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3&1/2 years on + Adjustable f/l for ASI120MM.....

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#1 Kokatha man

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Posted 08 January 2013 - 07:25 AM

Seeing folks' composite images this time of year has encouraged me to create a photo montage of my personal selection of images I have captured in the 3.5 years I've now been involved in this pursuit... :)

Although I started with a Toucam 840k and 6" achromat a couple of months earlier, it was in August 2009 that I began planetary imaging in earnest by purchasing a secondhand C11 and a DBKAU21 osc.....the rest, as they say, is history.

Addictive, engrossing, rewarding and challenging with a huge dose of the gambling element as far as seeing is concerned are aspects of this "occupation" - which for me also allows a lot of scope (pardon the pun! :grin:) for my inventiveness apropos fabricating specialised fittings to make everything easier and/or more efficient.

A couple of highlights during this time have been being asked to use one of my Saturnian images in the "nature International Journal of Science" paper on Saturn's Giant Storm (I had become slack about forwarding images to Jupos etc at that time) and my recent involvment in bringing the ASI120MM cmos camera online.....this latter particularly satisfying as I believe it to be the next advance in planetary imaging cameras, and also for the camaraderie I developed with the camera's maker Sam. :)

Anyway, here are the highlight images for me - a couple were easy picks but there were a few competing images in my collection also - not least being the recent Jovian image captured at 33 degrees near home recently...Uranus detail is one target I will work on in the future, as well as Venus & Mercury both of which have never been favourably placed when I have found the time to attempt any "real" imaging of either... :(

Also, in the following post, the "Mk1" version of an adjustable extension tube to alter the image scale of these small-pixelled cmos cameras from anywhere just below 5000mm to around 8000mm, creating scale variations up to the equivalent of around 12000mm using my old PGR Flea3 - this with basically "off the shelf" fittings. :)

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#2 Kokatha man

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Posted 08 January 2013 - 07:26 AM

This is the “Mk1” version of my variable extension fitting to “tame” the C14’s rather large native focal length (one reason they’re such great planetary imagers!) and also “tailor” said for the small pixel size of the ASI120MM cmos sensor.

I have used an 80mm extension tube manufactured by GSO in Taiwan, cutting it down to remove the 2” O.D section and fitting another brass compression band just inside the truncated end.

Into this end is fitted a standard 2” to 1&1/4” reducer (brass compression band type) in reverse positioning…..this required me also drilling an oversize hole into the shortened 80mm E.T. so that the 1&1/4” compression band can be actuated externally, the reducer being held in place by the (new) 2” compression band fitted to the truncated end of the 80mm E.T.

The 2” & 1&1/4” compression bands at this end are counter-opposed to each other to provide a measure of self-centring, and the ASI120MM camera (minus the plug that screws into the camera body) fits into the other end and is clamped by the 80mm E.T.’s original 2” compression band…it should be noted that the camera has its’ “plug” & “nosepiece” removed in this setup!

The EFW has 2 ET’s (1&1/4” variety) fitted onto its’ rear, with a TeleVue 2X lens element screwed into the back one of this composite ET.

This is the “Mk1” because I used a pre-made compression band clamp which is fitted to the EFW outlet…..”Mk2” will have a fitting so that the front of this composite ET is screwed to the EFW to create utter rigidity…weight isn’t overmuch even with the Mk1 and everything is rigid without “sag” – but Mk2 will be even more rock-solid, and if I was making it all from scratch I’d have lathed a unit with the 2” camera end the only aspect of this fitting that diameter, thus further reducing its’ weight.

By loosening the 1&1/4” compression band at the focuser end of this device the whole assembly (including camera) can slide along the composite internal ET which has the TeleVue lens element attached…..this literally brings the rear of the T/Vue lens almost right up against the camera sensor (it can’t strike it because of the stepped design of the camera herein) to provide around 1.2X…..or allow for a tad more than 40mm spacing from lens element to sensor – almost exactly what the T/Vue’s (discarded) body length is, to create the standard 2X amplification..!

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#3 Mert



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Posted 08 January 2013 - 07:51 AM

Beautiful selection of your 2012 best's and also a very
ingenious solution for the extension!!
Well done Darryl.

#4 Timthelder


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Posted 08 January 2013 - 09:56 AM

A veritable planetary smorgasbord there Daryl, well captured, processed and diplayed.


#5 Tassydevil


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Posted 08 January 2013 - 03:42 PM

Very nice, Seeing stuff like this makes me want to get back outside at night,thanks for sharing these great images.


#6 wenjha



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Posted 08 January 2013 - 10:46 PM

nice work!Darryl
seems you really take some time to work out the suitable balow scale!

