Sharpstar 61 EDPH III
Sharpstar 61 EDPH III is fully set up. Note that this cable setup was wired for my RASA so cable management for this wasn't the best.
Sharpstar EDPH III set on the mount waiting for dark skies to arrive.
Sharpstar 61EDPH III Dimensions - Sharpstar main website.
Sharpstar 61 EDPH III thread dimensions
Sharpstar 61 EDPH III Field Flattener dimensions.
Sharpstar 61 EDPH III Reducer/ flattener dimensions.
The Sharpstar 61 EDPH III (EDPH III) is the next-in-line triplet APO on the EDPH 61 series, which comprises two low-dispersion ED glass, but the third type is not mentioned.
This widefield scope is short, light, and red, white, and black in colour. So if you are a ZWO fan, or use ZWO products, these match perfectly with each other! The EDPH III has some updated features from the last version including a better dew shield, rotator, and dovetail rail. The stats for the EDPH III are the following and compared to the EDPH II.
This widefield scope is short, light, and red, white, and black in colour. So if you are a ZWO fan, or use ZWO products, these match perfectly with each other! The EDPH III has some updated features from the last version including a better dew shield, rotator, and dovetail rail. The stats for the EDPH III are the following and compared to the EDPH II.
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The scope comes with an accessory rail as well as a guide scope rail. The accessory rail also doubles as a carry handle. Other attachments are a camera rotator, an extendable dew shield, a threaded system for reducers and flatteners and a medium format 2.5" dual-speed rack-and-pinion precision focuser.
The scope has adapters for 2” and 1.25” attachments as well as grub screws to help tighten and keep it in place. Not only that but a copper band goes around the opening, so the pressure is applied all the way around the eyepiece/ camera attachment, to help keep them in place but the pressure is still only applied from multiple single points (3 for the 2” and 1 for the 1.25”) |
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The 2" slot opening shows the banding with 3 thread locks to help secure any lens you instal.
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The 1.25" opening with the single thread and banding holding the eye piece securely in place.
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This section can be removed to attach a 0.75 x reducer/ flattener or just a field flattener, which is screwed in place, which will help the Field of View (FoV) and curvature correction. Cameras can be directly attached to these reducers and flatteners.
The scope was very well packaged, with plenty of foam and a strong sturdy double-packed box.
The scope retails for £427.78 ($528 - conversion prices) which isn’t (at the time of printing but is currently only available on AliExpress or direct from the company and a few limited UK stockists. The reducer/ flattener and the flattener retail for £161.19 each ($199 each). UK prices are slightly elevated from these prices listed.
The scope was very well packaged, with plenty of foam and a strong sturdy double-packed box.
The scope retails for £427.78 ($528 - conversion prices) which isn’t (at the time of printing but is currently only available on AliExpress or direct from the company and a few limited UK stockists. The reducer/ flattener and the flattener retail for £161.19 each ($199 each). UK prices are slightly elevated from these prices listed.
The Improvements
Dew shield
The dew shield is a vastly improved design. There is no movement in the dew shield and also has a screw at the end to tighten the dew shield in place, which stops all movement and sliding during the night and also holds the weight of an A3 light panel (with the small power bank on top) with no issues. The lens cap also has a better grip and no longer wants to fall off when you hang the scope towards the ground.
When moving the dew shield out you can feel the grip, which doesn’t give too much resistance but allows the dew shield to be moved with ease and stays in place, regardless of where you position it.
The Dew shield is also slightly smaller in diameter when compared to the EDPH II.
The dew shield is a vastly improved design. There is no movement in the dew shield and also has a screw at the end to tighten the dew shield in place, which stops all movement and sliding during the night and also holds the weight of an A3 light panel (with the small power bank on top) with no issues. The lens cap also has a better grip and no longer wants to fall off when you hang the scope towards the ground.
When moving the dew shield out you can feel the grip, which doesn’t give too much resistance but allows the dew shield to be moved with ease and stays in place, regardless of where you position it.
The Dew shield is also slightly smaller in diameter when compared to the EDPH II.
Dew shield lock nut change. A welcomed change to stop the dew shield from moving during the night, although the dew shield does appear to be better fitted.
Dovetail rail
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Dew shield difference comparison between the EDPH II (left) and the EDPH III (Right)
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The dovetail rail supplied is longer, fitted to an extended arm so it is further away from the body, and the modular system with Allen key bolts which are quick and easy to adjust, just by removing the bolts and moving the rail to the position required, then just installing the bolts again.
