alexbb

1 hour ago, Susaron said:

I changed the m54 to m48 adapter from.one with 32mm length to another of 21mm

You mean the adapter to connect the flattener to the focuser?

The one provided by SkyWatcher at least is thinner, it adds maybe 5-8mm, I say this from memory.

You will notice more the wrong backfocus distance as the sensor size increases. An APS-C sensor is wider than the ASI1600/QHY168, but it also has larger pixels. However, I'd say you'll notice it.

The good thing is that you can increase the backfocus by adding some spacers between the flattener and a DSLR adapter, you have a few mm of thread available for that. I made one from a beer carton, it's 2-3mm thin and the stars shapes improved.

2 hours ago, Skyline said:

The 1100D has a pixel size of 5.2um

You'll notice even less then the aberrations.

2 minutes ago, Skyline said:

Which one is the Dedicated one ? the 0.85x ?

Yes. There's a "dedicated" flattener for the 72ED. I say "dedicated" because it's actually a flattener for the 80ED with a custom adapter for the focuser.

https://www.firstlightoptics.com/reducersflatteners/skywatcher-85x-reducerflattener-for-evostar-72ed-pro.html

Be careful that 60mm is the max backfocus with which you can still reach focus. I got acceptable results with an extra 2-3mm "spacer" with a DSLR. I believe the 1100D pixels are the same size as the 550D pixels are, 4.2um. With the ASI1600, the aberrations are a little more visible with 3.8um pixels.

Just now, Skyline said:

Which Flattener did you use may I ask please ?

The "dedicated" one with ~60mm backfocus.

Quick shot from last 2 nights, after main target and before dawn. 2 panels, each 36 or 38 x120s. IDAS-LP D2 filter was used. The halos (to the left) seem to appear also with other filters. I didn't notice them with the Esprit 80. Perhaps the flattener has a quite flat last element so it reflects more?!

I will keep adding to this, but for a preview you get the point.

Half res:

Full res:

I wasn't aware of the sensor size of your camera, I thought it was larger. Indeed, you will notice that the correct backfocus is not 55mm only with a larger sensor and smaller pixels. My pixels are 3.8um wide and I have 4656 of them on width.

2 minutes ago, Skyline said:

That is a full sensor image of a Atik 314L+

I only see it at 1391x1039

If only I knew...

OK, I put the ASI1600 on the little scope for some serious imaging (intended at least).

I increased the backfocus distance to 60mm and I'm left with 1-2mm focus distance. The stars don't look good enough around the corners and there's not enough focus distance to increase the backfocus. Meh..

You could probably get away with a small decrease in resolution or larger pixels. Mine's are 3.8um, an 18MP Canon APS-C sensor has 4.2um wide pixels.

Attached are a pic of the camera + adapters at the focus distance and an integration of 4h in Ha. No flats applied yet so the image was flattened in processing. A simple HT with STF parameters applied.

I did not spend too much time on this as I waited for the "dedicated" (cough) flattener to appear.

However, not having the stars shapes the same towards all corners means that something's not quite square. I somehow doubt that the optics are tilted, I would bet that the flattener doesn't stay perfect in the 2" holder. Try to improve on that.

On the real issue: you need to add more space. How much? I don't know. I put a few delrin spacers on the M42 thread and, since it wasn't enough and I did not have an available 7.5mm extender, I put also some more spacers between the flattener's last element (not really on the lens, but on it's holder) and the adapter to M42. I'm maybe 5mm further away now and the stars shape improved. Perhaps a few more mm would be even better.

All in all, I don't have an exact answer, but I believe an M42 7.5mm extender would do. Try also to tighten the flattener without tilt.

On 20/06/2018 at 17:10, FLO said:

Not sure what I think of running a dew-heater tape from USB...

Having a simple high/low switch in the cable is interesting but I think most people will want a dedicated controller. I might be wrong. 

Steve 

Seems TS or Astroshop have a few USB dew heaters https://www.teleskop-express.de/shop/product_info.php/info/p8576_AST-Optics-USB-Heating-Collar--40-cm-length.html

I will order one together with a Celestron Powertank Pro when they become available and let you know how it performs. It seems that in US the Celestron Powertank Pro is available already so it should be in EU soon too.

On 26/08/2018 at 12:51, FLO said:

We have learned the Evostar 72ED’s 0.85x reducer is the 0.85x reducer for Evostar 80ED, with a thread adapter. They are the same. So if someone already owns the reducer for 80ED then they need only our FLO 2” nosepiece adapter to use it with the 72ED. 

