ToUcam on WO ZenithStar 66

[Omaroo]

Hi all

After recently acquiring a William Optics ZenithStar 66 Petzval Semi-APO I've had good views though the GSO 2" SCT 99% dielectric star diagonal and my 1.25" EP's with the adapter. It's absolutely tack-sharp and focuses at around half focuser travel. The image is fantastic for the scope's size.

Last night I tried to fire up my ToUcam at prime focus and simply could not get a focused image at all - no matter what I tried. I tried mounting it with the 1.25" SCT-1.25" screw-on adapter that came with the scope - no go. I tried extending the light path by using a 2" extension tube off the top of the star diagonal - still no go.

Could someone who has one of these please let me know what arrangement they use to get a ToUcam or LPI to focus in one of these refractors?

Cheers
Chris

[ving]

do you need more in focus or out focus chris? for out use a barlow or extention tube and for in id probably guess take the diagonal out...

you had problems focusing the toucam in you 8" didnt you? was that sorted?

[Omaroo]

Hi David

Yep - I tried an extension tube off the diagonal. All I get is a fuzzy mess so I can't tell if the focus is improving by traveling in or out. I can mount a 1.25" 26mm EP and focus fine - after which I can merely stick the ToUcam over that EP and focus to a clear image - so the ToUcam is working fine.

Mysterious...... :shrug:

[ving]

ahhh!!!! have you taken teh lens out of the toucam?

sounds like the problem to me.

[Omaroo]

hehe... only to mount a 1.25" Mogg adapter. This works just wonderfully in the LX200...

[ving]

lol, well i have no idea then... can you focus on anythig terrestrial? try during day light.

[gbeal]

While all vary, I normally use my ToUcam in the 10" f5 newt, using a 5x Powermate. First I simply use an eyepiece of perhaps 16 - 20mm focal length, and achieve focus plus get the object (Jupiter or whatever) in the centre. Then I swap the eyepiece for the ToUcam, and finetune the focus and object placement from there. I am sure that if you can focus an eyepiece, then the object will not be overly different on the chip. Focus can be finicky though.
Gary

[ving]

ditto gary, i find my LPI to be similar to my 15mm ep focus wise. I put the 15mm in, center the star/planet and travel out just past focus.

[Omaroo]

I've tried this as well. I centre an object though an EP (a car) and I can't focus it no matter what when I swap it for the ToUcam. I'm starting to think that the SCT diagonal choice (i.e. brand and type) might be the critical factor.

[ving]

thats just weirding me out chris. EPs can focus but the toucam cant... its just strange. I take it that it works in other scopes tho?

[JohnG]

Hi Chris

Have you tried without the diagonal, this has all the symptoms of not enough inward focus.

Cheers

JohnG

[JohnH]

I have a WO66 ED and can only just reach focus with the LPI mounted on my Bintel SCT 2" diagonal I know it is not quite the same scope but...

The general problem is the 66mm scopes need a 2" SCT diagonal and won't reach focus with a 2" accessory back fitted and a standard 2" push fit diagonal inserted - they won't have enough inward focus.

My alternate mounting method is to take the SCT adapter from the Diagonal and attach a T to 1.25" ext tube and mount the LPI to that.

I do not own a 1.25" diagonal but imaging the problem would be less accute as the light path would be shorter.


BTW I would be very interested to hear of your results with the Toucam on this scope - especially if you are going to use it for guiding?

[Omaroo]

If you have a look at some of the posts on Cloudynights, this series of scope is very critical on diagonal choice. For instance - mine will focus with 1.25" EP's but not a GSO 2" EP for some reason. The GSO 2x Barlow also doesn't allow it to focus either. Some people state on CN that the distance to the mirror from the front thread on the SCT adapter is what differs between models and brands. I may have to do some experimentation with other brands...

[Omaroo]

Thanks John. Do you have a photo of your setup?

Yes, I plan to both guide witht he scope and do some wide-field on its own. It also makes a damn fine travel scope!

Cheers
Chris

[Omaroo]

I've tried this too John. I've tried using the SCT-1.25" adapter that came with the scope. Still doesn't seem to work - but I'll keep trying because I reckon that I don't have enough inward travel - not the other way around.

Cheers
Chris

[JohnG]

I will be interested in how this works out, I have one of these scopes on order for a guide scope in my field setup, I planned on using an autoguider in the straight through configuation.

EDIT: should have read the thread properly, I have a 66SD on order, still may have the same problems.

Cheers

JohnG

[Omaroo]

Dang! Fixed it with additional straight-through length by adding a WO SCT 10:1 focuser I have lying around on the end of the existing one. It needed the extended length, and would not work through the 2" star diag for some reason. I suspect that it will need a longer extension tube there too - and should work. Wow... It really needs length!!!! Looks cool with twin 10:1's running....... ;)

Cheers - and thanks for the help everyone!
Chris

Not pretty - but working:

[Omaroo]

You'll love the scope John. Mechanically "beautiful" if there is such a thing.

[Dennis]

I used the WO Zenithstar 66 F/6.1 OTA, Petzval design, 2 speed focuser and soft case as purchased from Sirius Optics in Underwood, Brisbane.

With my Orion Deep Space Star Shooter as an auto guider, I had to fit a WO 1 ¼” diagonal to achieve focus. IIRC, the scale on the focuser came out to close to the 3cm mark.

The set up did not have enough in-travel with the WO 2” Diagonal, so I re-fitted the SCT threaded 1 ¼ adapter that the ‘scope came with, inserted a WO 1 ¼ inch diagonal and magically, the Orion DSSS came to focus!

