174 replies to this topic

[bigbangbaby]

RodgerDodger008, have you thought about mounting your AZ-GTi on a wedge, adding a counterweight bar, and using it in equatorial mode?

[Far_Southern_Skies]

An unexpected use for a counter weight.

 

When I swapped out my old and trusty Vixen GPD for a Warp Astron WD17, I always knew I would run the risk of my refractor hitting a tripod leg, given the WD17 is a much lower profile mount. A quick daytime test showed that the clearance was just okay for the f4 imaging train, but the longer imaging train for a native f5.7 would hit the tripod legs near the zenith.

 

Up till now I have just been careful to set slewing limits to manage this when using the f5.7 imaging train. However, a lapse of concentration and a near miss the other night, has prompted me to do something more permanent about it. Measurements suggested I needed to raise my current tripod extension by about 50mm. The question was; what could I use as a temporary raiser to confirm the measurement? I was looking for a block of wood, or some other scrap in the workshop, that would do the trick.

 

Back at the mount I had a “light bulb moment”. I have a spare 5kg counter weight that is 55mm wide!

 

So, the counter weight and a spare piece of 3/8th inch threaded rod and spare nut have been put into service as a temporary raiser. Works perfectly and raises the mount sufficiently to ensure the f5.7 imaging train clears the tripod legs.

 

This could prove to be a long lived temporary solution! 

 

 

 

 

 

Edited by Far_Southern_Skies, 07 May 2025 - 06:59 PM.

[RodgerDodger008]

RodgerDodger008, have you thought about mounting your AZ-GTi on a wedge, adding a counterweight bar, and using it in equatorial mode?

It was a way I considered going but probably now inclined to buy a eq6 or eq5 mount at some point which I could use the ED72 and maybe a future 200mm reflector on.

The wedge idea is great but I am wondering if the lack of guide port on the gti and having the upgrade of the firmware switching the scope to the right side in alt az mode would bother me.

The other consideration I had was to get a star adventurer gti which seems to be a very capable eq scope.

Edited by RodgerDodger008, 07 May 2025 - 11:34 PM.

[bigbangbaby]

I decided to piggyback my 80 600 refractor atop my heavily modded 8” f4 Meade 826. Both rigs use a 294mm pro camera and ZWO eight place filter wheel loaded with narrowband and broadband filters. This complicates taking flat frames in Sharpcap because, to my knowledge, there is no way to uniquely name these devices.

 

That aside, the two scopes provide focal lengths of 450 mm and 812 mm. They share the 50 200 guide scope. Cable management was a bit of challenge, but I think it’s under control. I took flats and darks for both scopes. Just waiting for clear skies.

 

[RodgerDodger008]

Awesome setup, well done!

I recon you just save the flats for each with naming to identify then set up a unique profile for each scope with those flats and darks for each scope and camera saved for those profiles.

The bit I have often wondered about is how do you run two scopes off one mini pc with sharpcap. I know two instances of sharpcap is possible but can you connect the same mount and two different cameras.

Edited by RodgerDodger008, 18 May 2025 - 07:16 AM.

[bigbangbaby]

Thank you. Yeah, I take calibration frames for each scope and store them in separate folders. The issue is both cameras show up in the pull down. Unplugging the unused camera and filter wheel gets around it. I’m trying to figure out if you can assign a unique device name to each.

 

In any event, I haven’t any plans to simultaneously image with both scopes. Rather, it is a way to consolidate equipment and take advantage of the mount’s load capacity. I may try separately imaging the same target during a session to compare results.

 

Regarding running two instances of Sharpcap at once, I have had two open but haven’t tried it. I do know that NINA complains when I try to connect a camera that is already connected to Sharpcap. 
 

[Mark Lovik]

MAKING A SCOPE CART FOR EAA - PART 1: Context and Initial Work

 

Context and overview

 

I have a couple of astro projects in the works and had stalled on most of them this past year.    Some are general purpose … like updating my original observing chair to make it more ergonomic and useful, setting up StarSense push to for general purpose visual observing.

