35 replies to this topic

[Ballyhoo]

this is a bummer and I am not sure what could possibly be the solution. But then, the 3" explore scientific flattner/reducer is supposed to be compatible with the ES 127 ED.  However I was not able to achieve focus and I ran out of inward travel as I racked the focuser as far in as it could go.  Is there something I might do differently to make this work? I honestly do not see the solution here but maybe if I was going to upgrade my focuser to a Moonilight that would have more in-travel. But I should not have to do that.

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[StrStrck]

Hi, you seem to have a series of spacers/adapters in front of your camera. Remove some of those? Perhaps the camera could screw directly onto the flattener? Or is it the intended focal point of that particular flattener? 3rd edit as I’m waking up here: yes, of course it’s the focal point, disregard brain fart above. 

 

The description on ES: Recommended for our 127mm and 152mm refracting telescopes (excluding our doublet refractors)...

 

Sorry I’m of no help

Edited by StrStrck, 13 October 2019 - 04:40 AM.

[sg6]

F/R has 55mm back focus, the camera has 6.5mm mechanically so the spacers you have between the FR and ASI294 should be around 48.5mm.

 

Can only read one that says 16.5mm, big one starts with a 2 (maybe) and the small one no idea.

 

So what spacers in total have you between the 2 items?

 

May be a M42 ring in there as well that says (I think) 1.8mm. So that could drop the spacers required to 46.5mm. Cannot really see how to sort out 1.8mm from 2.0mm realistically so coumted it as 2.0mm.

Edited by sg6, 13 October 2019 - 04:56 AM.

[Ballyhoo]

F/R has 55mm back focus, the camera has 6.5mm mechanically so the spacers you have between the FR and ASI294 should be around 48.5mm.

 

Can only read one that says 16.5mm, big one starts with a 2 (maybe) and the small one no idea.

 

So what spacers in total have you between the 2 items?

 

May be a M42 ring in there as well that says (I think) 1.8mm. So that could drop the spacers required to 46.5mm. Cannot really see how to sort out 1.8mm from 2.0mm realistically so coumted it as 2.0mm.

the spacers I have is the same configuration I use for my Orion Flattner which requires 55mm. It is 26, 11, and 16.5

[OldManSky]

the spacers I have is the same configuration I use for my Orion Flattner which requires 55mm. It is 26, 11, and 16.5

If it's really 26, 11, and 16.5 (53.5mm) plus the 6.5mm for the camera, that puts you at 60mm out.  

I suspect, though, that the 26 is really 21mm (isn't that what comes with the camera?), which puts you right at 55mm.

So it may simply be that this particular flattener doesn't work with this particular scope...

At any rate, remove the smallest extender (11mm), and see what happens.  If you get closer to focus, keep removing spacers/changing them until you get to focus, and see how the stars look.

[Ballyhoo]

If it's really 26, 11, and 16.5 (53.5mm) plus the 6.5mm for the camera, that puts you at 60mm out.  

I suspect, though, that the 26 is really 21mm (isn't that what comes with the camera?), which puts you right at 55mm.

So it may simply be that this particular flattener doesn't work with this particular scope...

At any rate, remove the smallest extender (11mm), and see what happens.  If you get closer to focus, keep removing spacers/changing them until you get to focus, and see how the stars look.

You are correct, 21mm.

 

However this is what I am thinking: the 55m space that is required seems to be a common requirement for different reducers/flattners, because that is the same spec I am seeing with my Orion flattner and that is the spacing I am using (though that flatter is not working 100% on the left side of my frames. I am thinking this must be a common spacing configuration. I am using the spacers that came with my camera and I am using the same configuration on the Orion that was vetted pretty well on a different thread in the summer when I first got my Orion flattner.

 

Thank you very much for helping me. 

Edited by Ballyhoo, 13 October 2019 - 01:08 PM.

[OldManSky]

What's the model #/full name of your flattener/reducer?

Is it the Explore Scientific 3" Field Flattener .7x Focal Reducer - FFFR507X-00?

 

If it is, the web site says: "The field flattener/focal reducer offers 55 mm of back focus from the rear flange. The M42x0.75 adapter is 6.25 mm thick with a working length of 1.8 mm."  It looks like that's the one you're using, and that you're using the M42 adapter -- so that takes up 1.8mm of the 55mm, which means you're 1.8mm too far out with your adapters.  The thing is, your results look like you're more than 1.8mm too far back.

