| calibos |
| (Pooh-Bah) |
| 07/02/09 09:25 AM |
Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Hi guys,
Been a long time since I posted in this forum. However I never gave up on the idea of sometime getting myself a Mallincam Hyper Color Plus. Although I am still a ways off from ordering an MHCP, something brought the idea to the fore again.
That something is this:
I bought myself a 16" F4.5 Meade Lightbridge.
I embarked on a massive series of mods. Powered, motorised and Dewstrip protected devices everywhere. Put it this way, I have certain devices sharing outputs on a base mounted Dewbuster (Dewcontroller and 12v/3v source) that already has all its 15 outputs in use. This scope is now loaded with gear. All those cables would have made for a spagetti mess and a setup and breakdown nightmare. Thus I ambarked on a very complicated wiring install which while taking forever to do, will once completed mean I have just one heatshrink wrapped cable bundle running to the UTA. I simply connect the RCA jacks to a base mounted RCA connector plate and the same mounted on the UTA.
What does that have to do with the MCHP? Well, I was thinking before I complete the cable bundle and fit the RCA connector plates to the base and the UTA, if there was anything else I was forgetting. Then I thought of a future MCHP purchase. Thats what got me thinking about the MCHP again. That led me to investigate what was new in the Mallincam world and I got very enthused about the whole Mallincam idea again!
I am very excited about the new Cable and laptop software Menu control. So right off the bat I'd be thinking that I would want to include an extra 12v power run up to the UTA for a future PAL mallincam as well as a control cable run within my cable bundle. And sure why not include a Composite and S-Video run while I am at it. Control cable and Video cables would link up to my laptop and assosciated devices on its dob base mounted laptop table arm.
However, I then realised that I might be losing the run of myself. Maybe my new scope is not the ideal platform for the MCHP. I know a dob isn't the ideal platform regardless, a GEM mounted large apeture Hyperstar equipped SCT holds that honour, but maybe even as dobs go my LB16 is not ideal. So I thought I better run a few things by you guys.
In terms of tracking, I have the following:
A 28" Brian Reed RTP. Luckily I specced the large size even though I only had a 12" Dob at the time. ie. Its large enough to accomodate my 16" Lightbridge. I also fitted a JMI Track&Train system to my Lightbridge. Why both?? Well I figured for home visual observing or Visual outreach, I would just use the ALT/AZ 10 minute (before readjustment) simple tracking of the TNT and save myself having to transport or setup the RTP. For planetary imaging I would use my RTP for the main tracking and could use the ALT/AZ controlls of the TNT to smoothly adjust the scope without backlash. This could apply to the Mallincam too. The RTP provides the non Field rotating tracking with the TNT enabling fine pointing adjustments of the scope. My only problem was polar alignment of the platform. It didn't matter too much for visual observing. How long does it take to drift align?
In terms of target aquisition, I fitted a modified Orion Intelliscope DSC system designed for their SVP GEM mounts for use on my Lightbridge Dob.
So the question is. Is anyone using a DSC equipped dob on an equatorial platform with their mallincams with 56sec integrations or did everyone decide it was too much hassle and switch over to a Hyperstar GEM SCT like Neil Horne(SmokinOakim)??
If its workable I have in mind my Outreach dream machine. After polar aligning the platform, the rest of the setup would be very quick because there wouldn't be a mess of cables. For the Moon and maybe M42, I could connect the Mallincam to my Stellarvue F80M 80mm F4 finderscope, (With 45ºdiagonal removed with MCHP in the Straight thru 2" Helical focuser) For everthing else the MCHP would be in the Low profile Moonlite Motorised focuser(also have a Moonlite filterslide). I would view on the base mounted laptop and for outreach the laptop would be connected to a tiny Pico video projector displaying on a Pull up screen.
So is an F4.5 16" Lightbridge with Intelliscope DSC on a RTP a workable platform for the mallincam?
| Bowmoreman |
| (Post Laureate) |
| 07/02/09 11:41 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Keith, based on my direct experience with my XT10i on an RTP platform, it is totally doable...
You don't have to drift align the platform... I posted a while back on how I did my polars (and how I modded my RTP to make it dead easy)...
If you do that mod, all you then have to do is just ensure that your finder cross hairs are on Polaris, and you are close enough to do 56 seconds (in my experience).
Others use very large dobs (using ServoCat) with much success...
So, I'd say, "go for it"...
