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Back to basics - my ultimate system...


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@JeremyS can't say I noticed a smell but it was not new. I think it is the one in the review you linked to.

It's also not my first Takahashi, years ago I had a Sky 90 but was not impressed.

In a bid to design a lenless system I found that you could now get mirror infinity focus microscope objectives (tiny Cassegrain telescopes in reverse) but they cost nearly the same as a new 180c ! If they were a tenth of the price I would give it a go. I did in the past use a microscope tube with objective and eyepiece with a planetary Newt and it worked very well.

Only £1,500 to £1,700 from Edmund Optics.

objective.png.b57ad79781be98394ab9b55066d77a12.png

I am however, looking at playing with some ball eyepieces following up on a post from @John on William Herschel's eyepieces and finding the  Couture "Ball Singlets" in  W Paolini's "Choosing and using Astronomical eyepieces". Edmund seem to have all the bits needed at a very reasonable price. Time to fiddle.

Regards Andrew

PS don't know why the arrow heads in the diagram are the wrong way round!

How about a Hasting triplet as a monocentric. 

Edited by andrew s
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Mount ordered from FLO. Rowan AZ100 with the not quite back to basics DSC. Regards Andrew 

... or if you prefer my posers system. Having fully automated my main setup and shipped it to PixelSkies I have nothing to get my hands on. This together with the BAA back to basics drive made me

@FLO have informed me the Baader diagonal is on the way so the kit will soon be ready for action. I have made a small collection of second hand planetary eyepieces as their focal lengths better s

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33 minutes ago, andrew s said:

 

objective.png.b57ad79781be98394ab9b55066d77a12.png

 

PS don't know why the arrow heads in the diagram are the wrong way round!

May be they do things differently in Japan, or perhaps we've all been looking through the wrong end for years?

The scope looks great though, and I'll wait patiently for your views on the ball eyepieces. Exciting!

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  • 4 weeks later...

@FLO have informed me the Baader diagonal is on the way so the kit will soon be ready for action.

I have made a small collection of second hand planetary eyepieces as their focal lengths better suited the focal length of the Mewlon than do some modern ones.

I set up for a collimation test last night using an artificial star as far away as I could get it. It still took all my collection of T2 extensions, lens holders etc to reach focus.

Joy of joys it looked spot on with beautiful rings even with the SA due to being so close.

(Looks like it has been telling lies so it's nose grew?)

Regards Andrew 

20200711_140424.thumb.jpg.18cc74205b4ee25f731b1f9a3c3b0217.jpg

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4 hours ago, andrew s said:

Ok all phase 1 components arrived and working.20200713_125357.thumb.jpg.fa28570283761647443cd51c0f8f7022.jpg

Clearly not got this phone pictures down yet. However, you get the idea?

Regards Andrew 

So you've built a radio telescope, Andrew?

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Well the weather has been reminding me why I sent my main scope to Spain. Here is the prime focus box on the mk1 telescope at Jodrell bank at x120. It is about 15 miles away. Slightly better than my first attempt . 180 Mewlon and 18mm Brandon into my phone.

Regards Andrew 20200717_203426.thumb.jpg.6a6b801021181bd199d55a15bf8bbd97.jpg

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I'm just wndering how are you getting on with the scope Andrew?  My paper is nearly ready for submission (well the deadline is very close  🤣) so to encourage me during the final push on it and the 3 conference submissions I need to complete by Monday, I'm thinking about the reward .... Mewlon 🤔?

Thanks

Helen

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42 minutes ago, Helen said:

I'm just wndering how are you getting on with the scope Andrew?  My paper is nearly ready for submission (well the deadline is very close  🤣) so to encourage me during the final push on it and the 3 conference submissions I need to complete by Monday, I'm thinking about the reward .... Mewlon 🤔?

Thanks

Helen

Keep pushing Helen, it will make a nice reward. I have been enjoying it. I am rearly just learning visual observation  and relearning about the poor local weather.

It seems a very competent scope I keep it in an observatory so no cool down issues collimation is stable and very little if any focus shift.

Go on you deserve it.