HTH

I tried yesterday to increase the backfocus distance. I used an m48->m42 and an m42->eos adapters. The total backfocus increased by ~8mm. The problem was that I could not reach focus anymore. The m54->flattener provided by SkyWatcher adds 6mm between the focuser and the flattener. So that's a no go. Even more, I can't unscrew the m48->m42 adapter from the m42->eos adapter, yay.

I tried then to make another spacer from a beer holder. This adds 2-3mm to the backfocus and it seems to be about enough after last night's tests. But with this I'm left with not much focus space. So 2-3mm of added backfocus + 6mm the SkyWatcher adapter and there are just a few mm left. I'm afraid that with the lynx 2" compression adapter and with the custom 2"->flattener FLO adapter, you might not be able to reach focus, especially if you want to increase the backfocus distance for rounder stars.

I don't know how much the FLO custom 2" to flattener adapter adds, but someone please check if possible.

The first image is where I can't reach focus, the second is in focus.

If I was not clear enough, I apologise, I'm on the phone. I can come back later.

4 minutes ago, RayD said:

Yes I fully understand what you're saying.  

Unfortunately in many cases, as with the corrector, retailers like FLO have the same information as us so only get to see the product when it arrives, just as we do.  To be fair to @FLO, as soon as they were aware this was the same corrector they immediately updated their site and even offered a refund to those who bought one and already had one for their 80ED. You can't get better or fairer than that in my book.  I suspect that they would do the same wherever this applies, or at least would confirm that the alternative was the same fit.  Naturally I can't speak for other suppliers, but this is just another reason why I prefer to use FLO as my experience shows that they are totally honest and do the right thing.

In industry it makes commercial sense to reuse parts where possible.  Take a look at the motoring industry for a clear example of this, where underneath one car lies a completely different one (Jaguar and Ford Mondeo springs to mind).

 

I'm not trying to argue in any way, I apologize if I left this impression.

I was just trying to mention that there are alternatives to some items and this is not obvious at first glance. While the info about the flattener was added indeed by FLO to the site, the info about the other parts I was referring to is only on the forum.

1 minute ago, RayD said:

I don't doubt that for one minute.  Equally I have several M54 fittings here that I have tried and they don't fit, so anyone buying an adaptor who doesn't have newt ones to try, or doesn't want to play a game of hit and miss, is probably better getting the FLO ones, I would have thought.

I would say that's wise.

OTOH, I waited a few months for this adapter to become available, while the one for the Newtonian was already available for long. I also waited a few weeks for an AZ-EQ5 Berlebach tripod, while one for HEQ5 was already in stock and actually on mine it is written HEQ5. Not to mention for how long I waited for the flattener for the 72ED...

Hopefully this info comes up on search engines. It would be useful also if FLO and others updated their offers to reflect this.

15 hours ago, Susaron said:

Regarding the reducer spacing I have checked my numbers with my QHY168, (another nightmare of camera with a lot of spacers), and it gives me around 56.5mm, when I use the camera with the Baader Mpcc I need around 57 to 57.5 mm to eliminate the coma, I will see what happens with the ED72.

I'm interested to see what you get with 57.5mm, but I have a feeling that we need more. I'm afraid 2.5mm is not that much. Maybe you can get away with the QHY168, as the 4/3" sensor is smaller than the APS-C sensor which is quite wider.

15 hours ago, RayD said:

There are actually a few custom adaptors that FLO has had specially made specifically for the 72ED due to the thread cut of the draw tube.  You can find the compression one here and there is also a M42 (T) and M48 one, which are all very good and work well with this OTA.

I've a few 2" compression adapters for my Newtonians and the adapter for the 72ED. They are identical.

3 minutes ago, RayD said:

I have a feeling they were in the dark with this as much as we were, and were also expecting a dedicated corrector.  I'm sure they are trying to find out as much as possible, and also keeping an eye on our testing as it is all a bit of an unknown at the minute.

Of that I'm pretty sure too. But if they act upset, maybe SkyWatcher could lean an ear towards them and maybe tell them some additional information. I've a feeling that if I asked SkyWatcher directly, I would receive no answer.

TS state that their 72ED with the 0.79x reducer/flattener works with a 65mm backfocus. I hope I will be able to test next week the 6/8/10mm M48 spacers and see which one fits better.

But I also do wonder if SkyWatcher do actually test their products. I mean, did they take at least a picture through this scope and the flattener? How did it look like?

This might be the last of the SkyWatcher products I buy new, maybe only if I find some tested sh bargains.

It's a pity that FLO need to provide extra check and fix for some of the scopes or that we need to sort out how a new product works. It is expected that we don't read the manual, but at least provide all the needed parts.

