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Anyone with a Borg 77 , Feathertouch and a 0.65x reducer?


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Hi, I just bought one and I'm trying to fathom why I cannot get it to infinity focus.  As you know, it is a jigsaw of parts and I suspect one or more is wrong. I can focus to about 40m but nothing further away before the focuser runs out of travel. 

I suspect the draw tube adaptor or the couplings between the 0.65 super reducer and the feather touch focuser.  I have 294mm between the shoulder of the t-ring and the black edge of the optical cell. Is there another user out there who can share notes? I followed the instructions and have the thick spacer between the rear optics and the camera coupler.

cheers

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Hi all,  I have this resolved. The Borg is going back to its maker.

After a few weeks of pushback and rather belligerent advice, I have established that the Borg 77 with a 0.65 super reducer has insufficient back focus to work with a 55mm spaced T-coupled camera.

Borg initially shipped the wrong length main tube, which didn't help but once that was sorted, I was still not able to get infinity focus with the T-adaptor. 

My Starlight Xpress system has exactly 55mm (the T-thread standard) from the sensor to the T-flange. So does my Fuji X with its T-adaptor, same goes for the Canon EOS and Panasonic GF1.

The issue is with the flattener. The 0.65x super reducer assumes 55mm from its rear flange to the sensor. Borg make a huge range of adaptors to fit various camera bayonets to preserve this distance.

They also make a T-adaptor assembly, which is 13mm deep from the flange of the flattener to the T-thread shoulder.

It took a week with Borg, to agree the point that 55mm does not equal 13mm+55mm. I sent them the Wiki page for the T-thread standard but apparently I'm being demanding and unrealistic to expect them to make a solution for every possible camera.

I'm not impressed.  So, I either go for a FSQ65 and marriage counseling or perhaps down to a Zenithstar 71 for a season or two. (it appears the ZS has a screw-coupled reducer into the back of the focus tube)

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Sorry to hear that Chris, that's a very disappointing experience. I have a ZS71 and the reducer VI does have a screw thread but it pushes into the focuser tube and and compression screws are used to secure, I found that this can cause sag with imaging equipment attached and hence some field curvature if not correctly secured. This took me a little while to truly appreciate because everything looked fine.

I'm in the process of replacing the ZS71 as my main NB imaging scope now and hopefully I will get a few hours tonight to complete the process. 

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Gingergeek,  have you seen this? This looks like you unscrew the 2" clamp and put in a SCT coupler in-between the focuser tube and the field flattener. That would remove the droop?

What were your impressions of the ZS71 optically?  I have a FLT132 and FLT98, both with feather touches and I just need a wide field scope for a bit.

http://www.optcorp.com/william-optics-71mm-zenithstar-refractor-telescope-with-flattener-z71ap.html

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According to this chart it pushes in for the ZS71 and screws on for the ZS70. 

All my recent NB pictures are with the ZS71 so I can't complain about it not performing but the QC for me was lacking. I did speak to a WO rep at Astrofest on Friday and went through the issues. OK you get what you pay for and for me it was a good way to get into NB/CCD imaging. Faster than my ED80 and wider field, it is quite compact and easy to handle, in fact I took it to AstroAdventures in Devon over the summer. The RP focuser is good, I always used the focuser lock just to be sure of no slippage, but avoid using the tube rotator feature as for me it just created more issues with the field curvature.

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You are right - I took a close look at the images from the optcorp website. They have mixed up their images. The ZS71 has a temp gauge on the focuser wheel, yet the picture of the focuser with the SCT coupling has a different style knob.

So for anyone reading this thread, the ZS70 has a SCT coupling on the end of the focuser and the ZS71 does not.

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You are right - I took a close look at the images from the optcorp website. They have mixed up their images. The ZS71 has a temp gauge on the focuser wheel, yet the picture of the focuser with the SCT coupling has a different style knob.

So for anyone reading this thread, the ZS70 has a SCT coupling on the end of the focuser and the ZS71 does not.

