your thoughts on astrophotography accesories

[Joshua Bunn]

Hello all,


I'm looking to hear peoples ideas on what they would like to see on an imaging rig that is currently not on the market or is scarcely available.



It could be something that goes between the back of the scope and camera, (in the image train) to make life as an astrophotographer easier. It could be a bracket that holds a computer or power box that is mounted on the dovetail of the scope. Maybe an integrated adapter such as a tilter and manual rotator all in one compact unit that would free up back focus space.


What ever it is, please, post your ideas here. I have the capacity to produce items in numbers, so this wouldn't be a one off custom design for each person (although I'm happy to do a custom one :) ), rather something that can be used on many setups.


Cheers, Joshua

[floyd_2]

Hi Joshua,
I was considering grabbing a Pegasus Pocket Power Box Advance Gen2 but mounting it turned out to be a bit problematic for me as I wanted to be able to switch it between two OTAs. My ideal setup would be a dovetail with a riser that would fit into a standard finder shoe. To be honest, I’ve gone off the idea for now and have wired my rig in another way. But the power box ideally needs a way of mounting it onto an OTA that isn’t permanent and doesn’t require a screwdriver to remove it and doesn’t need the weight of an accessory rail.

[h0ughy]

Mine would be ability to mount 3 scopes on a mount with losmandy style connections in a triangle with ability to synchronise to central scope, likes for solar imaging etc can do white light and haplha at same time and can have one scope left for deepsky. That way your ready to roll in the observatory with everything all setup without having to change a thing, or can image say with wo132 and wide field at same time with redcat51 and do daylight solar with Lunt 60. In a done side by side doesn't work. Mount for guidecscope as well

[gregbradley]

A precise tilter and rotater that does not take up much backfocus sounds like a valuable adapter. It would have to be strong to handle weight without flex.

Basically anyone who uses these small pixelled CMOS cameras needs to adjust for tilt. Being also able to rotate without introducing tilt (some Tak CCAs have been known to introduce tilt) would be valuable for framing.

Full frame cameras need it most then the APSc sized then the smaller sensors. Fast scopes need it more than longer focal length scopes.

Greg.

[AdamJL]

Ha, this sounds familiar ;)
Dean also sees the merit, it appears!

You should show off the one we've got planned and see if there's any interest (although that one is specific to PLL hole spacing, it can be "generalised" fairly easily)

Anyway + 1 to the idea of a very accurate rotator and/or tilt adjuster. That would make my day.

[mura_gadi]

Not really to do with AP per say, but I'd guess marketable items might be oversizing user grips/screws options on the scopes. Similar to items built for arthritic complaints - larger grip pens, thicker handles on the can openers etc.

Larger tool free screw heads, for locking EP's in and associated tubes/adaptors, also handy for the glove users.

A slip over larger wheel for focuser wheels, allows for finer focus and a little more forgiving if you have arty in the hands.

I know I have seen lots of posts from people looking to extend their astronomy as illness or age make themselves felt.

[AdamJL]

I like that idea as well.

[Logieberra]

Is there a market for Astrodon-style large OAGs but at local prices?
I have a MMOAG - it’s amazing - but costly…

[DJT]

+ 1 for the MMOAG. Fantastic bits of kit. A rotator would also be good but set it up so a motor could be added later on?

Cheers

[Joshua Bunn]

Thanks for writing guys. there are some good suggestions here, some of which might be better suited as a as needed basis or custom type job.






Thanks David,
I also like the idea of developing an Aussie made OAG. regarding the rotator, I will start on a manual design, first.





Ill see what I can do mate.





Hi Steve, sounds like it could be a good thing. I'm happy to do these on an as needed basis.





Hey Adam, Ill put up some pictures of your completed one.





This is something I am going to prototype, and as discussed in PM, I'll send one out to you to try.

[Joshua Bunn]

Hi David. Do you mean a pointing style like one of the two attached?

[Joshua Bunn]

Hi Dean,

For some reason the quoting is not working for me.
I'm doing a computer / Pegasus Power box bracket for AdamJL at the moment, maybe something like that might interest you.


Thanks

[h0ughy]

Yes something similar more largest scope in middle with smaller on the triangle either side

[Joshua Bunn]

Looking from the back view?