 

The biggest is getting a 10" Schmidt-Newt up and running for EAA.  It needs:

• Teardown and rebuild the OTA (cleanup, collimate, replace the focuser, replace scope hardware, maybe flock the tube interior, setup a mirror mask for the primary, have a rear light shield, …
• Get better experience using the Losmandy mount for EAA.
• Reconfigure a computer to run the Losmandy mount for EAA.  The workflow is different enough that I screw everything up when stitching between my Skywatcher and Losmandy systems.  So I have a new (unused as yet) NUC computer to dedicate to the Losmandy mount.
• Time to setup a coma corrector for the scope.  The Schmidt-Newt has enough coma (it's F4 and has coma like an F5 Newt) that it needs a coma corrector for my APS-c sized camera.  I plan to use my 150P's 0.85 coma corrector and fiddle with the spacing to get better behavior than the raw Scope optics.  The resulting focal reduction will also help optimize the system resolution and speed with my imx571 class camera.  I want this to be reasonably solid optically … and fast!

Getting this successfully working has been an unexpected pain.  My normal process of just setting up each night and tearing down when done does not work with this system.  The telescope itself needs some work but the current workflow is keeping me from getting anything done.

 

My normal EAA process

 

I have a SkyWatcher AZ-EQ5 mount that has been a good choice for me.  I now only use it in Eq mode for EAA, but it is quick to setup and light.  In the past I have kept all my scopes under a 13 pound weight limit.  This works with the tuned AZ-EQ5 and works under moderate wind conditions for all my scopes.  Every piece of my rig is lightweight … 15 pounds is near the weight limit for any of the parts.  So my normal EAA process is relatively fast … the setup is not physically strenuous … and my body still works the next day!

 

Supporting a 10" Schmidt Newt

 

The base scope is over 33 pounds, and I am using a Losmandy G811 mount and the heavyweight tripod.  This system (with counterweights) is over 130 pounds.  Most of the parts to assemble the scope for EAA every night are over double my previous weight limits … and my body does not like it.  So I need to change my habits … or give up on a larger OTA for EAA.

 

Design Goals of the Scope Cart

1. It needs to work with rough and angled ground (my front yard or a possible new remote observing site). 
  a. This means traditional scope cart wheels will not work.
  b. It also means this needs to be setup a bit beefier than normal (weight of the cart is not a problem)
  c. This also means I want a larger cart footprint (width and length) to avoid problems with tipping over
2. I want this to be quick to rollout and setup for a night of observing.
3. Can easily handle
4. Cheap (or relatively so)
5. Naturally handle vibrations yet be a solid base for EAA (wood here can be very good)

 

So the scope cart will use

• wheels:  6  10" wheels  (5/8" standard hubs) - large mounting washers are included with each wheel https://www.amazon.c...asin_title&th=1
• 4x4 lumber - T style frame   (I can make this really stable using hand-tool woodworking approaches in my shop)
• 5/8" steel rod … cut for the wheels https://www.amazon.c...asin_title&th=1
• 6  Standard 5/8 rod caps - https://www.amazon.c...asin_title&th=1
• 4  5/8" clamp on shaft collars https://www.amazon.c...asin_title&th=1
     mount standoffs
• 6" 1/2x13 screws (local supply) - fitted with wood heads to float the mount
• 1/2-13 acorn nuts (smooth end to float wheels before observing) - https://www.amazon.c...7B-38D87AA1C01F
• 1/2x13 nuts embedded in bottom of the scope cart (local supply)

INITIAL PROGRESS - rear wheel assembly

 

· Measured the current Losmandy tripod in its lowered state 
  a. rear legs 33" from outside to outside
  b. Rear legs - baseline to outsize of front leg - 29"

• Create an H-shape rear leg assembly - want room for mount standoff assemblies and extra width for stability
  a. Plane (not hand tools here) wood to consistent dimensions - the rest is hand tool work (for fun)
  b. 42" main beam length
  c. 2-24" wheel beams at the end
  d. 5/8" bored holes in beam midlines for wheels
  e. Cut joinery and glue the H-frame assembly together
  f. Cut 5/8 rod in 7.5" lengths for wheel mounts - each wheel here is separate.

 

Diagram of rear wheel assembly (full and wheel closeup) - it's about 48" wide and 32 pounds assembled

Incomplete steps (not yet shown)

• the screw assembly for standoffs will be added later at the intersection of each wheel beam with the main mount beam. 
• This is a good time to finish the wood to avoid moisture problems with the wood.

Next steps - (hopefully this week)

• Front tripod beam and steerable wheel assembly 
• Supports to securely mount the tripod legs on the cart
• Elevate the cart and scope off the wheels for observation

 

PS - Larry ... I love your rigs, and smooth ground for the scope carts!  This may not be as elegant (clearly not as compact), but should work for my use.