Hi Chris,

Further to our communications, I have used an Altair 0.6X FF/FR with reasonable results with the ZS 71 giving me F3.5 and hell of a field of view, it is surely not a Tak @ 1/8th of the price but useful. The reducer also comes to focus with both my SW ED 80, blue tube and the SW 100 ED DS pro giving me a scope with 540mm of FL and F5.4. I am only ra ank hobby guy so absolute optical fidelity is not at the top of my agenda.

Regards,

A.G

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Interesting option to use the Altair FF/FR

I attach a capture of the M31 from last year using the ZS71 and the Altair 0.6X FF/FR, I am not very critical about image quality but you make up your own mind. The CCD was an Atik 428EXC.

Regards,

A.G

post-28808-0-15475800-1392057138_thumb.p

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  • 2 weeks later...

Hi, I got the ZS71 from IKI in the end, with the new 6-a flattener, which fully inserts into the focus tube. I was a bit nervous since my FLT98 last year with a DDG R&P focuser was so badly setup, the camera was like a tail on a dog.

I have to say that this scope and focuser was properly setup and aligned. The focuser was smooth, no play (in any direction) and with a small tweak on the tensioner, held a filter wheel and CCD.  Note, the latest version of the flattener fully inserts inside the focus tube and has a unique T-thread spacer for each scope this flattener goes onto. Lakeside do a focus motor adaptor for it too and I'll use that in due course.

Balancing is fun though with the camera attached. I reversed the foot and put it onto a short ADM Losmandy plate and it balances around the focus knob.  Focusing point is around 30mm travel, which means the focuser is not too extended in use. I need some clear skies and I can run some exposures from the CCD, and more challenging APS-C sensor on the Fuji, through CCDInspector to look at the field curvature.

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Hi, I got the ZS71 from IKI in the end, with the new 6-a flattener, which fully inserts into the focus tube. I was a bit nervous since my FLT98 last year with a DDG R&P focuser was so badly setup, the camera was like a tail on a dog.

I have to say that this scope and focuser was properly setup and aligned. The focuser was smooth, no play (in any direction) and with a small tweak on the tensioner, held a filter wheel and CCD.  Note, the latest version of the flattener fully inserts inside the focus tube and has a unique T-thread spacer for each scope this flattener goes onto. Lakeside do a focus motor adaptor for it too and I'll use that in due course.

Balancing is fun though with the camera attached. I reversed the foot and put it onto a short ADM Losmandy plate and it balances around the focus knob.  Focusing point is around 30mm travel, which means the focuser is not too extended in use. I need some clear skies and I can run some exposures from the CCD, and more challenging APS-C sensor on the Fuji, through CCDInspector to look at the field curvature.

Enjoy your new toy ,

Clear Skies,

A.G

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  • 4 weeks later...

A short update.  I just bought one of the new USB Lakeside focusers for the Zenithstar 71. The dedicated 'spacer' is just a t-extension tube of 13.5mm long, so I also tried a 15mm and a 12mm tube (10mm with two Baader delving rings) to compare the performance in 1.5mm increments. I autofocused a starlight Trius and filterwheel. 

CCD inspector showed very good flat field at the 13.5mm distance. I got the characteristic bump in the middle in one direction and progressive curvature in the other.

Stars were nice and round all the way to the corners at the right spacing.  

I think the scope will do well for a few years until I can afford a Tak FSQ85. The trick is to get everything rigid and square. I swapped the plastic grubscrew on the 2" eyepiece clamp with the main scope rotator lock. I tightened all the plastic grubs on the scope to prevent any movement on the rotator and assembled the camera to the spacer and flattener and then onto the scope, with the scope resting on its lens cap. I tighten all three knobs to ensure a firm and square assembly of the scope to the field flattener/spacer/camera assembly. Voila.

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  • 5 months later...

My ZS71 was  good optically but the mounting arrangment with the foot was not really man enough to take the weight of QSI camera on the back without flexure.  I noticed that William optics updated the ZS71 again, this time into a 5-element astrograph.  I took the plunge, sold the ZS71 (2013) and have the new one on order from IKI. It has a short throw R&P focuser, threaded mount and tube rings - which should give me better mounting stability.