There is a slight down point to this, the holes with the Allen key bolts are spaced about an inch apart throughout the rail, although I never had an issue with balancing nor adjusting the rail. I’m just thankful the rail was extended from 3” to 8” which makes a huge difference.
Because the rail is fitted further away from the body of the scope, it allows for an Electronic Auto Focuser (EAF) to be attached without the movement of the focuser to avoid clashes.
The shoe which holds the scope has been redesigned. It is now smaller and thinner which allows for the tightening screw to be further away from the scope, stopping you from catching the scope with your fingers when trying to tighten the screw. It is also now black.
This is a massive improvement – although now the housing and shoe design holding the dovetail has been redesigned as well, there is little need to rotate the scope as everything fits in the original position. But overall a massive improvement!
There is a slight down point to this, the holes with the Allen key bolts are spaced about an inch apart throughout the rail, although I never had an issue with balancing nor adjusting the rail. I’m just thankful the rail was extended from 3” to 8” which makes a huge difference.
Because the rail is fitted further away from the body of the scope, it allows for an Electronic Auto Focuser (EAF) to be attached without the movement of the focuser to avoid clashes.
The shoe which holds the scope has been redesigned. It is now smaller and thinner which allows for the tightening screw to be further away from the scope, stopping you from catching the scope with your fingers when trying to tighten the screw. It is also now black.
This is a massive improvement – although now the housing and shoe design holding the dovetail has been redesigned as well, there is little need to rotate the scope as everything fits in the original position. But overall a massive improvement!
Side view of the Dovetail plate which measures 8inches in length.
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The dovetail plate on the EDPH III. Connected by threaded holes and four Allen screws spaced about an inch apart.
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Reducer/ flattener
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Chromatic Aberration was an issue with the EDPH II which is known as longitudinal, or axial aberration. This is where the different wavelengths of coloured light are focused at different distances from the surface of the camera’s sensor.
Using the new Reducer/flattener and the new flattener, there is no Chromatic Aberration in the pictures taken. It is good to see this issue has been sorted out as some EDPH II scopes did suffer from this, although, it was only noticeable in Broadband targets with either no filter or a UV/IR filter installed. The new Field Flattener for the EDPH III gives you additional options for the scope, keeping its full focal length, and wide field and flattening the FoV. This gives more options for the larger targets in the night sky but at the cost of a higher F/ ratio compared to the reducer flattener. |
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Chromatic Aberration from the Sharpstar EDPH II. Very noticeable purple stars from the different wavelengths focusing on the cameras sensor at different distances.
Both the field flattener and reducer flattener have threaded cover caps at both ends to help protect and cover the lenses. Both are well-made and are of metal construction.
Note that both the Field Flattener and the reducer flattener have internal threads to allow 2" filters. While it can be advantageous to install filters inside here, it is not recommended unless you are in a dust-free environment. The use of a filter drawer is recommended with any setup, but if you only have back focus and no filter drawer, these will be a good place to instal your filters. Although the space is tight and you could end up touching the filter or reducer/flattener glass leaving a greasy imprint on it.
Keep in mind if you wish to change from broadband to narrowband (and vice versa), you will need to take the setup apart to change the filters.
Note that both the Field Flattener and the reducer flattener have internal threads to allow 2" filters. While it can be advantageous to install filters inside here, it is not recommended unless you are in a dust-free environment. The use of a filter drawer is recommended with any setup, but if you only have back focus and no filter drawer, these will be a good place to instal your filters. Although the space is tight and you could end up touching the filter or reducer/flattener glass leaving a greasy imprint on it.
Keep in mind if you wish to change from broadband to narrowband (and vice versa), you will need to take the setup apart to change the filters.
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The EDPH II reducer/ flattener was 0.8x and the new version is 0.75x giving a slight difference in magnification but a minimal difference in FoV (See below).
Furthermore, Keep a note of is both the reducer and flattener are proprietary equipment and both the older versions from the EDPH II and other brands will not work with this scope.
There is a chance for the OVL field flattener will work with this scope, but this would require it to be slotted in over-threaded. This was never tested but does fall into the F/5.5 - 6 Focal ratio which OVL is meant to work. slotting in an OVL Field flattener has disadvantages with threaded tightening and the weight it has to hold at the back of the scope. There is a good chance, especially on cold nights, the thread will loosen and the camera train will fall out. This has happened to me on several occasions using my old SW 72 ed and would not recommend without upgrading to the clamping system to ensure your camera and equipment are safe.