Edited by Mark Lovik, 18 May 2025 - 05:50 PM.

[bigbangbaby]

Hi Mark,

 

Sounds like a well considered plan. May I make a couple of suggestions.

 

The tires you chose look the same as on both my Scopebuggy (3 wheels) and JMI heavy-duty cart (6 wheels). I picked up the preowned JMI to carry my 12.5” f3.8 Newtonian and AP1200 because the Scopebuggy seemed overburdened. Check the load rating, but I don’t think tires are the limiting factor with the Scopebuggy, rather the frame itself. 
 

Reason I say this is, I much prefer navigating the Scopebuggy around than the JMI. The pairs of wheels on the JMI drag and skid when trying to make sharp turns. The steering wheels hit the frame and limit turn radius. In contrast, the Scopebuggy is easy to steer, which becomes important when trying to rough polar align. I plan to make a heavy-frame three-wheel cart for the 12.5” and sell the JMI.

 

Consider using acme-threaded rod for the leveling screws. And add knobs to make the adjustment tool-less. I would suggest using three 12x12 in. square (or thereabouts) pieces of 3/4” plywood that you place on the ground to distribute load from the leveling screws. No need for attached feet. I’ve been using the same plywood pieces for over two years. 
 

Good luck with your project.

Edited by bigbangbaby, 19 May 2025 - 09:53 AM.

[MarMax]

Mark, I've built two custom wheel rigs, bought and sold a ScopeBuggy and own two JMI's. Although the JMI's are not perfect nor inexpensive, they do a very nice job, especially the heavy-duty with the dual 10" wheels.

 

As Larry pointed out the maneuverability of the dual-wheel JMI is not ideal. Also, using lead screws versus bolts for leveling is much better. Bolts are intended to be fasteners and lead screws are designed for leveling (among other uses). McMaster-Carr is a good source for lead screws.

[MarMax]

I've not done much EAA lately and even with the Darwin, CA time the skies have been mostly cloudy. This has not slowed me down from purchasing kit. I've not been 100% satisfied with the AT72EDII guide scope setup on the C11, mainly because its 432mm FL is not quite enough.

 

I'm going to try the Celestron 80mm guide scope and see if I like it better. I've also picked up a Player One Uranus-M as the guide camera. This combination is 600mm, provides a 1.0° x 0.6° FOV and comes in at 1" resolution. I've never been satisfied with the PHD2 guiding since deforking the C11 and it's possible that some of the difficulty has been a slight guide scope mismatch.

 

It was clear at home last night and if it's clear tonight I may spark up the C11 kit and see if I can remember how to do EAA. I know it's asking a lot to start up a new guide scope and camera and expect everything to work, especially since I've not run the C11/G11G since early March.

 

 

[Mark Lovik]

Mike and Larry

 

Thanks for the comments.  I had some time to think about your comments and

 

1. Really like the idea of acme screws - it's been a bit since I last used them ... but they are a solid improvement in what I have been planning.   I have already planned on embedding a handle on each leveling screw ... it's a solid idea to use.

2. Having a larger surface area for elevating the mount off the wheels is a good idea.  My original plan was to just use something like a 4x4 planed down a bit to put under the screw would work.  Making a sandwich of this on top of a larger area of plywood sounds much better.  Here I really want to keep the exposed screw length to a minimum -- and still keep it easy to adjust.

3. Your comments on the front wheels is timely.  I have been kicking on a large number of ideas for the front-end steering section.  It looks like I have an idea solidified that should take the best of the ideas and make them work.  The main part is to keep the steering pivot as close as possible to the wheel center.  I have a clear idea on how to fit in a wood handle that will easily steer and pull the mount.

4. With the lengths of the main beams, the double rear wheels should not be a steering problem.  I have a stack of 5/8 fender washers to keep the wheels a bit from the wood on the frame.  The H-frame assembly seems to easily pivot under weight (but on flat ground).  I will be able to check this better in the future.

Edited by Mark Lovik, 19 May 2025 - 04:00 PM.

[Mark Lovik]

I've not done much EAA lately and even with the Darwin, CA time the skies have been mostly cloudy. This has not slowed me down from purchasing kit. I've not been 100% satisfied with the AT72EDII guide scope setup on the C11, mainly because its 432mm FL is not quite enough.