#7 Kokatha man

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Posted 09 January 2013 - 03:55 AM

Thanks Mert, Tim, Graeme & Sam! :)

Sam, you know me - no "half-measures!" :grin:

A variable image scale fitting is important to match seeing, resolution & framerate and gain settings anytime, but with the ASI120MM and the C14 it is even more beneficial imo, especially with different planets taken into account also!

With my special "fixed amplification" fitting I believe I optimised Jupiter for this apparition but Saturn is another "kettle of fish" - as Mars will be also late this year and next year...so the ability to adjust image scale not only takes care of seeing in general but also "tailors" the gain etc settings to requirements so that when I select a resolution and framerate I can manipulate gain requirements also. :grin:

Today I organised a T-coupler so that I can screw the inner unit of my device to the back of the EFW for complete rigidity.

Mert, I'm slow at times but occassionally I have the odd "brainwave" - realising that by sliding the outer unit back and forth along the inner gave me everything I wanted in the simplest and most efficient way suddenly dawned on me...and I did think it was a tad ingenious - even if somewhat obvious in hindsight..! :question: :lol:

#8 ToxMan



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Posted 09 January 2013 - 09:02 AM

Clever solution, Darryl.

The 1 or 2 commercial products I have seen looked too flimsy to maintain collimation. But, yours looks like a winner. I use the threaded tubes and stack for various lengths only because it was more rigid. What a pain...I like the simplicity.

So, when are you going into full scale production? :smash:

#9 tjensen



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Posted 09 January 2013 - 01:02 PM

Very nice collection of images Darryl. Well done! :bow:

#10 DesertRat


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Posted 09 January 2013 - 04:04 PM

Nice work Darryl!

A PGR Flea3 working at your equivalent 12000mm would make Jupiter bigger than the chip. You have more pixels!


#11 Kokatha man

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Posted 09 January 2013 - 06:43 PM

Thanks fellas - Paul, if I really were contemplating small-scale manufacturing of these units I would make the "Mk3" version with a short length of stock just under 2.5" O.D. for the 2" compression clamp and camera end.....this would be married (interference fit) to some 1.5" O.D. stock bored out to 1.25" internally and this section would have the 2 compression clamps set opposite each other and at opposite ends of said 1.25" section.

Doing it this way creates even greater self-centring and "grab" as well as lightening the unit further - using 2 different sized pieces of ally stock cuts costs also! :)

But as the ASI120MM only weighs 100gms I don't believe I'll have any issues with my present incarnation, particularly when I screw the inner assembly onto the EFW later this week with my new fitting there!

I have numerous 5mm thread, large knurled head pinchscrews (from finderscope alignment screws, using nylon tips) which I've used previously on reducers - they are longer and the larger thread means you can exert greater pressure/tightening so I'll employ a couple of them in the above unit also after retapping the holes bigger - it helps in the dark to have nice large knurled heads you can really tighten compression clamps right up with! :grin:

#12 mrlovt


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Posted 10 January 2013 - 08:28 PM

Those are all great, especially the detail on Mars and Saturn. Thanks for sharing! Do you think you'll get detail on Uranus with the ASI120MM?

#13 BKBrown



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Posted 10 January 2013 - 10:02 PM

Great stuff Darryl! You have been rather busy...and cranking out some fine work amigo. This hobby is quite addictive, I know I enjoy imaging with all of my scopes and shooting for the best I can do with each. I must say, you have certainly done very well indeed with your kit sir :grin:

Clear Skies,
Brian :waytogo:

#14 Kokatha man

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Posted 11 January 2013 - 05:46 AM

Thank you Aaron and Brian - "old amigos" I think you & I are by now Brian.....on this forum and elsewhere I feel we've been moving along similar paths for a fair while now! :)

Aaron, if it's possible (and I believe it is from a couple of images posted this last year) then I will grab some detail on Uranus, however scant.....it's the swapping of information/experiences that is the most valuable aspect of these forums - I certainly wouldn't have thought of using the exposures that a couple of "Uranus Pioneers" here used, rather like limiting histograms for Venus & Mercury...

I thrive on challenges but often you need some pointers when trying something different - and I hope I put back in a little of what I've gleaned - so perhaps this year I might crack something with those targets... :question:

I'd also like to see just what is possible with tiny Mars after my imaging it down to 4" diameters late this last (2012) year.....getting any sort of detail earlier in the year could also be a real challenge!

I was hoping to post a pikky of the finished "Mk2.5" variable image scale adapter but you know what they say about the best laid plans of mice & men.....in my rush I overlooked a vital aspect needed for a "screwed together" setup - and I still need to make another piece..! :question: :( :lol:

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