Mounting ZS66 on ST150 for Guiding.

[quantumpanda]

Hello all,

Could I please have some advice as to what I would need in order to be able to use my Zenithstar 66 as a guide with my Startravel 150? I'm unsure of the guide rings I'll need, although I know the 66 has a tube diameter of 75mm.

My ST150 has a single very shoddy mount for a camera on one of the guiderings. Does this come into play?

I really need information before I go spending money on something that might not work with my setup.

Thank you!

[ollypenrice]

What I would certainly do is reverse roles. The Startravel 150 will be hugely afflicted with false colour for DS imaging whereas the ZS66 is very competent if you have the reducer-flattener for it. There is no doubt at all that the 66 will out-image the big one ten times over.

Guide rings are expensive and prone to flexure, especially on the 66 which is so short that you get no distance between the rings. I did once try it and it was not a good idea. Just bolt the 66 camera shoe to a plate across the top of the 150 guide rings. You should find guide stars easily enough.

Olly

ollypenrice's Photos

[Komet]

whereas the ZS66 is very competent if you have the reducer-flattener for it. There is no doubt at all that the 66 will out-image the big one ten times over.

Amen to Olly. Great scope!

[gbealnz]

Yep, I'm with Olly, use the 66. If you are this unfamiliar (and I mean that in a nice way, please don't take it otherwise) with attaching them together then the suggestion to start imaging with the 66 is sound. It is light, has a short focal length, and will produce a very nice image, something we all need. The ST150 however will work, but like has been mentioned the false colour will annoy or put you off.

If you have a spare finder-scope, try attaching the guide camera to that, there are plenty of articles on how to, and fit the finder-guider to the W/O66. Mount it solid, don't muck with adjustment rings.

Then you'll be cooking.

Gary

[quantumpanda]

Thank you everyone.

Message received: Image with the ZS.

Gary, I like the idea of mounting the ZS solid, and then attaching a finder, since I haven't a clue how I'll safely mount the ZS onto the ST at all (Dodgy rings).

But just to be clear, I am familiar with the STs CA, and I partially fixed it with my Semi-Apo filter, and it doesn't bother me as much now.

Thanks for the help.

[ollypenrice]

Thank you everyone.

Message received: Image with the ZS.

Gary, I like the idea of mounting the ZS solid, and then attaching a finder, since I haven't a clue how I'll safely mount the ZS onto the ST at all (Dodgy rings).

But just to be clear, I am familiar with the STs CA, and I partially fixed it with my Semi-Apo filter, and it doesn't bother me as much now.

Thanks for the help.

Ah, but unfortunately your camera will be far more sensitive to the unwanted parts of the spectrum than your eye. I had a 'budget' Meade 127 triplet apo refractor and upgraded to a premium TEC140. In visual use honesty compels me to say that the difference was quite subtle, but stellar images in the TEC, using CCD, are in a different league and the Meade was a good apo visually, not an achromat.

Surely you could get a thick alloy plate and bolt the foot of the finder and the 66 to that. Estimate the balance point between them by balancing the plate and scopes-cameras along a pencil, and then bolt the plate along this line to the dovetail bar. A small imbalance with these little scopes won't matter. You can drill up through the foot of the SW finder bracket to bolt it to things. I've done that here.

Olly

PS Here's an early effort of mine with our 66. It's not too embarrassing given the fact that I hadn't a clue what I was doing! Good little scope. I will be teaming it up to shoot Ha alongside the Takahashi in a parallel rig this winter.

[Komet]

PS Here's an early effort of mine with our 66. It's not too embarrassing given the fact that I hadn't a clue what I was doing! Good little scope. I will be teaming it up to shoot Ha alongside the Takahashi in a parallel rig this winter.

.... and another ZS66SD image .....

The Rosette in narrowband

Fantastic little scope. I had mine mounted on the back of a Megrez88 (used as the guide scope - the ZS was better than it) using William Optics mountings.

[ollypenrice]

Mick, that's brilliant. I think the OP has found his way forward!

Olly

[quantumpanda]

Wow, they are both fantastic, inspirational images - thank you for posting them. Didn't think the ZS would be better than the Megrez 88.

Olly, your middle paragaph about how to balance the scopes sounds important, but I didn't really follow. Why can I just not mount the ZS as normal, and then attach the finder directly to it?

[ollypenrice]

Wow, they are both fantastic, inspirational images - thank you for posting them. Didn't think the ZS would be better than the Megrez 88.

Olly, your middle paragaph about how to balance the scopes sounds important, but I didn't really follow. Why can I just not mount the ZS as normal, and then attach the finder directly to it?

Mine has no fitting for a finder of any kind. Maybe yours does? So in my case I'd have to contrive a 'side by side' finder-gider of some kind of some kind, as demonstrated in this magnificent piece of artwork. POW for sure!!

Olly

[Komet]

Didn't think the ZS would be better than the Megrez 88.

