TS 61EDP II Review

(March 2021)

Introduction

I was looking for a suitable wide field telescope I could use together with my ZWO ASI1600MM-cool camera. Several candidates passed the review. The main criteria where :

In the table below I made a comparison of the different scopes with their focal range, price and image scale in combination with different cameras (prices are from March 2021). The line in blue are the specs of the setup I'm already using. I've put it in the table to be able to compare of course. 

The TS CF-APO 70 was also a worthy candidate, because I could use my reducer/flattener I already owned. In combination it gave also a 3° field of view. But finally I decided to go for the TS 61EDPH II because it gave a slightly bigger field of view and the supplied reducer/flattener was especially tailored to work with this scope. 

Unboxing

I had a long email conversation with Telescope Service in Germany before finally ordering the package. At a certain moment they already placed to order for me, because it was the second to last scope they had in stock. Next deliveries where due for June/July, so 3 month later. It was send with UPS on a Friday and the next Tuesday it was delivered at my pick-up-point of choice. Opening the parcel is always a special moment, feels like childhood days unraveling the bow from your gift. 

TS-Optics 61EDPH II 6-Element FPL53 Flatfield-Apochromat

From the seller: "The TS-Optics 61EDPH is designed for astrophotographers and nature photographers. It convinces with its compact dimensions and its high-quality 3-element FPL53 lens (glass from Ohara - Japan). The 3-element corrector has been specially developed for this APO and produces a corrected image field with 44 mm diameter and without chromatic aberration, ideal for full-frame cameras. The fast aperture ratio of f/4.5 allows short exposure times. The 61EDPH is a fast and portable travel scope for astrophotography. " 

I couldn't actually make a better summery for where this scope is for. It's exactly the reason why I bought it.  


Build Quality

Immediately obvious is the fine build quality of this telescope. Nice aluminum tube with white mat coating on the outside with red glossy highlights. The inside of the optical tube is like black mat paint with several very fine baffles the entire length. It all feels very robust and smooth at the same time. 

The retractable dew shield tends to slip a bit when pointing at the zenit and I see no way to tighten it more to lock it in place. The red aluminum tube cover sits also a bit loose and falls of when pointing down. I quickly prevented this from happening again by installing a second thin strip of black felt.  

There's no locking screw* for the focuser to lock it into place, but it has an "Load Adjusting Screw" instead, it controls the tension of the focuser. I've noticed that the focuser can easily hold focus with my image train (camera and filter wheel) or a DSLR attached to it. 

The nicely finished and CNC constructed tube ring gives the scope a touch of red fashion. But again a minor point of critique, when the tube ring is  screwed closed, the scope can still move inside the ring, meaning the ring doesn't clamp the scope like it should. Again I needed to add two small strips of black felt to the inside of the ring to reduce the play and have the tube ring really lock the scope. 

The carrying handle is a nice feature to install for example a guide scope or other accessories. But it's not a convenient way the really carry your scope because the balance point (when camera attached etc. ) is way off so you have to twist your hand to keep it balanced. 

*An attentive reader, Dominique Dierick, pointed out to me there should be a locking screw in the package delivery. I was actually already wondering why I couldn't lock the focus as normally all focusers have this kind of screw. Long story short, I ultimately found the 'missing' screw. Only the bag was labelled 'screw for finder base', so initially I discarded this little bag, thinking I didn't need the screw. But of course it turned out to be the missing lock screw. So yes, you can lock the focuser in place. Thanks to Dominique for rectifying this. 


Specs

From the website of the retail seller Telescope Service. 

First Light

As it is very unusual to be able to test your new equipment the same day, I was lucky! The next three nights where forecast to be clear. So I got to 'work' immediately. I mounted the scope on my Celestron AVX mount during the day. I wanted to test it with my old Canon 450D DSLR to use it as a telephoto lens. As I was doing this in my backyard, I only could take a few pictures of the church tower, a W.O.I remembrance statue and some blossoms. I played a bit with ISO and shutter speed. 

