Multi lens Astro GOTO camera

[DIYASTRO]

Been away from the SGL boards for a while but have been glancing every so often to see what everyone is doing, saw Gina's thread on widefield imaging rig and thought I would post some ideas that are simular in ideas.

I posted earlier today a thread called Fork mounted 250mm f1.7 / SPC900 yesyes style camera, this thread is to show variations that I have used to atemp to solve the problems of accurate focus remotely and avoiding crayford or other commercial focus units.

I began this project some two years ago and hopefully I shall live long enough to get it finished but thought I would post just now !

Simple idea.... just several cameras using different lenses mounted in the same structure capable of being operated 5 meters from pc and other anologue control gear. (I am old and hate the cold so all has to be done remotely!)

Some pics just now and explanations latter, would be quicker for anyone interested to ask and I will try to answer the question or I could be at this pc all night and that would be boring for everyone!

[DIYASTRO]

For: Lukeskywalker

Thanks for PM etc.

Not quite sure how heavy it all is but it wont shake too much in a breeze!

The forks are surprisingly strong and I have fitted the first counterweight system which you will see on the underside of the camera in the last pic. It balances quite well as is but will need refining when the DSLR is in place on the Pancake filter wheel. ( I posted a thread about this in DIY section some 18 months ago search and you will find it, its a double driven 2" filter wheel with focus and camera rotate facility)

When I get around to weighing the beast I will let you know!

Kind regards

Boyd

[LukeSkywatcher]

Thanks for that Boyd. Its a great idea and a great looking piece of gear. put a box around it and it looks like an old tv camera from the 50's.

[DIYASTRO]

Your quite right Paul, I just wish I had the Vinten mount that was used with some of those realy heavy tv cameras! One was up for sale on Ebay recently for around 2000$ but was collect only from Australia!

'The box' will in fact be a shroud with zips to allow easy access, susspect a high degree of maintenance!

Still lots to do including flocking tubes and refining / tweeking some of the gearing but after a two-three year on off build I am almost there with this one!

It will eventually be one of four fork mounts all under one roll off obsy. Have two complete, 10" sct GOTO and another composite solar / lunar config, This multi lens is the third and the last one will be the small 250mmf1.7 which is depicted in another thread.

Kind regards

Boyd

[Gina]

WOW!! That look intricate Hope it works

[DIYASTRO]

Gina,

Thanks for your reply.

Its not as complex as it looks! Its all made as modules that interchange and 'slip out' of the cradle as it where. Admit it was an initial nightmare to get started and went through a few sheets of A2 on the drw board!

The knack is to take the major components eg. lenses and work out the way in which you can stagger and offset the focal points to give the best config possible within the limitations of the final construction limited by the width and depth of the swing between the forks.

The bits that you may be interested in are poss. the two camera's top left and right.

Left as you see it in pic 1 is a 50mm Pentax tak. This I have done as a servo worm drive to a gear mounted on the lens focus ring. its not as fine as some of the other focus drives within the multi camera as yet but certainly fine enough. The other 'std' camera lens is a Bronica 150mm which has a focus system like the larger one that I posted in seperate thread (Fork mounted etc)

I can assure you that all the cameras that are in this config have been built as seperate units and have been tested on PC or video output in their own right before and after the final installation to the rig. It does all work! It would be a bit much to post images of equipment that doesnt work !

Kind regards

Boyd

[DIYASTRO]

Removed one of the small camera modules this morning to take some measurements and took a pic to post here.

The focus is done via the servo motor through a 50 :1 worm gear set driving a shaft with a 14tooth 48Dp gear which in turn meshes with a 128tooth gear fixed to the lens helical focus ring.

The movement of the lens equates to .08mm or .003" for one revolution of the servo.

tested the focus again using a std SPC900 and focus is nice and smooth with plenty of adjustment using a simple PWM drive circuit.

When I have cause to remove the Bronica 150mm camera module I will post seperate images of this also, that module is driven differently using the leadscrew meathod since the back focus on medium format lenses is much longer than 35mm types.

Boyd

[DIYASTRO]

Just to say thanks to Gina, Schorhr & laser_jock99 for responce!

