Skyliner-250PX FlexTube later attached to a HEQ5 Pro?

[billw]

I am considering upgrading to a Skywatcher Skyliner-250PX FlexTube, with the intention of later on getting a HEQ5 PRO Synscan to replace the mount with if I have the spare cash. Any opinions or guidance would be appreciated. I have heard you can mount a tube from a Dobsonian onto a Eq mount using large rings, but I don't know the limits of such a method. Apparently the 250PX tube weighs in at about 15kg, and the HEQ5 is good for up to 18 so the weight alone shouldn't be a problem, but I don't know how using jerry rigged mounting with rings would handle it. Also as it is a FlexTube maybe I won't be able to mount it at the optimal location, or maybe it just won't work at all and I would have to get a standard tube.

I want to try my hand at astrophotography, would I be able to do short exposures (10 seconds or maybe less) and use image stacking to generate a decent image using just the Dobsonian mount and a wide lens? Or will I have to wait until I get the HEQ5 as well? OR... am I better off waiting and getting a Schmidt Cassegrain with a smaller aperture instead?

[Tinker1947]

I think you will find the 250 really needs a NEQ6 if you going the AP route.....with Polar aligning and a HEQ or NEQ certainly 60 seconds will work very nicely....

[JamesF]

Getting the scope firmly attached and properly balanced would probably be quite tricky if it's even possible at all. I don't think you'd be able to fit scope rings where you really need them. An equatorial platform might make far more sense if you particularly want an EQ-aligned scope.

If you want to take some wide field images you can do that with a standard tripod for exposures up to about 30 seconds with a wide lens. If you want longer exposures then certainly you could just mount the camera on a GEM. An SCT is a completely different kettle of fish. You'd not use one for wide field imaging at all.

James

[Digz]

In addition to the comments above I don't think you'll be able to mount a flex tube satisfactory. Something tells me it will be very unstable when on a GEM as its not a complete, rigid, tube as well as struggling to locate the tube rings in a good place.

[JamesF]

Exactly. The balance point is not that far below the rim of the lower section of the OTA even without an eyepiece in. Stick a camera or heavy eyepiece on the end and it will be a pig to balance.

James

[Steve Ward]

I looked into going down this road with my 250PX when I decided to go to an EQ set-up.

Not a worthwhile exercise I'm afraid , too many problems with mounting , balance etc.

Did the right thing and sold the 250 , bought the HEQ5ProSynScan and the 200PDS combination , never looked back.

Steve.

[Sirius Bizness]

My MN190 at 10kg without accessories or camera is too much for the HEQ5. I had to get an extra counterweight (3 off) and they are all at max extension. It works but just. At 15kg I don't think it will.

[billw]

Thanks everyone that has replied! I am now thoroughly (and rightly it seems) dissuaded from my original plan!

My MN190 at 10kg without accessories or camera is too much for the HEQ5. I had to get an extra counterweight (3 off) and they are all at max extension. It works but just. At 15kg I don't think it will.

Hmm, what do you mean by "It works but just"? What problems do you experience during use? I am quite tempted by this idea. Possibly I will start with a EQ5 mount, put my existing Explorer 130P on it and try some AP on that, then upgrade to a better tube later..

[Sirius Bizness]

Just able to balance with with the three counterweights. I think a 4th further in might not even be enough for the 15kg+. I had some weird subs (not all) unguided with trails. Don't get the same issue on my lighter refractor. The 130P would be a good start.