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Astrophotography and Sketching >> Sketching

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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Chopin]
      #6248264 - 12/12/13 02:03 AM Attachment (12 downloads)

Jason & Norme, thanks for the comments. My apparent increase in sketching skills is a result of using a Bamboo tablet and stylus as opposed to a mouse to generate these renderings. My observation skills are still mediocre at best.

Anyway, on with tonight's adventure.

It had been clear for most of the day, crystal clear in fact. There were a few clouds later in the afternoon, just before sunset, then it cleared up again and stayed that way for most of the night. I consulted Stellarium early and determined that GRS would begin transit at right around 1140 EST my time and would be fully visible around 1215 or so once it cleared that “dead” area near the F limb. At 1115 I dressed in layers, assembled my sketching materials and went outside around 1130.

I set up my rig and found that it would be a perfect “sitting down” session as Jove was just clearing the tree in my backyard. No dramatic slewing, my chair was the perfect height. From 1140-1145 I observed using a 25mm EP, sketched the positions of the moons, and generally allowed my eyes to adjust. From 1145-1149 I observed through a 7.7mm Ortho with yellow filter keeping an eye on the SEB just forward of the F limb. I thought I could make out the beginning of something going on in this area, then...Jove faded noticeably. Initially, I though that I had accidentally breathed on the EP causing it to fog, then I looked up and...you guessed it...clouds.

At first they were sporadic, light and wispy, at times actually acting a filter against Jove's mighty glare. Then they thickened, blotting Jove out entirely at midnight, just when I figured the GRS would become apparent. By 1210 they dominated, so I packed up and called it a night.

Oh, the irony. A TV sitcom writer could have a field day with my observing sessions this season.

Scene 6: Stray looks into his telescope and sees nothing. He leans back and rubs his eyes, then he looks up. Clouds now obscure what only a minute ago had been a perfectly clear sky.

(Cue laugh track).

The evening wasn't a total bust though. I noticed a linear detail that I believe is the NTB. I've seen this before, last season, so I'm pretty sure that is what it is. Additionally, for just a second or two I noticed a definite shading in the southern region. This might be an aberration caused by the yellow filter that I was using, or possibly the STB, SSTB, (S)SSTB, and the S3TB blended together along with the always subtle SPR. Not sure. I might have imagined it. The NPR, NNTB, etc. were unusually vague this evening, probably because I wasn't paying much attention to this area. My primary focus was on the SEB at the F limb, everything else just kind of “popped” at one time or another.

Finally, I've exagerated the color for ease in viewing on a monitor. Also, with the exception of the festoon, the viewer should not confuse any apparent “structures” in the belts and bands as something that I actually saw. These, by and large, are artifacts left over from the blending process in Gimp.

Thanks for looking!

-stray-

PS—I'm not “really” complaining about the clouds. I've had not one...but TWO...nights in a row with Jove. I'm a happy man.

Edited by stray1 (12/12/13 02:14 AM)


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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6248276 - 12/12/13 02:28 AM

Quote:

Yes, the GRS should be near the preceding limb early in your observation (which is what side? I cannot tell conclusively from the dark southern belt fragment, it can go either way depending on mirror reversal.)




Norme, if I am not mistaken I think the view that I get through my refractor is the same that you get through your MCT--that is a mirror image; right side up but reversed.

Could be wrong (usually am according to the wife).



-stray-


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: stray1]
      #6248300 - 12/12/13 03:02 AM

Hmmm. My north and south are reversed and west depends on which part of the sky. Hope that clears it up.

<cue laugh track and hold>

Your additional sketch is stunning.


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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6248314 - 12/12/13 03:30 AM

Quote:

Hmmm. My north and south are reversed and west depends on which part of the sky. Hope that clears it up.

<cue laugh track and hold>

Your additional sketch is stunning.




If you are looking at an object on the ground--say a utility pole--is the object upside-down in your EP? With my refractor, this would not be the case. The image would be right-side up, but reversed.

