Home Made Remote Controlled Filter Wheel

[Gina]

Coming back to this project now. Been having thoughts on this in the meantime. Some changes to the design :-

• Arduino to control the wheel rather than Velleman USB interface card
  
• Optical position sensing with LEDs and phototransistors.
  
• Might use stepper motor instead of servo (still undecided)
  

Retaining the following :-

• 36mm unmounted filters (considered OK for DSLRs and thinner than mounted ones)
  
• 5 hole carousel kindly cut out by Francis
  
• 145mm diameter front and back plates
  

[Gina]

I've bitten the bullet and ordered a set of Baader 36mm NB filters from FLO. Also some M3 x 4mm Allen screws and fibre washers from ebay to hold the filters in place in the carousel.

Filter wheel project is now well and truly ON

[skybadger]

Hi Gina,

Had a brainwave after reviewing this thread - how about a rim drive with no central hub. Needs four small wheels , 2 either side acting in a recess on the edge of the filter disk to hold the wheel against two edge rollers. Major benefit you can make the interface couplers as stiff and heavy as you like to take the weight of cameras, the rest is just thin dust shield.

I'll knock up a drawing. Where have I seen this before ?

Mike

[Gina]

Hi Gina,

Had a brainwave after reviewing this thread - how about a rim drive with no central hub. Needs four small wheels , 2 either side acting in a recess on the edge of the filter disk to hold the wheel against two edge rollers. Major benefit you can make the interface couplers as stiff and heavy as you like to take the weight of cameras, the rest is just thin dust shield.

I'll knock up a drawing. Where have I seen this before ?

Mike

Thanks Mike I look forward to seeing your drawing

[skybadger]

I know you're committed, I just wanted to throw another drive mech into an internet resource. I have long had reservations about the thin metal casings that are used to hold the 2" stubs for insertion into telescopes on one side and the camera on the other.

Using a rim mount and drive allows all the weight to be concentrated into these parts, makes the disk accessible and .... manufacturing almost entirely about milling the edge drive.

On another topic, did the filter wheel with circular filters get threaded for 2" filters ? Did someone make a tap, buy one or turn them on the lathe ?

I had a go on the lathe a while back and it wasn't easy. Theyre still sitting there, waiting to be tapped in fact. I haven't committed myself to buying a 2" lump of silver steel to make a tap yet either.

regs

Mike

[Gina]

I know you're committed, I just wanted to throw another drive mech into an internet resource.

Although I have the carousel made I don't have to use the central hub. The disc has a semi-circular groove in the edge for a belt but I see no reason why this shouldn't run on wheels if that turns out to be better.

I have long had reservations about the thin metal casings that are used to hold the 2" stubs for insertion into telescopes on one side and the camera on the other.

My sides will be 3mm thick aluminium - I think it will be sufficiently stiff.

Using a rim mount and drive allows all the weight to be concentrated into these parts, makes the disk accessible and .... manufacturing almost entirely about milling the edge drive.

This is where I'm not quite with you and a diagram would help if you could do one

On another topic, did the filter wheel with circular filters get threaded for 2" filters ? Did someone make a tap, buy one or turn them on the lathe ?

I had a go on the lathe a while back and it wasn't easy. Theyre still sitting there, waiting to be tapped in fact. I haven't committed myself to buying a 2" lump of silver steel to make a tap yet either.

regs

Mike

The carousel takes unmounted 36mm filters and is not threaded but just has a ledge to retain the filter with 3mm tapped holes to take small screws and fibre washers to hold the filters in. I haven't tested it myself but others have said that 36mm filters are big enough for the usual DSLR size sensor to avoid vignetting. If you have a full-frame camera you will need 2" filters.

[Gina]

I'm trying to find a way of attaching the casing side plates to camera and scope focuser. Something like a bayonet fitting with a wide rim that I could bolt onto the side plate for the camera and a 2" tube for the focuser. So for the latter some sort of tube with a flange to bolt onto the FW plate. I'm not having much luck so far Anyone have any ideas. please?