 

...

You may have another possibility for guiding ...

 

I was using an FMA180 as a guide scope for a bit (when I was extensively trying out guiding).  I had everything working but could not really improve image quality compared to my unguided EAA.

 

My original guiding trial came from accidentally (while helping others one night) setting up 1.25 second subs for my targets.  The resulting file sizes were horrendous ... but the FWHM was 25% better.  At the time I thought this was an image drift problem over my normal 10s subs.  At the end of 3-6 months of testing it appears that I was really taking advantage of lucky(ish) EAA imaging.  I really put in some serious work to finally get to this conclusion and fixated on guiding during this time period.  I swapped guided and unguided images each night, and unceasingly fiddled with guiding parameters to improve my guided images.  Nothing improved things past my (optimized) unguided EAA ... bummer.

 

At the time I was using an ASI178mm camera for guiding on the FMA180 (no reducer ... so a bit longer focal 220mm focal length).  The smaller pixel size (2.4um) kept guiding under seeing errors (<.8 and usually less than .5 on nights of typical seeing).  The 178 now seems out of production ...it worked well with my little FMA180 ... but there are other small pixel mono cameras out there.

 

Smaller scopes with rigid mounting tends to have less flexure.  Flexure and seeing were my two identified variables that dominated the quality of guided images.  You may want to consider a smaller pixel monochrome guide camera instead of a longer focal length guide scope.

Edited by Mark Lovik, 19 May 2025 - 04:25 PM.

[bigbangbaby]

Mike and Larry

 

Thanks for the comments.  I had some time to think about your comments and

 

1. Really like the idea of acme screws - it's been a bit since I last used them ... but they are a solid improvement in what I have been planning.   I have already planned on embedding a handle on each leveling screw ... it's a solid idea to use.

2. Having a larger surface area for elevating the mount off the wheels is a good idea.  My original plan was to just use something like a 4x4 planed down a bit to put under the screw would work.  Making a sandwich of this on top of a larger area of plywood sounds much better.  Here I really want to keep the exposed screw length to a minimum -- and still keep it easy to adjust.

3. Your comments on the front wheels is timely.  I have been kicking on a large number of ideas for the front-end steering section.  It looks like I have an idea solidified that should take the best of the ideas and make them work.  The main part is to keep the steering pivot as close as possible to the wheel center.  I have a clear idea on how to fit in a wood handle that will easily steer and pull the mount.

4. With the lengths of the main beams, the double rear wheels should not be a steering problem.  I have a stack of 5/8 fender washers to keep the wheels a bit from the wood on the frame.  The H-frame assembly seems to easily pivot under weight (but on flat ground).  I will be able to check this better in the future.

4. I believe you’ll still find it difficult to turn the cart as designed. Watch a dual-axle trailer make a tight turn. The tires scuff and scrape across the road. If load capacity of a single wheel is a concern, perhaps a dual setup where you put two wheels on a single axle per side. That will be the approach when I build my heavy duty cart, should I need greater capacity than three wheels can provide. 
 

I look forward to see what you come up with. I’m sure it will be great!

[MarMax]

You may have another possibility for guiding ...

 

I was using an FMA180 as a guide scope for a bit (when I was extensively trying out guiding).  I had everything working but could not really improve image quality compared to my unguided EAA.

 

My original guiding trial came from accidentally (while helping others one night) setting up 1.25 second subs for my targets.  The resulting file sizes were horrendous ... but the FWHM was 25% better.  At the time I thought this was an image drift problem over my normal 10s subs.  At the end of 3-6 months of testing it appears that I was really taking advantage of lucky(ish) EAA imaging.  I really put in some serious work to finally get to this conclusion and fixated on guiding during this time period.  I swapped guided and unguided images each night, and unceasingly fiddled with guiding parameters to improve my guided images.  Nothing improved things past my (optimized) unguided EAA ... bummer.

 

At the time I was using an ASI178mm camera for guiding on the FMA180 (no reducer ... so a bit longer focal 220mm focal length).  The smaller pixel size (2.4um) kept guiding under seeing errors (<.8 and usually less than .5 on nights of typical seeing).  The 178 now seems out of production ...it worked well with my little FMA180 ... but there are other small pixel mono cameras out there.

