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?
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.
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
lol, well i have no idea then... can you focus on anythig terrestrial? try during day light.
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.
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.
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?
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?
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?
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...
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
Quote:
Originally Posted by 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?
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
Quote:
Originally Posted by JohnG
Hi Chris
Have you tried without the diagonal, this has all the symptoms of not enough infocus.
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.
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.......
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.
You'll love the scope John. Mechanically "beautiful" if there is such a thing.
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.
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
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...uton_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 ) even works as a medium telephoto lens so long as you use a decent tripod.
) even works as a medium telephoto lens so long as you use a decent tripod.