-stray-


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: stray1]
      #6248432 - 12/12/13 07:48 AM

I dunno, can't remember terrestrial viewing orientation. I think it would be right side up but reversed left to right, like yours. That does not seem right, though, maybe it is. Still, celestial objects change depending on which part of the sky and the orientation of the diagonal. Sometimes preceding side is up, sometimes it's down, other times it's more oblique. That's why its often nice to label your sketches which way is north or south and either west or east and the direction the planet is rotating along with the UT and system longitudes.

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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6276582 - 12/28/13 02:56 AM Attachment (10 downloads)

Hello!

Just a quick follow up on something that I mentioned in one of Asbytech's Jupiter threads. During the past three or four weeks of cloud induced downtime, I took the opportunity to break down the Astroview and give the baffles a good coating of flat black paint. Additionally, I noted that there was quite a bit of light "leakage" between the baffle's O.D. and the tube's I.D. so I globbed quite a bit of paint into these areas (had to duck tape my paint brush to a pencil to reach the center baffle). When I finished it was as dark as Satan's heart down there. I also noticed that there were some uncoated, raw areas on the objective housing so I dabbed a bit of black on these areas. Finally, I gave the inside of the dew shield a coat or two. I also noticed that the inside of the focuser tube, although factory coated with black, seems to reflect a great deal of incoming light. Although I did nothing to the tube at this time, I am considering flocking it with a thin layer of black felt.

Anyway, tonight I had excellent skies; however, I also had a steady cross wind that denied me any serious observing. Still, the stars have been rare around these parts lately so I decided to go ahead and set up the rig to determine if my "blacking" project had any positive effect.

All I can say is WOW!

Jove was my primary target and it came in clearer than I have ever seen it. The NTB, which usually appears as a half-scratch (see my last sketch above) was detectable all of the way across the face of the planet. Both polar regions were plainly visible...not hinted at...VISIBLE. Unfortunately, the wind was so bad that I only had very fleeting stability, but I swear I could see separation in these areas.

I then slewed over and took a peek at Betelgeuse to make a star check. Previous to this blacking project, diffraction rings were hard for me to come by. I could get them, but only with much difficulty and I still had to deal with weird light aberration even at good focus. Tonight the rings were clean and crisp, much to my delight.

Below is an aberration comparison image that I found online. The example second from the right illustrates what I used to see in the EP before. The image second from the left is close to what I am seeing now. If is like looking through a completely different scope.

Again...WOW!



-stray-


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PeterDob
scholastic sledgehammer


Reged: 07/29/05

Loc: CarĂą, Italy
Re: Juptier new [Re: stray1]
      #6276606 - 12/28/13 04:17 AM

Lovely Jupiter sketch, Stray! Your drawings are the absolute proof that you don't need mind-boggling aperture in order to see quite a lot of detail on this planet. I also love the way you elaborated it, with these soft pastel tones. Very realistic!

BTW, compliments about the telescope. Sounds like you've finally taken off and I wish you a lot of wonderful nights for 2014!

Peter


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: stray1]
      #6276610 - 12/28/13 04:22 AM

Mark, okay, I am stunned, too. Well done.

Couple of points to note. First, there is no doubt in my mind your blackening project is an improvement. That previously difficult bands are now more easily seen speaks to two things. First, you may well have dampened enough veiling glare (bouncing around your tube) to make a difference. Second, even though seeing was not perfect, some improvement might still be a result of better transparency or other atmospheric conditions. It's so hard to be sure on one night, it'll take time in average conditions to really note improvement that rules out uncommonly good transparency.

I am a little struck by your better star image. It looks like a slight collimation problem was repaired and reduced some flare. That's a big jump in performance, in and of itself. You tinkered with the focuser draw tube, did you tighten it or in any way alter it's alignment? I suspect so and for the better, I might add. Did it have some slop before? I ask because I can't see any other way blackening the tube would fix that flaring.