 

Smaller scopes with rigid mounting tends to have less flexure.  Flexure and seeing were my two identified variables that dominated the quality of guided images.  You may want to consider a smaller pixel monochrome guide camera instead of a longer focal length guide scope.

Mark, thanks for the feedback. I've tried several guidescope configurations with the C11 and since none have made me happy I must assume the problem is my lack of understanding of PHD2. There have been nights where guiding was decent (sub 1.0) but that has never been consistent.

 

I've tried the following:

 

Stellarvue 50mm (210mm FL) w/ 290MM

EvoGuide 50ED (242mm FL) w/ 462MM

Svbony 60mm (240mm FL) w/ 462MM

AT72EDII (432mm FL) w/ 462MM and 178MM

Celestron 80mm (600mm FL) w/ 585MM

 

My efforts last night with the Celestron 80mm and 585MM combo were dismal. The guidescope is crap compared to the AT72EDII and it adds weight. I'm going to switch back to the AT72 for now. I also tried no guiding (dithering only) with 8 second exposures and that was actually quite enjoyable. I've never liked PHD2, never understood it, and it's never really worked well for me on the C11/G11G kit.

 

Except for PHD2 the kit worked well last night. It was late February the last time I ran it. I've got some dust in the image train that needs to be removed but otherwise it did well. I'm also not that happy with the 533MM. Even with it's quirkiness regarding calibration frames the 294MM is much better IMO.

[bigbangbaby]

Mark, thanks for the feedback. I've tried several guidescope configurations with the C11 and since none have made me happy I must assume the problem is my lack of understanding of PHD2. There have been nights where guiding was decent (sub 1.0) but that has never been consistent.

 

I've tried the following:

 

Stellarvue 50mm (210mm FL) w/ 290MM

EvoGuide 50ED (242mm FL) w/ 462MM

Svbony 60mm (240mm FL) w/ 462MM

AT72EDII (432mm FL) w/ 462MM and 178MM

Celestron 80mm (600mm FL) w/ 585MM

 

My efforts last night with the Celestron 80mm and 585MM combo were dismal. The guidescope is crap compared to the AT72EDII and it adds weight. I'm going to switch back to the AT72 for now. I also tried no guiding (dithering only) with 8 second exposures and that was actually quite enjoyable. I've never liked PHD2, never understood it, and it's never really worked well for me on the C11/G11G kit.

 

Except for PHD2 the kit worked well last night. It was late February the last time I ran it. I've got some dust in the image train that needs to be removed but otherwise it did well. I'm also not that happy with the 533MM. Even with its quirkiness regarding calibration frames the 294MM is much better IMO.

Mike, I claim no expertise with PHD2, but I have gotten it to work pretty well with a few different scopes, mounts and guide scopes/cameras. I routinely see 0.5 arc-sec with the AM5 plus 8” f4 Newtonian and Orion 50 mm guide scope and ASI224. Slightly better with the 80 600 refractor and 50 200 guide scope with ASI120 camera. The AP900 plus 12.5” f3.8 Newtonian with an Orion ST 80 and 224 camera for guiding hits 0.2-0.3 arc-sec.

 

Disregard if you’ve tried all of this. 
 

1) Use PHD2 to make a new dark frame for the guide camera. Hot pixels can and do wreak havoc with guiding.

2) Calibrate near the meridian as the program prompts.

3) Run the automatic calibration optimization routine and accept the suggested parameters. 
4) Double check focus on your guide scope.

5) Work for the best possible polar alignment you can get. I use Sharpcap and always achieve an “Excellent” PA. Be sure all adjusters are clamped or locked down.

6) Always use stabilizer screws when using scope carts. 
7) Double check all tube rings and dovetail plates and clamps are fully secured.

8) I haven’t had to do this with my mounts, but you may need to check and adjust drive backlash.

9) Proper scope balance. 
10) Select multiple star option in PHD2.

Edited by bigbangbaby, 20 May 2025 - 07:55 PM.

[MarMax]

All good stuff Larry. I've been consistent with doing all each session except #3 which I'll try if things are not working.

 

Yesterday I swapped the AT7EDII back as the C11 guidescope and was able to run it for about 2 hours early this morning. PHD2 seemed to be behaving and the mount guided as I would expect for a G11G. Here is a couple screen grabs of the PHD2 info:

 

 

 

It seems like anything equal to or less than 0.8 with this mount is good. I ran the Calibration in the proper place and it completed with a warning message that I did not save nor understand. I just accepted the new parameters. When I run the Guiding Assistant it also completes with a warning message and I save the parameters. The warnings are related to parameters that PHD2 thinks are out of the normal range. It's all Estonian to me.