[Gina]

No? I see

Anyway, two of the three Baader filters arrived today - the OIII is on back order from FLO. I was able to confirm that the filters fit the carousel perfectly

[JamesF]

I'm trying to find a way of attaching the casing side plates to camera and scope focuser. Something like a bayonet fitting with a wide rim that I could bolt onto the side plate for the camera and a 2" tube for the focuser. So for the latter some sort of tube with a flange to bolt onto the FW plate. I'm not having much luck so far Anyone have any ideas. please?

If you know someone with a lathe I reckon it might be easiest just to get a piece turned up for this, GIna. A 2" external diameter tube with an external flange on one end with the flange drilled (and possibly tapped, depending on which way around you want to put the fixings) for three or four screws surely shouldn't be that hard to make.

James

[Gina]

Something like this James but preferably a wider flange :- http://www.firstlightoptics.com/adaptors/flo-2-inch-t-mount-camera-adapter.html

[Gina]

This might be a good idea for the scope side :- http://www.firstlightoptics.com/starlight-xpress-accessories/adapters-for-starlight-xpress-usb-filter-wheel.html

[NEM]

I'm trying to find a way of attaching the casing side plates to camera and scope focuser. Something like a bayonet fitting with a wide rim that I could bolt onto the side plate for the camera and a 2" tube for the focuser. So for the latter some sort of tube with a flange to bolt onto the FW plate. I'm not having much luck so far Anyone have any ideas. please?

Would something like this http://www.ebay.co.uk/itm/M42-screw-mount-lens-to-Canon-EOS-Adapter-for-600D-550D-1100D-60D-5D-II-III-650D-/150850670065?pt=UK_Photography_CameraLenses_Lens_caps_hoods_adaptors_ET&hash=item231f668df1 work to join the camera to the side plate? I used something similar to make an adapter to join M42 lenses to my recased webcam.

Noel

[Gina]

Would something like this http://www.ebay.co.u...=item231f668df1 work to join the camera to the side plate? I used something similar to make an adapter to join M42 lenses to my recased webcam.

Noel

Thank you for your suggestion Noel Funnily enough I was looking at that idea myself - I have a 42mm adapter I've bought for using old SLR lenses. I reckon there's just enough width to the flange to take some small countersunk screws to go into tapped holes in the FW plate.

[Gina]

I've bought a second hand manual filter wheel from another member here (it was advertised in the Classifieds). It has what's basically a 7 position 1.25" carousel but with one position occupied by a 45 degree mirror. It has a 2" scope attachment and a T2 camera attachment. I bought it with the idea of making use of the parts, saving having to get parts machined specially. However, in some months/years time I plan to buy an astro CCD and then I shall want a 1.25" filter carousel. The casing is quite wide to allow for the diagonal and eyepiece holder so one possibility would be to include both my 36mm unmounted filter carousel and the 1.25" filter carousel in one casing. The position for the diagonal could be cut out to allow access to the 36mm filters. Likewise an unused place in the 36mm wheel could be lined up for using the 1.25" filters. Anyway, it's all food for thought

I'll take and post some photos later.

[Gina]

Seems I can't count There's 6 positions not 7

Here are some photos :-

[Gina]

The filter wheel cannot be used with a DSLR as it is because the knob used to turn the filter wheel gets in the way of the camera. Also with the sprung ident roller adjusted to prevent slackness the knob is too difficult to turn. However, I don't want to use it as a manual wheel - the whole idea is to make a remote controlled one.

This photo shows a certain amount ofstripping down.

[Gina]

I think this project is going to be on hold for a while. With just Ha and SII filters only and no sign of the OIII coming in the near future I wouldn't be able to do much with it anyway. In any case I have a vast backlog of imaging projects on the list for whenever we get any clear nights so not really in any hurry.

Of course, that doesn't mean I'm not thinking about it at times.

[Gina]

I'm afraid this project is dead as the proverbial do-do as far as 36mm NB filters for the 1100D is concerned. A 36mm OIII filter is evidently not forthcoming and I now have a mono CCD camera that I plan to couple up to a camera lens for the wider DSOs and on the scope for the narrower ones. I shall still be using DSLRs for OSC work for the moment.

The home made remote controlled filter wheel is not totally off the books however. I plan to motorise the manual wheel above for use with coloured filters and webcam for planetary a bit later on.