Regards Andrew 

 

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If only Damien Peach came with it..... :hippy2:  It would go on the Mesu instead of the C11, but I was looking for something portable as my south horizon is obscured so planets from the obs are challenging...  Might be cool for 67P return though 👀

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17 minutes ago, Helen said:

If only Damien Peach came with it..... :hippy2:  It would go on the Mesu instead of the C11, but I was looking for something portable as my south horizon is obscured so planets from the obs are challenging...  Might be cool for 67P return though 👀

Well, it's gotta be the Mewlon 180 then, Helen 🙂

 

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15 minutes ago, JeremyS said:

Or there is this: https://www.astrobuysell.com/uk/propview.php?view=165467

But you'd need to add your own handle 🙂

Its around £4526 for the package TSA-120 new, so around £700 off. Is that usual for Tak's resale price? In two minds between a 120 or 130 mm scope, so if I the 120 mm was not enough I could resell without taking the hit. 🤨

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23 hours ago, andrew s said:

Excuse me no refractor talk on my thread 👹

Regards Andrew 

 

On 17/07/2020 at 14:59, andrew s said:

Well the weather has been reminding me why I sent my main scope to Spain

:grin:

Can't help but bring something up you most likely already know. Mag vs image brightness in the EP and the telescope. Some might say reflectors give a washed out view.... well they can under certain circumstances. Refractors guys inadvertently (?) get around this on here- simple really- they are dimming the object, say Jupiter while getting the mag in the strike zone. The old exit pupil deal again.

Most reflectors are faster than the fracs- yours is not- and this is a good thing for you- but you might still need seeing that supports over 300x to get the effect.

ie my TSA120 gets 225x at a dimming .5mmish exit pupil.  Your Mewlon goes 360x to get the same dimming .5mm exit.  I think @mikeDnight uses this very effectively when there is light cloud and aerosols etc in the atmosphere causing washed out appearances.

Have you experienced this Andrew?

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@jetstream, not sure I have due mainly to limited experience and observing time.

Technically I understand the relation between aperture,  magnification, transmittance/refectance, exit pupil and image brightness but am not clear on what you mean by "washed out" do you mean low contrast or illumination or perhaps something else?

I have read some reports of refractors giving a colour cast due to a combination of the anti reflection coatings and or the absorption in the glass. However, I have no personal experience of the effect.

Regards Andrew 

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1 hour ago, andrew s said:

what you mean by "washed out"

Jupiter is a prime example of a target that can easily lose contrast if it appears too "bright" in the eyepiece. One technique I use is to observe it right at dusk, where the sky background is not completely dark as it seems to enhance planetary "contrast" at times. A Baader single polarizer can be super effective just before dusk as well.

Sometimes highish eye illumination combined with certain skies- super clear +avg or worse seeing can wash out detail (reduce contrast). However dimming the object with high mag, low exit pupils with appropriate mag (right scope) can really pull out detail sometimes IMHO.

Another trick is to use binoviewers as the beamsplitter naturally dims which can really pull detail out of Jupiter and Saturn. This in combination with aspects of binocular summation really can work.

So reflectors... many dobs have scatter issues- and not just the mirrors- the whole thing can scatter and blow light all over. They really need attention to detail to have them work properly. My 15" Astrosystems is a good example of a low scatter/low stray light scope- from the mirror cell to the secondary cage, all is controlled, including a must have focuser baffle.

Your superb Mewlon will have stray light well controlled and should give very high contrast lunar/planetary views, obstruction and all. Sorry if I didn't define "washed out" well, but many reflector users seems to report the issue- too bright, no detail etc. There are many tricks to getting good views, regardless of seeing.

I eagerly wait reports!

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  • 2 months later...
1 minute ago, dweller25 said:

Hello @andrew s

How’s it going with the M180 ? Would be interested in your Mars viewing feedback.....

Still very much a beginner at visual. I am still trying to learn how to observe rather than just have a quick look. The scope seems fine though due to the weather and personal circumstances have not been out that much.

I am the limit not the scope. Sorry I can't  be more help full. 

Regards Andrew 

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