 

So you're likely 1.8mm too far back, so you can remove the M42 adapter from the flattener and use the M48 threads with the adapters you already have, and see how that works.  Then like I said above, start removing adapters one at a time and see if you can reach focus, and what the field looks like.  You can do that in the daytime without waiting for stars...

[Ballyhoo]

What's the model #/full name of your flattener/reducer?

Is it the Explore Scientific 3" Field Flattener .7x Focal Reducer - FFFR507X-00?

 

If it is, the web site says: "The field flattener/focal reducer offers 55 mm of back focus from the rear flange. The M42x0.75 adapter is 6.25 mm thick with a working length of 1.8 mm."  It looks like that's the one you're using, and that you're using the M42 adapter -- so that takes up 1.8mm of the 55mm, which means you're 1.8mm too far out with your adapters.  The thing is, your results look like you're more than 1.8mm too far back.

 

So you're likely 1.8mm too far back, so you can remove the M42 adapter from the flattener and use the M48 threads with the adapters you already have, and see how that works.  Then like I said above, start removing adapters one at a time and see if you can reach focus, and what the field looks like.  You can do that in the daytime without waiting for stars...

Great,

 

Aslo I have sent a service request to Explore Scientific they will look at it tomorrow. Hopefully they will have firm answers. Thing is, on Astrobin I have found the same combination of gear (but with different cameras). Is it possible the camera is the problem? 

 

Edit, yes that is the model # 

Edited by Ballyhoo, 13 October 2019 - 01:31 PM.

[OldManSky]

Not at all likely to be the camera.

Is your 127ED a doublet or triplet?

[Ballyhoo]

Not at all likely to be the camera.

Is your 127ED a doublet or triplet?

it is the triplet.

 

I can not get it to thread camera to adapters when I remove the 11mm (M42). But when I remove the 16.5 I can get them all to thread and that would probably give me the in-focus I need. Still that throws out the 55mm spacing requirement. 

Edited by Ballyhoo, 13 October 2019 - 01:47 PM.

[Ballyhoo]

Sorry I also posted this in B&II forum but I thought someone might see this here. Does anyone here have the Explore Scientific ES 127 ED triplet (the entry level triplet with the standard  non-hex focuser,) and also the 3" .7 ES flattner/reducer? I tried last night but I ran out of in-travel.  

 

edit, the spacers I am using are the 16.5, 11 and 21mm

 

https://www.highpoin...fRoCQjYQAvD_BwE

 

thank you

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Edited by Ballyhoo, 13 October 2019 - 02:57 PM.

[SilverLitz]

Have you tried using some of the ES extension tubes before the FF/FR?

 

For my ED102CF I needed 1 of the extension tubes before my Hotech FF, and without the FF I needed 2.

[Ballyhoo]

Have you tried using some of the ES extension tubes before the FF/FR?

 

For my ED102CF I needed 1 of the extension tubes before my Hotech FF, and without the FF I needed 2.

why might  I use an extension tube if I need more in-focus? 

[sg6]

Try an emsil to ES asking if the back focus is different on the 127 f/7.5 Triplets.

ES site says they were designed for the f/8

 

While technically this was designed for the f/8 system, through user experiences and our subsequent testing we have concluded that our 3-inch field flattener/reducer performs very well with our f/7.5 refractors.

 

Thinking it might work well but not exactly the same. As in you have to set up for 52mm back focus. Example idea only.

[noisejammer]

It's not clear what you're asking.

 

If you've picked spacers to provide (roughly) the correct gap between reducer & image plane, then running out of in-focus can only be cured by shortening the tube. You may be able to achieve this by installing a different focuser.

 

If you're referring to the squashed disc, that could be a result of focuser sag or a misaligned sensor or collimation problems. If the image is from the edge of the field, it could also be caused by vignetting from the draw-tube.

[Ballyhoo]

It's not clear what you're asking.

 

If you've picked spacers to provide (roughly) the correct gap between reducer & image plane, then running out of in-focus can only be cured by shortening the tube. You may be able to achieve this by installing a different focuser.

 

If you're referring to the squashed disc, that could be a result of focuser sag or a misaligned sensor or collimation problems. If the image is from the edge of the field, it could also be caused by vignetting from the draw-tube.

So the problem I have is clearly the focuser I have does not allow for enough in-travel and I just cannot rack in enough. I have this issue on that telescope using my Big Barlow -- I cannot bc the intravel is inadequate.  That flange I have circled in red I think is getting in the way. If I could remove that I would probably be golden here.

