Gina's Esprit 80ED Pro Unboxing and First Impressions

[Gina]

This is the stock I'm planning to use for the rings - 80mm OD x 10mm wall thickness = 60mm ID.  So the thin ring can remain at 80mm with a knurl and the wide ring OD turned down to 75mm to match the flattener and knurled.  The inside turned out and threaded to form the 65mm thread to go on the core piece.  The core will have to be made out of solid bar I think as I have so far been unable to find a suitable tube.

Edited November 10, 2013 by Gina

[Tinker1947]

If you don't have a knurling tool there on ebay..........

RDGTOOLS LATHE KNURLING TOOL 3/8" shank FOR MINI LATHE

Edited November 10, 2013 by Tinker1947

[Gina]

I have bought a knurling tool from ebay - bit smaller, 1/4" wide.  That's my first first tool purchase   I have other tools ordered with the lathe but they've yet to arrive.

Edited November 10, 2013 by Gina

[sloz1664]

Hi Gina,

I don't know if you have used a lathe before. If not, the most important piece of advice I would give is not to wear any rings, watches, or loose fitting

clothing especially around the arms. Obviously, as already mentioned safety glasses. That's the H&S dealt with.

The next is always ensure your tools are set up on the centreline axis. Align your tools with the tailstock centre.

We'll make a toolmaker out of you yet.     

Good luck and be SAFE...

Steve

[Gina]

Hi Gina,

I don't know if you have used a lathe before. If not, the most important piece of advice I would give is not to wear any rings, watches, or loose fitting

clothing especially around the arms. Obviously, as already mentioned safety glasses. That's the H&S dealt with.

The next is always ensure your tools are set up on the centreline axis. Align your tools with the tailstock centre.

We'll make a toolmaker out of you yet.     

Good luck and be SAFE...

Steve

Thank you Steve   Yes I have used a lathe but it was a long time ago.  I do have protective clothing, face shield, hard hat, various gloves etc.

[Davey-T]

, as already mentioned safety glasses.

Steve

Safety glasses are not enough, you need full face protection, my friend had safety glasses but they didn't save him.

Dave

[Gina]

Yet another redesign of the adapter - this time to enable me to use tube stock for both the rings and the body/core.  The long ring now has two different threads on the inside - one for the flattener and the other, a bit smaller to fit the body/core part, which is now small enough to allow a smaller tube stock to be used, with smaller OD and ID, the ID now giving enough "body" to allow a 5mm thickness on the 54mm end.

This shows an "exploded" view of the adapter.  As shown the bottom of the adapter  screws onto the flattener and the top of the middle section into the filter wheel.

Edited November 10, 2013 by Gina

[Gina]

Now to calculate the thicknesses (or focal length) of each of the parts   This is determined by the shortest and longest optical path obtained by the adjustment or maybe the other way round

The shortest the adapter can be is when the "body" part is screwed in up to the end of the male thread on the flattener.  The longest is obtained by unscrewing the body out of the thick ring but allowing enough thread length left to ensure a stable connection.  In the shortest position the locking ring can be almost up to the filter wheel.

[RogerTheDodger]

Safety glasses are not enough, you need full face protection, my friend had safety glasses but they didn't save him.

Dave

Indeed, I have had a tool break and make a nasty gouge in my Lexan full face mask... scared the heck out of me.

[Gina]

Here are my calculations for the measurements of the component parts of the adapter.

My calculation of the nominal length for this adapter is 18.9mm - we can call this 19mm.  If we say we want +- 2mm this gives a minimum length of 17mm and a maximum of 21mm.

With the minimum length the body part can go up against the end of the flattener male thread.  This is 5mm leaving 12mm as the body length.

The depth of the 65mm threaded part of the thick ring that screws onto the flattener wants to be greater than the length of thread on the flattener as we want to reference the base of of the flattener so I would like 6mm.

When set to maximum length the body would be unscrewed from the thick ring by 4mm (the total range of adjustment) and allowing for a minimum threaded connection between body and thick ring of 5mm this gives 8mm for the thickness of the smaller ID part of the thick ring.

The drawing below shows a cross-section through the adapter - to scale with horizontal and vertical scales showing mm.  The vertical scale numbers also show diameters as well as radii.  The brown outline shows the body screwed right in to get the minimum adjustment setting while the maximum is shown in grey.  The filter wheel positions are also shown in matching colours.

This shows that with an adjustment range of 2mm less or more than nominal would mean a locking ring only 3mm thick.  This strikes me as rather thin.  Anyone have any thoughts on this, please?