[h0ughy]

Yes

[Drac0]

I've seen that a number of mini pc's have vesa compliant mounting, something that works with that would be good.
Mark

[Logieberra]

Takahashi owners have to fork out big coin for the Tak finder quick release. FQ-R-1. It’s not a complicated design. Half goes on the finder, other half on scope. It just lets you take the darn finder off! Might be of interest…

[Joshua Bunn]

Is this what you refer to, Mark?
https://www.oneforall-australia.com.au/explore/vesa-mounting-standard#/step-1

[Drac0]

I guess...LOL

This is the one that comes with MeLE mini pc's. https://m.media-amazon.com/images/I/71amTl3cLwL._AC_SL1500_.jpg

[Sunfish]

A big impossible 72mm OAG only 20mm thick with at least one dovetail scope side adapter including a short t2 threaded guide camera mount.

[Joshua Bunn]

I like it :)

[PRejto]

Hi Josh,

I've never seen a device that could correct for an off-centered chip! Tilt, sure, off center, no way!

One way I thought of doing it would be to measure the chip offset, then intentionally offset the threads on both ends of the adapter the same amount, i.e., make them non-concentric. The device would be rotated until it compensated for the chip offset and then locked down with a locking ring.

Would that work?

Cheers,

Peter

[Paul Haese]

How about a counterweight for cameras? That is for cameras with large filter wheels, where the counterweight provides balance the correct balance for the whole imaging system.

[gregbradley]

A thinner MMOAG type OAG would be great. Especially if it were able to rotate.

Greg.

[Joshua Bunn]

Thanks Guys!





Sounds familiar Peter :) and an interesting idea.

I have my reservations about making the threads non-concentric with each other. This would be quite costly. Also, yes, you could lock it down at the desired location, but this will alter your backfocus. This would most likely need another adapter to then get your backfocus right. I think probably the cheapest and simplest way would be to use a dovetail that has a couple of millimeters of lateral movement, by which the camera can be moved left, right, up and down.





I could see a need for that Paul. Something like a "tube ring" to go around an adapter which then has a CW bar threaded into it.





That's a great idea Greg, something that could be built.
Is there a big need to be able to rotate the OAG/guide cam separate to the imaging camera, especially with square chips, as opposed to rotating the guide cam and imaging camera together?

[PRejto]

"I think probably the cheapest and simplest way would be to use a dovetail that has a couple of millimeters of lateral movement, by which the camera can be moved left, right, up and down."

Yes, you are right Josh, but where would you place such a dovetail in the optical train. To not disturb the back focus it would need to be located somewhere in front of that assembly. The Gemini rotator in my system has a dovetail...perhaps there is some room to play with???

P

[Joshua Bunn]

Are you still having off axis issues Peter on rotation?
The only place for such a thing would be right in front of the camera, that is where the issue lies. Putting it infront of a filter wheel or OAG will put them off axis which is a bad idea. :)


Josh

[PRejto]

Hi Josh,

Yes, I am. But of course putting it right in front of the camera will totally mess up my flattener distance!

Anyway, I'm just about to get going in my new observatory. Time will tell if I can live with things the way they are.

Peter

[Joshua Bunn]

Hi Peter.
Best of luck with your observatory build, that's awesome.
Do you do a closed loop slew after rotation or a meridian flip?


Regards Josh

[PRejto]

Yes, a CLS does solve pointing. That isn't the problem though annoying.

What it will not solve are differences in star shapes at field edges upon rotation.

[Peter Ward]

My wish list would be a thin non-rotating focuser/spacer...AP (2.7") threaded..

Say 8mm-13mm thick (i.e 5mm of travel) . to allow for perfect backfocus adjustment.

[Joshua Bunn]

Ahh yes, I feel your pain there Peter.
My STL11K has that issue on the cdk12.5 that I use to have, when your imaging circle is just large enough for the sensor size.
Remind me again what connection You have to your camera. For memory, you have lots of backfocus to spare from the adapters I made you, correct?





That's a good one Peter, leave it with me. I Made one of these for PRejto ^ but it was a rotating one, not the easiest to use.

[Peter Ward]

Indeed, non-rotating helical would be the tricky (but essential) bit.

If you can create such a beastie, send me a PM...I'd bee happy to fund the project.

P.S. I'm thinking a fine thread, outer focus ring might be the way to go?

[gregbradley]

Yes I would want one of these also.

Greg.

