Sky-Watcher Evostar 72ED DS-Pro

[Shelster1973]

Have been humming and having over getting one of these, but seeing that image has swayed me and have just hit the button and bought one from FLO plus a flattener.  Went for the ED80 flattener with the adaptor as the dedicated ED72 one was showing a lead time of 7 million days.

Hopefully should all be here this week some time...along with 8 months of clouds

[Skyline]

Thanks for the clouds in Advance.

[knobby]

On 11/01/2019 at 09:02, Susaron said:

I also had to discard the SW reducer as I was not able to focus, due to the reducer thickness, then I went for the TS 0x79 using 65mm distance and it focus perfectly with both the IDAS and the Halpha filters.

The TS has a 2'' barrel and M48 thread for filter on the tube side so it fit better. I made the measurements in another comment in this same thread.

Is it me or is the TS flattener incredibly similar to the WO flat 6

https://www.darkframeoptics.com/product/william-optics-0x8-flattener-reducer-zs71

[Shelster1973]

Scope has arrived.....along with predicted rain too.

Flattener and adapter turn up tomorrow and will then only be waiting for the M48 adapter so I can attach my Nikon.

May have a try with my CCD and see what I can achieve with that

[knobby]

Seriously thinking of joining this club ! Going to try one on my SAM, WO ZS71 too heavy, WO ZS66 Petzval poor star shapes ... 72ED looks very interesting

[simmo39]

18 hours ago, knobby said:

Is it me or is the TS flattener incredibly similar to the WO flat 6

https://www.darkframeoptics.com/product/william-optics-0x8-flattener-reducer-zs71

I see what you mean, and its a bit cheaper too. I think some good research is needed here.?. I wonder if anybody has used one with an ED72. Im looking into getting  one and the TS flattener was the one I was looking at adding to the ED72 but this WO looks like another option.

[knobby]

Well, I'm joining club, just ordered a 72ED from FLO ...

I have a William Optics flat 6a, I'll give it a whirl.

[Shelster1973]

Can someone please sanity check the following.

FLO website shows the ED80 flattener (which works on the ED72) as 55mm.  Flange focal distance for my D7100 F-mount is 46.5mm, 48mm>Nikon adapter is 10mm which means I have 56.5mm which is beyond the focal point?  

This is sort of bourne out in real world as with it fitted i can focus on cars approx 50m away, yet cannot get focus on far objects / infinity as the draw tube does not retract far enough.

This leads on to the question of how on gods earth do i overcome this and get a useable setup?

[Cozzy]

Sounds like you need a thinner Nikon adaptor -if there is such a thing?

 

Tim 

[Shelster1973]

Just now, Cozzy said:

Sounds like you need a thinner Nikon adaptor -if there is such a thing?

 

Tim 

Am not sure if there is.  Have emailed FLO to see if they have any solution.

Will do some major Googleing to see if i can find a thinner one

[Cozzy]

I'm waiting for a clear night to try and get my spacing right for the ED72 -OVL FF to Canon 450D using the Delron spacers.

 

 

Tim

Edited January 31, 2019 by Cozzy

[Shelster1973]

4 minutes ago, Cozzy said:

I'm waiting for a clear night to try and get my spacing right for the ED72 -OVL FL to Canon 450D using the Delron spacers.

 

 

Tim

Cant you do this during the day on a far away object (not small...but far away...).  This is what I am doing at the moment as am lucky to be able to see houses on the far horizon

[Cozzy]

I unfortunately don't have sight of Horizons, I live at the edge of an housing estate.

I can get focus with no problems, my issue is slight curvature, so my OVL FF needs to be a bit further away from the camera chip (according to CCD Inspector)

OVL flattener at F5.5 to F6 should apparently be a perfect match for the ED72 F5.8, but hay-ho that's astronomy for you, you gotta love it.

good luck with your search hope you find a fix soon.

Edited January 31, 2019 by Cozzy

[Shelster1973]

I had similar in my last house.  Could get very far objects to start with, but as they continued with the development that view went away.

