John

Those are "big ones"

Is that Tom Yate's 7" Meade ED by any chance ?

45 minutes ago, DRT said:

Thanks, John. The Ethos 6mm and 8mm will give me identical magnification with these scopes so I will use those. Now all I need to do is identify the name of a suitable crater, which is not one of my strengths

 

I find the Virtual Moon Atlas useful and it's free !!!:

https://www.ap-i.net/avl/en/start

14 minutes ago, DRT said:

Question: in order to make this a fair test should I try to equalise the magnification by using different EPs (e.g. E8mm in the Evo and E6mm in the Altair) or would it be more accurate to use the same EP to avoid contaminating the result?

I'd probably go for getting the magnification about equal Derek. Eyepieces of comparable quality would be good to but I guess they don't need to be exactly the same.

When I was comparing a Skywatcher 150 F/8 with a minus violet filter, with no filter and with a chromacor, I tried to put some order of magnitude of the amount of CA that was being shown around the moons edge by finding a lunar crater that was appeared about the same size as the CA halo was wide, if that makes any sense. It's not exact of course but it did help me to quantify the differences to some extent

1 hour ago, Arminovski said:

Hi

If you could compare your scope with a standard doublet, which focal length would roughly equal it?

What's the focal length of the front lens?

 

Thanks

 

I'm not the original poster here but I can say that the objective lens of the scope (which has 2 elements like all achromatic objectives) has a focal length of 900mm and a focal ratio of f/5.9. You multiply the aperture of the objective lens (152mm in this case) by the focal ratio to get the focal length.

I've seen reports the colour correction of this scope is actually slightly better than that of one of the chinese 150mm F/8 achromats such as the Skywatcher Evostar and the Meade AR152. Thats quite an achievement for an F/5.9 achromat 

Lovely looking scopes those

There is a palpable excitement about being at the eyepiece end of a long white tube like that with the stars twinkling invitingly above.

The AFoV of the Baader Classic 32mm (which is a plossl) is closer to 46-47 degrees I felt when I compared one with other ~30mm eyepieces. 

Not posted in this thread yet so here are my ED120 and TMB / LZOS 130 triplet sharing the Giro:

Thats a great setup

I used to use my ED120 Pro on my AZ-4 from time to time but I felt that it was not quite stable enough at high power for my liking. You obviously find yours good though.

21 minutes ago, Chris Lock said:

Definitely, Roy  I just needed some way of setting up the pun hehe.

Thats why everyone is "russian" to get one !

I'll get me coat .....

No problem Gerry

..... eagerly waiting for the clouds and rain to clear off

Here is a photo of the underneath of the tripod hub. The large metal disk pressed against the bottom of the hub is cut from 4mm thick steel so pretty strong:

1 hour ago, jetstream said:

You have a fantastic set up John, what great scopes. If I may ask- what mount do use on the wooden tripod? Would this mount be a direct fit for the Oberwork? I may need a sturdy mount for a little newt that is upcoming.

Hi Gerry,

The mount in those photos is a Giro II (German made). It is not a direct fit for the tripod top though. I had a strong steel plate made which sits below the mount head and then I run an M10 bolt through it and into the bottom of the Giro II mount. The flat base of the mount sits against the flat tripod hub top and a large knurled knob, threaded for M10, is used to tension the bolt and plate holding the mount firmly onto the tripod hub.

I believe that you can get an HEQ5 / EQ5 adapter to fit the Oberwerk version of the tripod but whether that is an Oberwerk product or a 3rd parties, I don't know I'm afriad.

I'll try and get some photos of my arrangement and post them as soon as I get a chance.

1 hour ago, Telescope40 said:

John. A bit off topic but may I ask about the hardwood tripod.  Is it any particular make. I've been hunting around for a similar item - Fleabay etc. 