[Mark Lovik]

MAKING A SCOPE CART FOR EAA - PART 2: Little Stuff Before Final Assembly

 

It's been a bunch of work (but I am having fun doing this).

 

Here is the monstrosity (10" Schmidt-Newt) and mount that is just to big and heavy for me to assemble each night.  I needed to purchase a 7lbs counterweight to really get things balanced.  Total weight is somewhere in the 130+ pound range.  Fixing this scope up is the next step ... after the mount is complete.

 

A big part of the mount is a 4x4 milled wood structural frame.  This will be 50-65 pounds when done, and I wanted to work quietly in the basement to create the mount.  A big part of getting everything right - and doing everything in a decent time period is using appropriate jigs.  The following is one of my favorites - and it's used for specialized joinery (lap and saddle joints are examples)

 

The mount (except for the handle) is now complete, finished, and ready for assembly (tomorrow?).  One of the steps in this process was fitting the tripod to the mount to confirm and setup fittings.  Just carrying the tripod downstairs, setting things up, then promptly putting the tripod away reminded me why I am making this mount in the first place.  I was done for the day after this picture (what a wimp!!!)

 

Tomorrow - hopefully is the day the scope mount is completed (with pictures of course)

 

Guys -- the acme screw ideas and general comments made this whole process much easier.  So far everything is looking better than I expected when I started this project.  Thanks for your help.

Edited by Mark Lovik, 28 May 2025 - 02:24 AM.

[bigbangbaby]

Nice craftsmanship, Mark. Looks great!

[Mark Lovik]

MAKING A SCOPE CART FOR EAA - PART 3: The final indoor steps

 

Nearly done ... just need the weather to clear to show the assembled mount in the yard.  I may fiddle in the future, but the basics are ready to go.

This is a big assembly (4' by over 6') but should be stable for yard tests.

 

4x4 wood front steering assembly (it's not light but steering is clean under load with this assembly)

This also shows the mount lift in the front.  The lift screws will never extend much past the bottom of the base (1/2 to 1") - but rests in planed (and a drilled recess for the lift screws) 4x4 ground standoffs.  The back plywood plate is for Jackery 1000 and electronics.

 

View with the tripod on the mount.  This was assembled for the final tripod leg attachments.

Notice my original 8" Pyrex telescope mirror from high school (top left). I still have a few parts from my original scope.

Also notice my hand tool workshop area is small ... still works.

Edited by Mark Lovik, 30 May 2025 - 12:28 AM.

[Mark Lovik]

MAKING A SCOPE CART FOR EAA - PART 4: It Works

 

 

Finally assembled everything outside (for garage storage tonight).  My back is reminding me why I did this in the first place.

 

Now I can iterate (without setup and teardown) on the scope and electronics.  The cart is very solid and works well.  I currently do not see any flex or vibration problems.  Access to the scope for adjustments (polar alignment, focusing, and general fiddling) is very good.

 

I may be able to move this to a new dark sky site near home.  This may be the best part of an integrated rig on a cart.

 

Latest work

• Setup new Ryzen 7 astro computer (had this for a bit) using the common setup process
  • Use a usb mouse, keyboard, and my astro usb second monitor for startup and initial configuration (access web here)
  • Enable and setup remote desktop (rdp)
  • Load astro software (SharpCap and object files, ASCOM, zwo drivers, Losmandy drivers, Astro Planner software)
  • Make sure the system boots up for RDP (login or not)
• Now I can fiddle with the 10" Schmidt-Newt.
  • Looking at things .. my coma corrector does not go into the stock focuser enough to reach focus.   Horrible focuser in the first place.
  • Have the updated focuser ... it's next on the list.  Mechanical (screws and things) need some TLC at the same time.
  • I made a rear light shield out of cosplay foam for my Quattro 150P.  This worked out very well ... so I will do the same for the 10" SN.
  • For the short term I am going to cobble up a dew shield.  Not going commercial for this ... and want it a bit longer than usual for passive dew control.
  • Figure I will need to adjust back focus on the coma corrector.  I initially tried the scope without a coma corrector last year ... this was not acceptable.​

 

Let the EAA fun part of this begin!








