Digiscoping adaptor

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I have bought a digiscoping adapter from eBay. Until I receive it I shall use the vendor's excellent pictures.

He is being remarkably communicative with email updates of order acceptance and despatch. It is supposed to be coming from Germany so there is hope for an early delivery. Possibly even before Christmas? I doubt it.

It was long overdue that I stopped my hand-held snapping away at astro objects through the eyepiece. I did use an eyepiece clamp and camera plate for the Venus transit. But, it was so incredibly awkward to use with the telescope pointing high up that I never used it again!

I couldn't see the camera focusing screen hidden underneath the camera body without crawling on my knees. Or lying on the wet grass on my back! Even if I did, I couldn't focus my own eyes with my glasses having the reading section at the bottom of the lenses. (as is perfectly normal of course) 

I wanted to use my star diagonal but my home made clamp was for my 2" draw-tube. My star diagonal (at that time) only accepted (normal) 1.25" eyepieces! I now have a 2" star diagonal but it is massively oversized for my 2" clamp. Grrr.  So I really needed a universal camera platform which clamped onto the outside of my 1.25" eyepieces. One which could be (hopefully) set and forgotten. 

I went to the city (Odense) and  dashed about between milling Christmas shoppers. But I failed to find an adaptor in any of the local camera or hunting shops. (Hunting shops stock spotting telescopes)

So I tried eBay. I missed a secondhand one. This went higher than I wanted to pay for a used one including international postage.

So I paid a "Buy it Now" price for half what it would cost me from an online Danish vendor. (Including their ridiculous postal charges!)

The eBay vendor claimed their stock is in Germany. Right next door to Denmark. Their international postal charges are still lower than within Denmark. I will name the vendor on receipt if their service is good enough.  

I'll leave this note until it arrives. Then I can take my own pictures with my camera fitted to an eyepiece. Hopefully the device will improve my astro snaps. I shall write a proper review when I can examine the adapter for myself. Hopefully with some decent lunar images taken with its help.

Click on any image for an enlargement.

Dec 10th 2011 partial lunar eclipse.

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As usual (for me) the partial eclipse was very low and blocked by clouds. The eclipse was already under way as the moon rose. Though it was completely invisible behind the clouds. When it did become visible I took a few snaps with my Panasonic TZ7. The camera was resting on a garden tool handle.

Full zoom with a variety of settings. Night landscape, Normal picture and various AF (auto focussing) settings. Had it been more worthwhile I could have got out my video tripod or even a telescope at low power. As can be seen here the Moon was almost behind the garden hedge. The clouds only added to the drama.

These are only for a record of the event. I have cropped some of them to bring out the moonlit clouds.

Click on any image for an enlargement.

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December 2nd 2011

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Another clear evening with occasional plates of cloud passing over. Half moon to the south. Jupiter rising steeply in the east.

6" F:8 Celestron CR150HD refractor on Fullerscopes MkIV mounting. Stopped down to 4" F:12. Afocal image using 20mm no-name Plossl. Sony P71 camera hand-held to eyepiece. No drives running. Cropped, Contrast and Gamma adjusted in PhotoFiltre to bring out detail away from the terminator. 37F. Heavy dew. Thermal effects clearly visible. Moon just above house roof and chimney.

I fitted the black foam into the extended dewshield to kill internal reflections.

Still struggling with dewing of the back of the objective.

The Panasonic TZ7 camera is still failing to capture decent images. This is a snap using a 15mm Meade Plossl. Heavy vignetting, tiny field of view and too high a contrast. Heavily cropped and adjusted in PhotoFiltre. I found a description online of this problem being related to using wide angle camera lens settings. Using a slight amount of zoom may help.

Guy's MkIII thrust bearing.

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Guy has fitted a thrust bearing to his MkIII. A very neat job it is too! 

Here is Guy's MkIII mounting after a tidy up and repaint. Note the screwed declination shaft. Suggesting a later model. As does the clarity of the Fullerscopes logo cast directly onto the polar axis castings and the pot base. Guy has fitted a longer pier pipe to raise the mounting for his refractor use. Originally this MlkIII held an 8" Fullerscopes reflector. The brass ring houses the ball, thrust bearing and protects it from the elements. The slow motion drives and motors, shown in an earlier post, have yet to be fitted in this image.

The polar axis is slightly withdrawn here to show the bearing assembly.

The thrust bearing with deep groove steel races and caged balls.

The brass bearing housing with the lower bearing slightly protruding to rest on the polar axis casting. Normally a MkIII would have a PTFE (Teflon) washer sandwiched between the castings to take thrust (end) loads. For lower friction with a heavier instrument the thrust bearing is a useful modification. The thrust bearing adds very little height to the polar axis so will not affect stability. The declination axis "T" rests on the upper brass face.  