Taken out the other smaller camera module (Bonica 150mm lens) today to fit the 5V dc fan and re-route a couple of cables etc. As promised, posting a couple of pics which hopefully show the drive mecanism etc while it sits on its maintenance cradle. Yet to do accurate measurement of the focus drive but testing with the Sony effio board camera as in pics, it comes to focus very well.

I will post images of the guidescope camera later when again, it comes out of the mount for work to be done on it, this one is a bit more complex since it has not only the leadscrew focus mechanism but also motorised / geared x/y axis to assist in guidestar location.

Boyd

[Gina]

Have to say the workmanship and machining on your lens systems is superb Makes my DIY look crude in comparison Still, I'm happy as long as it works

[DIYASTRO]

Thankyou Gina. Thanks also to Rodger The Dodger for kind comments.

Intended to have a look at the guidescope camera module today but have got a little sidetracked with some electronics for the fork mounted camera that I have in another post . Will have to delay pics of this module for a few days me thinks.

Boyd

[fwm891]

WOW!! That look intricate Hope it works

Superb stuff - I was going to say don't let Gina see this but its seemingly too late

[Gina]

"Don't look Ethel... Too late!! Shes's already been mooned!" (from the song "The Streak") It's alright Francis I prefer the simpler approach

[emadmoussa]

Wow!!

Almost like the Transformers Well done!

[fwm891]

"Don't look Ethel... Too late!! Shes's already been mooned!" (from the song "The Streak") It's alright Francis I prefer the simpler approach

Maybe - but I bet the grey cells were working overtime reading this....

[DIYASTRO]

Sometime ago I said that when I had cause to remove the Guidescope camera I would post some pics, so as promised.

This was the first of several camera modules that I have built and requires some rethinking!

It works very well and the lens for this can be seen in my first post of this thread in the first picture. Its the largest lens and equates to 250mm f/l at f1.8,lots of nice photons hopefully!

The idea was to use the threaded rod focus drive system as described before, the problem is I only used two drive threads and two guide rods/rails. The threads are only 4mm metric and I know that it can be rebuilt to perform better. The x/y axis is formulated around two microscope mechanical stage mechanisms driven via worm gears and small servo motor. (one can be easily seen in bottom right pic, the blue 'box' being the small servo)

The pic in this post bottom left shows a large motorised iris diaphram which in the rebuild will be omited, not sure why I put this in!!!!

The camera is an spc900nc modded as per yes yes specs. and has 5vdc fan for cooling, another larger 12v fan is in the rear plate which supports the electric skts (25pin D, usb etc.

I have been working on its replacement for a couple of weeks hence the neccesary removal of this earlier module. I will post pics of the new build soon, I have taken a few so as to show the development of the module as opposed to just posting pictures of a mass of components which perhaps dont mean that much.

Some people may spot linear pots!!! these feed back to anologue volt meters and the needle gives the user a fairly accurate idea as to the position of the camera relative to the x/y axis, the focus placement and the extent as to the apature of the iris diaphram.

Hope some find this of interest. happy to answer or try to answer any questions as always!

Boyd

[DIYASTRO]

As stated yesterday in my last post, the xy guidescope camera module is up for replacement.

It works well but wanted to change one or two things such as the lead screws from 2 to 4

I also wanted to make a simpler xy system for maintenance reasons!

I decided to try a simple rack and pinion type system but this required small guide blocks which I found difficult to source. Decided to make my own from cast resin. Here are a few pics on the construction so far.

Pic 1 & 2 are the moulds for the cast components made from Ali and brass.

The top mould is for the camera block which holds the camera on the xy axis the bottom mould is for the guide rails.

3rd pic. This is the moulds filled with resin awaiting cure. ( the cicular moulds for seperate project)

4th pic. this is the camera block casting removed from mould. it has four seperate sections to be cut which hold different types of camera boards such as SPC900 and video cams.

5th pic.shows the camera block casting cut and sanded with the long rail casting below.

6th pic. camera block with SPC900nc mounted showing x axis rails

7th pic. As pic 6 but both x & y rail blocks attached

8th pic. This is the xy camera block and rails fitted to the focus plate with racks fitted to the rail blocks (.5MOD) The four metal inserts are the leadscrew threads for the focus drive.