[AdamJL]

just want to re-iterate the suggestion of a tilt adjuster. Shooting now and I've got some crazy tilt out of nowhere.
Would love a large tilt adjuster with M48 threads, because otherwise I wouldn't be able to access the screws since the filter wheel and flattener bulk out enough to prevent access. Maybe something 100mm in diameter.
Something like this just isn't big enough

https://www.firstlightoptics.com/adapters/astro-essentials-m48-m48-tilt-adjuster.html

[Joshua Bunn]

Hi Adam,
Absolutely, I am in the process of designing a tilt adapter, that can be adjusted from the edge (not the face) and having an integrated rotator as well. Just a manual one at this stage :)

[AdamJL]

That's awesome to hear, Joshua! Can't wait to see what you come up with.

Also, I really like this idea
https://astrodymium.com/products/rotating-tilt-adjusters

I'm imagining something that instead of being three pieces, is one piece with the same rotation concept as the above. You shift one or two pieces in various directions to adjust tilt.

Big benefit, these are as thin as shims, so take up almost nothing from your back-focus.

That said, if yours has a built in rotator, well mate you are onto a winner there.

[Joshua Bunn]

That's a pretty simple and elegant solution.
The only issue that may happen there is if you have a particularly heavy image train that could compress the edge of that plastic shim, especially if the torque was perpendicular to a line that goes through the raised section of the shim.

[AdamJL]

Good point! I've ordered some anyway to test out and use as an interim solution until you've finished your design ;)

[Joshua Bunn]

Cool, it'll be interesting to see what you think of them.

[Rerouter]

A way to mount a DSLR directly to a telescope dovetail mount, they kind of exist, but they all are rather crappy, assuming you need to source your own means of connecting it,

[By.Jove]

This is beginning to sound like the tilt-shift mechanism used in special wideangle lenses for photographing architecture. Similar issue.

[Stefan Buda]

Very cold in my workshop these days and I'd rather be spending time inside the house drawing lines on a computer screen, but 5mm of travel for an effective thickness of 8mm is a bit too much. Would 4mm of travel be acceptable? Also how much weight would you like it to carry?

[AdamJL]

Pie in the sky idea: something to make the mount east heavy after a meridian flip. Wouldn't have a clue how to do this, mind :)

[Joshua Bunn]

I saw a rather simple solution to this a while ago, and that was to place a rope over the RA axis somewhere and to have it hang down on the east side of the mount. this way, the the bias is always on the same side of the mount. :)

[Peter Ward]

4mm would be fine. 3kg payload.

[Stefan Buda]

Thanks Peter, I'll have a go at the "drawing board" and if it looks doable I'll post the drawing in this thread.

[Peter Ward]

Excellent :thumbsup:

[Stefan Buda]

Ok, here's a preliminary design.
Josh, or anyone, please feel free to copy or improve.

I wanted to add compression springs for preloading the threads but the 8mm thickness is not quite enough for effective implementation. Instead, backlash elimination would have to rely on high viscosity dampening grease and that would make turning the outer ring a bit hard, so I added a lever for that purpose. The lever would also help with estimating the adjustment amount.
The red ring has 1mm pitch threads, left and right handed, so it would take two full turns for the full 4mm stroke.
The three custom SS screws act as guides and limit the stroke to 4mm.

The 6mm depth for the female 2.7" thread can be increased to 7mm.

[Joshua Bunn]

Hello Stefan.
Nice design, what locks the final spacing in its place?
Regards
Josh

[Stefan Buda]

The three grey custom M3 screws.

[Joshua Bunn]

Sorry, I may be missing something. As far as I understand, those 3 SS screws are fixed in place in the blue adapter and the heads can slide inside the green adapter, and can not be turned, and they are to limit travel and to stop the 2 halves rotating with respect to each other. Is my understanding correct?

[Stefan Buda]

That is correct. I should have pointed out that the three screws need to be locktited into the blue piece.

[Joshua Bunn]

Yes, I thought they would need something like that to keep them secure.
So once the desired length is acquired, how is it locked so the backspacing is maintained?

[Stefan Buda]

No locking should be required. The large diameter threads combined with high viscosity grease should maintain the orientation of the lever. Of course this mechanism would have to be made to very tight tolerances. The threads may need a bit of diamond lapping after the anodising.

[Joshua Bunn]

It looks like a Good design, Stefan, and in theory with tight enough tolerances, it should work.

[Peter Ward]

Very clever Stefan :thumbsup:

Josh...are small bills OK ?

[Joshua Bunn]

Hi Stefan.


