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Darth Takahashi

Jupiter and no Onion rings

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A big thank you to everyone who commented on my Onion ringing problem because its now solved :icon_salut: , great! I think the decisive fact was the Gamma needed to be at 100 or greater.

At approximately 02:30 I managed to get this set of Jupiter images using the modified Mewlon M250S (CR Baffle added) and the DMK21 with the correct settings!!!

They are only mono, taken using and IR-Pass filter; one day I will invest in a manual filter wheel and the necessary RGB filters but for now I'm very happy with the results.

Still need some advise; As anyone used Metaguide? I'm trying to use this for collimation of the scope? I have read the manual and I think collimation is bang-on but want to push to get that last bit of perfection!!! Problem was that the "red dot" was moving around too much. Very close to the centre of the star and not too far away but perhaps I could have got a better result with a better technique??? :grin:

Anyway, I hope that you like the images

post-3011-0-49774500-1350461396_thumb.jp

Most probably seeing conditions were the limiting factor

Edited by Darth Takahashi

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That is one hell of a telescope, saliva dripping from my mouth as i read what it was. Lovely images. glad the onion skin has gone. I would love to see you push this monster scope to double the focal length you took here. i am sure it could easily take it. Nice captures

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Hi Neil P,

Well your the master of the planets here, so I need your advise to push the scope harder! I did have a 2x barlow from WO but it wasn't very satisfactory, even though it claimed to be an APO, so I sold it!!! Anyway, the ExtQ works as advertised so what barlow lens would you recommend beyond the TV-Powermates?

The other piece of the puzzle is collimation, although I'm confident that its 95% bang-on, I'm currently trying to push for that last bit of performance using "Metaguide" but here I'm also a novice at present???

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Nice, work, I'm glad you solved your onion rings. Your images look great.

I use Metaguide and I think it is great, but the red dot does fly around quite a bit under UK seeing - more so with bigger scopes. My best advice:

* Use an IR pass filter for collimation, this light is far less affected by seeing.

* Thermal currents in your scope can have the same affect as seeing, do a star test to check for currents.

* Collimate on nights with better seeing (good luck with that one!)

* When the red dot is as still as you can get it, collimate until the red dot dances around the centre rather than off to one side.

I hope this helps.

Cheers,

Chris

Edited by cgarry

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Nice, work, I'm glad you solved your onion rings. Your images look great.

I use Metaguide and I think it is great, but the red dot does fly around quite a bit under UK seeing - more so with bigger scopes. My best advice:

* Use an IR pass filter for collimation, this light is far less affected by seeing.

* Thermal currents in your scope can have the same affect as seeing, do a star test to check for currents.

* Collimate on nights with better seeing (good luck with that one!)

* When the red dot is as still as you can get it, collimate until the red dot dances around the centre rather than off to one side.

I hope this helps.

Cheers,

Chris

Thanks Chris, steps 1 and 2 I'm already doing. The scope was out for a good 2 hours, before set up and collimation. I think like you that its step 3 that's going to be the issue! Waiting for a good steady night where the seeing allows for precise collimation!!!

Still I was hoping that there is a trick or something I have missed in Metaguide..! Changing the frame rate to 30 frames/s seem the slow the "red dot" down a bit... just a bit!!!

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Hi Neil P,

Well your the master of the planets here, so I need your advise to push the scope harder! I did have a 2x barlow from WO but it wasn't very satisfactory, even though it claimed to be an APO, so I sold it!!! Anyway, the ExtQ works as advertised so what barlow lens would you recommend beyond the TV-Powermates?

The other piece of the puzzle is collimation, although I'm confident that its 95% bang-on, I'm currently trying to push for that last bit of performance using "Metaguide" but here I'm also a novice at present???

Hi considering you have a rolls royce of a scope. Only a great Barlow will do. If you could find a Celestron ultima 2x ( they dont make them anymore ) those are some of the best 2x barlows that were ever made period in my opinion. Better than TV Barlows. Other than Powermates which i rate. But i havent used any other than the 5x. which is superb. this new Celestron x cel looks quite good. But its early days on me testing that. and to be honest i think you should get better. Ive seen pentax barlows around i would imagine thay are quite good. I could swear i saw a Zeiss barlow somewhere recently. My advice would be look for a zeiss if you can find one. or a good condition 2x ultima. The ultima will save you a lot of money so worth a try. you can easily sell it on if you dont like it. ( and can find one ) A zeiss barlow has to be the best in the world. something to go hand in hand with the lovely TAK

Considering you have a rolls royce

Edited by neil phillips
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Neil P,

I have just placed an ad asking for a Celestron Ultima 2x barlow on my favourite Dutch website www.te-les-koop.nl = a play on words which means "buy more cheaply" or pay less which ever you prefer!!!

Just found this other link to an ABBE ZEISS barlow lens http://www.unitronitalia.com/prodotti.asp?cod=BP&type=130 I think this is the one that you mean?

Finally, what's your opinion of these eyepiece projection systems? This could be another alternative? I have a nice TAK LE 25 mm that might be suitable for use it such a system.

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Very nice images, very good detail. The DMK21 really nails the detail wonderfully (that scope of yours also helps of course!). I have just snapped up both a filter wheel and LRGB + IR filters secondhand, but I still need the grey-scale camera to attach to them (and some clear skies would also help). Once I have all that in order I hope to have a bash at Jupiter again

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Very nice images, very good detail. The DMK21 really nails the detail wonderfully (that scope of yours also helps of course!). I have just snapped up both a filter wheel and LRGB + IR filters secondhand, but I still need the grey-scale camera to attach to them (and some clear skies would also help). Once I have all that in order I hope to have a bash at Jupiter again

Try looking on the Dutch site I saw a DMK21 on there a while back. Jupiter is great this year, really high up in the sky which also helps of course... I woke my son up this morning to take a look!!! :grin: He really appreciated it, spent 10 mins with me and went back to bed... Hes on school holiday at the moment... The weather here has taken a turn for the worse though, never mind. :mad:

Edited by Darth Takahashi

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Thanks Chris, steps 1 and 2 I'm already doing. The scope was out for a good 2 hours, before set up and collimation. I think like you that its step 3 that's going to be the issue! Waiting for a good steady night where the seeing allows for precise collimation!!!