The OTA fitted nicely inside the WO 100mm Guide Rings with 3 point adjustment, that I purchased from Astronomy On Line at the Qld Astrofest in 2006.

Cheers

Dennis

[JohnH]

No images with with the LPI mounted so I'll take a couple of images of the focusable configs and post them here. BTW as a non-Toucam owner with ambitions is there any practical difference between the 830K and 840K models for astro purposes, the formaer seems to be a lot cheaper?

And yes there little scopes are very nice for wide field shots (Here is one I took with it: http://www.william-optics.com/wo_gal/catalog/images/zs66sdapo_ngc3372_houton_apr06.jpg and very portable for travel and for guiding - 3 in one and they are well made and look good....mmmm ( sounds of sad man stroking OTA :screwy: ) even works as a medium telephoto lens so long as you use a decent tripod.

[Omaroo]

John - not sure about the practical differences between the two. I have the ToUcam Pro II (840K) in the newer case and bought it off eBay for about AU$60 delivered. I'll be modifying it soon to try it on DSO's and wide star fields.

Here's a page you might be interested in - it's a webcam comparison table, and it outlines the differences between several cameras and rates their acceptability in terms of astrophotography:

http://homepage.ntlworld.com/molyned/web-cameras.htm

Cheers
Chris

[Dennis]

Hi

Here is my set up with the Orion Deep Space Star Shoot on the WO 66 Petzval using the stock WO SCT to 1 ¼ inch adapter, with a WO 1 ¼ inch diagonal. The focuser is at approx 3 cms of its 6 cms overall travel.

As stated previously, focus could not be achieved using the WO SCT threaded 2 inch diagonal which is used for visual observation.

There may be some slight advantage having the camera mounted thus, as its own weight and the weight of the cables is less likely to pull it from the diagonal, compared to a straight through position?

Cheers

Dennis

[Rigel003]

I have a similar setup to Dennis, using the 66SD as a guidescope for my 102mm Tak. I use the Meade DSI for guiding, mounted on the 1/4" WO diagonal and it comes to focus about 3 cm out.

[Omaroo]

Thanks for that Dennis. A beautiful setup indeed. You've just cleared it up - I need the 1.25" diagonal instead of presuming that the 2" would take care of everything by itself. I take it that a cheaper GSO dielectric diagonal would work the same as the WO?

Cheers
Chris

[JohnH]

Hi Dennis !

That looks the same as my setup - except the WO66 ED and ADM rings and rail in my case.

Do you use this config for guiding or imaging, and if the latter do you want to compare experiances - I have been having dramas which you may have seen in posts elsewhere tring to conjure decent sub-pixel guiding out of PHD and Maxim EE...

[JohnG]

I would also like to hear of your experiences, I intend to mount a CCD Labs, Q Guider in the straight through configuration.

Anything I need to know other than the use of extenders (have plenty of them). :D

Cheers

JohnG

[Dennis]

Hi Guys

Chris
I’m not sure how similar the WO and GSO diagonals are so cannot really comment on whether or not the GSO would work. IIRC, the WO 66mm has 6cms of focus travel, and the WO diagonal brings the Orion DSSS to focus at 3cms, so hopefully, any minor differences between the WO and GSO 1 ¼ diagonals could be catered for with the amount of spare travel?

JohnH & JohnG
I have only used the WO 80mm F7 (560mm), ODSSS and PHD Guiding to auto guide the C9.25 at 1480mm (i.e. with F6.3 R/C) once or twice, and managed to retain approx 75% of the 5 minute sub frames. The rest suffered from some trailing.

At F10 (2350mm) I had to discard approx 60% of the 3 minute sub frames for the one attempt I made to auto guide at the native fl of the C9.25.

Using the WO 66mm, Orion DSSS and PHD Guiding combo with my Vixen 102mm f9 (918mm) refractor, I had no problem for 2 and 3 min sub frames, and that is the extent of my testing so far. I suspect I could easily go up to 10 or 15 mins with no problems at this short fl.

This auto guiding lark at 2 metres + focal length, sure isn’t easy! My next attempt will be to use the Tak 180mm Mewlon at F12 (2160mm) with the WO 66mm, Orion DSSS and PHD Guiding combo to see how I fare auto guiding at approx 400mm focal length. All this is on a Tak EM200, which in theory, should make it easier!

Cheers

Dennis

[JohnG]

Thanks Dennis

This is mainly for my field setup, SW ED80 with WO 0.8 Reducer/Flattener and a WO 66SD as the guidescope as I said with a Q Guider on a GM-8.

So it appears that guiding at this F/L (around 600mm) should be OK.

The ED80 doubles as my guidescope for the Tak FS-102 in the Observatory and operates with an ST-4 on a G-11.

Cheers

JohnG

[JohnH]

Picture attached - What I did to do this - took the SCT adapter off my 2" bintel diagonal - that gave me a male T thread - took a T to 1.25" adapter off my Viven flip mirror and screwed it in.

The really odd thing is if I use the diagonal I have to rack the focus all the way in - I am sure the distance from the back of the OTA to the chip is then quite a bit smaller so the tube end to mirror and mirror to chip distances musy be critical in some way I do not understand - not just the total distance...

[Dennis]

Very nice set up there John. Those VC200L's are a lovely 'scope. IIRC it is an F9 system? FL of 1800mm?

Cheers

Dennis

[JohnH]

Your memory is correct - though with a Canon20D attached I use a FR to bring it back to f6.3 approx. Nice flat field free of colour problems so good for DSO but not the best of contrast is planetary is your thing....I have not got the best out of this gear yet...