After processing all of the images have had their levels adjusted to that the image is fully stretched with no midpoint adjustment and no image data clipped. It should be noted that the final images have not been produced to make them ‘pretty’ they are purely for the comparison of the wavelet/deconvolution options available. To improve the visual appearance of the final image a mid point adjustment and an unsharp mask is applied, as shown in the final image.

The original 30 second video (15fps) was captured with the DMK41 mounted to a PST Stage 1 modified Lyra Optic 4″ f/11 refractor, seeing conditions was no more than average with the sun very low over the surrounding rooftops.

The images below show various treatments applied to the single stacked FITS image produced by Registax v6 after alignment of the video frames.

This is the single stacked image straight from Registax v6. If you want to play with the original FITS file it can be downloaded here

The next three images show the stacked image with Registax v6 wavelets applied in 3 levels of aggression.

The next image shows the Registax v6 stacked image processed in PixInsight to remove the vignetting on the right hand side of the original image. The vignetting was removed by using the Dynamic Background Extraction (DBE) in PixInsight.

The image below is the DBE processed image with the PixInsight deconvolution function applied.

A levels mid point adjustment is now applied to lighten the image and a touch of unsharp mask to tighten up the edges.

Other adjustments could be made to visually improve the image like curves adjustment and colourising.

With the expert help of -the solar imagers on Stargazers Lounge (SGL), including Merlin66 and JohninDerby,  this post covers the journey of one Coronado PST solarscope as it is converted into an 1100mm f/11 solar imaging system using a Lyra Optic 4″ f/11 refractor telescope. The standard PST has a focal length of 400mm and an aperture of f/10 and is very capable of taking excellent images like the one below but we always want more.

The Stage 1 modification allows the PST black box to be used in the back of a larger telescope by the addition of a nose piece to the PST and the fitting of an Energy Rejection Filter (ERF) on the front of the telescope. The nose piece needs to be anodised and then lined with 0.020″ Protostar Flockboard to minimise any internal reflections. This simple Stage 1 modification will allow me to check the amount of telescope tube I need to remove in order to place the etalon 200mm inside the prime focus of the telescope.

The Stage 2 modification will replace the PST black box with a helical focuser and Coronado BF-15 blocking filter.

The heart of the PST system is the Fabry-Perot Etalon. The PST can tune the filter by the rotation of the “tilting” element, an aluminum grid covered in textured rubber. This way it is possible to tune the filter onto the “correct” frequency, and mechanically the effect is that of translating one of the two filter components, and to compress or relax the orange elastic seal in between the two filters.

The next step will be to calculate the optimum position of the PST etalon relative to the objective lens of the Lyra Optic telescope

….. to be continued

01/11/11
The Baader D-ERF has arrived and I collected the Lyra Optic 4″ f11 refractor telescope today. The Lyra Optic scope is almost too pretty to cut up but it is being sacrificed for a good cause and the very smooth high quality dual speed crayford focuser will be refitted the back of the scope during the conversion. A Celestron CG5-GT mount is due to be delivered tomorrow, more toys to play with

02/12/11
I decided to return the Baader 75mm D-ERF which was going to be installed internally and I’ve ordered the Baader 110mm D-ERF from Teleskop-Service so I can make up a D-ERF cell that will simply fit on the end of the Lyra Optic telescope. This will give me the full 4″ aperture and remove any issues with thermal currents that an internal ERF may of caused.

The Celestron CG5-GT mount also arrived today, if the weather is ok tomorrow I’ll take a few pictures of the scope and mount.

03/12/11
The BF-15 blocking filter arrived from HandsOnOptics (LP = 80mm)

04/12/11
The Lyra Optic 4″ f/11 refractor telescope

05/12/11
A little bit of the sun playing hide and seek with the clouds allowed me to measure the optimum cutting distance on the scope tube. With the focuser drawtube at 15mm it looks like I need to remove 75mm of tube to put the front of the etalon ‘rubber band’ 200mm inside the focal point of the objective lens.

06/12/11
Superb service from Teleskop-Service saw the replacement Baader 110mm D-ERF arrive today

The Lyra Optic scope tube is in workshop being chopped down and re-threaded, and a 4″ male to male adaptor is being made to allow me to restore the telescope back to its original length. Things are moving along very nicely for the Stage 1 modification, my thanks go to BICO Engineering for their support.

I still need to source the Helical focuser and extension tubes for the Stage 2 modification.

07/12/11
The Borg Helical Focuser M – M68.8 – Part #7835 has been located and ordered from Hutech in the States, this was the main piece missing for the Stage 2 modification. (LP = 63-83mm)

Borg Helical Focuser M - M68.8 - Part #7835

14/12/11
The Lyra optic refractor came back from the workshop today with the modifications complete.

The modified Lyra Optic refractor with the 4″ diameter 75mm long extension tube made from the cutoff section of scope tube

The 4″ diameter 75mm long extension tube made from the cutoff section of scope tube

The 4″ diameter x 1mm pitch male to male adaptor piece.