The MkIII on its new, taller pier.



The "legs" are Fullerscopes Heavy Duty in cast iron. Offering greater stability  than the lighter, alloy model.

The MkIII stripped and ready for a repaint on its original, shorter, "reflector" pier.

The MkIII before restoration with its reflector.

 






An assortment of Fullerscopes parts and accessories. Including a threaded weight, finder/guide scope and VFO drive parts.






Click on any image for an enlargement.

Comments moderation

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I have finally discovered how to have comments notifications sent to me by email. Blogspot had made it so difficult that I had completely missed several comments made on older posts.

If anybody has not had a response to their comments feel free to have another try. I have set all comments to be moderated. I will then be notified automatically whenever comments are posted on any of my blogs.

New Dewshield:

The new plastic dewshield in place on the 6". It is 3 x aperture in length from the cell shoulder. Thanks to its light weight it does not make the tube any more nose heavy than it already was. It looks a bit long but this is due to the short length of the F:8 OTA. It slips over the original, metal dewshield. Which provides support and security. 

The material is not stiff enough, on its own, to stay in place with only a small overlap on the lip of the objective cell. Nor could the telescope stay safely parked "on its nose" without the tough, metal dewshield. So the plastic dewshield is removed after use and stored upright on a shelf. It keeps its cylindrical shape well and has a smart, lightly textured finish. I will have to make a long one for the Vixen now. It too has a rather short dewshield for optimum protection on dewy and frosty nights.

The CR150HD6 F:8 beside the Vixen 90M F:11 on the Fullerscopes MkIV.

I now stand on an old beer crate to reach the cradle more easily. The extra weight of the Vixen would otherwise be a bit of a struggle. When set horizontal the cradle is well above head height.  Probably 7' above the ground due to the tall but massive stand/pier. Thanks to the beneficial geometry the hinged, open rings accept the main tube and hold it safely without any risk of slipping out or falling. I lock the wormwheel clutches to fit and remove the OTA.

The pictures aren't great but it was a heavily overcast day and almost dusk. I shall take some better pictures when conditions allow.

The polar axis is far too long but I am still deciding whether to add a taper roller or axial thrust ball bearing races at the bottom. The  MkIV provides low friction with such light telescopes. Though friction does rise when large and heavy OTAs are fitted.

My idea was to add a screwed collar to the polar casting. Which would allow fine adjustment of end loads on the Polar Axis via a thrust bearing.You can't just add a collar and spring to the shaft itself. Or it would pull even harder on the thrust surfaces.

Some mountings have had a single steel ball taking thrust loads on the end of the polar axis. Because of the very small surface area of contact it reduces friction considerably. One still needs the thrust faces because they offer improved damping and stability over plain shafts.

I have removed a 10lb weight and replaced it with a larger one of 14lb. This compensates nicely for the extra weight of the Vixen. Releasing the wormwheel clutches and swinging the OTAs (gently) produces a similar momentum in both directions. By watching how soon the tubes stop in their rotation (in each direction) about the axes one can soon tell if a reasonable balance has been achieved.

Though not impossible, it is difficult to add the 90mm Vixen to the already mounted CR150HD. There is simply not enough room between the cradle and the tube of the 6" refractor. The Vixen's rings will not pass through this space without releasing the 6" tube from each ring in turn. Suitable packing pieces between the hinged rings of the 6" and the cradle would easily solve this problem. Being able to add the Vixen later would save lifting the pair of OTAs onto the MkIV together. 

I managed to find a couple of A3 sheets of the matt black, thin foam to kill internal reflections inside the new dewshield. I may reduce the length of the dewshield to 2.5x aperture. This would give a more balanced look to such a short F:8 instrument. Hopefully without compromising its shielding ability against dew and stray light.

I spent a couple of hours observing Jupiter again. Though beautifully clear at first plates of cloud kept crossing over. There was also a breeze which made my eyes water. Jupiter wasn't high enough to get a really sharp view. I left the scope out while I had dinner. Then found it fully clouded over when I went out again. To finish off the evening I fell headlong over the stand in the dark! Fortunately I wasn't carrying anything at the time. No ill effects.

Click on any image for an enlargement.

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November 15-11

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Dewshield:

I found a coiled tube of pre-curved, black, plastic sheet in a supermarket. Designed as a bin bag support for gardeners. It looked ideal for making an extension dewshield for the 6". Which has always suffered from objective dewing due to its ridiculously short dewshield length. The objective also projects well forward of the shoulder on which the dewshield is fitted. (by friction) Further increasing its exposure to dewing.

