First pictures of Nemesis, my new 16" scope

[bird]

I drove to Sydney on Friday and picked up most of the metal parts for my new scope (Nemesis), a 16" f/4 newt.

I'm still waiting on the mirror, but in the meantime I can use one of my other mirrors around here, a royce 14.5", until the 16" mirror arrives.

Here's some piccies for your amusement...

http://www.acquerra.com.au/astro/equipment/Nemesis-16/index.html

cheers, Bird

[Omaroo]

Nice Anthony...but why "Nemesis"? Did you run out of ideas? LOL!

[saturn c]

That's massive bird ! your gona have aload of fun and aweosome veiws with that!

[bird]

LOL Chris - good question... I've been trying new names out for the last couple of months and nothing grabbed me until this one, then it just felt kinda right so I guess it chose itself :-)

cheers, Bird

[xnomad]

If it was my scope, it would be my Fiancée calling it "Nemesis" :lol:

[wavelandscott]

Pretty nifty stuff!

I hope you keep up the pictorial record it is really neat to watch "Nemesis" come together.

[toryglen-boy]

why even give a scope a 'name' at all?


:shrug:

[33South]

Hey Anthony you're gonna need a bigger car.

Chris

[OneOfOne]

I guess resistance is futile now...

If it doesn't work, it will make a great hot water heater!

[Lester]

Looks very impressive Anthony; I am just trying to picture the Jupiter images now when this is working at its best.

Will the Titan carry it?

[iceman]

Looks awesome! So you're dropping back the focal length? Is that so you can get a bright enough image to capture data at a faster frame rate with the bigger mirror?

[bird]

Mike, I've chosen to drop the focal length back so the scope picks up less wind loading. The new camera I'm looking at (Grasshopper2) has smaller pixels so I'll gain back the magnification there.

I have a larger central obstruction with the new scope - 25% vs 20% with LEXX but all the simulations I've done with abberrator etc show that's not a problem.

ps I'm testing a bintel 5x barlow, haven't had good enough conditions yet to see how the quality compares with my 5x powermate but I have found that the bintel 5x gives a lot more "gain" than the powermate, I can get the same size with no extension tubes on the bintel barlow as with 100mm extension tubes on the powermate.

But one potential gotcha with the bintel barlow is that the rgb channels focus at very different offsets, so maybe that's not so good. Definitely bad if you're using a colour camera but even with a mono camera this may lead to a softer image even within each channel. I'll know more when I get good conditions again...

cheers, Bird

[Quark]

Looking good there Bird,

What will the overall weight be with the 16" mirror in this tube assembly?

How much will you need, as far as counterweights go?

I have 50 kg of counter weights on my 16, 45 kg of adjustable weights consisting of 4 x 10kg and 1 x 5 kg individual weights that have 1" BSW internal threads that I can run up or down a length of 1" BSW studding, with a single 5kg end cap that locks onto the end of the studding.

I suspect my tube would be heavier than your tube and my primary mirror cell would be double the weight of yours.

I look forward to following the development of Nemesis.

Regards
Trevor

[Paul Haese]

Ah so there it is. I have heard a great deal about this OTA over the last couple of months. The finish looks superb and in keeping with the temperature release you spoke of several years ago. I like the idea of the middle adapter so that you can use the 14" while the 16 is being ground.

Has the mirror come out of the kiln yet Anthony? Or is it now at Marks?

Shorter focal length can be accommodated by using an extension if need be anyway. You could get a custom made extension if you find that the image scale is too small. Although having said that, I have found you can get a bit of extension just by simply spreading all the components out a little at setup. This can cause some flop with some of the gear, so you have to be careful not to cause decollimation.

Looks good so far, looking forward to the images.

[Troy]

Man would you look at the size of that thing!
Can’t wait for your planetary pictures with Nemesis


:eyepop:

[bird]

I heard back from Ray at Newport glass today, the mirror is out of the oven and almost ready to ship, hopefully it will get here in a couple of weeks or less. Then it'll go to Mark asap. There was one small mishap (the mirror moved while being fused in the oven) and the back surface of the mirror will have diameter 400mm while the front is 406mm but no great problem.

Trevor I don't know yet what the final weight will be, I made sure Nemesis had a much stronger mirror cell than Lexx to stop some of the flexing that I think causes most of my decollimation problems with Lexx. But all up, sans optics, the metalwork would only be maybe 10kg. With optics included and all the rest (bolts etc) probably looking at close to 30kg. By comparison Lexx is 23kg fully loaded.

I have 4 Losmandy counterweights, Lexx needs 3 of them but I'll likely end up with all 4 on the bar for Nemesis. It will be more-or-less permanently mounted on the pier, so I also have to build a roll-off cover that will fit over it.

Paul, the shorter focal length is ok, I can screw on more T adapters to move the camera further away from the filter wheel if I need it. The longer term plan is to upgrade to the Grasshopper2 camera which has 5.5u pixels, that gives me back the image size I lose from the shorter mirror plus some more.

I went shopping today and bought some of the nuts and bolts I need, also re-checked everything against the measurements I put into newt, still looks ok.

cheers, Bird

[mental4astro]

Cooool, ;).

Inspirational work.

Screaming fast f/ratio in your cyclops.

I only know of one other scope of this size with a ratio faster than 4.5, a 17.5" f/3.5 and it is set into a dob mount.

I'll be following your progress most keenly, :thumbsup:.

Mental

[PCH]

Hi Guys,

a little off topic - but related. Can anyone explain how Mark (or anyone) goes about making the mirrors? I mean, do they just set to it with a piece of sandpaper, or is it done on a machine - or what?

Feel free to move this if deemed too off-topic

Cheers :thumbsup:

[mental4astro]

Paul, most professionally made mirrors are machine made on custom made grinding jigs and using various slurries ranging in coursness of grit.

Final figuring is either machine or hand done.

On an f/4, they may have started with a chiesel first though.