16/12/11
Teleskop-Service excelled again with a very fast delivery of the TS 8×50 right angle finder scope from Germany

Modified Lyra Optic 4″ f/11 refractor telescope with Teleskop-Service 8×50 right angle finder scope fitted with a Baader solar film cap to act as a sunfinder.

The Borg Helical Focuser M – M68.8 – Part #7835 also arrived today from Hutech in the USA. A beautifully engineered helical focuser that has a remarkably smooth and precise focusing adjustment.

Focuser details

• Index Marks – 80 microns
• Length – 63 to 82 mm (19 mm travel)
• Weight – 320 g
• Front interface – M68.8 P0.75 Male
• Rear interface – M60 P0.75 Male, M57 P0.75 Female

A few adaptors to acquired and machine in the new year and the Stage 2 PST modification will be complete.

Borg adaptors#7522 (LP=12mm) and #7317 (LP=24mm) will convert the rear of the focuser into a 1.25″ EP holder.

Borg #7522 - M57 to M36.4 /M42p0.75 T-thread Adapter

Borg #7317- 1.25" eyepiece holder

and modifying the Borg SCT to Helical Focuser M/T Adapter – Part #7428 (LP = 29mm) will give me the adaptor for connecting the helical focuser to the PST Etalon.

Borg #7428 - SCT to Helical Focuser M/T Adapter

These extra Borg components have been ordered from www.hutech.com so they should be with me in the new year.

17/12/11
First Light

The image above was taken using a DMK41 CCD without the 2.5x Powermate.

The images below are with the 2.5x Powermate

18/12/11
During First Light yesterday I noticed that my normal tuning position of the etalon, which is typically about 5mm from the travel end stop, had shifted slightly and I was having to put the tuning ring right against the travel end stop for the imaging. As I wasn’t totally sure that I had reached the optimum tuning position I opted to reset the travel end stop of the PST etalon. I moved the end stop by 2 holes and then tried some imaging today and sure enough I wasn’t quite tuned correctly yesterday and todays images are an improvement.

<———————————————– 343,000 kilometers ————————————————–>

I also did some magnification and resolution calculations.

The Lyra Optic 4″ f/11 has an 1100mm focal length and using the DMK41 CCD camera I am achieving the following fields of view (FoV) when imaging the sun which has a subtended angle of 0.52 degrees.

• Without a 2.5x Powermate the FoV is 0.32 x 0.24 degrees
• With a 2.5x Powermate the FoV is 0.13 x 0.10 degrees

Given that the sun diameter is 1,392,000 kilometers this means that at the maximum magnification with the Powermate my horizontal field of view is 343,000 kilometers. Putting this in perspective in the high magnification image above I could put about 27 Earths, which has a diameter of  12,756 km, across the image!

Dawes Limit: The theoretical Dawes limit for a 4″ telescope is 1.14 arcsecs so:

• Using the DMK41 without the 2.5X Powermate I get 0.85 arcsec/pixel
• Using the DMK41 with the 2.5X Powermate I get 0.34 arcsec/pixel

The atmospheric turbulence typically limits resolution to 1-2 arcsecs.

The Baader D-ERF needs to be securely mounted to the front of the Lyra Optic refractor telescope and needs to be manufactured. If it comes off then either the camera or my eyes are at risk.

The Baader D-ERF will have nitrile o-rings around the sides and top and bottom to act as shock absorbers and allow some movement of the filter so it can be tilted to avoid any ghost reflections.

23/12/11
A quick play, in white light, with the Lyra Optic 4″ f/11 refractor fitted with a DMK41 and 2.5x Powermate to image Jupiter. I used a 80mm 2″ extension tube and Williams Optics Dielectric diagonal to achieve focus rather than fitting the specially manufactured 4″ extension tube.

04/01/12

The D-ERF lens cell has been completed, it was made from Tufnol in the end as I couldn’t locate any 150mm diameter aluminium bar stock. The Borg components have arrived but are currently going through the UK customs system. One final piece will need to be manufactured, this piece will allow the Borg #7428 – SCT to Helical Focuser M/T Adapter to be connected to the rear of the PST Etalon.

05/01/12

Trial fit of the BF-15 blocking filter, the Borg focuser and adaptors and the PST Etalon with 2″ nose piece.

The front Borg adaptor has a SCT thread (2″ x 24 tpi) on the scope end which I need to remove and replace with a M50 x1P thread to connect to the PST Etalon. At the moment the working distance from the front of the BF-15 housing to the front of the PST Etalon knurled ring is 145mm when the focuser is at 10mm i.e. mid travel.

I think when I modify the Borg adaptor I’ll shorten it another 5-10mm as it will be easier to make the optical path longer but more difficult to shorten it.

11/01/12
All of the machining is now completed and all the optics have been cleaned off ready for ‘first light’ with the PST Stage 2 modified Lyra Optic 4″ f/11 refractor. Hopefully the weather will be good this weekend ! The SCT adaptor was machined out to remove the 2″ x 24tpi thread and an aluminium bush press fitted into the recess, this bush was then threaded with a female M50 x 1p thread to fit the rear of the PST etalon.

