Help with Skywatcher Esprit 100 and flattener

[Craig123]

Hi all 

I have just been getting things ready for a new season of imaging  with a new scope but wondered if anyone can pitch in with advice on the flattener and measuring the 56mm backfocus. The flattener comes with an 8mm  adaptor ring to connect the rest of the imaging train.. In my case ending with  an asi 1600  mono. Should I measure the back focus from the edge of the flattener by itself or from the edge of the assembled two parts ie. Ring and flattener .With the two parts together plus zwo spacers and FW it comes to 50mm  so adding the extra distance to  camera sensor gives 56.5..otherwise I might need to look at different spacers. Thanks 

Edited August 2, 2020 by Craig123

[johnturley]

59 minutes ago, Craig123 said:

 

I'm amazed how long the dew shield is, almost as long as the rest of the OTA, and a lot longer than on the 150

John 

Edited August 2, 2020 by johnturley

[Craig123]

3 minutes ago, johnturley said:

I'm amazed how long the dew shield is., almost as long as the rest of the OTA, and a lot longer than on the 150

John 

Yes.. When i opened the box I wasn't expecting it to slide out like that after being used to the Ed80 with its fixed dw shield 

[Stuart1971]

I think it should be measured from the back of the flattener...not the back of the small spacer, so you may have too much back focus there... unless the small spacer is part of the recommended 56mm, you will need to check that...

Edited August 2, 2020 by Stuart1971

[teoria_del_big_bang]

I need to double check but I thought the back focus distance should be 63mm from the edge below where it says 100 Field Corrector to the image sensor.

Also do not forget to add 1/3 of the thickness of your filters. In my case they were 2 mm so needed to add 0.67 mm (or approximately 0.7 mm ).

I also have the Esprit 100ED, a filter wheel which according to documentation is 29.6 mm wide (but measured it at 29.7 mm) and the AS1600 and have the following:

Seems to work fine for me. 

EDIT: The above is actually an old photo. The distances on the top row (6.5 + 29.7 + 20 + 8 ) actually add up to 64.2 which is 0..5 mm longer than the required 63.7 mm. This is because the nearest spacer I had was 20 mm and had to use this to begin with. Eventually I bought  15 mm + 4 mm + 0.5 mm spacers to make it correct. To be honest I am not sure I could see any difference when it was 0.5 mm incorrect.

Steve

 

 

Edited August 2, 2020 by teoria_del_big_bang

[teoria_del_big_bang]

Just double checked and I think we are both right. The distance is 63 mm but that includes the 8mm thick spacer that you are measuring from so in that case it would be 55 mm.

But astill do not forget to correct for the thickness of the filters as this could add up to 1 mm if they were 3 mm thick.

Below is from the manual:

Steve

[Juicy6]

[Craig123]

27 minutes ago, teoria_del_big_bang said:

I need to double check but I thought the back focus distance should be 63mm from the edge below where it says 100 Field Corrector to the image sensor.

Also do not forget to add 1/3 of the thickness of your filters. In my case they were 2 mm so needed to add 0.67 mm (or approximately 0.7 mm ).

I also have the Esprit 100ED, a filter wheel which according to documentation is 29.6 mm wide (but measured it at 29.7 mm) and the AS1600 and have the following:

Seems to work fine for me. I bought some thin spacers one which was 1 mm to just tune it in to the right length.

Steve

 

 

Thanks Steve. Really appreciate that from an Esprit owner . I saw the 63mm in the manual  but a few threads on the net had 56mm mentioned and the extra attachment for FF  had me stumped abit. 

[Craig123]

27 minutes ago, Juicy6 said:

Great. That really helps. Many thanks for posting it up. 

[teoria_del_big_bang]

1 minute ago, Craig123 said:

Thanks Steve. Really appreciate that from an Esprit owner . I saw the 63mm in the manual  but a few threads on the net had 56mm mentioned and the extra attachment for FF  had me stumped abit. 

No problem, happy to help. 