Furthermore, Keep a note of is both the reducer and flattener are proprietary equipment and both the older versions from the EDPH II and other brands will not work with this scope.
There is a chance for the OVL field flattener will work with this scope, but this would require it to be slotted in over-threaded. This was never tested but does fall into the F/5.5 - 6 Focal ratio which OVL is meant to work. slotting in an OVL Field flattener has disadvantages with threaded tightening and the weight it has to hold at the back of the scope. There is a good chance, especially on cold nights, the thread will loosen and the camera train will fall out. This has happened to me on several occasions using my old SW 72 ed and would not recommend without upgrading to the clamping system to ensure your camera and equipment are safe.
Focusing
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The EDPH III is equipped with a medium format 2.5" dual-speed rack-and-pinion precision focuser. The colouring matches the scope over the gold colour from the EDPH II, but I can’t say much more than this as I only briefly tested this out before attaching an EAF to the scope.
On the plus side – the focusing chamber is still numbered. Allowing you to find your focal point faster by remembering the number over the distance from the edge of the focuser. |
The Dual-speed focuser with the EAF attached.
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Rotator
The rotator has gone through a big change. You no longer need a screwdriver to tighten the rotator, it is now a threaded bolt which is easy to grip and tighten, making rotating your scope much easier! Rotating the imaging train with the camera attached during the night was easy. It had minimal friction and was easy to tighten. While there are notches around the rotator, these are the same colour as the rotator, making it hard to see and also no angles to help with alignment or orientation. Overall a massive improvement. |
The Camera rotator. The black screw to control the movement and the notches for grip and orientation. Sadly no angles of degree for precise adjustment.
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Scopes thread
For the reducer: The primary lens focuser is attached to one end of the thread (M68 x 1), and a 2" filter thread is incorporated into the other end (M48 x 0.75). 55mm is the required back focus. The back focus changes to 75mm when the adapter is removed, revealing the M54 x 0.75 male thread. For the flattener: The primary lens focuser is attached to one end of the thread (M68 x 1), and a 2" filter thread is incorporated into the other end (M48 x 0.75). 55mm is the required back focus. The back focus changes to 81.5mm when the adapter is removed, revealing the M54 x 0.75 male thread. |
EDPH III threads to allow reducer/ flattener or the field flattener. M68
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FoV comparison between the EDPH II and III
Below are some comparisons between different cameras on the EDPH III and a comparison between the EDPH II and EDPH III. On the cross-comparison, you will notice minor FoV changes between the EDPH II and III with the EDPH III having a tighter FoV on both the reducer and without the reducer. The bottom picture shows some different camera options to use on the EDPH III.
Below are some comparisons between different cameras on the EDPH III and a comparison between the EDPH II and EDPH III. On the cross-comparison, you will notice minor FoV changes between the EDPH II and III with the EDPH III having a tighter FoV on both the reducer and without the reducer. The bottom picture shows some different camera options to use on the EDPH III.
FoV Comparison between the EDPH II and III with and without the reducer.
Other camera FoV options.
The CCD suitability also shows pixel sizes between 1.2 and 3.45 as min and max OK settings. Although under-sampling is not an issue with dithering and drizzling. it is also less of an issue with widefield lenses.
Additionally, the CCD suitability with the reducer attached is slightly different. showing between 0.9 and 2.55 as min and max. Again, under-sampling is not an issue as stated above.
Unless you are using a camera with very small pixel sizes, you will be under-sampled with nearly all cameras so Dithering and drizzling can be used to remove blocky pixels. With widefield images (seen further down) this won't really be an issue.
Additionally, the CCD suitability with the reducer attached is slightly different. showing between 0.9 and 2.55 as min and max. Again, under-sampling is not an issue as stated above.
Unless you are using a camera with very small pixel sizes, you will be under-sampled with nearly all cameras so Dithering and drizzling can be used to remove blocky pixels. With widefield images (seen further down) this won't really be an issue.
The night of data.
I've collected data for testing with every option on the EDPH III. 60 mins on both narrowband and broadband with the reducer attached, and about 45 mins on both Broadband and narrowband with the flattener attached. Keep in mind the Broadband was not for the picture but to test the stars.
Both attachments were of M13 - the Great Globular Cluster of Hercules and IC1396 - The elephants Trunk Nebula using the following settings and equipment.
Both attachments were of M13 - the Great Globular Cluster of Hercules and IC1396 - The elephants Trunk Nebula using the following settings and equipment.