I Think the design is probably the best way to do it given the constraints, however I'm going to try add a way of locking it in place while at the same time, removing any tolerance that may be present in the threads. I'll post my design here when I've come up with something.


Josh

[Joshua Bunn]

The kind of locking system I was trying to make had another threaded ring on top of the ring you turn to change the spacing. This outer ring, when turned, applied compression to the turning ring by way of a tapered fit. The inner ring you turn to change the spacing has a slit in it to allow it to close up. I realised its design has some manufacturing challenges so a simpler idea would be to machine the turning ring on Stefans design, to be an interference fit on the threads, then cut a slit in it axially, allowing it to open up just enough for a firm fit. The thickness of this ring could be adjusted if more resistance is needed. Some testing will be needed to see what mass can be held comfortably by the part without tilt caused by the outer ring opening up under the load. an alternative would be to have two tabs machined into the outer ring, with the slit in between them, and a screw through the two tabs to provide locking of the outer ring.

All things to work with :)

[JA]

Alternatively (if using the slit tube) you could lock the assembly using a separate split locking collar not unlike an OTA split tube ring.

Best
JA

[Joshua Bunn]

Hi JA,
I believe that is a Similar concept to what I suggested in my last sentence. I'll put up a drawing tonight :)
Thanks,
Josh

[JA]

Hi Josh,

What I got from your last sentence description was a locking mechanism (2 tabs + screw between them) something like this....
291539


I was suggesting a not dissimilar OTA split style clamp - I should have added of the hinged type (like a mini Parallax Brand clamp, which could bear down on a plain outer surface of the red ring, however, now reconsidering it given the slim size, forget it. Yours would be easier to manufacture. Heck, one could even use a jubilee style hose clamp if there was a plain outer surface on the red outer part to help quick prototyping.

Best
JA

[Joshua Bunn]

Hi JA,


Yes exactly like that.
I to thought of a something like a hose clamp or an over center clamp, but that would be too bulky, would look kind of unsightly and would need another tool to operate :)
So, yeah I recon something like in your photo would do the trick, it would easy enough to manufacture, be made to look aesthetic and easy to use.
I'm actualy going to make the clamp integral to the outer rotation threaded ring.

Cheers
Josh

[Joshua Bunn]

I'm thinking something like this. Its the same as Stefans design, but with the compression ring which also acts as the rotating ring. That is an m4 bolt, probably overkill, I may reduce the size of it. There are no real beveled edges on this drawing, the real thing will have, though.


Josh

[Stefan Buda]

Should work. For locking, maybe even a thumb screw with an 8mm diameter head might be sufficient.

[Peter Ward]

Indeed: NO tools. A thumb screw/knob is essential.

[Joshua Bunn]

I appreciate the desire for no tools, however, this is something that will get used a few times then not anymore for a while just like a tilt adapter, which uses tools. Having said that, Ill try to fit in a thumb screw/knob, big enough to get enough purchase on it.
The other limitation with a thumb screw is the head really shouldn't be any bigger in diameter than the width of the adapter, in this case 8mm, to avoid it hitting any other adapter that might be near the face of this adapter.

Josh

[MarkInSpace]

ohh - so these dont exist? I've been looking, but never found one!!

[AdamJL]

they turned up today! And of course, there's so much rain here I could fill a pool within a day. Will be a while until I can test them out, but they appear to be fairly simple. 3D printed and thickness of 0.7mm, 0.6mm and 0.48mm (should be 0.5, but I'm splitting hairs :))

[AdamJL]

okay here's a suggestion, Josh!

filter masks :)
the ones out there now (at least for QHY cameras, I can't confirm for ZWO) are 3D printed. I'd love some metal ones with maybe a thin layer of felt underneath to protect the glass. I feel they wouldn't flex as much as the 3D printed ones can. I have a couple of sets, and the ones from BuckeyeStargazer deform into a shape that isn't circular!

Don't know how hard this is to do, considering how small/thin they'd have to be.

[Joshua Bunn]

You know me Adam, Ill certainly give it a go if its something you want to try :)

[joshman]

I've been thinking on this a bit over the last few weeks, could using some kind of slip ring or dovetail ring on one side simplify the design?

I'm envisioning a 3 piece system, very similar to what has already been proposed, the telescope side would have a thread for attachment, and a dovetail ring. your adjustment ring would slip over this and be able to freely rotate on the dovetail ring. it would extend out past the front (camera side) of the dovetail and similar to the existing design would engage with an externally threaded piece that will move in or out based on the rotation of the adjustment ring.

