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Edge HD 8" with SE Mount?

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#1 mitaccio

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Posted 01 October 2013 - 10:19 PM

I have the chance to acquire an Edge HD 8" ota only in exchange for my 8SE ota. I will be keeping the SE mount. If the Edge HD ota has the CG5 rail, will it work on the SE mount? I realize that the focuser will be at the 9 o'clock instead of the 6 o'clock position.

#2 Dunkstar

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Posted 02 October 2013 - 05:56 AM

There is a lip on the Celestron dovetail that causes it to foul the clamp housing on the mount. I solved this by replacing the Celestron dovetail with an ADM C8 part. Works beautifully :cool:

#3 Eddgie

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Posted 02 October 2013 - 05:17 PM

I am using my EdgeHD 8" on the 8SE, and I am using a Mark V binoviewer and a Losmandy dovetail (the EdgeHD comes with a CGE dovetail so this will have to be replaced).

I did not have to do anything special. The scope fits fine.

My setup is using a very short visual back (10mm) and a 1.25" diagonal, but I would think that using a very short light path (in particular, the Baader 2" Clicklock with the mirror box screwed directly on to the rear port) would work just as well..

If using a very long setup like a Clicklock and a 2" diagonal, this would require the modifications mentioned.

But keeping it short might work better because less mass is hanging out there.

Here is the Baader diagonal.

This would be the best possible 2" diagonal for an EdgeHD on an 8SE mount because it would both keep the center of balance further forward and have clearance.

It also helps by keeping the focal length under 2100mm.

Baader Clicklock Diagonal instructoins

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#4 Dunkstar

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Posted 03 October 2013 - 10:05 PM

The Clicklock 2" diagonal Eddgie describes screws directly onto the rear SCT thread like this:

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#5 Dunkstar

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Posted 03 October 2013 - 10:06 PM

Also note the focuser at the 6 o'clock position. This is a semi-permanent setup because it's necessary to remove the focus rubber and shaft to screw the diagonal onto the rear thread.

#6 Eddgie

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Posted 04 October 2013 - 08:11 AM

If I were not primarly a binoviewer user, I would have this diagonal for sure.

I have come to beleive that the shortest possible light path in an SCT is the very best way to configure the scope for visual use.

Especially the EdgeHD 8" that is already more like 2150mm with a standard 2" diagonal and visual back.

Even with the binoviewer, I am using the T2 Prism mounted directly to the visual port with a 10mm light path SCT to T2 adapter.

It does not require the removal of the knob, but with no lock ring, It cannot be easily rotated.

That was one of the main reasons I went with the 8SE mount. I could mount it in one position and leave it alone.

Has worked out pretty good.

Still trying to stiffen it up.

I went to thick wall aluminum legs which helped a lot, but found that stainless legs (thicker than the stock legs, thinner than the aluminum legs) would have been stiffer.

I was not going to upgrade (to be honest, I don't use the scope that much), but it bothers me to know I can improve it some.

#7 Eddgie

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Posted 04 October 2013 - 08:12 AM

By the way, how do you like it?

Do you notice any difference? Do you recommend it?

#8 Dunkstar

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Posted 05 October 2013 - 05:56 AM

It's a great combo IMO the diagonal is large but well made and the Clicklock is really effective. Along with the locking ring it fastens very securely and is confidence inspiring, I frequently use my Ethos without concern. It's hard to comment on the FOV as switching to the locking ring configuration is not something I'd want to try in the field. Another plus with the locking ring is that it's easy to clear the SE mount base when viewing at or near the zenith. It's much harder to achieve that using the Clicklock visual back as essentially adds almost 2" additional length.

I'm keenly watching your experiments with the tripod as the SE mount / tripod introduces a little vibration into the experience, although I'm used to it now and it doesn't really bother me so much. It's a great portable setup though. I haven't used my bigger scope in months :grin:

#9 Eddgie

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Posted 05 October 2013 - 09:27 AM

In the name of science, I have decided that I will go ahead and upgrade to the Stainless legs.

I whish I had asked the question of which was stiffer berfor going to the aluminum. While the Aluminum is almost twice as stiff as the factory thin wall stainless, the 1/16th stainless would have been almost 3 times as stiff.

It is working pretty well now, but I really just want to go all the way for the fun of it.

I may do it this week, and if I do, I will post the result.

Again, just by putting the base directly on the ground though, I know that single arm mount itself is the real upper limit.

Still, aluminum legs made a difference, and if there is a bit of further improvement, I want to know it.

The aluminum legs were in the "Taking one for the Team" catagory.

Thanks for the report on the Baader. This would be the diagonal I would use if I were going to put a 2" diagonal on my EdgeHD, but since I binoview almost excllusivly these days, I am configured with the 10mm SCT to T2 Connector and the T2 Prism.

#10 Dunkstar

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Posted 07 October 2013 - 09:00 AM

I look forward to it Eddgie! I think I'll probably be stuck with the retractable legs as it is my travel scope and it can be deployed on uneven ground :(

Also the next time I'm out with it I'll run an experiment re: the single arm since I've had it I've got a little addicted to the wider aFOV eyepieces, so I'll attempt to reduce the weight by using a 1.25" diagonal and lighter eyepieces and see how much that helps with the vibration.

#11 Eddgie

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Posted 07 October 2013 - 01:19 PM

Well, I am running a pretty heavy load with 1.25" diagonal, Mark V binoviewer, and 2 ES 2468 eyepieces.

Still, the diagonal is screwed on with a 10mm light path connector which keeps the CG very close to the rear cell, which should present a low moment.

It is better with the aluminum legs. Much better. They are only 36" long too, so I don't see a big problem with transporting it, but then I rarely do more than carry it out the back door.

Will try to get to the metal shop and have the stainless legs cut this week, but getting ready to go on vacation so just may not get to it.






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