The first two images were taken outside in my backyard and without the reducer attached so at a focal length op 336 mm. The last two with the reducer/flattener attached to the scope making it a 274 mm focal length and  were taken from inside thru double panned window. These images are the raw image from the camera, no editing done to it. 

The following hours after this, I was trying to get the equipment talking to my computer. I want to be as remote as possible. So the AVX mount is commanded by Cartes du Ciel and obviously I've installed a guide scope as well to be able to guide with PHD2. I orderded the guide scope with the package and it's a 50/162mm guide scope that you can mount on a simple finder shoe. 

Balancing the scope on the mount along the declination axis isn't so easy. It appears that the supplied dovetail is rather short. When you attach the camera and filter wheel it becomes really heavy at that side. So I'll probably have to invest in a larger dovetail to be able to slide it more forward. 

When night fell, I was finally ready to take a few pictures of the Horsehead Nebula. But not after a tedious process of trying to get optimal focus with my new guide scope. It's said that the focal plane of this scope is 22 mm behind the 1.25" receptacle. So I needed to fix the guide camera, my ASI120MC, as far out of the tube as I could and than fine tune with the rotatable lens cell in the front. As said, this took a while, but in theory it should only be done once. 

After calibrating in PHD2 I was ready for the very first test run.  I used N.I.N.A. to get the sub frames and to control the imaging session. 

Below you can see the Horsehead Nebula in H-alpha. Filter Astronomik 6nm and the camera ASI1600MM-Cool at -20°C. It's a stack of 3 frames only, total 720 seconds integration time. The backfocus isn't optimal yet, I need to buy different extension rings to reach the optimum of 55mm. In the corners you can see small elongated stars. Also Alnitak star (magnitude 1.85) has a significant halo. Unfortunately I don't think there's a way to get rid of it. It must be inherent to the setup I use. Anyway for 12 minutes of data this is absolutely promising.  I did some very basic post-processing to it in PixInsight, like noise reduction, dynamic background extraction, stretching and curves.

Second Light

The second night I wanted to see if I could use this wide field OTA on my primary (TS 130/910) setup. In total I'm having now around 16 kgs on my EQ6. The idea is to be able in the future to take the same DSO at different focal length and so also field of view. While looking for a nice wide field target, I realized I never shot NGC 1499, the California Nebula. So here I go. I had to hurry up though, because I only had a few hours before it went below my rooftop. In total I manged to get 40 minutes of total exposure, again some quick post-processing in PixInsight. 

This time the backfocus was better as I used another extension ring, but still not optimal. The halo around the bring star Menkib (magnitude 3.95) seems under control. 

The Reducer/Flattener

The reducer is a sturdy constructed 3-element APO lens. You can attach 2 inch filters to it, but than you have to first unscrew the reducer into two pieces. Than you can very carefully screw a 2 inch filter inside the reducer and put the two pieces back together. I have no 2 inch filters, but I imagine this will definitely take some practice to do this without putting dirty fingers on your filter.  

The back-focus required when using the reducer is 55 mm. In my case where I use a ASI1600MM-C camera and EFW, I need an additional spacing. I calculated this by subtracting  the 20 mm of the EFW and 6,5 mm of the camera from the 55 mm. So, 55-20-6,5 = 26,5 mm. I've solved this by using two adapters and some spacer rings. The 55 mm correct back-focus is quite critical for a correct illumination of the focal plane and thus round stars into the edges.

Third Light - Visual Observation 

The third night I spent some time using this telescope for visual use. To be able to use it visually you have to remove the reducer making the focal length of this scope 336 mm. I inserted my 2 inch diagonal in combination with a Baader 8-24 mm zoom eyepiece. With the big diagonal I had just a few millimeters to spare for focusing (the focuser was almost fully in).  