Good scope the Megrez but did suffer from coma. I use the WO 0.8x Reducer flattener (the type II) with my ZS and get a flat field to the edge of the frame.

Mine hasn't got a finder mounting as such but there is provision for a RDF. You would need to mount another scope/finder on something solid and Ollys suggestion looks sound to me. Get them as rigid and solid as you can. Flexure is your enemy!

[quantumpanda]

Cheers Olly! Loving the image...and I understand now. Looks like I'll have some fun doing DIY engineering, since I'm fairly sure my ZS has no attachment for a finder.

Komet...I have a field flattener, but the vIII version, so I'm slightly worried I'll have problems. I've posted a thread in the trade section for a vII, but they're really hard to come across!

[Komet]

I believe the vIII is suitable for the ZS66. Doesn't it just attach via the SCT thread directly to the focuser?

[ollypenrice]

My ZS66 reducer says it is dedicated the 66 but I'm sure that Ian King would be able to give you chapter and verse on the alternatives which work. My own winter project (greatly encouraged by Komet's Rosette) is to side-by-side the 66 and Tak 85 for OSC in the Tak and NB in the 66 at the same time. I'd forgotten what the 66 could do!

Olly

[quantumpanda]

I believe the vIII is suitable for the ZS66. Doesn't it just attach via the SCT thread directly to the focuser?

I thought that it would but it doesn't. It has a large female thread, and one of similar SCT size, but doesn't fit, I think it may be for 2" filters?

It came with a 2" adaptor, so I use that with a SCT -> 2" adaptor I bought. Unfortunately now, I'm not able to bring the ZS to focus with my DSLR, so I'm searching for a low profile adaptor...or the v2 Flattener which would eradicate all of these problems.

I'm having a tough time with equipment at the moment.

[Glider]

If you unscrew the tube with the 2" thread on it does what you are left with screw on the end of your focuser tube?

[quantumpanda]

Nope.

[Glider]

On my FF II I use Borg series #7424 M57/60AD then #7502 M57-2"AD to get from end of focuser to FF, with the tube unscrewed.

The handy bit is I can then get a standard 2" astro filter into the optical train.

[quantumpanda]

Are you saying the FF 2 doesn't just screw onto the focuser either?

[Glider]

Um, interesting, I've never actually tried it like that as I got the flattener and Borg adaptors all together and have only used them as described above.

OK, yes, if you take the end off the flattener it does physically screw straight onto the focuser, I've just done it.

But, the Borg adapters together are about 10mm long and the focuser is about 10mm from maximum out travel with them on.

Looking at the flattener straight onto the focuser I'm wondering if that would get focus. Seems daft but it looks tight. I cannot say for sure without trying it.

Perhaps you have to use an SCT-2" and fit the flattener into that using the 2" tube screwed in?

[Glider]

Can Komet in post #11 confirm how he uses his flattener on his ZS66? I'd be interested myself.

Note....I've got the Petzval not the SD, if that makes any difference?

[Komet]

The VII comes in three parts - I believe the VIII does the same.

There is the 2" nosepiece, the lens body and the adaptor.

The adaptor has a T thread on one side of it. The other side locates on the lens bosy. There is a thumbscrew on this so it can be rotated. The nosepiece screws into the other side of the lens body.

Removing the nosepiece allows the lens body to screw onto the end of the draw tube on the focuser (you remove any adaptor that is already on there of course). I have asked William Optics about this and they say this .....

"Yes, FlatIII also will work with ZS66SD.

You will need to remove 2" nosepiece from FlatIII then you will be able to attach flattener to the scope SCT thread.

REgards,

Tim

WO"

From the horses mouth.

Having just tried my ZS66SD with my OAG (to see how well it would work) I have a very solid system.

OTA - Flattener - OAG - Filter wheel - camera. All screwed together. Solid as a rock. It looks totally ridiculous just that little OTA on a whole NEQ6 and with just one counterweight almost at the top of the shaft but the quality of the subs that came off it the other night - excellent (in a Mr Burns stylii)

You may have to use extension tubes to achieve focus - I had to when I tried a DSLR.

[quantumpanda]

I honestly cannot get it to fit on my ZS. It looks almost the same size, but the female thread appears to be too small. I'll just have to use the 2" nosepiece.

Seems a shame that after paying so much for William Optics 'quality' products, they don't all appear to be machined correctly.

[Komet]

That is strange. The threads of both the ZS66SD and the flattenerIII are SCT. Could you try and compare the male thread on the nosepiece to the threads on the end of the ZS66 drawtube. You should be able to interlock one with the other. That would show any pitch discrepancy. Diameter difference would be obvious.

You could try screwing the nosepiece into the 1.25" adaptor you removed from the draw tube. That should screw on there without a problem.

I atke it that it is the original WO focusser on the scope? Has it been changed? (Don't know if that is possible even.)

[Glider]

William Optics 66SD, comments that FF III is not recommended for ZS66SD.