Optec Leo for Epsilon

I made sure my mounting flange was parallel with the saddle before I installed it. I did this by placing the saddle on a flat surface and using micrometers to measure the distance to the flange. It seemed to work because a few weeks ago I made a jig with some thread to measure whether my focuser axis was collinear with  my ota axis and it was dead on.
I also bought longer screws for mounting the focuser to the tube, the stock ones are a little short imho for the Optec.
Dan

Dan:
I also bought longer screws for mounting the focuser to the tube, the stock ones are a little short imho for the Optec.

thanks Dan. Do you remember the screw types/sizes by any chance? 

while i'm certain clouds will oppressively blanket the sky when it gets here, I'm still anxious to have everything ready. 

If any of you all would like to share your Autofocus settings, that would also be welcomed!

Dan:
Alternatively, if you know that your collimation is good, just install the focuser and re-collimate by adjusting the focuser tilt adjuster.
Dan

This may off-center the optical axis which would be a problem for a full frame sensor.    You should really collimate by adjusting the mirrors and not the drawtube angle.  I always recommend that people lock the tilt feature on the focuser down and forget it exists.  It really shouldnt be there in my opinion.

When you install the focuser leave the 4 nuts a little bit loose.  Install the tak tool and slide the focuser and flange into position where the crosshair is centered on the secondary spot.  This will simplify collimation later as you will be aligning the center of the drawtube with the center of the secondary. This way you dont need to move the secondary itself.  The holes in the OTA tube are slotted so you can position as desired and then tighten the nuts. 

Collimation is not that difficult with this scope, and you can use the tak tools to do it in the daytime.  You will need to recollimate when replacing the focuser, and this is not to be feared.  You will want to become familiar with collimation process and the mechanics of the scope. Epsilon is very well built.

*** Also, the interior of the scope and the nuts are coated with a spray on flocking.  It's delicate, so be careful not to scrape it too much when installing.  For example, when you tighten the nuts, dont actually rotate the nuts... just hold them with a socket and use a screw driver to do the actual tightening.  This will protect that flocking.

Hi All, I feel like I'd just turned a corner on this epic journey. Once I finally installed the Leo, it seemed to have a faulty mechanical issue to get to home. Optec was impressive with support though. (no issues, no BS, just wanted to get it right for me) I got the replacement a few days ago. 

I've got the scope out tonight and I feel like i'm crazy because I can't retract enough to get in focus. I'm at 57mm backfocus with the optical train out from the corrector. I installed the focuser checked collimation after. (all looked good so far) 

But now I'm bottomed out at 100 on the focuser. Any thoughts? It's the Optec Leo kit for the 160 that I installed. Did I miss something?

Dunk:
Backfocus should be 56.2mm

I could be wrong on this one, but I calculated about 57.2mm to be ideal given that my filters are 3mm. (they say to add 1/3 of your filter thickness to the optical train) Is that incorrect??

Should this be a factor though. I was guessing this is all prior to the corrector.

here's what i'm using

https://agenaastro.com/chroma-h-alpha-8nm-imaging-filter-50mm-round-unmounted.html

It says the glass substrate is 3mm thick. My assumption is that is the glass itself. (even though the bandpass is 8nm)

Anyone smarter, please chime in, but the 8nm is the FWHM size of the bandpass for the targeted emission line. Totally different. But in fairness, it is late so I could be a couple beverages too late for clear logic ;-)

Nick Grundy:
Hi All, I feel like I'd just turned a corner on this epic journey. Once I finally installed the Leo, it seemed to have a faulty mechanical issue to get to home. Optec was impressive with support though. (no issues, no BS, just wanted to get it right for me) I got the replacement a few days ago. 

I've got the scope out tonight and I feel like i'm crazy because I can't retract enough to get in focus. I'm at 57mm backfocus with the optical train out from the corrector. I installed the focuser checked collimation after. (all looked good so far) 

But now I'm bottomed out at 100 on the focuser. Any thoughts? It's the Optec Leo kit for the 160 that I installed. Did I miss something?

Nick, if you can't move the focuser in enough to reach focus you need to lower the focuser. Underneath is a gold ring. This locks the height. Thread the pieces together more to lower the entire focuser and lock with the ring. 

If you Are already bottomed out there are two more things you can do. 

1) loosen the 4 bolts where the focuser flange bolts to the ota and slide the entire assembly towards the primary. The holes on the ota are slotted, so you can choose position. Moving the focuser closer to the primary will require you to re-enter the secondary under the focuser. By moving the secondary closer to the primary you will push the focal plane further out. You should check to make sure the secondary is centered under the focuser anyway. 

2) instead of moving the focuser you can move the primary closer to the secondary. This will do the same thing with the focal plane, however the primary travel may be limited depending on your setup. 

Most likely, the original idea I gave you will solve your problem.

Hi Nick could you provide some background on the light leaks in the stock focuser? Is this a known problem with the Epsilon focuser? Thanks, John

Nick Grundy:

light leaks in the stock focuser?

I think it's known issue. I never saw it in actual images, but I tested it myself with a flashlight. there was definitely an angle where light from the flashlight on one side would be shown in the image preview. 

There was actually someone that made a light collar to fix it. https://www.thingiverse.com/thing:5402209

I tried that and it needs a little adjusting, but I could see it helping. I ended up pulling the trigger on the Leo because I wanted backlash free focusing. The ZWO EAF was doing ok, but I was a little worried about the focuser tube shifting a bit under a heavier load.

4um steps are not fine enough for epsilon either. The leo has 0.08um steps, and as you mentioned... no backlash. 

@Bill Long - Dark Matters Astrophotography let me borrow an eaf while my LEO was on order and it was functional but between that and the stock focuser it was not precise enough for my standards.

Nick Grundy:

Chris White- Overcast Observatory:
Underneath is a gold ring. This locks the height.

this is definitely feeling like a dumb question, but .....

Is there some trick to loosening the gold lock ring? I'm putting some force in it, but figured I'd ask before I get crazy

Not that I recall.  Remove the focuser from the base by loosening the three grub screws on the lower flange.  That will give you better access.

Nick Grundy:
thanks! I was able to adjust but I had to unscrew the whole insert just to get to the gold ring. Looking good now and just fussing my Nina AF settings. 

Is anyone using Nina and willing to share their AF settings? 

I'm guessing, but there should be no backlash?

for hocus focus?. I don't use Nina otherwise. For analysis use:

10s exposures
​​​​​​1000 step size
4 steps out at start
use a high camera gain
lum filter
Zero backlash