Star Clusters

I've decided to go for some nice and easy targets to start. The Pleiades M45 are just an astonishing  view with the 24 mm setting giving a 14x magnification. The same was true for the Beehive Cluster M44. Those two examples yield a very nice field of bright stars complimented with a lot of dimmer but fine jewels. Another obvious target was M42, Orion Nebula. The trapezium was nicely visible and around it the core nebulosity of Orion lit up.  

Next step was to explore the somehow smaller star clusters like, M35, M36, M37, M38, M48, M67, and NGC2244, they all where clearly visible. Although not what you would expect in a larger aperture scope, but still recognizable. Some dozens of small pin-point stars would best describe the view I had at these clusters. 

Double Stars

With this telescope having a resolving resolution of 2,26 arcsec. I tried a couple of double stars. To get the most out of my setup I turned the zoom eyepiece to 8 mm yielding a magnification of 42x. First was 54 Leonis a binary star with an angular separation of 6,60" in the constellation of Leo,  this seemed no problem at all. Another binary star I looked at was 38 Geminorum in Gemini. These stars have an angular separation of 7,40" so again no problem to resolve the two stars. 

Galaxies

As a final test I went to the pair of M81 (Bode's Galaxy) and M82 (Cigar Galaxy) galaxies. The two appeared beautifully in the eyepiece, again at 24 mm, although a bit faint the elliptical shape of M81 was clearly recognizable as well as the elongated shape of M82. 

M51, the Whirlpool Galaxy proved to be the limit of what I could see, at that night anyway. I was able to glimpse the faint structures of this galaxy using peripheral sight. 

Nature Observation

This telescope also suits well for nature observation or bird watching. The dovetail also has a 1/4" photo thread, so this APO fits, like a telephoto lens or DSLR, directly on every photo tripod. Together with my Baader Hyperion zoom eyepiece from 8 to 24 mm this gives a magnification range of 14x to 42x with very fine contrast and detail. So this scope is ideal as a grab and go for nature/daylight observing.  Below also a small movie of a tomtit, this was filmed with my mobile through the eyepiece at 14x magnification. 


First Full Color Image

In June 2021 I was finally able to put the TS-61EDPH-II to the ultimate test. The North America Nebula, NGC7000 is an ideal fit for the field of view of this wide field setup. Though the nights at my site are not astronomically dark, there were a few moonless nights with about four hours of potential imaging time.   I was also able to use the ZWO EAF (the new-5V version) for optimal auto focus. This new 5V version doesn't need a separate power supply, but gets its power from the USB cable directly connect to the PC. It's a great advantage and one cable less.

I decided to take RGB broadband and Ha, OIII narrowband data. The filters are from Astronomik 31mm, unmounted. The bandwidth of the narrowband is 6nm. In total 5.5 hrs of H-Alpha and O-III data combined with 1.1 hrs of RGB. The calibration and integration was done in Astro Pixel Processor and the processing in PixInsight together with Affinity Photo. For the combination of the NB data I used the NBRGBCombination script in PI to combine the RGB with HOO. 

Overall I'm quite pleased with the result and the performance of this telescope. At f4.5 it gives great details and contrast in a short amout of time. The stars in the corners keep their shape and color on my ASI1600MM sensor. 

Details of the Image

Date: June 7,8 - 2021

Integration Time: 6.6 hrs

Telescope: TS61EDPH-II at f4.5

Mount: Skywatcher EQ6-Synscan Go-To

Camera: ZWO ASI1600MM-Cool                             

Filters: Ha 31x300", OIII 35x300" R 20x60", G 21x60", B 25x60"

Bigger sensor test

Some widefield targets I took with this telescope can be found below. It's together with the QHY168C with APS-C sensor. I'm quite impressed about the star forms being almost perfect up into the corners. Sensor details: 4952x3288 pixels and 4.8 um pixel size. 