Although the ZS71 was harmonous with my Paramount, both being a nice shade of red, the Versaplate was longer than the scope itself and it looked faintly ridiculous!

I will assess it as soon as I get it and the obligatory month of cloud has passed. I'm wondering, at 350mm FL, whether this will work well on an Astrotrac for the holidays.

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My ZS71 was  good optically but the mounting arrangment with the foot was not really man enough to take the weight of QSI camera on the back without flexure.  I noticed that William optics updated the ZS71 again, this time into a 5-element astrograph.  I took the plunge, sold the ZS71 (2013) and have the new one on order from IKI. It has a short throw R&P focuser, threaded mount and tube rings - which should give me better mounting stability.

Although the ZS71 was harmonous with my Paramount, both being a nice shade of red, the Versaplate was longer than the scope itself and it looked faintly ridiculous!

I will assess it as soon as I get it and the obligatory month of cloud has passed. I'm wondering, at 350mm FL, whether this will work well on an Astrotrac for the holidays.

I have been playing with my new Star 71 for a few days now, optically it is superb, construction is excellent but it does have a few silly points too.

A.G

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I have found one of them. The two brass screws on the top stop the focus tube slopping about. Mine were loose. As soon as I put the slightest tension on them, the tube was rigid. They are very free though and I think Loctite is in order. I have got some spacers made up to mount it onto a long Losmandy plate, and give back end clearance. The bolt system has changed to metric and once I have longer M6 bolts, I can post assembly pictures.

Sent from my iPad using Tapatalk

Regards

Chris

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That is a fantastic image - I'm going to use mine with a QSI683wsg so as long as the 48-T adaptor has that spacing in mind, I should be ok on the filter front. Good point about the tube rings, I have mine moved out already so that I can mount it on a big Losmandy plate. If I extend the plate out forwards, it helps with the balance too.

I'm just getting Peter at Lakeside to make up an adaptor for the focuser and I should be there. The dew shield is obviously designed for compactness. I think I will simply make up an extender and mount it to the protruding Losmandy plate.

Still much cheaper than the Tak 85

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I took mine apart yesterday to see how it was constructed and to align the focuser. It is very straightforward. The optical tube unscrews from the focuser body. All the optics are in one tube and have a fixed relationship to each other. The lens is constructed like a classical manual focus SLR lens. All the focuser does is space the camera from the lens. The exact spacing from the camera adaptor to its sensor is irrelevant so long as you can achieve focus. There is no normal flat-field spacing to worry about.

The rear optics are in a cone-like protrusion that inserts into the focuser body, There should be no danger of pinching optics on the rear cell as they are suspended inside and not in contact with the outer body. The front optics are within the lens hood area, away from the straight tube and "should" be relatively immune from clamp ring pinching.

This is how I tuned my focuser:  I did this at my own risk, but having rebuilt a damaged Feathertouch system, I just took things carefully.

The tube slides on three teflon pads, aka feather touch, with two brass screws adjusting tension. I removed the worm assembly by loosening the tension adjust and lock bolt and removing the two bolts. Without the worm in place, the brass screw are adjusted so the tube moves smoothly without play.

The worm assembly has four set screws and two fasteners. The set screws hold the assembly off the pinion but are not needed and in mine they were retracted within the focuser body. Even retracted, the worm and pinion are not fully engaged (with the grub screw and bolt loose).  (In my feathertouch, I used the four set screws to accurately position the worm over the pinion so there was 'just' no play without using the tensioner to engage the worm.)

Tightening the two worm block fasteners, one tests for play in focusing direction. The grub screw mostly adjusts friction, it is applied to the shaft quite close to a bearing and has a compliant material as a friction device. The long screw bends a brass ‘plunger’ to in effect bend the worm shaft and offer up the worm to the pinion, reducing play.