Clear enough skies
| calibos |
| (Pooh-Bah) |
| 07/02/09 01:23 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Hi Dave,
I don't suppose you could post a link to that post about your polars and the RTP mod you did. I just spent 20 minutes searching and couldn't find it. Does the scope have to be on the platform while making the adjustments?
Just realised that I probably shouldn't combine the Mallincam cables with my Dewstrip/12v cable bundle. Theres really no need. It would still be a very quick setup with just 2 cable bundles going to the UTA. The cable bundle already planned and then a Mallincam assosciated cable bundle. No point in having all those mallincam cables hanging loose as part of the main cable bundle when not using the mallincam.
Anyway, it means I can proceed with my current mods as planned without waiting for Mallincam cables or indeed the mallincam.
BTW. How long is the waiting list for the Mallincam these days.
| Bowmoreman |
| (Post Laureate) |
| 07/02/09 04:41 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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I tried to find it... and failed
Heres the basic idea... (going from MEMORY here, haven't done Dob Visual or MCHP in months - weather has sucked, and I've been concentrating on AP on my GEM. So you might have to "think" through some of what follows!):
1) Mark a N/S Axis line on both the ground board of the RTP, and on the top plate - critical that this go through the exact center of both circles! Take your time here.
Now do the same thing for your dobsonian base plate; mark a radial line from the center of the azimuth rotational axis point out to the exact North edge.
precision is key on these measurements and lines!
2) put a metal bracket hanging over the edge, centered on those lines for both the OTA ground board, and the RTP brackets, such that if you use a screw or bolt down through the top one, it aligns through each down to the bottom one
then when you setup the RTP first (alone), make sure they are both aligned with each other and roughly aim the RTP to Polaris.
3) Put your OTA on the rig, and move the ENTIRE thing, keeping the top aligned to the bottom so that it points roughly at Polaris, close is ok for now
4) Then raise/lower your ota altitude only using Alt on the dob mount, and you can go Azimuth using the ground board of the OTA (which does mean that it no longer aligns to the RTP N/S lines... Do this to get polaris centered.
5) Mentally see how far off you are - in Azimuth only - and "scoot" the bottom RTP platform rotationally approximately that amount.
6) Then align all three, and see if you can center polaris, using ONLY Altitude on the Dob...
Repeat at step 5 until done.
I find it only takes about 5 minutes, 10 max, to get a Polar alignment good enough for Mallincamming.
I'll try to take some pictures sometime to make it more obvious.
But, the good news is the parts cost is about $5 or less, a few stainless steel "L" brackets and some bolts/screws...
HTH
Clear enough skies
| calibos |
| (Pooh-Bah) |
| 07/02/09 05:47 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Thanks a million for the explanation Dave!
| Jack Huerkamp |
| (Vendor - Waning Moon) |
| 07/03/09 09:59 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Keith,
I use my MallinCams on several scopes, one of which is a truss tube AstroSystems TeleKit. I run two wires up the poles - a 12 VDC power cable and an S-video cable. I use Velcro straps to secure them to one of the trus poles. The 12 VDC goes to a splitter at the upper cage where it provides power to the DewGuard on the secondary mirror, the MallinCam and the Watec 3.5" monitor. I use a short 1' BNC to BNC cable to provide the video to the Watec. I use the s-video from the camera to go to a Speco VM-905C monitor that sits on a table away from the scope.
Regarding the current wait time for a PAL camera, contact me at my e-mail address below.
jackhuerkamp at gmail dot com
Jack
| calibos |
| (Pooh-Bah) |
| 07/03/09 10:48 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Thanks for that information Jack.
| calibos |
| (Pooh-Bah) |
| 07/03/09 05:41 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Dave,
If I am reading your post correctly, your alignments with your finderscope were enough for 56sec integrations on the Mallincam. If I understand correctly this would be no more accurate than Tom O's RDF platform polar alignment stalk....but its enough for the Mallincam?
Its just I put the scope on the platform today and there is no way in hell I'd be able to adjust the platform with the bulk of the 16" Lightbridge on it. But if your finder method is accurate enough for Mallincam and Tom O's stalk is just as accurate, then I could purchase a Tom O RDF stalk to align my platform before I place the scope down on it. (I know I would have to drill out a hole in the top of my RTP to attach a stalk to the south bearing as its not exposed on the RTP like it is on a Tom O platform)
This would be fine for Dark Sky trips or outreach where I could see Polaris but I had a Homer Simpson moment when I remembered that the last time I used the platform was at my old house with a view of Polaris. My new house is blocking the view!!