NGC 7000 - North America Nebula  - IC 5070 - Pelican Nebula

Chromatic Aberration

I was using this telescope for about 6 months when I got the chance of buying a dedicated one-shot-color camera, the QHY168C. Of course I was eager to try this OSC out together with this wide-field wonder. At first glance it gave a wonderful result. Have a look at these images: M31 - Andromeda Galaxy , NGC 7023 - Iris Nebula , Heart and Soul Nebula . 

Then I saw a video from Cuiv The Lazy Geek, explaining the potential problem with chromatic aberration in the Sharpstar 61 series. TS61 is basically the same telescope but other branding, so I did a closer investigation of my own pictures. Unfortunately I found out that my TS61 suffers indeed from this chromatic sickness. To be honest I was already wondering why I had all those blue halos around my bright stars, but this video made it all clear for me. I started to investigate further...

Image (left) taken with TS61 and without the reducer in the image train, to rule out the problem is in the reducer. In the close-up of M31 (below) the same blue halos are visible. That picture was taken with the reducer. 

On top of the chromatic aberration, the image without reducer (left, suffers also from coma. These elongated stars are very good visible in all four corners of this APS-sensor format camera, the QHY168C. This is why of course the reducer/field flattener has to be in place to take wide field, flat image frames. Below you see the same corner in the image of M31 taken with the reducer. The stars are round, but still some CA. 

Further testing for chromatic aberration I did with my mono camera, the ASI1600MM-cool. So I compared the 3 filters RGB. Obviously the Blue filter gave very blown-out stars with halos, so the conclusion for me was obvious, my TS61 suffers from "Chromatic Sickness". 

Return to Seller

After having coped with the shock of the diagnoses, I immediately contacted Telescope Service  in October 2021, my telescope had still warranty. They offered immediately to help to find out the problem and troubleshoot. That's why I took some of the test-images from above. Eventually the proposed to have it shipped back to them. They are going to replace the front lens-element or give me an entire new one. Both is fine for me. In the meantime of writing (December 2021). 

Got new Lens Cel

After more than 6 months due to the know delivery issues at that time (Covid-19) I finally got my telescope back from TS. They installed a new front lens cel and put it on the test bench. Customer service from TS assured me that I now would have a very good optical assemble performing very well with no to very little CA. Of course it took some time to put it the test due to lack of free time at the right (weather-wise) moment.  Below you see an image of Messier 45, the Pleiades, an remarkable result in my opinion. There's an obvious improvement in respect to the previous lens cel version. 

These are the 3 channels RGB. There's absolutely no halo anymore around the Bleu channel stars. In fact there's little or no halo around all the channels. 

The impressive improvement with the new lens cell can clearly be seen. To the far right was the original lens with CA. In the middle new data with the new lens. To the left the same data from the middle processed with "BlurXTerminator" in PixInsight. 

The come in the corners is with the reducer is also minimal. I'm quite happy with the result. 

Details of this image on Telescopius. 

Conclusion

TS-Optics has made a very affordable wide field telescope. Fulfilling my criteria, portability, weight, multi-discipline use. It has a very nice finish and it is definitely a well constructed telescope. Whether you are looking for a small refractor to do nature observation or for a small wide field APO for astrophotography, I can recommend this scope.  Given the small points of criticism, like the tube ring and dew cap issue, which were easily solved, it's a fine instrument. The reducer is a very nice instrument, only a little unfortunate that the attachment of a 2 inch filter inside takes a bit of fiddling. I'm very looking forward to put this scope to the ultimate test in Autumn when the most wide field targets present themselves in our Northern hemisphere. 

Finally after I got a new lens cel from TS and I was able to test the TS61 further I was really blown away. I'm really happy that TS was able  and willing to replace old lens cel. This is a really nice affordable telescope as an cheaper alternative for the high-end trademarks. Now, would I recommend it? Yes, but be sure to have an newer sample or one that has been upgraded with a new lens cel. I'm going to have lot's of fun with this one.