But, what an improvement, huh? When you can see stuff on Jupiter than you have not seen before, there is nothing wrong and everything right with that. Your scope is performing more as it should.

Really, I suspect your improved observation was related to all three things: blackening, descent weather conditions, and somehow getting a little better alignment. Maybe you can tinker with the focuser draw tube (or replace the focuser entirely) and tweak out the remainder of that flaring. If that was the cause...

Well done, Mark, I can hear the enthusiasm in your voice. Now, you're Jonesing more so, like the rest of us, to see Jupiter, again, I'd bet. That's the down side.


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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6276628 - 12/28/13 04:54 AM

First off, Peter, thank you for your comments on my sketch! Hopefully the blackening project will allow for more detail in the future.

Norme, I have been considering purchasing a Crayford style focuser for the Astroview for some time now. Moonlite (http://www.focuser.com/) carries one for the Orion Skyview 90mm that, according to tech support at Orion, should work with my rig. However, these Crayfords cost around $300 so I'm wondering if it might be better to put that cash aside and save up for a better scope?

As for my current focuser: yes, it has some slop in fit. This is "reduced" by simply tightening a thumb screw...very low tech. I'm wondering if maybe "shimming" the gap between the tube and the focuser body might help? It is a fairly tight fit as is, so I do not know what I would use.


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: stray1]
      #6276637 - 12/28/13 05:11 AM

Shimming might help and save you come cash (for a 8" Dob, maybe? .) Try some thin tape, like scotch tape. Maybe one strip near the opening on the bottom to hold up that part of the draw tube. Another on the top toward the upper end of the tube to keep that part from shifting up as the back end falls. If it shifts from side to side, maybe a small piece at the upper end will dampen that slop. You can always remove it.

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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6276642 - 12/28/13 05:25 AM

No, not a DOB. More like a 180mm Cas. Saving $300 would put me 1/4 of the way there.

I will try shimming with tape and see what that produces.

Thanks!



-s-


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: stray1]
      #6276660 - 12/28/13 06:22 AM

Was thinking, maybe a coating of grease? Or if you're good with tools and not shy about drilling holes, maybe drill and tap another screw near the top to push the top end of the draw tube down (or in the right direction.) You mentioned being tight already, there may be little room for shimming. Just gotta look it over and see what can be done.

Does the tightness come from the draw tube or the rack and pinion being squeezed when you tightened it? If you can get the draw tube to run true and fairly free, you're in business.

Yea, wish I had gone bigger with a 180MCT, but happy with the 150.


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Chopin
Canis Insanus
*****

Reged: 02/03/05

Loc: In the doghouse.
Re: Juptier new [Re: Asbytec]
      #6277684 - 12/28/13 05:49 PM

Mark, it's great to see you posting. I'm with Norme, I think the star pattern is a result of collimation improvement somewhere. Whatever caused it, roll with it and enjoy those views.

BTW, if you want a truly killer scope for the money, consider building a Newtonian reflector from the ground up. You could do a 6" with a contrast maximizing secondary/spider design and avoid the cooling issues of a 7" MCT. Don't get me wrong. I dream of a huge Mak (8-10") mounted in an observatory in the backyard. But since you live in Ohio, which is even colder than CT this time of year, you might want to consider cool down times. Norme might have some practical solutions to add.

Ah, never mind, don't listen to me. I'm just a Newt-nut. I've finished two ground-up projects and I'm already designing another.


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: Chopin]
      #6278253 - 12/28/13 11:36 PM

Quote:

Norme might have some practical solutions to add.



Buy one. LOL


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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6278500 - 12/29/13 04:03 AM

Norme and Chop,

Since the clouds have moved back in, this gives yet more time to take a closer look at the focuser. First off, it is already factory shimmed between the body and the tube; however, there is still a bit a play in the fit...not a great deal, but just enough to allow for some "rattle" between the moving parts. I'll probably go with Norme's "scotch tape" solution to tighten this up.

