Sky-Watcher Evostar 72ED DS-Pro

[Skyline]

I think SW need to go back to the drawing board and produce a dedicated reducer for the scope. 

Someone call me lazy if you wish...

Edited November 6, 2018 by Skyline

[Stub Mandrel]

I have a suspicion that they are always made to require at least a small spacer to allow for variations in camera sensor distances.

Coma correctors don't seem to need similar adjustment so I'm guessing they are less critical as they work in a different way.

Edited November 6, 2018 by Stub Mandrel

[Adam J]

Has anyone tried this with a 1:1 flattner (no reduction) will that allow more back focus? If so which one did you use. I can live with F5.8.

This is shoddy from SW. 

Adam

 

[alexbb]

14 hours ago, Adam J said:

Has anyone tried this with a 1:1 flattner (no reduction) will that allow more back focus? If so which one did you use. I can live with F5.8.

This is shoddy from SW. 

Adam

 

I have some results with the OVL field flattener. I only added a few mm to the flattener-sensor distance so about 57mm and I was left with enough focus travel.

 

[RayD]

1 hour ago, moise212 said:

I have some results with the OVL field flattener. I only added a few mm to the flattener-sensor distance so about 57mm and I was left with enough focus travel.

Agreed.  I tried all sorts of spacing and testing with both, and for me the OVL one works better over all.

[alexbb]

One more thing: with the OVL flattener I measured the FL to be ~430mm and with the "dedicated" flattener, ~377mm. These were with the extra-spacers I used. With the OVL I had the backfocus at ~57mm and with the SW one it was at ~60mm.

[smr]

I'm still yet to get around to buying my first refractor. 

As the ED72 has been out for a few months now, I have a couple of questions...

Firstly, will it hold the weight of my Canon 80D DSLR? It's an APS-C DSLR and weighs a bit more than a Canon 700D but not more than a 7D Mk2.

Secondly, how easy is it to achieve a good reliable performance. Ideally I would want a refractor which I can just plug things into and it works, because I come from a photography background where you just pop a lens on and away you go, so spacing, and measuring, and back focus distance is all alien to me. Would it be easy enough for me to achieve, if someone would be so kind as to tell me what I need and give clear instructions as to how to go about fitting everything together.

Or 3) Would it be too much hassle and would I be better off buying a refractor like say, a Z73 and just buying the flattener for that and everything works straight away?

That's where I am at, any help or advice would be greatly appreciated.

[Susaron]

3 hours ago, smr said:

I'm still yet to get around to buying my first refractor. 

As the ED72 has been out for a few months now, I have a couple of questions...

Firstly, will it hold the weight of my Canon 80D DSLR? It's an APS-C DSLR and weighs a bit more than a Canon 700D but not more than a 7D Mk2.

Secondly, how easy is it to achieve a good reliable performance. Ideally I would want a refractor which I can just plug things into and it works, because I come from a photography background where you just pop a lens on and away you go, so spacing, and measuring, and back focus distance is all alien to me. Would it be easy enough for me to achieve, if someone would be so kind as to tell me what I need and give clear instructions as to how to go about fitting everything together.

Or 3) Would it be too much hassle and would I be better off buying a refractor like say, a Z73 and just buying the flattener for that and everything works straight away?

That's where I am at, any help or advice would be greatly appreciated.

 

Let´s go little by little.

1st Weight: I own a QHY168C cooled its weight is 700 grams aprox. plus the weight of the flattener-reducer and spacers I guess the total weight for the imaging trains could be around 1kg. At least I haven´t seen tilt or slip on the focuser.

2º As the QHY168C sensor is an APS-C from Nikon, I would recommend you the TS x0.79 reducer flattener in order to achieve focus. For a usual DSLR the distance from the M42 thread from the flattener to the sensor use to be 55mm, but with the TS reducer and this scope of 420mm focal length you will need 65mm. So the math is the following

Focuser + TS reducer + Extensors +M42 to Canon Bayonet (like this https://www.teleskop-express.de/shop/product_info.php/info/p194_TS-Optics-T2-Adaptor-for-CANON-EOS-Cameras.html)

The problem is that in TS page they do not specify the thickness of the M42 to Canon adapter, something important you need in order to achieve a perfect field with any refractor.

A list of M42 (T2) extensors with different thicknesses are available.

https://www.firstlightoptics.com/adapters/baader-t2-extension-12-16mm.html

https://www.firstlightoptics.com/adapters/t2-extension-tube-set.html

You should ask FLO or TS or any other dealer to get the data

Edited November 9, 2018 by Susaron

[smr]

On 09/11/2018 at 20:50, Susaron said:

 

Let´s go little by little.