- Sharpstar EDPH III with a ZWO EAF
- 0.8 Field flattener/ reducer on both targets
- Field Flattener on both targets
- ZWO Asi 533mc pro with a ZWO filter drawer
- UV/IR filter (M13)
- Optolong L Extreme (IC1396)
- ZWO 30mm Guide scope
- ZWO Asi 120mm mini guide camera
- ZWO ASIAir pro
- Skywatcher EQ 6 R pro goto mount
- Fox Halo power bank 96k
The night was calm, with little to no wind and clear all night. The moon was at around 45% and temperatures never fell below 6 degrees C.
I was at my regular Bortal 4 location in the south of the UK and the dew point was around 5 degrees and never affected the scope, nor the guide scope. Overall I had from about 23:00 to 03:00 darkish skies. Sunset was around 21:00-21:30 and the skies didn't darken till around 22:30 enough for certain stars to appear but the gradient of the night sky and the sunset didn't fully disappear until around 23:00.
I was at my regular Bortal 4 location in the south of the UK and the dew point was around 5 degrees and never affected the scope, nor the guide scope. Overall I had from about 23:00 to 03:00 darkish skies. Sunset was around 21:00-21:30 and the skies didn't darken till around 22:30 enough for certain stars to appear but the gradient of the night sky and the sunset didn't fully disappear until around 23:00.
Photos in session during the night. around 01:00.
Narrowband
I took 300 seconds sub-exposures in narrowband using the Optolong L extreme on IC1396, also known as the Elephants Trunk Nebula. This Nebula is a large nebula and the 0.8 reducer just about captures the target in one frame. The flattener only can capture the central part of the nebula, cutting out the outer edges but both came out very nicely.
Processing was simple and straightforward using the following method in Pixinsight:
I took 300 seconds sub-exposures in narrowband using the Optolong L extreme on IC1396, also known as the Elephants Trunk Nebula. This Nebula is a large nebula and the 0.8 reducer just about captures the target in one frame. The flattener only can capture the central part of the nebula, cutting out the outer edges but both came out very nicely.
Processing was simple and straightforward using the following method in Pixinsight:
- BlurXTerminator
- NoiseXTerminator
- Stretch the image with Histogram
- SCNR
- Background neutralization
- StarXTerminator
- Curve manipulation (stretch the image to bring out the detail)
- EZ HDR
- Dark Structure Enhance
- Add stars using Pixelmath
- Crop the image to remove the artefacts on the edges
Elephants trunk Nebula - 55 mins total exposure at 300 secs sub-exposures.
Elephants trunk Nebula - 45mins of total exposure at 300 secs sub-exposure.
IC1396 starless with the reducer/ flattener.
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IC1396 starless with the flattener only.
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Overall, the images came out well. Considering both pictures were under 1 hour of total exposure and on an OSC. I can only imagine what the pictures would look like with more exposure time and even a mono camera.
Broadband
Below is M13. The Great Globular Cluster of Hercules. these images are at 60 mins of exposure with the reducer and, only 35 mins with just the flattener at 60 sec sub-exposures (The sunrise crept up faster than I was hoping). Overall the stars appear to be a decent colour and have no Chromatic Aberration.
Although, one thing to note. my EAF was finding it difficult to find focus on the flattener. I'm putting this down to human error, as I have my ASIAir setup for my RASA mainly and never got the chance to correct the EAF for other scopes. So I had to manually focus with the EAF and I don't think I quite nailed the focus as the larger stars are slightly bloated.
Broadband
Below is M13. The Great Globular Cluster of Hercules. these images are at 60 mins of exposure with the reducer and, only 35 mins with just the flattener at 60 sec sub-exposures (The sunrise crept up faster than I was hoping). Overall the stars appear to be a decent colour and have no Chromatic Aberration.
Although, one thing to note. my EAF was finding it difficult to find focus on the flattener. I'm putting this down to human error, as I have my ASIAir setup for my RASA mainly and never got the chance to correct the EAF for other scopes. So I had to manually focus with the EAF and I don't think I quite nailed the focus as the larger stars are slightly bloated.
M13 - 34mins of total exposure at 60 secs sub-exposure. UV/IR filter. Flattener only.