So for Home observing sessions I couldn't even use this method of aligning the platform.
However all might not be lost. Did you ever re-adjust or mark your compass face. ie. when you did your polar alignment and new you had great mallincam tracking, did you ever readjust the dial on the compass to get N aligned to the compass needle or did you ever mark the compass face in line with the needle, such that in future aligning the needle to these marks would give you an approximation of your finder on scope on platform alignment technique results which gave you good mallincam tracking.
If thats all thats needed then I would be good to go regardless of my house blocking polaris. I'd just need to to a good alignment once even if it broke my back and save on the cost of a Tom O stalk too
| Bowmoreman |
| (Post Laureate) |
| 07/03/09 11:47 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Hi Keith...
I never marked (re-marked) the compass since I have easy-peasy view of Polaris...
What I did do, to make things highly repeatable, was place flat patio bricks in the yard, with marks for where the feet should go so as to ensure repeatability...
I'm not at all certain how (if?) my method would work without a direct view of Polaris.... have to think about that...
Sometimes, I am brought to my knees with awe and wonder that we've been provided with such a gift as Polaris - so very close to the CNP - in OUR lifetimes... truly a gift.
I'm not familiar with Tom O's "stalk"... what is that all about (he says BEFORE he does any Internet research!)...
clear enough skies
| calibos |
| (Pooh-Bah) |
| 07/04/09 07:27 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Heres the link Dave.
http://www.equatorialplatforms.com/eq_platform.alignment.tool.shtml
Its something I could use in the field alright but I wouldn't be able to use your method or the Tom O method from home because I forgot all about the new house blocking my view of Polaris.
I am just wondering about whether readjusting the dial on the compass to coincide with a known good polar alignment would be accurate enough for Mallincam. Which would mean I would only have to do a good alignment once using either your method or a drift align. Hence forth I could then just use the compass in the field or at home.
Did your paving slab marking trick work good enough that you didn't have to use your finderscope method again. ie. After marking the slabs, all you ever had to do from then on was to set the platform down exactly on the marks and you were good to go with the mallincam without any further polar alignment??
Basically I am trying to figure out what I can get away with.
ie.
1. Good alignment once (whether it breaks my back or not
) and then rely on the re-adjusted compass at home or in the fieldor
2. Good alignment once and mark paving slabs at home and purchase Tom O RDF stalk for use in the field
or
3. Drift align everytime everywhere
Option one is most preferable as it involves me wrestling with the massive weight of the LB16 on the platform only once and involves no extra cost.
Option two is OK too as it only involves the cost of a few paving slabs and a $90(50 euro) RDF stalk.
Option 3 is a non starter and could put an end to my Mallincam dreams if it was the only way to get reliable enough tracking for the mallincam. The hassle of a drift align and trying to move the platform with the weight of that scope on it every single time I wanted to mallincam with the scope would kill me in no time at all.
Is Brian Reed himself still Mallincaming? I might drop him an email in a few days to get his opinion too. He's incommunicado at the moment going on other posts on CN. Must be on vacation:D
BTW.
Happy July 4th USAians!!
| calibos |
| (Pooh-Bah) |
| 07/04/09 08:03 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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BTW Dave. What F ratio would my F4.5 LB16 run at with the MFR3 and 15mm spacer?
| Jack Huerkamp |
| (Vendor - Waning Moon) |
| 07/04/09 11:22 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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About f/2.8 - if you have enough in travel on your focuser to achieve focus.
Jack
| calibos |
| (Pooh-Bah) |
| 07/07/09 08:05 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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If the other alignment ideas turn out not to be feasible. ie. if a Tom O stalk is not accurate enough which now that I think of it is a possibility. A Zero mag RDF based alignment can't be as accurate as an alignment with a 9x finderscope. Not for mallincam anyway. Or if compass re-adjustment after a drift align is not accurate/repeatable enough, well......
I have an idea that just might work with a drift align without me having to manhandle the huge weight with the 16" Lightbridge on top. Its not so much the act of drift aligning every session that scares me, its that its next to impossible to finely adjust the rotation or level of the platform with the weight of the 16" Lightbridge on top.