The plastic cut easily with scissors provided I held it flat with weights. It had a strong curling tendency. In fact it wanted to coil into a neat 4" diameter cylinder. Ideal for my purpose!

I slid the Celestron dewshield back into the middle of my new, smaller cylinder and taped the lengthways cut edges neatly on he outside with black gaffer tape. Then I removed the metal dewshield and taped the inside. I made the plastic cylinder 18" long overall. It now slides easily over the original dewshield but stays firmly in place.

I put the 6" onto the MkIV mounting and after several hours the lens was still dry. Though everything else was dripping wet with dew. So the dewshield extension is working as intended.

The inside of the plastic is a bit shiny but the dew matted it down. I intend to line the new dewshield  with thin, matt black foam from a toy/model shop. I'll post some pictures of the dewshield when it is light enough for photography.

Jupiter:

Having fitted the dewshield I spent the evening trying to take better images of Jupiter. I'd take a dozen images. Then go back indoors to see if I was making progress by viewing them in Picasa3. After each photo session I would take a snap of the monitor to separate the images into groups. Otherwise they all looked so similar it was hard to see where each sequence started and finished.

The TZ7 failed to capture a single image worth keeping. My old Sony DSCP71 produced something useful with almost every exposure!

As usual, I simply held the camera up to the eyepiece and centred it by touch. I took an exposure when there was a bright blob visible on the camera screen. 

The images which had potential were put through PhotoFiltre. I played endlessly with Gamma, Contrast, Dust Removal and Colour to bring out as much detail as possible. The four visible moons were captured but lost in the processing. 

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None of these is particularly good but satisfying enough considering the crude methods I used.  The Great Red Spot is just visible on the lower belt, left limb on my screen. I doubt it shows on the blog images. The third image shows it best. The Sony camera has captured all that I could see visually.

I tried a number of eyepieces and even the 2x Barlow and moved the Baader "Fringe Killer" filter across to each new option.

I tried all sorts of settings on the TZ7. Including spot metering and zoom but nothing helped show any belts. Though the moons were well captured as were a few background stars. The trend was always overexposure.

The evening session ended when the inside surface of the objective dewed up. The front surface was still dry. I had swung over to the rising Moon  to see if the seeing was any good that low. It was then that I discovered the misted lens surface. The telescopes are parked nose down so the 6" may have collected some fluff on the back surface. I'll have to take the objective cell off and clean the glass.

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November dew

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A first clear night for ages pushed me into having a look at a rapidly rising Jupiter in the East. The brilliant full Moon was hanging nearby slightly further to the north east. It was so bright I had no need of a torch when selecting eyepieces from my box.

I had to drag out the massive, welded stand supporting the MkIV. The wheels had sunk into the lawn since the last time I was observing. The pier legs are too big to allow the car to turn safely. So the whole thing has to be pushed out of the way each time I pack up for the night.



My original observing position became completely pointless as trees grew (and grew) around our garden. Ironically the view is clear all round in the drive just beyond the gate. But our neighbours are all afraid of the dark and need multiple bright lights on all night or they cannot sleep.

Somehow I had loosened the drive worm housings so the control paddle had no effect. The worm housings were moving around the wormwheels instead of the wormwheels being driven. I couldn't see this at first despite the bright moonlight. A 13mm spanner to the hex headed screw holding the housings soon solved that problem. The mounting then responded to the paddle controls.  

Full moon TZ7, 20mm no-name Plossl, 6" F:8 refractor. 
PhotoFiltre improved! Gamma reduction and contrast increase.

I was concentrating on Jupiter. Meanwhile everything was dripping wet with dew. Once, when I glanced through the telescope without the eyepiece and the objective was completely misted over! I broke with convention and mopped the front face with a clean handkerchief. 

I have a long, tubular, foam, slip-over dewshield extension but it was hiding somewhere in the shed. It is nothing fancy. Just a roll of black camping mattress and a rubber band. It works amazingly well compared with the stumpy, original, metal dewshield which came with the Celestron CR150HD.

 Jupiter proved far more difficult to capture. No visible markings even in the "best" of my hand-held, afocal snaps. I literally held the camera up to the eyepiece and snapped away every time I could see a bright blob on the camera screen. Two belts were clearly visible visually but I completely failed to capture them. I also lost a moon while reducing gamma in PhotoFiltre!  This is a heavily cropped shot with considerable gamma reduction to kill flare. Had I the patience I could have gone through the endless TZ7 menus and found spot metering. But I didn't. I had slightly more success with older digital cameras when photographing the planets in this crude way in the past.