13/01/12

PST Stage 2 – First Light

The following images are taken with the PST Stage 2 modification, the system still needs tweaking but I’m pleased with the first light images considering the high hazy cloud. With the components I’ve use the system comes to focus using a DMK41 ccd camera with the Borg focuser at 8mm, very close to the midpoint of the 19mm of travel so I’m pleased with the adjustment I have.

30/01/12
I’ve just taken delivery of a Skywatcher N-EQ6 Pro syntrek mount and Hitec EQMod adaptor to stiffen up the telescope and mount to improve the image quality. I’ve also started a small project to remote control the focus on the telescope to remove any vibration issues.

03/02/2012
On the advice of the more experienced Solar imagers I’ve removed the mini-ERF from the front (scope side) of the Coronado BF-15 blocking filter diagonal. This should reduce some ghosting which is apparent where the light is hitting one glass surface and bouncing back onto another surface in the optical path. A benefit of controlling the ghost problem is the increase in contrast which will improve the image quality.

The 3M HTD pulleys and belts have also arrived to finish off the remote focusing project which will be driven using a Hitec DcFocuser and Skywatcher focus motor controlled with the Ascom drivers.

It’s important to say that the PST Solarscope is completely unmodified by this addition.

Click here to view the video on YouTube.

I’ve mounted the Coronado PST Solarscope in an aluminium channel primarily so I can have the skywatcher dovetail on the side of the PST Solarscope. This allows the eye piece tube and CCD camera to be positioned above the solarscope rather than hanging off sideways during normal use on an Skywatcher EQ3 Synscan Pro mount.

The aluminium channel is then used to provide a mounting location for the Orion Accufocus motor system to avoid any damage to the PST. The gearing is 1 : 1 and is made from a Como/MFA multi ratio gear kit. The adaptor shafts to connect the gears to the motor and the PST focus knob have been machined up to suit the various diameters and small grub screws are used to lock the adaptors onto the motor and PST focus knob.

The Lee big stopper ND filter is a high quality neutral density (ND) filter which provides 10 stops of light attenuation. To put this into perspective most ND filters only have between 1 and 3 stops of light attenuation.

A typical photograph, taken in full sun without a filter, might have an exposure of 1/60 second @ f16 iso 100. With the filter installed on the lens to get the same photograph the exposure would need to be 15 seconds @ f16 iso 100. If you photograph a stream in a shaded woodland, without the filter the shutter speed might be 1 second @ f16, with the Lee big stopper filter the shutter speed would be 15 minutes ! yes, that’s not a typo the exposure would be 15 minutes @ f16 iso 100.

The extreme increase in shutter speed means that the photograph will contain a lot of motion blur, the water will turn to a silky smooth finish and you get some blurring of the foliage unless there is zero wind which is very rare. It also means your tripod needs to be rock solid and a cable release is essential to get a really sharp photograph. I would also recommend turning off long exposure noise reduction in the camera unless you want to wait for the dark frame to be processed.

This example shows the difference between a photograph taken at 1/50 second and one taken at 15 minutes.

(hover your mouse over the image to see the long exposure version)

One thing to note about the filter is the slight colour cast it produces, this colour cast can easily be removed in Photoshop or by using a custom white balance in the camera. Personally I like the colour cast as it gives photographs a slightly old feeling to them.

Click here to view the video on YouTube.

A few more images taken during the same session using exposures between 10 and 20 minutes.

and finally an HDR image taken with 5 minute, 10 minute and 20 minute exposures

The development of the Lyra Optic 4″ f/11 H-a Solarscope can be seen here

A short tutorial for processing the Hydrogen Alpha photographs can be read on this page

Current solar images from February 2012, taken using the excellent Daves Solar System Recorder software (DSSR) which is now available as a beta release for public use.

The International Space Station (ISS) can easily be spotted with the naked eye and can be photographed fairly easily. Because of its size (110m x 100m x 30m) it reflects a lot of sunlight. The International Space Station webpage on the NASA website contains a wealth of information on the ISS.

The best time to observe the ISS is when it is night time at your location, but the Space Station needs to be sunlit. This normally occurs in the morning before sunrise or in the evening after sunset.

The Google gadget below shows is the current ISS position in realtime.

The visibilty of the ISS from your location depends on the current track of the ISS and the local time so there are long periods when the ISS isn’t visible. For example during July 2011 the ISS is rarely visible from the UK but in August 2011 it is visible every day except one.

The Heavens Above website allows you to enter your location and find out when the ISS is visible. Another good site for tracking the ISS is Calsky, this site has the benefit of calculating Solar transits which can be fascinating to observe BUT you must use adequate solar protection if you are using a telescope or binoculars, the sun is capable of blinding you so please do not be stupid. A good realtime tracking website to see where the ISS is and where it can be observed from is called ISS Tracker.

The ferrofluid can be used in the design of high quality loud speakers, low friction bearings and medical use. It can also be fun to photograph the magnetic poles that are shown by the magnetic particles in the base liquid!

Click here to view the video on YouTube.

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