9th pic. This has the .5MOD 60t gears fitted on drive shafts with servo mount plates / servo drives in place.

Pleased to say that this drive is not only more effective but is much lower on the maintenance issue.

I am now beginning work on the drive lead screws and mounting plates etc. should be mechanically functional by early next week and then just the electronic bits to add.

Will post pics of this when available.

Boyd

[DIYASTRO]

Made a good start on the focus drive system i.e. drive threads and also the plate support rods and plates.

Assemblled these just now to see how it all fits together and although it may appear not a lot done its acctually the most important part of the build. Getting the bearings for the drive threads set in the plates perpendicular / accurate location takes some time!

So

Pic 1. 5mm metric drive threads turned each end to locate in bearings. (The longer thread is for the servo drive) Also the support rods which seperate / support the module plates.

Pic 2. The camera xy axis plate positioned within the support plates with threaded drive rods in place.

Pic 3. Closer view of assembly showing the servo drive of the y axis on camera drive plate. This also shows one of the 4 drive threads which will eventually have the pulley and drive belt which provides the focus for the camera.

Pic 4 Old (right) New (left)! my hope is that this new replacement module will not only be more efficient and lower on maintenance but also less weight!

Will post more when able, awaiting drive belts so perhaps may start on the electronics bits!

Boyd

[Gina]

Nice job

[DIYASTRO]

Thankyou Gina.

Bit frustrated since no drive belts have arrived yet and both my soldering iron's have given up providing heat! So... No electronics as yet but spent some time working on the drive system for the leadscrew focus.

Could not quite decide which to opt for so went for a combo.

You will see the two servos ( which have yet to be converted to full rotation by removal of R/C circuit and gear stop)

Pic 1. This is the full guidescope camera module, the focus servos are the two to the left of the lens.

Pic 2. Closer view of servo drives, the one to the top right is a direct drive to the leadscrew which is coupled eventually to the other three leadscrews by the drive belt.

The servo lower center is conected to the same leadscrew via a 50:1 worm gear set.

Pic 3 A better view of the worm gear set / 10 tooth pulley on main leadscrew.

The grub screws in the direct drive coupling on that servo will have to be unscrewed if the worm drive is to be used and likewise, the grub screw on the worm gear if direct drive is required. Could do with a small clutch for the servos but that will have to wait!

Hopefully should get replacement soldering gear in a few days along with drive belts. Will post on progress.

Boyd

[DIYASTRO]

Drive belts arrived along with new soldering iron so able to do a little more to the guidescope module.

Pic. 1 This is the servo drive system as described in last post. two seperate drives one direct to main leadscrew the other via a 50:1 worm gear set. This gives option of focus plate / camera movement .8mm travel per rev for direct drive and .016mm travel per rev for the worm drive.

Pic. 2 Drive belt (250tooth MXL) in position and pulleys (10t MXL) locked in position on the four drive screws. The three stand off posts for the location of the drive servos.

Pic. 3 Drive servo plate in position.

Pic. 4 view of direct drive servo also showing worm gear of the fine drive servo on main lead screw.

Hope to be able to start the electronics for the spc900nc (yes yes mod) after the weekend and position cooling fans etc. will post pics of this when able.

Boyd

[DIYASTRO]

Just to say many thanks to all who have replied and added 'like's' to this post.

Blinky, you of course are the only other person to have seen this for real so to speak!

Would like to post a video at some point to show how the drives on the modules works so people can see just how smooth and accurate they can be. Perhaps some one could send / post a link as to how!

Looking forward to getting the guidescope module finished since my mount which supports it looks quite odd with gaping holes in the plates! After that, its the double filter wheel and camera rotation module.... lots to do on that!

Oh, nearly forgot, reason for this post actually is to ask if anyone knows of supplier for very small drive clutch?

Boyd

[DIYASTRO]

Began to start the elecronic bits to the guidescope this morning.

Managed to do the cut outs of the rear support plate for skt's etc and started the proccess of fitting up.

A few pics to show progress.

Pic 1. Rear plate drilled / cut outs for fan and electrical connections

Pic 2. Rear plate fitted with some of the components for connection to PC and mount etc.