One reason I now always take a picture of the final setup is that often determining this back focus is not straight forward and obvious and sometimes the spacer size is not easily obtained as a standard size. In my case a 20 mm spacer was pretty close and the 1mm just brought it in almost exactly. Although never done any tests to see how much an issue an odd 1 mm or so error would make.

Steve

[Craig123]

2 minutes ago, teoria_del_big_bang said:

No problem, happy to help. 

One reason I now always take a picture of the final setup is that often determining this back focus is not straight forward and obvious and sometimes the spacer size is not easily obtained as a standard size. In my case a 20 mm spacer was pretty close and the 1mm just brought it in almost exactly. Although never done any tests to see how much an issue an odd 1 mm or so error would make.

Steve

Yes.. I'm just trying to get everything in place and wondered if I would need some extra spacers. I already realised I need to change the Heq5 vixen to a losmandy clamp. A few unexpected hurdles and ££s I hadn't thought about as it's abit hstcser to get orders through. 

[teoria_del_big_bang]

It will be worth it - you will like the scope (a lot).

[teoria_del_big_bang]

Just be real careful. When I got mine I was searching other threads about this scope and read one horror story about one person's rig slipping on the mount and he only just caught it before it crashed to the floor. I will see if I can find it again.

I think he claimed that the losmandy as supplied is slightly narrower than normal and as it was a pretty short clamp it did not tighten quite right in the clamp. Not sure how true this is about the width but for the size of scope (and weight) it is pretty short. So I bought a longer losmandy and fitted a clamp so that it cannot slip back any further than the clamp when I put it on the mount even of not clamped fully tight. Maybe a bit over-kill but this was too much money to risk dropping it on the floor and I am clumsy 🙂 

Steve

[Stuart1971]

2 minutes ago, teoria_del_big_bang said:

Just be real careful. When I got mine I was searching other threads about this scope and read one horror story about one person's rig slipping on the mount and he only just caught it before it crashed to the floor. I will see if I can find it again.

I think he claimed that the losmandy as supplied is slightly narrower than normal and as it was a pretty short clamp it did not tighten quite right in the clamp. Not sure how true this is about the width but for the size of scope (and weight) it is pretty short. So I bought a longer losmandy and fitted a clamp so that it cannot slip back any further than the clamp when I put it on the mount even of not clamped fully tight. Maybe a bit over-kill but this was too much money to risk dropping it on the floor and I am clumsy 🙂 

Steve

There is normally a threaded hole in the end of Losmandy dovetails, usually in the centre,  for a stop bolt to be fitted, all mine have these, and then a bolt should be screwed in to the front end, to stop it sliding out backwards... 👍

[Stuart1971]

Here for example..

 

[teoria_del_big_bang]

5 minutes ago, Stuart1971 said:

There is normally a threaded hole in the end of Losmandy dovetails, usually in the centre,  for a stop bolt to be fitted, all mine have these, and then a bolt should be screwed in to the front end, to stop it sliding out backwards... 👍

Yes that's all that is needed but not sure it's in the one supplied (but easily added).  Also the supplied losmandy is pretty short so not sure it is long enough to do that, depends on where centre of gravity is and where it ends up in the clamp when balanced I suppose.

The clamp is more expensive and over-kill but also means I can place it exactly at the balance point so making balancing much easier. Also I had the clamp and needed to do with it 🙂 

Steve

Edited August 2, 2020 by teoria_del_big_bang

[Craig123]

42 minutes ago, teoria_del_big_bang said:

Just be real careful. When I got mine I was searching other threads about this scope and read one horror story about one person's rig slipping on the mount and he only just caught it before it crashed to the floor. I will see if I can find it again.