Another thing that I've discovered is that there are two additional baffles INSIDE the focus tube and these are leaking light as well. I'll hit them with some paint without actually disturbing the factory blacking in the focus tube body.

Also, the focuser end of the main scope tube appears to have been neglected during the factory blacking process. It looks like this end simply received a light coating of over-spray while they were applying the black (paint?) down the front (objective) end of the tube. I'll take care of this with a can of flat black spray paint...weather permitting...my wife would strike me over the pate with a rolling pin if I started spraying in the house.

Also, again, the interior surfaces of the focuser body look like they've only received a light "spritz" of black. Inside there are 7 small, circular "tabs" (that I believe are casting ejection points) that sit perpendicular to centerline of the light path. If these tabs are acting as mirrors to any stray light photons, they may be causing some of the aberration that I'm trying to eliminate by shooting light back up into the main tube. A coat of black paint appears to be in order in this area.

Question: the outer surface of the focuser tube is a matte silver finish. Should I also paint this?



-stray-


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier new [Re: stray1]
      #6278506 - 12/29/13 04:16 AM

Quote:

Question: the outer surface of the focuser tube is a matte silver finish. Should I also paint this?



You can, but you're rapidly reaching a point of diminishing returns doing so. You might blacken the outer edge of it, though. It's shiny and with a bright enough light source can reflect of your lens and be seen at the focal plane. It's minor, but since you at it anyway...


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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier new [Re: Asbytec]
      #6278547 - 12/29/13 05:19 AM

Norme, I dig.

I am not going to paint the outside of the focuser tube, I am, however, slathering every other appropriate surface with a coat of Melissa & Doug's Black Poster Paint. That way while I sitting in my driveway peering through the EP I can least note an aberration and know what is NOT causing it.

Thank you kindly for all of your advice. It helps!



-stray-


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Juptier [Re: stray1]
      #6278552 - 12/29/13 05:36 AM

Hey, when you look up the tube and it's pitch black, that's a great feeling. Well done, Mark.

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Chopin
Canis Insanus
*****

Reged: 02/03/05

Loc: In the doghouse.
Re: Juptier [Re: Asbytec]
      #6278780 - 12/29/13 09:55 AM

Mark, you mentioned the idea of potentially flocking the tube. If you are interested in what flocking can do, even versus a good solid coat of flat black paint, here you go:

Painted:




Flocked:




I believe in flocking everything that can be easily flocked. it makes a huge difference on bright objects. Especially planets, lunar, and tight imbalanced doubles. I will say, though that doing what you are doing is probably enough to get you 90% of the way there. Like Norme suggests, there is a point of diminishing returns. For me, with the 10", I was going for that last 99.9%, which is why I not only flocked my inner focuser tube, but also added my own custom baffle to match the field stop to my lowest power eyepiece. Do I obssess much? Yup.


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stray1
sage


Reged: 09/03/12

Loc: SW Ohio
Re: Juptier [Re: Chopin]
      #6280430 - 12/30/13 03:43 AM

Hey Chop,

Thanks for the "day & night" comparison photos. As of right now, when looking down the tube, what I see is comparable to your "night" photo. Keep in mind that I have three baffles in the Astroview (a refractor) and the biggest culprit in this area was light leaking between them and the I.D. of the tube. This leakage is 99.9% history.

The interior surfaces of the focuser body are now coated as well and not throwing back any major reflections under a flashlight. This, in and of itself, "should" knock me a notch or two toward an improvement.

I still have a few dabs of paint to apply to certain areas of the interior of the objective housing, but otherwise I'm done.

You are correct about obsessive. That would be me, but it is now time to call the project "in the bag" and wait for a clear night to test the results.

Thanks to all for the advice and encouragement!



-stray-


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