So - if the factory set it correctly, you shouldn't need the long screw - but this is provided as a customer adjustment to gear play, rather than fiddle with the set screws (which are redundant on my one.)

My focuser is pretty good now, no play and slightly tighter fully-in, but that is down to tolerances in the focuser tube dimensions. My feathertouch does the same but not quite to the same degree.

Just need my T-adaptor and I can test the optics.

The four silver screws and the little black nylon screws are not functional and are for attaching finders.

hope this helps

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I took mine apart yesterday to see how it was constructed and to align the focuser. It is very straightforward. The optical tube unscrews from the focuser body. All the optics are in one tube and have a fixed relationship to each other. The lens is constructed like a classical manual focus SLR lens. All the focuser does is space the camera from the lens. The exact spacing from the camera adaptor to its sensor is irrelevant so long as you can achieve focus. There is no normal flat-field spacing to worry about.

The rear optics are in a cone-like protrusion that inserts into the focuser body, There should be no danger of pinching optics on the rear cell as they are suspended inside and not in contact with the outer body. The front optics are within the lens hood area, away from the straight tube and "should" be relatively immune from clamp ring pinching.

This is how I tuned my focuser:  I did this at my own risk, but having rebuilt a damaged Feathertouch system, I just took things carefully.

The tube slides on three teflon pads, aka feather touch, with two brass screws adjusting tension. I removed the worm assembly by loosening the tension adjust and lock bolt and removing the two bolts. Without the worm in place, the brass screw are adjusted so the tube moves smoothly without play.

The worm assembly has four set screws and two fasteners. The set screws hold the assembly off the pinion but are not needed and in mine they were retracted within the focuser body. Even retracted, the worm and pinion are not fully engaged (with the grub screw and bolt loose).  (In my feathertouch, I used the four set screws to accurately position the worm over the pinion so there was 'just' no play without using the tensioner to engage the worm.)

Tightening the two worm block fasteners, one tests for play in focusing direction. The grub screw mostly adjusts friction, it is applied to the shaft quite close to a bearing and has a compliant material as a friction device. The long screw bends a brass ‘plunger’ to in effect bend the worm shaft and offer up the worm to the pinion, reducing play.

So - if the factory set it correctly, you shouldn't need the long screw - but this is provided as a customer adjustment to gear play, rather than fiddle with the set screws (which are redundant on my one.)

My focuser is pretty good now, no play and slightly tighter fully-in, but that is down to tolerances in the focuser tube dimensions. My feathertouch does the same but not quite to the same degree.

Just need my T-adaptor and I can test the optics.

The four silver screws and the little black nylon screws are not functional and are for attaching finders.

hope this helps

Great write up Chris. I now have a 383L+ ( purchased used ) and it is a heavy camera. It will be interesting to see how the focuser copes with the camera and the FW.I was talking about the Star 71 BTW not the Borg so apologies if I caused any confusion.

A.G

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Hi A G -  Lakeside is now making a coupler for their focus motor. The one thing I have learned with these scopes is they demand the highest focus accuracy. When I get some images I will analyze them with CCDInspector and post some results back here.  I got some precision 20mm spacers made up to fit in-between the tube rings and a longish Losmandy plate. That gives me clearance between the QSI and the back end of the Versaplate. I got john@jtech to make them up.  I have to say, this scope looks ridiculous sitting on top of a Paramount MX. It won't move in the wind though.

spacer.pdf

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Hi A G -  Lakeside is now making a coupler for their focus motor. The one thing I have learned with these scopes is they demand the highest focus accuracy. When I get some images I will analyze them with CCDInspector and post some results back here.  I got some precision 20mm spacers made up to fit in-between the tube rings and a longish Losmandy plate. That gives me clearance between the QSI and the back end of the Versaplate. I got john@jtech to make them up.  I have to say, this scope looks ridiculous sitting on top of a Paramount MX. It won't move in the wind though.

Hi Chris,

I am just looking at the 383 and thinking how ridiculous it would look at the back of the scope.

A.G

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