M13 - 60 mins of total exposure at 60 secs sub-exposure. UV/IR filter. Reducer/ flattener
Pros, cons, and the negatives
I consider the cons to be two different types. There are bad points which aren’t necessarily an issue, but more of a pet hate of mine and the Negatives which I would consider bad points which would be better off changing, updating or improving. But that doesn’t mean to say they are wholly negative, but some aspects might be bad, but overall the item/ thing could be positive.
Pros
I consider the cons to be two different types. There are bad points which aren’t necessarily an issue, but more of a pet hate of mine and the Negatives which I would consider bad points which would be better off changing, updating or improving. But that doesn’t mean to say they are wholly negative, but some aspects might be bad, but overall the item/ thing could be positive.
Pros
- Improved dew shield and lens cap
- Improved camera rotation
- Improved dovetail shoe
- The options of a flattener and reducer/ flattener
- Improved scope housing
- Better colouring system of the scope and accessories
- No need to rotate the scope to attach an EAF to avoid clashing.
- Lightweight design
- No Chromatic Aberration in the broadband pictures
- Accessory rail and a guide scope shoe
- No degree markers on the camera rotator
- Dave tail shoe attachment holes are too far apart for precise movement. Although on Goto mounts this won’t be an issue if the mount’s shoe is large enough.
- Grub screws on the 2” and 1.25” adapter for eyepieces apply pressure on a single point, although it will apply more pressure to a wider surface due to the copper plate.
- Cost of the field flattener is slightly high. It has direct competition with the OVL Field Flattener.
- No UK stockist (at the time of writing)
- UPDATE - First Light optics have stock of this scope. Few others also but had no stock.
Conclusion
This scope is small, light, and compact. And is a vast improvement over the EDPH II by a large amount. Yes, there are some minor tweaks and changes which could be done but these are only minor. The negatives such as no or limited UK stockist are an easy fix, and I can’t understand why this hasn’t been implemented yet.
The big one, for me at least, is the cost of the field flattener compared to the reducer/ flattener. The reducer/ flattener holds so many more advantages over the flattener and with the price being the same, the most obvious choice is the reducer/ flattener for the better F/ratio. I feel the Flattener needs to be reduced in price to make it more competitive over its counterpart, especially since this is proprietary equipment.
The big win is with the comatic aberration. This alone is a relief to see that it has been sorted out, as seeing this in stars on Broadband targets was a big negative.
Overall, the changes which have been made are all positive, with only some silly cons which are not game-breaking but more helpful and make life simpler preferences. The change in the dew shield and the screw to secure it was a good change. It is now able to hold large light panels for calibration frames at the end of the night (or during the night if you so choose to), as well as actually holding up during the night.
The camera rotator is a vast improvement over the previous version, making it simpler and easier to rotate your camera during the night to frame up your target, although there is no measurement to know how much you have changed, but overall a very good improvement.
Overall this scope is a vast improvement over its predecessor and is a far better option if comparing both scopes. The option for a reducer/ flattener and a flattener can’t be ignored either (even with the disadvantage of the flattener) and is a requirement to have one or the other to make sure the FoV is flat. Something to think about if you are going to purchase this scope.
This scope is small, light, and compact. And is a vast improvement over the EDPH II by a large amount. Yes, there are some minor tweaks and changes which could be done but these are only minor. The negatives such as no or limited UK stockist are an easy fix, and I can’t understand why this hasn’t been implemented yet.
The big one, for me at least, is the cost of the field flattener compared to the reducer/ flattener. The reducer/ flattener holds so many more advantages over the flattener and with the price being the same, the most obvious choice is the reducer/ flattener for the better F/ratio. I feel the Flattener needs to be reduced in price to make it more competitive over its counterpart, especially since this is proprietary equipment.
The big win is with the comatic aberration. This alone is a relief to see that it has been sorted out, as seeing this in stars on Broadband targets was a big negative.
Overall, the changes which have been made are all positive, with only some silly cons which are not game-breaking but more helpful and make life simpler preferences. The change in the dew shield and the screw to secure it was a good change. It is now able to hold large light panels for calibration frames at the end of the night (or during the night if you so choose to), as well as actually holding up during the night.
The camera rotator is a vast improvement over the previous version, making it simpler and easier to rotate your camera during the night to frame up your target, although there is no measurement to know how much you have changed, but overall a very good improvement.
Overall this scope is a vast improvement over its predecessor and is a far better option if comparing both scopes. The option for a reducer/ flattener and a flattener can’t be ignored either (even with the disadvantage of the flattener) and is a requirement to have one or the other to make sure the FoV is flat. Something to think about if you are going to purchase this scope.