Have just had the following in from the great gods that are FLO

Hi Paul

Focus has nothing to do the reducer and its back focus requirement. The back focus of 55mm is to get the images free of distortion, it doesn't effect focus in any way and you should try on the night sky rather that on a terrestrial target. If you have the M48 ring fitted to the camera you will be at the correct distance as the rings are designed to give you the correct 55mm when connect to the reducer.

Will wait for a clear night (Ihopefully there will be one along soon) and see what I can achieve. Fingers crossed all is good

 

[Cozzy]

38 minutes ago, Shelster1973 said:

I had similar in my last house.  Could get very far objects to start with, but as they continued with the development that view went away.

Have just had the following in from the great gods that are FLO

Hi Paul

Focus has nothing to do the reducer and its back focus requirement. The back focus of 55mm is to get the images free of distortion, it doesn't effect focus in any way and you should try on the night sky rather that on a terrestrial target. If you have the M48 ring fitted to the camera you will be at the correct distance as the rings are designed to give you the correct 55mm when connect to the reducer.

Will wait for a clear night (Ihopefully there will be one along soon) and see what I can achieve. Fingers crossed all is good

 

 

That makes perfect sense.

If that's the same for the OVL FF and Canon adaptor I should be just 'fine tuning' my setup to alleviate the very slight curvature.

If I get time I will try both the unmodded and modded Canon cameras (1000D/450D). Just wondering whether the filter removal in the 450D is playing a part in the slight curvature.

looking like I may have a chance to test tonight. I'll feedback when/if I get the results.

Tim

[alexbb]

There are a few posts of mine where you can see how the field looks at 55mm, both with the OVL non reducing flattener and the SkyWatcher one. Both need more than 55mm of backfocus, I found ~60mm as acceptable. I used the SkyWatcher one more often and I focus at between the center and a corner, somewhere at 1/3 of the distance, away from the center to have a better performance at the corners without any noticeable loss at the center.

I measured the focal length with the OVL non reducing flattener as ~430mm and the focal length with the SW one as ~375mm. Both at ~60mm backfocus.

With the SW flattener and 60mm backfocus, I can barely reach focus at infinity.

[Cozzy]

Thanks for the info Alex?

[Shelster1973]

Think I may have found what the first parts I will be using my new 3D printer for...can anyone say M48 spacers?

[simmo39]

3 hours ago, knobby said:

Well, I'm joining club, just ordered a 72ED from FLO ...

I have a William Optics flat 6a, I'll give it a whirl.

Looking forward to hearing your thoughts on the William Optics flat 6a. Hope it works, it will save a few quid if it does!

[Shelster1973]

Have tried just now on a visible moon and no joy, cannot get draw tube retracted enough to achieve focus.  Is nearly there, but not quite.

Have emailed FLO with update, so now onwards to find a solution...

[knobby]

16 hours ago, Shelster1973 said:

Have tried just now on a visible moon and no joy, cannot get draw tube retracted enough to achieve focus.  Is nearly there, but not quite.

Have emailed FLO with update, so now onwards to find a solution...

I have 2 Nikon T adaptors and they are 0.5mm different in thickness ... not much but there are differences. Not sure when or where I got them though, had them years.

I'll be playing the spacing game tonight if scope arrives today !

[knobby]

Okey dokey, just got in from social duties, scope arrived safely from @FLO swiftly stuck the William Optics ZS71 flattener in the scope to see if I had enough focus range ...

Well a picture paints a thousand words so here's one showing the flattener in position and the same again but exposed to show the 'very rough handheld Moon shot ' on the monitor.

No time or chance to check star shapes but hopefully tomorrow if clear.

[Susaron]

It was I experimented, it is not the backfocus but the geometrical configuration of the sw reducer what denyes focus. The wo or the ts reducers are able to be inserted longer into the drawtube and also the barrel bigger than 2'' is thinner than in the sw. 

From my point of view it is a disaster that retailers still.offer the sw reducer for this scope having more valid options, the ts, altair astro, wo.

Edited January 19, 2019 by Susaron

[Susaron]

My focus point with the ts is approximately the same than.in knobby's picture

[knobby]

Hopefully I'll be able to check star shapes tonight ...