sketch constitutes a good attempt.

The equatorial area strek (almost parallel to the Terminator) is highly probably illusory (see the website http://alpo-j.sakura.ne.jp/indexE.htm for comparison on the dates).

There is no streak refererence showing yours for the 26th date.

However, when looking at the working conditions, you are using a 102-714 refractor, probably semi-apo kind, 

we may have comments about.

142x magnification is not too big, but may be too strong with regards the seeing level. Personally on my 102mm I am using 95 to 112x for the best possible Under seeing 5/10, during day. With 150x this is washed images too strongly.

The 102-714 may be also not good enough, I used in past a 110mm F7 of same design, working well on the moon but failing on planets as the venus and mars, and wonderful saturn images. On small features low contrasted, this was a strong fight for collecting few things.

Its "strehl" ratio, good on contrasted features, more than average on the lower.

For a stunning status that: the 102 F10 ACR worked strongly better than the 102 semi-apo, even the 102 F6.6 ACR by vixen.

So here the OTA status may be the limiting factor.

As you reported delicate features anyway and subtil light variations on the disk, an higher OTA with an higher stehl ratio will boost your data, surely.

This is my feeling globally.

After, the filter serie to be used will not be for purpose of enhancing only the contrast image but to see what happens into color segments.

My opinion about.

Don't hesitate to reply, this is for exchanging on the topic.

Good skies, keep healthy.

Stanislas-Jean



#28 David Gray

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Posted 01 April 2020 - 04:09 AM

Hi,

Your [26th] march [??????] sketch constitutes a good attempt.

 

???????????


Edited by David Gray, 01 April 2020 - 04:09 AM.


#29 stanislas-jean

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Posted 01 April 2020 - 06:17 AM

Sorry David, you're not be concerned. There was a post from reptilicus that has been removed where a 26th sketch was inserted.

Comments were done for.

Stanislas-Jean



#30 Reptilicus

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Posted 01 April 2020 - 03:18 PM

My apologies for the mixup gentleman! My intention was to delete one of my sketches for simplification and respond to Stanislas-jean. I am only now getting around to reforming the post. As always Dave, your observational notes and sketches are inspirational...bow.gif  Below is a sketch I did during the late afternoon hours of 26 March. I have been doubling up on my daily observations of Venus given her northernly declination and my fairly unobstructed views of the southern and western skies.

 

Hi,

Your 26th march sketch constitutes a good attempt.

The equatorial area strek (almost parallel to the Terminator) is highly probably illusory (see the website http://alpo-j.sakura.ne.jp/indexE.htm for comparison on the dates).

There is no streak refererence showing yours for the 26th date.

However, when looking at the working conditions, you are using a 102-714 refractor, probably semi-apo kind, 

we may have comments about.

142x magnification is not too big, but may be too strong with regards the seeing level. Personally on my 102mm I am using 95 to 112x for the best possible Under seeing 5/10, during day. With 150x this is washed images too strongly.

The 102-714 may be also not good enough, I used in past a 110mm F7 of same design, working well on the moon but failing on planets as the venus and mars, and wonderful saturn images. On small features low contrasted, this was a strong fight for collecting few things.

Its "strehl" ratio, good on contrasted features, more than average on the lower.

For a stunning status that: the 102 F10 ACR worked strongly better than the 102 semi-apo, even the 102 F6.6 ACR by vixen.

So here the OTA status may be the limiting factor.

As you reported delicate features anyway and subtil light variations on the disk, an higher OTA with an higher stehl ratio will boost your data, surely.

This is my feeling globally.

After, the filter serie to be used will not be for purpose of enhancing only the contrast image but to see what happens into color segments.

My opinion about.

Don't hesitate to reply, this is for exchanging on the topic.

Good skies, keep healthy.

Stanislas-Jean

LOL...thanks for the response Stanislas-jean...I think...I’m not sure if I was going for “a good attempt”, but I’ll take it. I realize that the diagonal streaks are illusionary. I try my best to represent what I observe at the eyepiece and apply a couple of techniques to eliminate spurious “features”. Doesn’t always work, but I don’t care. I’m just having fun observing this magnificent planet. My telescope on this particular observation was a 102mm triplet f/7 Stellarvue Raptor refractor with a focal length of 714mm. The OTA is carbon fiber with a strehl of .951 as supplied by the manufacturer. I’ve had this telescope for a while now and enjoy its performance. I own several refractors, this one being the only carbon fiber one. The telescope was mounted on a Televue G5 Gibraltar altazimuth mount with a Televue 3mm-6mm zoom eyepiece. This is an excellent eyepiece which allows the observer to:

 

1) change powers rapidly without changing focus and

 

2) allowing for adjustments in power requirements according to local seeing conditions.

 

I live on the windward side of a mountain at an elevation of 1,050 feet. I record meteorological data of each session as well as cloud types (if present)...I’m also a amateur nephologist. So yes, I am aware of atmospheric influences like rising and falling columns of air and barometric pressure (as examples) that play games with the final formed image. Thanks for your interest in my sketches and be well...

 

Bill

Attached Thumbnails

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Edited by Reptilicus, 01 April 2020 - 09:01 PM.

  • steve t and David Gray like this

#31 stanislas-jean

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Posted 02 April 2020 - 03:20 AM

Thanks Bill for your prompt answer.

I realize now your refractor is good one. Probably a triplet with a fpl 51 lens, it doesn't matter as the control bulletin you own is furnished showing a good strehl (I was thinking a simple ED dublet OTA on action widely sold).

Remains the glaring light effect, this comes easily even with 142x.

Why not a use of a double polarising filter in order to settle the light surface of the planet disk in order to get the best lighting conditions to your view.

The optimum settlement is relatively narrow.

Personally this is magnification D (in mm) more or less with the said color filters on action.

Well enough admitted that exit eye pupill diameter ranging from 1.2 until 0.7mm depending on the observer and seeing level provides the best viewing conditions, the W11 yellow-green use too.

Matter of tests and patience.

If desired, to be followed.

Stanislas-Jean




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