Reeny

I am in the early stages of using the 1.25-inch VisionKing ES clone 2x barlow (4-element) The results for your set-up will be slightly different, but I expect you will be pleasantly surprised using 50-52 degree Plossl type eyepieces on the ES or equivalent versions of the 4-element Barlow. I tried the 12mm Revelation/GSO type Plossl with 2x Barlow in the Heritage150 dob and wow - this is the combination I will be using the most from now on due to the unexpected wide angle view, and pin sharp image at 125x magnification. Sharp focus with wider angle 60-66-degree EP's was difficult due to edge distortion - probably due to the small secondary mirror . And the scope runs out of clarity at high magnification, so the 9mm barlowed Plossl worked OK, but was not ideal for the conditions during the initial test at 170x mag. The wider view needs to be checked out properly once the clouds clear. I still don't quite believe it myself, but there was at least 58-degrees or more available from the Barlowed Plossl. Maybe it was an optical illusion due to extended eye relief.

I use a similar filter and set-up on a 3" reflector scope (the cheap & chearful 76x700 type). The results were so good I upgraded to a Coronado PST last year. The 2x systems are useful depending on the solar features available. The cheap white light system is better for showing sun spots / the PST Ha scope for flares & surface disturbances. The full disc is visible for me at 700x focal length if the correct magnification of eyepiece is used (visual observing) Full disc photography is not possible with the 2m pixel SV105 or SV305 USB colour cameras.

I have the 150p Heritage (the manual scope, not go to) and I would struggle to use a barlow with the Heritage screw in plastic focuser. The barlow will extend the focal point away from the scope body, and require several turns of the focuser to get the sharpness back. The focus is the weak point on these telescopes. I can only use light weight eyepieces to avoid flex in the light path components. And I have nearly unscrewed the eyepiece holder completely out by accident. A 5mm eyepiece will be much better than 2x 10mm. The 25mm as supplied is a good eyepiece, but the 10mm is awful. My 4mm eyepiece has too much magnification to give a sharp image on most nights (at 188x mag) so a 5mm at 150x should be perfect for the scope. Make sure you get a light wieght 5mm if you go down that route. You can use O-rings or spacers to get all your EPs at the same focal point, to ease the set up time, with less twisting in & out of the focus adjuster.

Peter - my mistake, you are correct about the prism making no difference to the view. The black-outs have gone, but the view is just as bad - even with the prism adjusted. The left side of the view = 30-40% faded and blurred / The right side = 10% at the edge with missing detail. I found that lower magnification eyepieces can work around the problem by keeping a decent portion of the sun inside the sweet spot. ELP - most of the advice suggested to leave the settings alone, so I only moved the ring one hole - then I needed to move the ring back a few weeks ago. I have a hunch that squaring up the main prism has adjusted the light path. The elaton needed a tweak each time / both times. The main elaton on the gold tube appears to be OK now - but I will attempt a few adjustments beyond the limits of the factory settings in search of a better view. The double stack elaton has terrible slack & wobble on the adjuster threads as the ring screws out - the threads tighten up again as the elaton is screwed back towards the inner stop. Once the PST scope starts to work as it should, I can try to make improvements on the double stack unit by finding a decent setting further down the adjuster threads to stop the slack & wobble. For anyone considering the PST without the double stack unit - I can recommend binoviewers on a single stack PST to reduce light transmission, while increasing detail and contrast. I have a cheap pair of bino's which work well with the 1.85 barlow supplied, and 23mm Aspheric 62deg eyepieces (= 32x mag). The Bino's are used more than the £700 double stack unit.

The optical view was not good. The other thread I opened suggested that excessive tilt can cause banding - the picture of the prism above is with the tilt reduced. Either I am getting used to the "hit & miss" view, or the low powered 18mm supplied eyepiece and 12mm Plossl are helping to mask the problem. I don't notice any reflections at all, and the visual image is half decent. Note, As supplied new, the visual image needed to be moved left to right within the view finder to avoid looking at the burry bits. The prominences on the edge would completely disappear in certain dead spots within the eyepiece.

The thread could have placed this in equipment - but I thought solar observing would be a better place to find the advice for PST users.

Below is a summary of some easy gains on Coronado PST 40mm solar scopes. My apologies if some of the terminology is incorrect 1) Elaton - had backlash, slack and wobble. The M2 screw is located in a countersunk threaded hole, with very little of the Aluminium ring to grip onto. I managed to strip the threads on mine. Solution = Tap out to M3 so the hole is "less countersunk", and can grip the lock screw better. The new M3 screw should still fit nicely into the tuning ring below for a tighter fit. If not, you can thread that hole as well. 2) Small finder prism - comes loose easily if knocked while fixing the other faults. From the factory, mine was way off centre and needed fixing. Solution = Clean off all of the old loose clear silicone sealer with a knife / use a removable glue such as impact adhesive to re-attach the prism (fix the prism flush with the rear and the front inner surface of the case) Note: I avoided using 2-pack Araldite to allow re-adjusting at a later date. 3) Focus adjuster - had slack and sideways wobble. It was getting worse day-by-day as the hole in the case appeared to wear out on the steel bar. Solution = Pull the circlip off the shaft (just above the spring loaded brass spacer on the threaded bar) / remove the assembly / Take up the slack with a sleeve or spacer - e.g. a strip of white plastic, cut from a milk carton. Wrap the shim around the shaft. / reassemble. 4) Large focus prism adjustment - the usual mis-alignment, and the reason the side panel was removed. Solution = Twist the assembly back into shape, using the top surface as a guide. The soft tacky adhesive (holding the prism to the back plate) has loads of stretch - so do not be too gentle. Note: if the gold tube can be unscrewed from the front - you can check the alignment quickly & easily, without the need to remove the side panel.