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[Ballyhoo]

I am going to post this on equipment how to remove flange.

[SilverLitz]

Are you sure it needs more in-focus?  

 

I have no insight on the ED127, but my ED102 required extra extension to achieve focus.

 

Did your ED127 come with extensions?  (MY ED102 came with two.) If it did, I would expect it is because they are necessary to achieve focus for AP.  If you have the tubes, give it a try.  (Again, no predictions, but a cheap experiment.)

 

I believe the ED127 and ED102 have similar focusers (2" focusers with M54 tubes for FCD1 versions), and my ED102 has limited 35mm of travel.  The focuser is definitely a weak point of my ED102CF.

[raguramm]

I didn't have the field flattener, but I definitely needed a lot of extra space to reach focus. I now have a shiny moonlite that only gets to focus with its 4.5" tube racked almost all the way out.

Edit: same scope and ZWO 1600 cam.

Edited by raguramm, 13 October 2019 - 07:45 PM.

[rkelley61]

This doesn't help you with the stock focuser, but I have the same model ES scope and ES .7 field flattener.  I replaced the stock focuser with a Moonlite CFL 2.5 and it can reach focus with my ASI1600mm.  Using the 1.75" flange extender I have about 1-2mm inward travel available when in focus.  There is a 1.25" flange extender available but I haven't needed the additional inward travel so far.

[Ballyhoo]

This doesn't help you with the stock focuser, but I have the same model ES scope and ES .7 field flattener.  I replaced the stock focuser with a Moonlite CFL 2.5 and it can reach focus with my ASI1600mm.  Using the 1.75" flange extender I have about 1-2mm inward travel available when in focus.  There is a 1.25" flange extender available but I haven't needed the additional inward travel so far.

yeah I think I am going to end up ordering that focuser from Ron. T the post above that, I presume it is an in-focus issue because the big blob was getting smaller as I racked in and smaller then I ran out of in-travel.

 

I would love to remove that inner flange.

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[rkelley61]

Your focuser is designed a little differently than the one that came on my ES127ED.  Mine is almost 1 year old and doesn't have the inner flange you want to remove, the focuser segment attaches directly to the tube flange with a rotatable dovetail joint.

[Ballyhoo]

Your focuser is designed a little differently than the one that came on my ES127ED.  Mine is almost 1 year old and doesn't have the inner flange you want to remove, the focuser segment attaches directly to the tube flange with a rotatable dovetail joint.

Nonetheless you replaced everything with a Moonliite, no? I have been wanting to replace my focuser for a long while so maybe this is the option I should go. I just want to make sure that I will get the in-travel I need by purchasing that moonlight. Do you have a picture or your moon lite on your ES 127? Or maybe I could send my focuser into ES for them to remove the flange. However, a better focuser is in order.

 

edit 

also what is the purpose of the flange extender? I would think that causes out-travel, but you imply it provides in travel?   I am about ready to order this new focuser if I can confirm it will work.

 

Did you enjoy the upgraded moonlite focuser on your telescope overall?

 

THANK YOU!

Edited by Ballyhoo, 13 October 2019 - 10:15 PM.

[rkelley61]

The extender flange helps set the correct placement of the focuser so the range of the focuser covers the inward and outward travel you need.  You can use different widths of the extender to move the focuser in or out if needed.  I like the Moonlite focuser, it works well with SGP and NINA, and handles my camera with filter wheel without problems.  I own three Moonlite focusers now for different scopes.  I like having a single type of focuser as it helps simplify changing between scopes.  In the case of the ES 127 ED stock focuser, it was fairly difficult to get the stock focuser off the telescope tube.  Based on what I read in various posts at the time it seems to vary from scope to scope so I don't know how hard yours might be to remove.

 

[Ballyhoo]

Oh I see you got the auto focuser? It is quite a bit more expensive and I was not sure if I should have a focuser that costs nearly as much as the OTA. My version is the FCD1 triplet.  Nonetheless I plan on keeping this refractor and therefore I will consider auto focus as well.  thanks a great deal for your information!

 

While I cannot easily remove that needless extension ring, I do know that the entire draw tube comes off the OTA easy because one time I purchased a secondhand hex focuser and I tried to exchange it for what I have. Sadly the threading is not the same

Edited by Ballyhoo, 13 October 2019 - 11:54 PM.