Edited November 11, 2013 by Gina

[Gina]

If the adjustment range were to be reduced to 1.5mm less or more than nominal, the figures change to 12.5mm thick for the main part of the body and it would be screwed only 3mm out for maximum so the inner thread on the thick ring could be reduced by 1mm leaving 4.5mm room for the thin ring.  I'm wondering if this would be a better idea.

Edited November 11, 2013 by Gina

[JohnC64]

3mm for the thin ring sounds ok to me Gina.  How much stress is it going to be put under? Hopefully not much.  Get a 3mm piece of Aluminium and see how sturdy it is would be my suggestion.  You could retain the 2mm adjustment then if it feels ok

John

Edited November 12, 2013 by JohnC64

[Gina]

3mm for the thin ring sounds ok to me Gina.  How much stress is it going to be put under? Hopefully not much.  Get a 3mm piece of Aluminium and see how sturdy it is would be my suggestion.  You could retain the 2mm adjustment then if it feels ok

John

Thank you John   I'll give it a try.  I shall try to get the threads on the thick ring and body a nice snug fit.  I think if I turn the inside thread first and then make the outside thread a fairly tight fit it should be alright.  The anodising process removes some metal - I shall have to make sure it isnt too much.  I'll have some practising to do before I get it right

One possibility would be mask off the threads concerned and leave just the part that would be in the light path when fully extended, for anodising.

Edited November 12, 2013 by Gina

[Gina]

Clear sky but dreadful transparency tonight and cloud at low altitudes in the east and south preclude tittivating my PA as I had intended so I've been testing the PA by imaging a high target - The Heart Nebula.  I cannot get FWHM better than around 6 unbinned and 3 binned 2x2 so I'm taking a series of 2x2 binned subs of ever increasing length, unguided, to see how I've done with my PA so far.

I've got up to 16m Ha subs and no sign of eggy stars in the middle of the image but the stars can be seen to elongate towards the corners showing the curved field without the flattener.

[Merlin66]

Gina,

I use the Baader T thread locking rings and I think they are only 1 or 1.5mm thick....they do the job.

[Chris]

16 minutes unguided!

[Gina]

Gina,

I use the Baader T thread locking rings and I think they are only 1 or 1.5mm thick....they do the job.

Thank you   That confirms that 3mm should be fine   Good

[Gina]

I found my DIY focussing system had slackened a bit and the belt was slipping - now fixed.  This is just a temporary setup and I'll be making a better version.  Anyway, I now have much better focussing and getting an FWHM of 1.6-1.8 unbinned.

Here is a single Ha sub unbinned of 10m and resized and a section from the top left hand corner pixel for pixel showing the affect of field curvature.

[Marvaz]

Are you happy with the stars shape Gina?

I wasn't with mine. I've purchased Esprit 100 and found that stars aren't rounded. It was exactly like on your picture above. That's typical defect for pinched optics. I've changed for another one and it has same issue. I was very disappointed with this scope. I' af raid yours one has same issue. I couldn't live with it and swap for WO FLT 98.

Regards

Marek

[Gina]

Are you happy with the stars shape Gina?

I wasn't with mine. I've purchased Esprit 100 and found that stars aren't rounded. It was exactly like on your picture above. That's typical defect for pinched optics. I've changed for another one and it has same issue. I was very disappointed with this scope. I' af raid yours one has same issue. I couldn't live with it and swap for WO FLT 98.

Regards

Marek

I think the stars in the centre are probably alright - the corners and edges show field curvature.  I'll reserve final opinion until I get the flattener in place and the correct back focus.

[Gina]

Here is a centre crop from one of the Ha 10m subs from last night.  This is 1:1 pixel ratio image to upload file, simply stretched and cropped and saved as JPEG.

[swag72]

What's your thoughts on the star shapes Gina - Are you happy with them?

[Sp@ce_d]

One thing I'm finding.. the spacing seems more critical on this than my 80ED and both the faster ZS66 & 71

[Gina]

What's your thoughts on the star shapes Gina - Are you happy with them?

They are rather "bumpy" I have to agree.  I'll see if things are any better with the flattener once I get the variable length adapter made.  That could be a week or two.  The mini lathe has yet to arrive and then I will need some practice before I can produce decent threaded parts no doubt.  Then after all that comes the wait for a clear night

[Gina]

Here's that centre crop after applying Noel's Actions star reduction several times - makes the star points more noticeable, I think.  Since this is an early batch from Skywatcher I would think the QC would be pretty good so maybe this is the best they can do.  It certainly isn't perfect!   I did an overnight imaging run last night and will be stacking and processing the subs later today so we'll see what it's like without so much noise.

Edited November 13, 2013 by Gina