1st Weight: I own a QHY168C cooled its weight is 700 grams aprox. plus the weight of the flattener-reducer and spacers I guess the total weight for the imaging trains could be around 1kg. At least I haven´t seen tilt or slip on the focuser.

2º As the QHY168C sensor is an APS-C from Nikon, I would recommend you the TS x0.79 reducer flattener in order to achieve focus. For a usual DSLR the distance from the M42 thread from the flattener to the sensor use to be 55mm, but with the TS reducer and this scope of 420mm focal length you will need 65mm. So the math is the following

Focuser + TS reducer + Extensors +M42 to Canon Bayonet (like this https://www.teleskop-express.de/shop/product_info.php/info/p194_TS-Optics-T2-Adaptor-for-CANON-EOS-Cameras.html)

The problem is that in TS page they do not specify the thickness of the M42 to Canon adapter, something important you need in order to achieve a perfect field with any refractor.

A list of M42 (T2) extensors with different thicknesses are available.

https://www.firstlightoptics.com/adapters/baader-t2-extension-12-16mm.html

https://www.firstlightoptics.com/adapters/t2-extension-tube-set.html

You should ask FLO or TS or any other dealer to get the data

exactly as I thought then, that just all sounds like loads of hassle and not what I want anyway, all I want is to buy the scope and whatever else I need, plug it all together and start imaging, I haven't got the knowledge or expertise to start faffing around with spacing etc. disappointing really as the scope is so cheap for what looks like great IQ. I don't want to reduce an already very wide focal length either.

[Susaron]

Mount, point and shoot....?? Unfortunately It is never as easy.

[smr]

26 minutes ago, Susaron said:

Mount, point and shoot....?? Unfortunately It is never as easy.

even compared to spending a bit more, ie. if I bought a WOZ73 scope and the flattener (and whatever else is needed to connect my DSLR) would I still have to faff around trying to get it to work, guessing what sort of combination will produce good images?

[Thalestris24]

Hi

Can someone kindly tell me how much just the evostar 72ed ota actually weighs (with or without tube rings)?

Oh, and how good/bad the colour correction is when imaging.

Also, has anyone compared it with the TS carbon tube 70ed? 

Thanks

Louise  

[Davey-T]

1 hour ago, Thalestris24 said:

Hi

Can someone kindly tell me how much just the evostar 72ed ota actually weighs (with or without tube rings)?

Oh, and how good/bad the colour correction is when imaging.

Also, has anyone compared it with the TS carbon tube 70ed? 

Thanks

Louise  

Not sure what he's covered but Ray has done a review of it.

Dave

https://www.youtube.com/watch?v=8AGEZULMwcg

 

[alexbb]

2 hours ago, Thalestris24 said:

Hi

Can someone kindly tell me how much just the evostar 72ed ota actually weighs (with or without tube rings)?

Oh, and how good/bad the colour correction is when imaging.

Also, has anyone compared it with the TS carbon tube 70ed? 

Thanks

Louise  

With rings, longer dovetail, flattener, it seems to weight 2.4kg.

Here you can see some images I shot with it. The Iris is solely with it, unfortunately I didn't process it properly yet, the others contain some older narrowband data too. You shouldn't see any CA effects on narrowband though.

Iris: https://stargazerslounge.com/topic/323530-iris-nebula-with-skywatcher-72ed/

Flaming star and Tadpoles: https://www.astrobin.com/373373/

Heart and Soul: https://www.astrobin.com/374116/

Clear skies,

Alex

 

[Thalestris24]

Thanks guys! The youtube video (Ray) says 1.95kg out of the box, with tube rings and dovetail. Obviously need to add the weights of bits. The ts carbon tube 70ED appears to be 1.7kg. I've been toying with the idea of using a 70/72mm as a guide scope that I could also use to image with (using an appropriate camera  ) but weight could be an issue so I want to get the lightest I can. At the moment I have a Celestron Travelscope 70 as a guide scope. With extension tube and qhy5l-ii guide cam it weighs a mere 0.8Kg - very light. Hmm... I'll have to think about it.

Cheers

Louise

[alexbb]

2 minutes ago, Thalestris24 said:

Thanks guys! The youtube video (Ray) says 1.95kg out of the box, with tube rings and dovetail. Obviously need to add the weights of bits. The ts carbon tube 70ED appears to be 1.7kg. I've been toying with the idea of using a 70/72mm as a guide scope that I could also use to image with (using an appropriate camera  ) but weight could be an issue so I want to get the lightest I can. At the moment I have a Celestron Travelscope 70 as a guide scope. With extension tube and qhy5l-ii guide cam it weighs a mere 0.8Kg - very light. Hmm... I'll have to think about it.

Cheers

Louise

I need to mention that I measured this by weighting myself with and without the scope and then subtracting. I cannot guarantee the measurement is 100% precise.