 

Hi John,

The tripod is one of the ones that are used on the Helios big binoculars:

https://www.firstlightoptics.com/helios/helios-quantum-7-25x100-binoculars.html

I got mine (just the tripod) from the Astroboot website for around £110 I seem to recall. I've modified the head slightly to take the HEQ5 type mounts. Currently the spreader bars are plastic but I intend to replace them with metal ones or chains.

In the USA they are sold under the Oberwerk branding:

https://oberwerk.com/product/oberwerk-wooden-tripod/

It's a stable tripod even when the legs are extended. It's at least as stable as the EQ6 tripod that I had before it and a touch taller as well.

Hi Bart,

Nice case !!!

Whats the eyepiece to the right of the Nagler 7mm ?

Looks interesting !

Thats a well thought out set Mark

My 12" dob on Saturn tonight. Shows how low the planet is from the UK currently

Newt - Jules, Newt - Jules ...... I'm gradually getting used to the concept !

Thats just the sort of setup I love Dave

Hi Mark,

I'd read a few complaints from folks with the 152 ED's and some rather defensive posts including from the chap that runs APM. I started this thread on the CN forum:

http://www.cloudynights.com/topic/535732-apm-lunt-152mm-f8-ed-doublet-optical-quality/

It's had a few diversions here and there, as you get on CN, but my summary is that I don't feel that my confidence has soared in the scope unless it's bought from a source where you can be confident of really good support should there be any issues.

It's a bit inconclusive of course but when paying out a couple of grand or more I tend to be a bit risk averse

I should get 2nd light with the LZOS 130 tonight, if it stays reasoably clear

I did get the Interstellarium Deep Sky Atlas Alan and I like it very much

The innovative presentation of objects by visibiliy in aperture groups is clever and useful. It's more user friendly than Uranometria as well.

Of course my other half wants to know why I need 2 detailed star atlases as well as Stellarium, Cartes du Ciel, S&T's Pocket Atlas and my old Nortons

If I ever write a book it will be called "Astronomers Excuses and Justifications for Equipment"

5 hours ago, alan potts said:

Very nice indeed John, two weeks away and look what I miss. From a pretty point of view the APM wins for me but the Tak is a fine instrument I am sure. With having the 115mm I feel that if I were to go for another it is going to have to be a 6 inch which is not cheap as you know, maybe a SW Espirit will be the winner as it is about half the price of the APM, one day.

Alan

I'd still like a 6" as well but it will have to avoid the mounting / handling issues that were presented by the Istar 6" F/12 that you might recall I had a little while back. I thought long and hard about an APM / Lunt 152mm F/8 ED doublet but I've seen enough doubts posted about their objective cells to put me off those a bit. The new APM 140 ED which uses an FPL-53 element looks interesting and is around the same weight / size to the LZOS 130 I believe. One of our members here has one of those.

There is, or was, a nice Esprit 150 for sale here and I did think about that one as well. It's too heavy for my mounts at the current time though but they get great reports generally.

The Tak was a limited edition of just 100 units worldwide (very unusual for Takahashi) and I managed to get the last one sold of the UK allocation. It's a slender lightweight OTA which cools really fast. I grabbed a couple of hours with it last night and the views of Saturn were pretty sublime for a 3.9" aperture scope, there is no CA whatsoever on anything and it splits tight doubles like nobody's business

I cleaned the mirror of the 12" dob yesterday so that's ready for the darker skies and won't be left to gather dust just because a couple of flash new scopes are around

Great looking refractor

How do you find the Altair Sabre mount with it ?

I'm wondering about getting one for my LZOS 130.

1 hour ago, alan potts said:

Sounds like buses. I must have missed something in what was a quick run through read, so you have two Lzos type scopes.....

Nope Alan - one Tak FC100DL Flourite and one APM / TMB / LZOS 130 F/9.2 Triplet

Lovely frac(s) kirkster 

Those flextube dobs still remind me of R2D2 when they are in the "down" configuration

I've not posted a pic of my LZOS 130 F/9.2 in this thread yet so yer tiz with the ED120 for scale:

My original plan was to get one really top end scope but in the event two came along !