I think the problem has been cracked with your help. Thank you to all the contributors. Focus prisms appear to be OK and will be left alone. The issue is likely to be the small-sweet spot, causing darkness and out-of-focus regions at the edge of the field of view (for visual and for imaging) - as described by InFINNityDeck above. A 2-week break in Scotland gave me at least one sunny day to test the basic set-up of the scope. Test = 24th Sept / exposure time reduced to around 6ms / focus adjusted for prominences / PST only, with no blocking filter / SV305 turned 180 degrees in the eyepiece holder to check for camera faults / eyepiece visual check for problems around the field of view. Outcome = single frames of the quick & dirty test videos were good enough to process without stacking / blocking filter not required for imaging / camera darkens and blurs the focus at the frame edges (left side & right side) / eyepiece viewing darkens and blurs the focus all around the edge circumference of the field of view / focus and brightness are good in centre of the field of view (or frame) / bleaching is tolerable if the camera image is taken in the middle of the frame (at the sweet spot). I found a review on AstronomySource-dot-com which sums up the problems with the relatively small diameter of the PST when used for imaging. Quote: the sweet spot would be smaller than the field of view, meaning the images would have a banded appearance. Note: the attached photos were a test to push the boundaries - not a final result. Hopefully the pictures will improve as I learn more.

Thanks Rusty, To simplify the process - I should be able to check the operation of the focus prism first, before the double stack etalon is attached. Then re-check with the double stack etalon fitted. I was surprised at the decent quality of the single stack optical view when setting up the PST last time, so I assume the scope & prism are OK, and my adjustments are to blame. No way would I consider opening up the side of a brand-new scope - The warranty will be used to return to the supplier if I have evidence of a mechanical fault. By chance, I used to operate spectrophotometer equipment in a chemical analysis laboratory 25-35 years ago - so I am (was) familiar with the tuning of diffraction gratings to single wavelengths, and I know it can be a fine a balance to get it spot on. I am happy with the results as a newbie with only 2x serious attempts so far, and know there is lots more to learn. Luckily I am in the right place.

Thanks everyone, I will play around with the tilt & etalon adjustments over the next few weeks. My tuning adjustments are likely to be the problem. If the problem remains, I can investigate the tuning prism as a last resort via the manufacturers warranty. The PST is a discounted customer return, so the "as new" scope has had a few trips with the courier before it reached me.

Thanks, I needed to get a clear picture on the laptop screen in bright sunlight. And the focus was targeted on getting rid of the blur at the edge of the disc, with a potential loss of focus in the centre of the image. I will try to adjust the exposure down a bit. I assume the process is focus and adjust contrast first, then tune down the exposure to a lower level. If I reduce the exposure rate down to around 12m/s, I will need to increase the gain to see the target. Yesterday the increased gain seemed to disturb the contrast. More tinkering and adjustment will be required to get a happy balance.

3-weeks on and the clouds have cleared, and I have had some spare time today to play with the settings. For some strange reason the 200 frame videos came out blue (the Sharpcap input may have been set to monochrome) / PIPP selected the best 8x pictures / sharpened / stacked / then converted to negative to obtain the orange colour. With Steve's help and advice above, I am more than happy with the results from the SV305 camera on my second attempt. My main problems appeared to be: A) not enough tilt on the double stack filter, causing a ghost image and difficulty with the focus / B the etalon needed to be re-tuned for the camera, not left adjusted for the best visual contrast / c) the lower exposure level of 25ms works well, I tuned the settings for the best view of the prominences - there will be even more improvement to come next time.

Thanks Steve, Reducing the exposure should bring the prominence's into focus, and sharpen up the left hand trailing edge as the sun moves left to right. (maybe due to pixel burn and slow response) Tuning the exposure may end up solving all 3x problems. - Cheers

While I try to tinker with the settings and sort out the problem by myself, I have a few newbie questions - just incase there is an easy answer out there. The Coronado PST / SV305 2mp colour camera / on an AZ mount is giving reasonable results for an amateurs slightly out of focus first attempt at solar imaging. The main issue is the bleaching at centre of frame, with darker edges to the sun = is there an easy fix, or a better way to capture. I am using Starcap, around 50ms exposure rate, with a medium gain adjusted to give contrast & detail, 200 frame avi video, 20x best frames kept, PIPP centering, registax, then picture sharpening & colour enhancing for contrast. The left hand side of the image was slightly out of focus when captured - I don't understand. Filters - I assume that an infra red / UV cut filter will be of no benfit to a double stacked <0.5 angstrom solar scope (as the signal will have been filtered by the scope already) Thanks in advance - a search of the forum topics failed to uncover any similar problems.