[Gina]

I'm looking into this project again as I have just bought a second 314L+ mono CCD camera and exhausted present funds so anything else must wait.

I have the carousel with 5 holes to take 36mm unmounted filters and Baader Ha and SII matching filters. What other filters might go in it I've yet to decide. But either of these will go quite nicely in a dual imaging rig with an OIII in my main wheel (EFW2). That would give a narrow band dual imaging rig as soon as I get side plates and scope/camera connections set up and the whole thing light and dust sealed.

[Gina]

I've been looking at that manual filter wheel and I think I've come to the conclusion that there would be a lot of work in modifying it for present use. So I'm looking at using flat aluminium plates for the sides. I have 3 possible ideas for attaching camera and scope/lens to the sides :-

1. Adapter with a wide flange
   
2. Two adapters fitted through the hole and screwed onto each other with the side plate between
   
3. Adapters glued on
   

I currently have a variety of scopes/lenses I want to use as a dual rig imager. Firstly, two scopes - 510 and 400 mm FL :-

ED80 with FR/FF - this will have OAG and EFW2 connected to 314L+

ST80 - T2 thread - this will have the home made FW and 2nd 314L+

Widefield rig with two prime lenses :-

Lens - 42mm adapter - EFW2 & 314L+

Lens - 42mm adapter - my FW & 314L+

In both cases my FW will be connecting to a T2 male thread on the camera side and a female T2 thread for the camera. The SX flanged adapter looks virtually ideal though I do just wonder about the accuracy of optical axis alignment. I guess if it's good enough for Starlite Xpress I guess it's good enough for me. I can ensure that the side platres match by drilling and tapping both together using a pillar drill. The attachment method also means it's possible to rotate the camera while keeping the FW fixed - this is useful for the WF rig where the FW is used to mount the kit. I could cover the angles where the screws would land outside the slots by having 6 threaded holes in the plates.

[Gina]

Use of the ST80 depends if it turns out to be good enough. Being an achromat it would need refocussing with any filter change but the idea is to run for the whole night during the summer with the same filter so it doesn't even want a remote controlled wheel. For an imaging scope the ST80 will also need motorised focussing - the manual focus is far too coarse. I think I shall do a test before I use this scope in dual imaging mode for real.

Two ideas for a replacement for the ST80 are another Evostar ED80 or the forthcoming Esprit. The latter will depend on the price but this has great hopes of well outdoing the Evoster 80 ED Pro.

[drhemlock2]

Plans win thin plans eh Gina, i know what you mean i almost cannot sleep when i get to thinking about the projects i want to finish and or start. my hand problems relegate just what i can do nerve damage and all. i wish you luck and i am sure whatever you do decide will be interesting to follow as all of your projects are to me. how is Tim doing?

doc

[Gina]

Plans win thin plans eh Gina, i know what you mean i almost cannot sleep when i get to thinking about the projects i want to finish and or start. my hand problems relegate just what i can do nerve damage and all. i wish you luck and i am sure whatever you do decide will be interesting to follow as all of your projects are to me. how is Tim doing?

doc

Sorry to read you have hand problems - that must be most frustrating. Mine aren't quite as good as they used to be which I think is purely due to age but they're not too bad. Thank you for asking about Tim - he's coming along slowly He's frustrated at not being able to get about much, of course.

[Gina]

Ok so I have a 5 hole carousel for 36mm filter discs and just two filters to go in it. Any other filters I shall want to use are likely to be 1.25" screw-in type so I need some adapters from 1.25" filter thread to 36mm plain. Anyone know how accurately the filters need to be in their plane being at right-angles to the light path?

Alternatively, are any of you budding machinists like to quote me for making me a few of these adapters - practice your thread cutting? I've never seen such an adapter advertised so I guess nobody makes them.

[Gina]

New design of casing and drive system. The case will consist of two aluminium plates 125mm square and I've decided on timing belt and stepper motor drive controlled by Arduino. The carousel will have an inverted timing belt attached to it to act as a very large pulley. Then a small timing pulley on the stepper motor shaft will drive it with a larger timing belt. This is the system I have used successfully with my camera lenses for focussing.