[Thalestris24]

1 minute ago, moise212 said:

I need to mention that I measured this by weighting myself with and without the scope and then subtracting. I cannot guarantee the measurement is 100% precise.

Probably why your value came in higher than Ray's ?

[alexbb]

1 minute ago, Thalestris24 said:

Probably why your value came in higher than Ray's ?

I would expect the longer dovetail and the flattener to add to the weight, though not by half a kilo.

[Thalestris24]

1 minute ago, moise212 said:

I would expect the longer dovetail and the flattener to add to the weight, though not by half a kilo.

It's ok, I'll take 1.95kg as the weight. The TS carbon tube at 1.7kg is pretty much the same but is a slightly smaller lens but no rings. It might just go directly in place of the Travelscope though I'll have to check tube diameters.

Cheers

Louise

[Davey-T]

1 hour ago, Thalestris24 said:

I'll have to check tube diameters.

The ED72E is 75mm.

Dave

[Thalestris24]

7 minutes ago, Davey-T said:

The ED72E is 75mm.

Dave

Thanks, but, um, it's 70ED I need to know the diameter of. The evostar comes with tube rings, the ts 70 doesn't so need to know if I can just put it in place of the Travelscope which appears to be 70mm. Hmm... TS quote 85mm which seems rather big but maybe something to do with the carbon tube?

Louise

[RayD]

11 hours ago, Thalestris24 said:

Thanks, but, um, it's 70ED I need to know the diameter of. The evostar comes with tube rings, the ts 70 doesn't so need to know if I can just put it in place of the Travelscope which appears to be 70mm. Hmm... TS quote 85mm which seems rather big but maybe something to do with the carbon tube?

Louise

Hi Louise,

I'd say that TS dimension isn't far out.  According to 365Astronomy the internal treaded dimension of the dew shield is 85mm (outside 97mm) so this would be about right.  I've not used or seen one, but looking at some images it does look like it has a pretty 'chunky' tube compared to the SW 72ED.

[Thalestris24]

1 hour ago, RayD said:

Hi Louise,

I'd say that TS dimension isn't far out.  According to 365Astronomy the internal treaded dimension of the dew shield is 85mm (outside 97mm) so this would be about right.  I've not used or seen one, but looking at some images it does look like it has a pretty 'chunky' tube compared to the SW 72ED.

Yeah, I've seen that, thanks. It's not of any real consequence though I might double check with TS. It's probably right as they offer 85mm clampshells as an accessory. How do you find the Evostar ED72? The business with the non-standard thread put me off a bit... Do you by any chance know much the Evostar tube on it's own weighs? No worries if you don't.

Cheers

Louise

[RayD]

1 hour ago, Thalestris24 said:

Yeah, I've seen that, thanks. It's not of any real consequence though I might double check with TS. It's probably right as they offer 85mm clampshells as an accessory. How do you find the Evostar ED72? The business with the non-standard thread put me off a bit... Do you by any chance know much the Evostar tube on it's own weighs? No worries if you don't.

Cheers

Louise

Unfortunately I don't recall weighing it on its own, sorry.  I'm away at the moment so can weigh it Saturday.

It's a good OTA for the price.  Naturally it isn't as well corrected as a decent triplet, but as a single box travel item it is ideal due to the light weight and small size.  I use mine with the OVL flattener at the minute as I just felt I got better results from that than the SW 80 one, but the SW does work adequately with a bit of fettling.

As I noted in my opening video, I suspect they have intended on this primarily being used for visual, for which it works well, albeit you need to be careful what eyepieces you use due to the limited inward focuser travel. 

In all I guess I would give it a 7/10 for imaging, 8/10 for visual and 10/10 for value.

[Thalestris24]

38 minutes ago, RayD said:

Unfortunately I don't recall weighing it on its own, sorry.  I'm away at the moment so can weigh it Saturday.

It's a good OTA for the price.  Naturally it isn't as well corrected as a decent triplet, but as a single box travel item it is ideal due to the light weight and small size.  I use mine with the OVL flattener at the minute as I just felt I got better results from that than the SW 80 one, but the SW does work adequately with a bit of fettling.

As I noted in my opening video, I suspect they have intended on this primarily being used for visual, for which it works well, albeit you need to be careful what eyepieces you use due to the limited inward focuser travel. 

In all I guess I would give it a 7/10 for imaging, 8/10 for visual and 10/10 for value.

No worries! As mentioned earlier, I was toying with the idea of using a small scope as a dual guidescope/imaging scope (in place of my lightweight Travelscope 70 guidescope) using a fast cmos camera with a small sensor. So wouldn't need a flattener but would need an extension tube. I need to dwell on it for a bit Thanks for the info

Louise