Yes - I think they were called shorties - it was the version with the camera threads on the end. As a 2x barlow, it was so bad that I cut it up when I needed parts to make adaptor bits & bobs, and was left with the removable end piece. The revelation 2x barlow has never let me down. My efforts above were in daylight focusing on distant trees. I had the binoviewer first light tonight on the crescent moon. And wow, it was worth the effort. With the supplied 1.85x barlow I could get focus, but there was a fringe halo of rainbow colours trying to come through on the edge of the moon = the set-up was difficult to focus, and never really sharp enough. Time to roll out the Revelation 3-element 2x Barlow. This gave a sharp focus, no edge colours, no shimmer from the atmosphere, and a massive magnification. It had the wow factor, so job done. When I tried the barlow and 16mm Maxvision 68-degree without the bino's - I got lots of shimmer. My guess is that the brain will cancel out the wobble due to atmospheric conditions when using the bino's. Ali express have 0.5 focal reducers for £4.69p with the sellers discount, so it would be rude not to buy one. It should be here in 4-weeks time.

A quick update on the Binoviewer. They arrived with the expected 20% import duty, well packaged in a cardboard box - no bag or aluminium case was advertised, so all good so far. The cost with the included 1.85x and 3x end piece barlows = £67.90p plus £21.34p import duty = £89.24p, Two 23mm cheap eyepieces (at £5.78p each) bring the total up to a very reasonable £101 The Skywatcher 200p dob reaches focus with the 1.85 barlow only. The 76mm x 700 newtonian needs the 1.85x and a skywatcher 2x barlow endpiece to extend the focal length. Magnification options are going to be more restrictive than I thought. Advice for gaining focus without a massive barlow magnification would be appreciated. I had hoped to have nice wide 23mm views. But I am stuck with a single magnification for each scope - 100x on the 200p / and over 100x on the cheap 3-inch Newt. Weirdly, the dob focus appears to be: too short with no barlow / just right with the 1.85x / too long with the 3x barlow Good points They are very comfortable and relaxing to use. They are good quality kit, similar to the BST / OVL version. With lots of independent focus on each eyepiece holder - about 12mm adjustment. So you can lock the scope focus and use the 2x eyepiece adjusters to fine tune if required. Bad points Needs the additional 1.85x Barlow for most Newtonian type scopes to reach focus. They add weight - I need to tighten up the focus tube tensioner screw to stop it slipping down. You may need 2x good quality eyepieces to get the best out of the binos = double the cost

Ali-Express should be able to deliver to Oz if you want a set of cheap binoveiwers to get you started. There is a sale on at the moment, so I ordered a set which are very similar, or the same as the BST Binoviewer. $130 Australian dollars, with a further money off voucher available from the seller if you click the right button, and $4 US discount voucher for new Ali-Express customers https://www.aliexpress.com/item/Free-shipping-Celestron-astronomical-telescope-eyepiece-double-binocular-head-clear-binoculars-special-accessories/32857924895.html?spm=a2g0s.9042311.0.0.6d9f4c4dmNVhwa I also bought 2x 23mm 62degree eyepieces for £6.60p / $12.20 Au https://www.aliexpress.com/item/SVBONY-Aspheric-Eyepiece-Telescope-HD-Wide-Angle-62-Degree-Lens-4-10-23mm-Fully-Coated-for/32788041500.html?spm=a2g0s.9042311.0.0.378d4c4dckvHEL Focal reducers are also available - but I am going to wait and see before buying https://www.aliexpress.com/item/SVBONY-1-25-Focal-Reducer-X-0-5-for-Astronomical-Telescope-Thread-M28x0-6-for-Astronomy/32809751148.html?spm=a2g0s.8937460.0.0.57ed2e0eIxkh3j I don't expect these to be the best kit available, but the package should light up the views of the moon on our little 76x700 Newtonian travel scope, and on Jupiter through the 200p Dob.

Get anything but the £21 Seben 7.5-22.5mm Zoom eyepiece. They are made with plastic internal parts, including the bottom two lenses in the Zoom mechanism.

They do a smaller 3-compartment version for 99p + £4 postage. I was hoping to get 2 for £6 all in. But no, they wanted £6 postage for goods worth less than £2 (£8 total). I was desperately looking for more stuff to add onto my order, but I ain't no fisherman.

This soft carry case came today. £4.99 and £4 postage = £9 delivered. It takes all 6x eyepieces, and 3x filter cases. I wasn't keen on the see-through plastic top - but it works well when you need to know where everything is. It was originally meant to house carp fishing bait tins, but the velcro dividers can be moved around to suit your EP sizes perfectly. Search for Koala products on Ebay http://stores.ebay.co.uk/KOALA-PRODUCTS-LTD-FISHING-TACKLE_Bait-Tackle-Acc-Bags_W0QQLHQ5fSellerWithStoreZ1QQLHQ5fTitleDescZ1QQ_fsubZ604052014QQ_sasiZ1QQ_sidZ361533554QQ_trksidZp4634Q2ec0Q2em322