I'm increasingly disappointed by SkyWatcher lately with their strategy. The 150ED seems to have a lot of issues, the flattener for the 72ED was supposed to be a dedicated one and I waited since February to receive a flattener for actually an 80ED. Should I knew that by that time... Oh well, I hope at least we can figure out the spacing.

I wonder if @FLO has more priority to get an answer from SW about the correct distance for the 72ED + flattener.

1 minute ago, Marky1973 said:

This is interesting to know. Will follow this with interest and start experimenting when I get my camera back....was hoping the 56mm would still apply....but should have known it wouldn't be that easy! ??

Should be 55mm - 44mm + 11mm (the adapter). I hope you can shed some light with the Atik before I buy all the M48 extenders

1 minute ago, RayD said:

Thanks @moise212 very useful information. 

I think the spacing for the SW corrector is going to be different anyway as it is optimised for the 80ED meaning the 55mm is @ 600mm FL (f7.5).  With the 72 being 420mm FL (f5.8) I would have thought this will need some fettling, with the shorter FL needing more spacing (I think I'm right here but could equally be wrong and it needs less as my tiny brain finds it all very confusing).  The difference in spacing could be a fair bit.  As such I doubt very much that the standard 11mm T-ring is going to work perfectly with this corrector on the 72ED without additional spacing.

I am still waiting for some clear skies here to carry out any meaningful testing, but for me at the moment it seems the OVL FF works a little better, but it isn't a reducer.  However, at f5.8 I personally don't think the reducer element is essential as it is pretty quick anyway.

These are all just my thoughts and opinions of course, and I could be way off the mark and am happy to be corrected, but I am still actively trying to test and provide updated reviews.

I've the OVL flattener too, but I couldn't figure out the spacing yet for it. I added a few delring spacers on the M42 thread and some between the glass and the _something_ -> M42 adapter and it seems better. I will remove the spacers at some point and replace them with a 7.5mm M42 extender, but I'm not so excited about the 420mm FL. I really wanted the ~360mm FL.

The big issue is that I don't know the proper working distance of this combo, I don't know which length the M48 extender should be and I don't want to buy that many to sort out the spacing. Good thing is that I know somebody who might have a set.

All the SkyWatcher Panorama eyepieces reach focus with a SkyWatcher 2" diagonal. The 23mm 2" and the 15mm/7mm 1.25" with the 2"->1.25" adapter. The 1.25" eyepieces at the limit. But my SW 2"->1.25" adapter seems thinner than yours, Ray.

Anyway, I'm more interested about imaging with this scope and the "dedicated" flattener for 80ED disappoints me. The stars towards the edges don't look round, unfortunately. I used an M48 -> Canon EF adapter, screwed directly on the flattener.

I just came back from holiday yesterday and yesterday I received the flattener too. I will try to add a few more mm to the backfocus, but with the mono camera not soon. I don't have 48mm spacers/extenders to try this for the Canon DSLR.

This is a stack of 12x60s with a Canon 550D. Some darks, no flats, sorry, flattened in APP, STF in Pix. However, you can see the star shapes at the corners

Recently I opened my AZ-EQ5 mount for adjusting and greasing.

I did not find any complete tutorial for this nor worm or bearings dimensions. I plan to replace some of those if I have the chance.

Meanwhile, I will add some pics of the disassembly process.

1. Open the plastic top case. Please excuse the USB hub attached, I did not remove that.
   
    
2. Pull out the cable connectors. Put the top case with the controller board aside.
   
    
3. The bolt inside the green circle can help you remembering or adjusting the belt tension. Loosen down the RA motor screws. Remove the belt. Unscrew the bolts. Remove the motor.
   
    
4. The bolts inside the green circles can help you remember and adjust the worm distance to the RA main gear. Remove the bolts holding the worm case.
   
    
5. Parts: RA main gear, worm case.
   
    
6. Remove the screws holding the encoder board. You get access to the nut holding the worm in place. Remove this too.
   
    
7. Remove the bolts inside the driving gear attached to the worm. Sorry, not the best pic.
   
    
8. You can now proceed to push out the worm and the bearings. No pics for this, sorry.
   The bearings are 688Z, 16mm outer diameter, 8mm inner diameter, 5mm width.
   Worm dimensions measured with the caliper: 69mm, 36mm.
   

Hope someone finds this useful.

I'd be interested if the worm is identical to the ones used in the HEQ5.

Clear skies!

Alex

Seems that the power source that I got does it job easily, as expected.

This should do