I have two spare motors from my JMI TNT warranty replacement. I could make a flat plywood base with something akin to a Lazy Susan for the platform to sit on.
ie. Flat piece of 3/4" ply with 3 spike feet to dig into the ground. A lazy susan riding on roller bearings on top of that. One motor with a drive wheel to rotate and another motor attached to the RTP groundboard driving a screw to raise and lower the RTP.
ie. Place adjustable lazy susan on ground. Stand on it to drive spikes into ground. Place RTP on top. Do a rough spirit level and compass align of the RTP. Place scope on RTP. Do a drift align. But instead of having to lift the gargantuan weight of the scope to adjust RTP feet or to twist the platform left or right, I just press the motor control buttons to very finely adjust the rotation and level of the platform.
| calibos |
| (Pooh-Bah) |
| 07/12/09 10:45 AM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Like I said above, I am pretty sure I can work something out in terms of aligning the platform with the weight of the scope on top whether that be doing something like I described above or going the manual route and just using a piece of wood under the Platform to make it easier to rotate and maybe using a mini jack to lift the platform/scope in altitude after which I'd lower the platform feet and utilising Daves nethod.
Something else I thought of however. I never was able to get very accurate co-ordinates from my Intelliscope DSC when used in conjunction with the platform. It would be close but thats not good enough with the limited FOV of the Mallincam.
I wonder has anyone else purchased a cheap goto like a NexStar 114 SLT (289 euros)and mounted a GLP to it. If the goto in this scope was accurate enough and if zeroing in the big dob on the GLP was accurate enough then maybe this would be a decent alternative to an innaccurate Platform/DSC method. This would also mean I could hook the Laptop up to the Nexstar handset and initiate Goto's from Planetarium software.
Of course this could all turn out to be moot. As previously mentioned I also have a JMI TNT alt/az manual drive system fitted to the Lightbridge. The Intelliscope works flawlessly with this. The thing about the TNT is it is not computer controlled. One turns dials on the controllers to adjust tracking speed in Alt and Az independently until one has cancelled drift. Obviously this is a straight line vector one has manually set which lasts about 10 minutes before the object drifts out of the FOV as the target makes its curved trajectory across the sky. Obviously Field rotation would come back into play without the platform but the Other ALT/AZ dob guys seem to do well enough without platforms. Obviously it all depends on the manual tracking speed accuracy.
However, maybe the tracking is good enough for a 28 or 56 second integration?? If this turned out to be the case then this would be brilliant. No need to lug around the platform. DSC will work flawlessly. No need to polar align etc. I have a feeling though that no other Mallincam owner has tried their cam on a JMI TNT equipped scope. Looks like I would be the Guinea Pig!
| ZRX-Steve |
| (super member) |
| 07/12/09 12:08 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Keith:
I had an email conversation with JMI regarding using a TNT and Mallincam and they thought it would be doable. I also saw some posts from dob users with Servocat that said it worked well though they would start seeing rotational errors at 56 second integrations.
/s
| calibos |
| (Pooh-Bah) |
| 07/12/09 05:05 PM |
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Re: Mallincam+16" F4.5 Lightbridge Dob+BrianReed RTP ?
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Cool, thats reasonably good news Steve. Of course when I think about it, I'll be able to get a better idea whether its truely possible before I even get a Mallincam by testing the tracking with a webcam. Anyone know the effective focal length of a Philips SPC900 and the Mallincam?? If they are similar then I could practice tracking with the webcam with K3CCDTools on screen crosshairs and get some idea whether its a non starter or whether its worth further investigation.
Actually is there some freeware software I could use with the webcam to measure drift. Then I could come back to you guys with some numbers and you might be able to tell me whether those figures are good enough for Mallincam use??
Like I said, this would be the ideal scenario.
For private casual Visual observing - TNT tracking
For F15+ Planetary Imaging with a webcam or future Imagesource cam - Platform Tracking with rough compass and spirit level alignment with TNT used for vibration/backlash/overshoot free Drift correction.
For Visual Public Outreach - Platform tracking with rough compass and spirit level alignment. DSC inaccuracy with platform doesn't matter because Public Outreach is generally Moon, Planets or Bright easy to find DSO's and where I need to slew back and forth from object to object quite often. TNT use in this scenario would mean a lot of manual speed corrections. Platform is more preferable here because visual use only requires a rough alignment and then the tracking is constant without need for adjustment no matter where I slew the scope.
For Private or Outreach Mallincam use - The ideal would be TNT tracking only. Like I said, Intelliscope DSC works flawlessly in combo with TNT and less to setup or pack too.