 

Edited by Mark Lovik, 10 June 2025 - 09:12 PM.

[Far_Southern_Skies]

Looks good, Mark. Do you have the tripod secured to the cart? I have the tripods secured on both of my wheeled dollies just to eliminate any chance of a fall.

Edited by Far_Southern_Skies, 11 June 2025 - 01:21 AM.

[bigbangbaby]

Mark, cart looks good! Glad it works well for you.

 

You mentioned replacing the focuser in your SN-10. I concur. The stock one is basically useless, even for visual. I have a project SN-10 and made a special tool to remove the secondary. The rubber gaskets were deteriorated, letting the secondary housing rotate. I replaced them with cork. You’re probably aware that the focuser is factory offset from the corrector plate. You must retain that offset when replacing the focuser or the scope will not focus properly. A company used to offer a kit with a sliding base to properly position the focuser, but they no longer make it. It may have been JMI, but not sure. I also read that maintaining corrector and primary clocking is essential, though that doesn’t make sense to me because both elements are axisymmetric. 

[Mark Lovik]

Looks good, Mark. Do you have the tripod secured to the cart? I have the tripods secured on both of my wheeled dollies just to eliminate any chance of a fall.

Picture does not show the tiedowns implemented but I am using ratcheting tie downs (wrapped a few times) around each tripod leg.  The scope is mostly stable with the scope and mount -- mostly does not count.  I am also using this on some rougher ground and some jumps going to the garage.  That is the reason for the larger wheels and the bottom-heavy cart design.  Having a wider wheelbase than common solutions is also deliberate.   Securing the legs to the cart is the last critical component to avoid a tipping and falling scope.

 

Thanks for this reminder ....

This is a very good recommendation everyone should remember.  It's a cheap solution to what could be a costly and dangerous mistake.

Edited by Mark Lovik, 12 June 2025 - 01:12 AM.

[Mark Lovik]

Mark, cart looks good! Glad it works well for you.

 

You mentioned replacing the focuser in your SN-10. I concur. The stock one is basically useless, even for visual. I have a project SN-10 and made a special tool to remove the secondary. The rubber gaskets were deteriorated, letting the secondary housing rotate. I replaced them with cork. You’re probably aware that the focuser is factory offset from the corrector plate. You must retain that offset when replacing the focuser or the scope will not focus properly. A company used to offer a kit with a sliding base to properly position the focuser, but they no longer make it. It may have been JMI, but not sure. I also read that maintaining corrector and primary clocking is essential, though that doesn’t make sense to me because both elements are axisymmetric. 

Thanks for these comments ... this is my current focus for the scope.  It needs some help to reliably work.  The secondary already looks like one of the pain points - it is easy to rotate and move the secondary housing on the corrector.  That alone does not make me comfortable with the aging components.

 

Measuring the geometry and marking the orientation of all the optical components is part of my next steps.  I may want to handle internal reflection and stray light issues at the same time.  I am using a reducer in the optical path, and these have been reported in the AP forums to cause secondary problems because of stray lights (often during flats).

• These issues normally show up when really pushing the views (stretching that exposes the background flaws in the system) - like looking at Dark Nebula, or faint extended nebulosity in the skies.  It is also reported to be an issue when looking at galaxies with low surface brightness.
• Being able to see these stinker objects is one of the reasons building up the scope in the first place -- to extend what I can see with EAA.  I don't just want this to work ... I want it to work better than my current optimized rigs.

Edited by Mark Lovik, 12 June 2025 - 01:13 AM.

[Mark Lovik]

I break Bhatinov masks ... not always ... but it happens unexpectedly enough of the time. Been wanting to make a case for the darned things for years (every time I break a mask).

 

SO

I am tearing down a Meade 10" Schmidt-Newtonian, and have had an unused Bhatinov mask sitting in its packing material. Finally decided to make a simple case for this large (and fragile) mask.

 

Not sophisticated and maybe $5.00 in materials. Just a simple thin luan plywood top and bottom, and a cast off 2x12 ripped into thin slices as the perimeter.

 

Also used some of the spare material to make a smaller Bhatinov mask storage box for my Quattro 150p at the same time.  It even fits in my case for the scope!

 

Edited by Mark Lovik, 15 June 2025 - 04:27 AM.