APM LZOS 130 f6 - first light

[Stu]

27 minutes ago, Alan White said:

A real shame you have to hide it under a dark cloth though Stu 😉🤣

What make is that, the top end design looks different to those I have seen before?

Actually it is a home build job Alan, but very well done and based on an Obsession type design I believe. It was a comparative bargain; I couldn’t afford the similar aperture Sumerian which was also available. In a way it was a bit of a risk, I know little about the mirror, but it was bought from the chairman of an Astro club who had used it successfully for years so I’m optimistic it will be good when I finally get to use it. I’ll post up separately about it when that happens.

[Deadlake]

53 minutes ago, Stu said:

yep. 👍

What make, how smooth is the mirror and how fast?
Do you need a step to use?
To be honest with the LZOS and the Dob you have both bases covered.
 

[Deadlake]

7 minutes ago, Stu said:

🤣🤣 me too! I came back to it last night and wondered what the heck had happened! 🤪🤪

Regarding the focal length, in the end I’ve been driven by practicality and also the fact that I enjoy wider fields as much as high power. I wanted something I would use frequently, and having seen and felt the weight of this one, I know I’ve made the right decision for me. I’m sure there is a little more ultimate performance at high power in the f9.2 but we are talking tiny increments I should think, mine is 0.973 strehl so hardly a slouch 😀. Knowing how much I’ve used my Tak simply because of its portability, this one will still get used less due to the larger mounting needed, but hopefully still frequently when a good night shows up.

We went off at a tangent when playing what else has Stu bought. 😀 @jetstream Dob fondness.

[Deadlake]

Just now, Deadlake said:

I’m sure there is a little more ultimate performance at high power in the f9.2 but we are talking tiny increments I should think, mine is 0.973 strehl so hardly a slouch

The F9.2 have a Strehl on average of 0.99 and are better colour corrected. However the F6 is more flexible IMHO.

[Stu]

13 minutes ago, Deadlake said:

What make, how smooth is the mirror and how fast?
Do you need a step to use?

As said, home built to a high standard, based on Obsession type design. I don’t have specs on the mirror and the price I paid reflected that. It is f4.2 and no I don’t need a step. I may need a Paracorr but I’ll try it and see first. My previous 16” f4.5 had SIPS and that was a great system.

[Deadlake]

42 minutes ago, Stu said:

SIPS

nice!

I'd be interested to know which you will use the most, DOB or APO?

[Alan White]

12 minutes ago, Deadlake said:

I'd be interested to know which you will use the most, DOB or APO?

So would I, but I hazard a guess that the 130 will get more use.

[John]

How heavy are the 130 F/6's ?

My F/9.2 weighs 9.4kg including tube rings / finder / diagonal and Losmandy DT bar.

I think the optical reports with the LZOS refractors are to demonstrate that the objective meets or exceeds APM's lens spec. Or at least that's what Markus at APM told me. In practice they tend to independantly test a little better I think. It's not just the raw strehl, RMS and PV figures. The lens surfaces are hand finished and matched to each other on an objective by objective basis and then fitted into a precision cell where the contact points and spacing are precisely aligned, again by hand. So each objective is an individual work, as it were.

It's what you would expect for their cost of course. The LZOS objectives on their own in LZOS cells are fearsomely expensive:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11283_APM---LZOS-130-mm-f-6-Triplet-Apo-Objektiv-in-Zelle.html

Here is the APM minimum spec for the objectives:

APMApo-Linsen-Spezifikationen.pdf

That is a superb pair of scopes @Stu. Unless aperture fever strikes, they should set you up for a lifetime's observing

And I'm sure you have a couple of other quality "lightweights" for travel / grab and go observing as well

 

Edited September 11, 2021 by John

[Stu]

1 hour ago, John said:

How heavy are the 130 F/6's ?

My F/9.2 weighs 9.4kg including tube rings / finder / diagonal and Losmandy DT bar.

I think the optical reports with the LZOS refractors are to demonstrate that the objective meets or exceeds APM's lens spec. Or at least that's what Markus at APM told me. In practice they tend to independantly test a little better I think. It's not just the raw strehl, RMS and PV figures. The lens surfaces are hand finished and matched to each other on an objective by objective basis and then fitted into a precision cell where the contact points and spacing are precisely aligned, again by hand. So each objective is an individual work, as it were.

It's what you would expect for their cost of course. The LZOS objectives on their own in LZOS cells are fearsomely expensive:

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11283_APM---LZOS-130-mm-f-6-Triplet-Apo-Objektiv-in-Zelle.html

Here is the APM minimum spec for the objectives:

APMApo-Linsen-Spezifikationen.pdf 468.53 kB · 1 download

That is a superb pair of scopes @Stu. Unless aperture fever strikes, they should set you up for a lifetime's observing

And I'm sure you have a couple of other quality "lightweights" for travel / grab and go observing as well

 

Thanks John. Haven’t actually weighed it but I think it’s heavier than yours. The lens will be thicker due to the shorter focal length. For me the weight is fine, but the shorter physical length is important for manageability, storage and also I’m likely to take it away with me so that’s easier.

As you say John, I’m well setup now with no need for change. I have no intention of going larger that 16”, I just wouldn’t use a scope that big. This one is actually really nice; much more solid and rigid than the Sumerians I have had, and the motion is very smooth, with little stiction but it also just stays put wherever you point it.

The other benefit is that the scope itself is relatively light, but you add a series of balance weights under the mirror cell. This means each component is much more manageable, but it will still cope with heavy eyepieces.

You are right about other scopes of course. I still have the FC100DC which is very portable and great for grab and go purposes, and the Vixen FL102S which is very manageable on a smaller mount.

EDIT: how could I forget the Genesis too!!

[Deadlake]

I suspect yours might be a little lighter, APM focuser, tube rings a little lighter KUO tube heavier. Around 11.1 kg's:

[Deadlake]

@Stu Did you ever look thru @GavStar AP130GTX? Wonder how they compared, given the AP130GTX costs €3500 more?  

[Stu]

8 minutes ago, Deadlake said:

@Stu Did you ever look thru @GavStar AP130GTX? Wonder how they compared, given the AP130GTX costs €3500 more?  

Yes I did. Amazing scope, really lovely views but without trying them side by side it would be impossible to say which is best. There was one in ABS which I was tempted by but too pricey for a second hand unit, even AP! They are quite a bit lighter which is a benefit.

[Deadlake]

4 minutes ago, Stu said:

Yes I did. Amazing scope, really lovely views but without trying them side by side it would be impossible to say which is best. There was one in ABS which I was tempted by but too pricey for a second hand unit, even AP! They are quite a bit lighter which is a benefit.

When I get a lighter mount for the LZOS maybe I’ll bring it to Walton. If @GavStaris interested we could compare views with his AP130GTX.

[Jokacha]

Why is it a lifetime scope? Think big. Perhaps you can upgrade to an FPL-53 or FC-100 scope one day.