[joshman]

Possibly something like the attached?

Silver retaining ring, screwed to the face of the Orange threaded piece. Blue piece rotates and screws the green piece in and out. To lock the position I envision the current split ring design? For the below i've sized it with a M48x0.75 internal, and am using a M54x0.75 as the screw thread. I haven't dimensioned it very well, but the idea makes sense...i think?

If you incoorporate index marking around the outside, it can double as a rotator as well.

[Joshua Bunn]

Hello Josh,


I like your thoughts here, I recon it would work well, just need a few dowel pins to keep the orange and green parts orientated. There is one thing i would try and change though... the dovetail need some clearance to rotate (if it has no locking ring), and unfortunately clearance mean free-play and movement, possibly introducing tilt. did you have a solution to this?


I have a different design (to yours and Stefans) that I am working on now, Ill see how that goes.


regards Josh :)

[AstroViking]

Hi Josh,

I'm contemplating asking for an adaptor - what sort of drawings / info do you need from me? (I am crap at driving a CAD package, so detailed drawings or 3D models are not going to happen.)

Cheers,
V

[Joshua Bunn]

Hi Steve,


You can send me an email to scastrophotography@outlook.com detailing in words and a drawing if you like, what it is you are after and we can go from there.


Cheers.

[joshman]

Thats good to know i'm on the right track. i was thinking of making the blue piece a split ring, with the split cut on a fairly steep angle to stop light leak.

EDIT: On second thought, maybe trying some kind of wedge system instead?, maybe the silver piece could thread in to wedge and lock the dovetail piece in place? being a wedge design it would self-centre as well. that way you can lock it in place as well without having to worry about light leaks. Personally I would still forego the dowel pin in favour of being able to use it as a rotator. Maybe have a secondary lock between the blue and green pieces to preserve your spacing?

Another idea is to use a tried and true Turn-bucklet style LH and RH thread combo something like the attached. I've used a very coarse 2mm pitch for the extension thread, for every full 360deg of the centre piece you gain 4mm overall of extension. you could put a pin from each of the recievers that will stop on a centre obstruction to prevent completely unthreading and limit the overall in/out travel. still not sure how tightening this would work with regards to light leaks. Again, index marking the central piece could translate to pretty precise extension values (1mm/90deg turned, mark at 9deg increment for 0.1mm of extension.

[Stefan Buda]

Josh,

Don't forget the constraints before you put more thought into this: Minimum thickness 8mm, extended thickness at least 12mm.

[joshman]

Ok, Constraints of minimum 8mm thickness, +4mm of extension. i think the first design could be made to suit that. I assume a female-male connection is required?

I think the second design could get down to minimum 10mm thick with upto 4mm of extension.

Out interest, how deep are you allowing for the engagement of scope/camera side threads? 3mm?

[AdamJL]

What about tripod spreaders?

Geoptik make a set for the SkyWatcher tripods, but I feel they're excessively expensive considering DIYers can make some for about $50.

https://www.testar.com.au/products/triangle-tripod

A set like that would be great, plus some for different sized tripods (like my ZWO carbon fibre one!)

[Joshua Bunn]

Hey Adam,


Thanks for the suggestion, if someone wants one, I will make it :)

[AdamJL]

haha cheers, Josh. We'll see what the Mrs says after she sees the one you're working on now :rofl:

[Joshua Bunn]

:scared3:

[AdamJL]

Fancy building harmonic mounts, Josh? :)

https://www.youtube.com/watch?v=k2GoMa2DpH8

This dude has just done it. $700 USD in materials. Mind blown.

[Joshua Bunn]

Well, not Harmonic drive mounts, Adam, but I will be building direct drive mounts after I've done one for myself :)


After a few prototypes, I've got a Working variable backspace adapter that Peter Ward was asking for.
The time is well over due to send it to him so he can test it out.


Cheers, Josh.

[AdamJL]

very cool, Josh.
Are those three grub screws the parts that drive the extension? Just thinking about any introduction of tilt if you had to do each one individually and you got one slightly wrong.

[Joshua Bunn]

Thanks Adam.
No, those screws are what limits it's travel, and stops rotation of the left and right hand threads with respect to each other. The 3 screws were Stefan's idea, I came up with the split outer ring design for the extension and locking, once at the required length.

[TrevorW]

Really like the idea of the Harmonic Mount suggested earlier, there's a challenge Josh :)