I think he claimed that the losmandy as supplied is slightly narrower than normal and as it was a pretty short clamp it did not tighten quite right in the clamp. Not sure how true this is about the width but for the size of scope (and weight) it is pretty short. So I bought a longer losmandy and fitted a clamp so that it cannot slip back any further than the clamp when I put it on the mount even of not clamped fully tight. Maybe a bit over-kill but this was too much money to risk dropping it on the floor and I am clumsy 🙂 

Steve

I already imagined this horror story as this was suggested as a replacement.I may be wrong but  it looks  small to  deal with balance etc. 

https://www.rothervalleyoptics.co.uk/geoptik-mini-universal-saddle-plate-dual-fit-for-heq5.html

I'm guessing from experience you wouldn't recommend it. 

Edited August 2, 2020 by Craig123

[Craig123]

39 minutes ago, Stuart1971 said:

There is normally a threaded hole in the end of Losmandy dovetails, usually in the centre,  for a stop bolt to be fitted, all mine have these, and then a bolt should be screwed in to the front end, to stop it sliding out backwards... 👍

Great tip. Thanks 

[teoria_del_big_bang]

I had same issue as I had a HEQ5 when I got the scope and swapped the saddle clamp for this one:

geoptik-universal-dual-load-mounting-saddle-plate

However you do need the puck to go with it:

geoptik-adaptor-puck-for-heq5-mounts-to-use-universal-mounting-plate

So is about another £50. Personally I would go with this better option, the smaller one may do okay I cannot really comment. Ring the supplier or send email and ask them they will tell you for sure.

Steve

[Craig123]

14 minutes ago, teoria_del_big_bang said:

I had same issue as I had a HEQ5 when I got the scope and swapped the saddle clamp for this one:

geoptik-universal-dual-load-mounting-saddle-plate

However you do need the puck to go with it:

geoptik-adaptor-puck-for-heq5-mounts-to-use-universal-mounting-plate

So is about another £50. Personally I would go with this better option, the smaller one may do okay I cannot really comment. Ring the supplier or send email and ask them they will tell you for sure.

Steve

Yep.Looks much better, I have found a primuluce one that is very similar aswell. 

Great stuff. Thanks again. 

[teoria_del_big_bang]

Looking at the photo I had in my first reply the numbers didn't add up so had to think what I actually did and why I had the 20 mm spacer and not a 19.5 mm spacer.

That was actually an old photo.

The distances on the top row (6.5 + 29.7 + 20 + 8 ) actually add up to 64.2 which is 0..5 mm longer than the required 63.7 mm. This is because the nearest spacer I had was 20 mm and had to use this to begin with. Eventually I bought  15 mm + 4 mm + 0.5 mm spacers to make it correct. To be honest I am not sure I could see any difference when it was 0.5 mm incorrect.

But i think it did answer your question  

Steve

[Craig123]

19 minutes ago, teoria_del_big_bang said:

Looking at the photo I had in my first reply the numbers didn't add up so had to think what I actually did and why I had the 20 mm spacer and not a 19.5 mm spacer.

That was actually an old photo.

The distances on the top row (6.5 + 29.7 + 20 + 8 ) actually add up to 64.2 which is 0..5 mm longer than the required 63.7 mm. This is because the nearest spacer I had was 20 mm and had to use this to begin with. Eventually I bought  15 mm + 4 mm + 0.5 mm spacers to make it correct. To be honest I am not sure I could see any difference when it was 0.5 mm incorrect.

But i think it did answer your question  

Steve

Well done for figuring out something from back then. I'm struggling to remember what happened this morning when I had spacers and bits lying all over the place. 😂. However, I'm more confident I can get ready for the impending astro darkness once again thanks to you chaps. 

[Tenor Viol]

It is one of these that I am waiting for... I am hoping it's soon. My HEQ5 is new and has a dual saddle as standard. I'll keep an eye on things to see if I need an alternative saddle 

[Juicy6]

12 hours ago, teoria_del_big_bang said:

One reason I now always take a picture of the final setup is that often determining this back focus is not straight forward...

Steve

Me too. I use same camera on two scopes. So easy to forget the thin spacers.

[teoria_del_big_bang]

@Juicy6 Out of interest what is the thing ringed in red below?

Steve