 What I really need is a sleeve on the focussing mount to give the camera lens something to locate into. This would ensure centring on the eyepiece and also help with squaring-on.

I am always afraid to use a simple camera clamp to the focussing mount. Because the zoom lens might strike the eyepiece under power on camera switch-on. The lens seems to automatically extend for about an inch (25mm) each time the camera is switched on. This gives a fixed clamp no leeway to avoid direct camera lens to eyepiece contact.

These are my best images of Mars using simple hand-held, afocal methods.

A run through PhotoFiltre to enlarge, then adjust gamma and contrast has helped to bring out detail and reduce flare and false colour on the limb.

 Each image shows a different face of Mars.

A magnifying lens on the centre of the focussing screen would be useful for astronomy. I can't easily wear my reading glasses at the telescope just to enable me to monitor the camera screen. 

I don't own a laptop so can't try my webcam at the telescope. Without a camera clamp or lens, "nose socket" I can't take decent HD astro videos either.

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Fullerscopes drives

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I had a recent contact from France, enquiring about the drives on his MkIII. This has prompted me into publishing some details.

To follow the stars, the polar axis on an equatorial telescope mounting should be made to rotate in slightly less than 24 hours . In fact 23Hours : 56Minutes : 04Seconds is the desired period of rotation. The so-called Sidereal Day. A star will pass the same point on the night sky in this time. The polar axis is required to rotate once in 1436 minutes.

A clock running at Sidereal time runs slightly faster than a normal clock. The latter is based on 24 hours per day.  Or one revolution of the polar axis in 1440 minutes. 24 x 60 = 1440.

A 24 hour telescope drive is usually close enough. Because a variable frequency oscillator (VFO) will easily allow the motor to be sped up a little. Just enough to follow the stars more accurately.

The Fullerscopes MKIII mounting uses 144 tooth, bronze, worm wheels of about 82mm diameter. The 144:1 gear ratio requires a drive of one revolution in ten minutes on the worm. Or 1/10th rpm.

The MkIV mountings used much larger 6" worm wheels with 359 teeth. A difference of 2.5:1 compared with the MkIII mounting. The MkIV used much faster final drive speeds on their synchronous, drive motors. My own motor is rated at 1/4 rpm.  Or one final drive shaft revolution to the worm in four minutes.

The polar axis worm drive is usually provided by a geared, Crouzet, mains, synchronous motor. The motor requires 240Volts @ 50Hz mains supply in Europe.

Some basic MkIII mountings would have only a hand wheel or flexible stalk for a rather laborious hand drive to the worm. As seen in this image of a dual hand and motor drive (above). A slipping clutch in the bronze bush on the left of the worm housing allows the two drives to act independently. The clutch is a simple nylon plug pressing against the worm shaft. 

A much better drive option than manual on the MkIII was a tiny, synchronous, gearbox motor. (even without any means of variation to drive speed) This still provided all that was needed for visual observation. (see image) This tiny motor lasted for decades before the internal wiring broke away flush with the motor housing.

I have no idea if any Fullerscopes were exported to lands with alternative voltages or frequencies. They certainly called their best instruments their "Export" models.

The Crouzet motor backplates are always clearly marked with their power requirements and usually their final drive speed on the gearbox output shaft.

The declination axis was also supplied with an identical worm wheel and a reversible motor drive at extra cost when ordering.

Guy's MkIII mounting motors. The RA on the left and the reversible Dec motor on the right.

Only photography really requires greater accuracy in drive speed than a simple motor. The eye can easily forgive an object drifting slowly off-centre in the field of view. The telescope can be easily nudged to bring it back to centre again. While a camera will produce only fuzzy pictures if there is any "wandering" of the image being recorded. Long exposure photographs, particularly with long focus optics, are the most demanding of all!

Modern digital cameras can take very reasonable "snaps" of the Moon and planets. Provided, of course, that there is a drive to keep the object adequately centred in the eyepiece.

Fullerscopes could provide variable frequency oscillator drive boxes with control paddles. These VFOs changed over time. They usually consisted of a large, black box with various sockets and a hand-held, control paddle. The paddle and drive motors would be plugged into the sockets on the box via flexible leads furnished with a variety of "DIN" type plugs.

'Guy's complete VFO drive system with Hz indicator box. The paddle has a rear frequency control knob. Unlike mine which is on the front.

The Fullerscopes VFO box isolated the outputs with relays and transformers to ensure safety at the telescope. It would still be a good idea to provide an earth spike close to the telescope. To earth the pier and mounting together. A wooden tripod would need to be bypassed and an earth taken direct to the mounting.