Still I was hoping that there is a trick or something I have missed in Metaguide..! Changing the frame rate to 30 frames/s seem the slow the "red dot" down a bit... just a bit!!!

Depending on the size of your scope, sorting out the thermal currents is not always as simple as leaving you scope out to equalise for long enough. On my C14 I had lots of trouble where the top of the scope and dew shield that was exposed to the sky became significantly cooler than the bottom of the scope and dew shield that was not exposed to the sky. This caused convection currents in the tube and dew shield that ruined high magnification work and these currents never stopped, no matter how long you waited.

I am not sure how big a scope has to be before this is a problem though.

Cheers,

Chris

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Try looking on the Dutch site I saw a DMK21 on there a while back. Jupiter is great this year, really high up in the sky which also helps of course... I woke my son up this morning to take a look!!! :grin: He really appreciated it, spent 10 mins with me and went back to bed... Hes on school holiday at the moment... The weather here has taken a turn for the worse though, never mind. :mad:

I saw the DMK on offer in the Netherlands, but that was an older one. I am gunning for the 618 version, as they have twice the q.e.

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Depending on the size of your scope, sorting out the thermal currents is not always as simple as leaving you scope out to equalise for long enough. On my C14 I had lots of trouble where the top of the scope and dew shield that was exposed to the sky became significantly cooler than the bottom of the scope and dew shield that was not exposed to the sky. This caused convection currents in the tube and dew shield that ruined high magnification work and these currents never stopped, no matter how long you waited.

I am not sure how big a scope has to be before this is a problem though.

Cheers,

Chris

Are... You should look up Takahashi Mewlon M250S or take a look at my website? The Mewlon is a Dall-Kirkham Cassegrain which has no corrector plate, open tube design the same as a newton, the corrector/s now sits in the central baffle tube behind the secondary mirror, hence, no issues with trapped thermal currents inside the tube. I have never done it but the rear plate is also removable to allow for faster cooling, normally its cooled down inside 1 hour. You can see this when you observe the out of focus star when checking collimation. Tube currents appear as distortions / waves running around the diffraction rings. It obvious when its cooled down you get a fairly steady image. Its one of the benefits of this design of telescope.

But your right, you do need to be careful here, otherwise you can end up chasing your own tail!!! :huh:

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Indeed, your Takahashi Mewlon M250S does look awesome. Having the corrector down the tube must save a lot of issues with dew!

Cheers,

Chris

Edited by cgarry
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Fantastic detail mr takahashi! with shots like that i would leave collimation well alone.

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Neil P,

I have just placed an ad asking for a Celestron Ultima 2x barlow on my favourite Dutch website www.te-les-koop.nl = a play on words which means "buy more cheaply" or pay less which ever you prefer!!!

Just found this other link to an ABBE ZEISS barlow lens http://www.unitronitalia.com/prodotti.asp?cod=BP&type=130 I think this is the one that you mean?

Finally, what's your opinion of these eyepiece projection systems? This could be another alternative? I have a nice TAK LE 25 mm that might be suitable for use it such a system.

Hi again

I have never tried apart from when i started years ago with camcorders. But nearly all the top planetary imagers use barlows. So i suspect theres no advantage using eyepiece projection. Different maybe. advantage, likely not i would have thought.

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Pentax designed some EPs specifically for EP projection, but most imagers I know have switched to Barlows, PowerMates or TeleXtenders. These are often simpler to use. One reason is simply that not all modern EPs fit inside EP projection adaptors for scopes. Plossls and Orthos often do, but even my Vixen LVs didn't. Radians and XWs have even worse problems.

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Pentax designed some EPs specifically for EP projection, but most imagers I know have switched to Barlows, PowerMates or TeleXtenders. These are often simpler to use. One reason is simply that not all modern EPs fit inside EP projection adaptors for scopes. Plossls and Orthos often do, but even my Vixen LVs didn't. Radians and XWs have even worse problems.

The reason that I asked is that you see some bizarre figures quoted on some sites regarding F numbers that are clearly not a multiple of the orignal telescopes F# etc... Of course, using a good barlow makes things easier, getting a good barlow that doesn't cost a fortune is more difficult. Let's see if I can get a Celestron Ultima 2x to test out, if not then I'll try a TV or Zeiss barlow / Powermate....

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what's your opinion of these eyepiece projection systems? This could be another alternative? I have a nice TAK LE 25 mm that might be suitable for use it such a system

Eyepiece projection systems tend to use much longer focal length eyepieces, thereby removing the potential for defects at short focal lengths. For instance I use a 15mm ep with a projection distance of roughly 40mm + camera depth to achieve a large f/40 image. This is because the powermate I own at x2.5 only gets me to about f/15 or so depending on scope. Works well, biggest issue is getting the planet on the chip in the first place.

I have the really simple single piece adapter from Celestron and a more complex multi-part DX adapter from Vixen. With the vixen one you can insert filters easily. Saved me buying a x5 powermate.

HTH

Mike

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Glad you got those rings sorted! Will be interesting to see what kind of images you get with that tasty looking scope at a longer fl. :shocked:

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