Pic 3. Reverse of the plate showing Fan for cooling, usb skt, 25 pin D skt, GPUSB for link from camera to mount and switch for LX mode of yes yes mod to camera.

Pic 4. Whole camera module with rear plate in position showing brass tube which goes through all the plates to carry cables for the two focus drive servos and ultimately the two heavier cables for the lens heater dew band.

Pic 5. closer view of rear of camera module.

Still lots to do! hope to begin the yes yes mod on SPC900NC this week, which has the B&W ccd sensor(ICX098BL) which coupled with the 250mm fl / f1.8 lens should give sufficient choise of guide stars!

Boyd

[DIYASTRO]

Started to install the spc 900 nc camera.

I am using a std colour one for know, (modded yes yes style) will swap it for a more sensitive B&W one after I have seen how it performs, with luck the large apature lens should provide enough of those little photons to enable sufficient guidestars to be sellected using the std camera.

You will see from the pics that I have retained the GPUSB and wired this into one of the spare ports of the 4 way USB hub on the YES YES mod electronics. So its simply a single usb cable from pc operating PHD guiding and and a 6 way RJ lead from the GPUSB to the mount electronics.

Looking forward to testing, hopefully this evening, abscence of cloud permiting and will post results from that.

You will also see from the pics that I have temp.screwed a 1.25" adaptor in the camera block to take a UV filter, this will be changed for a simple filter screwed on to the camera mount block.

I think I may also try one of the sony effio video camera boards with a video graber. I have been quite surprised with these little cameras. 700 tv lines and .001 lux at f1.4. I get mine from a company called Cricklewood electronics ( most of my electronic bits come from them and are very quick and helpfull) and I think they are currently about £60. They also have quite a few in stock, I would recomend them for potential all sky camera etc.

Boyd

[DIYASTRO]

No chance of outdoor trial at the moment due to cloud rain etc. So... been busy with the operating electronics for the focus servos and the xy axis servo drives.

Couple of pics to show progress.

Pic 1 Circuit board with a couple of 6v voltage regulators (two circuits with heatsinks) One to power the PWM circuit in centre of main board the other to power the two 'bolt on' circuits to the left which are the servo controller boards from Technobots.

Pic 2 front of control panel. Three push switches on the left, top is power on/ centre is power to the servo controler boards and bottom is power to 12 volt cooling fan.

Red pot knob is for PWM speed control for the focus servos.

Three DTDP switches along the top. first is focus servo selector (ie, Direct drive and 50:1 worm drive servo)

Second is the forward/reverse switch for Direct drive and third is the forward / reverse switch for the 50:1 drive

The two red push to make square switch buttons on bottom row are the actuation for focus drives.

The blue knob is for x axis servo motion and the yellow is for the y axis servo.

Pic 3 All wirred up and placed in temp. housing until the main console is finalised and constructed.

Given it all a whorl and the only prob at present is interference from one axis control servo to the other which I suspected may happen so another DPDT switch to be wired in so as to isolate x & y servo controller boards from each other, a selector switch in essence.

So... so far so good. Looking forward to straping it on a mount to star test.

Oh. someone is bound to notice an unconnected pair of cables (blue & yellow in the box....) These are for the alternative red/green led from the GPUSB. By wiring this back through the connection cable it gives a nice visable indicator for usb connection esp when used with the GPUSB check programme enabling led to change from green to red etc.

Boyd

[DIYASTRO]

Spent a little time sorting out the problem of feedback to the xy axis drive servos.

Easiest solution was to isolate each drive board from each other using a DPDT switch and effecively making a selector.

Added the GPUSB led and also a further red led just as an indicator to show that power is on.

Tested intensively this morning and all works very well, the xy camera movements are very smooth and that makes all the effort of making moulds and casting accurate components worth while. I have simply taped the control panel to the box / housing for now until I get the final measurements for the console that I want. I can not label the panel just now, awaiting new tape for the printer!

Really looking forward to star testing. I have done a few calculations and I may benifit from fitting an optional focal reducer to give an even larger field of view, will know when star test is complete.

Soon have it back in its rightfull place within the mount and then I think I shall begin work on the double filterwheel / camera rotator / focuser!

Boyd