The "Sync" light flashes at the frequency rate supplied by the VFO. Giving a handy confirmation that it is actually working. The flashing rate can change from a steady glow to rapid flashing when the VFO is set to maximum on the paddle control knob.

Reverse on the Polar Axis motor is simply an off switch. It just relies on the sky overtaking the now-stationary mounting. The VFO cannot provide enough over-speed to achieve meaningful slewing. So it does not attempt to.

Internal components of the VFO box. The two transformers isolate the output. Ensuring no heavy currents can flow in the event of a fault in the motor wiring.

My Own VFO box has 3 and 5 pin motor connection sockets. 

In the UK it is common practice to use an RCD device on the mains lead to any electrical equipment which is used outside. Some European countries have only 2-pin plugs without any earth lead at all. Talking to a qualified electrician might be advisable. Particularly when considering the often damp nature of everything when observing under the night sky. Dew and icing is almost always a problem in some places. I have tried a simple test screwdriver on my mounting but it did not "light up".

A scan of an old, 1970s, Fullerscopes catalogue describing the "Skytracker" and MkIV mounting details.

A cropped and enlarged image of the Skytracker text.

Click for an enlargement.

Fullerscopes used the name "Skytracker" for their VFO drive systems. The one illustrated is a MkIV. This has nothing to do with which particular mounting it was used with. The 9 pin socket is for the paddle lead.


The mains socket has a lift up tab concealing the fuse. Do not be tempted to uprate the fuse if it blows! It is there for your safety and that of the electronics.

My MkIV mounting RA motor.

The colour codes for the connecting wires are: Orange to Live and grey to Neutral from the Skytracker lead.The Earth wire is earthed to a motor fixing screw.

These leads are from the output sockets of the Skytracker. Not the mains lead going into the Skytracker box.

 

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My reversible, MkIV mounting, Declination drive synchronous motor.

Here, the central Earth wire from the Skytracker box is connected to the purple motor wires.

The Live and Neutral Skytracker wires are connected to the motor's brown and white wires respectively.

The connecting lead from the Skytracker box to the Declination motor is pre-coiled. This allows the much greater movements typical of the Declination axis.

My control paddle seems less sophisticated than Guy's in some respects. 

His has lights to indicate in which direction the drive is being corrected. This gives direct confirmation that something is happening. Which is not always obvious through the eyepiece. Sometimes without a considerable delay.

The large knob on the front of my paddle adjusts the drive frequency up and down on either side of 50Hz. Judging by the flashing light on the large VFO box the top frequency is well over 100hz. It really is very rapid. The light stays steady when I have an exact 50Hz setting.

Push buttons provide a red light for use when the observer's eyes are dark adapted at the telescope. 

The other button brings the base frequency of the Skytracker back to 50hz. 

Internal view of the control paddle.

Here is Guy's superb website:

 http://astronomiedelangrola.pagesperso-orange.fr/index.html

Click on any image for an enlargement.

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Lunar eclipse Jun 2011

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A front was forecast to cross southern Denmark after an earlier promise of clear skies. At 55N the totality was taking place before moonrise. The eclipse would also be shorter than from viewpoints further south.

I spent a frustrating hour standing and staring at a strip of cloud travelling slowly across a very low moon. It was actually hovering between trees on the horizon for the first half hour. At times it was completely clear over much of the sky except where the invisible moon should have been! Only after 3/4 of an hour was there anything to see. Though I was determined not to miss any clearing. By the time it actually cleared only the last of the Earth's shadow was still covering the moon. 

The low line of sight was bound to put a lot more atmosphere (clouds) between the moon and my viewpoint compared with anything overhead. The eclipse was more than half over by the time I was able to recognise and capture the true disk of the moon. Until then it was just an occasional dim glow. Or oddly-shaped lighter blobs seen through gaps in the darker clouds. None of the images taken in the first 3/4 of an hour were worth sharing here. The later ones are bad enough!

23:48

 23:49

 23:52

 23:54

 23:55

23:55

23:58

At midnight the Moon clouded over again so I went to bed. The last shot above was adjusted to bring out the clouds. All the previous shots were gamma reduced to minimise the clouds and the flare they caused.

All Images taken  with a Panasonic Lumix TZ7 digital compact camera on Auto2. Usually resting on a fence post to help with the long exposures. Mostly at full, or near full optical zoom. The images were then heavily cropped to get more image scale. The cloud and very low lunar altitude made it a complete waste of time to get any of the telescopes out. Most of the eclipse took place behind a neighbour's tree. So I would have had to drag a heavy mounting the length of the drive. Then have no mains power for the drives.

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