John

17 minutes ago, jetstream said:

Vlaiv can you MTF plot a near perfect 4" refractor against a 12" newt obstructed 20% and with a Strehl of .90? This gets interesting IMHO. Assuming perfect focus, on axis  (no coma)and perfect seeing.

If we get a clear night I can compare my Tak FC100-DL with my OO 12" F/5.3 dob which has a 21% obstruction and, according the paperwork, a primary of Strehl .987

What targets would be the most suitable for a fair comparison I wonder

Those Berlebach foldable spreaders are about the best upgrade you can make to a Berlebach tripod. Not much else you can improve in all honesty.

Speak up Robin, we can't hear you ! 

MTF ?

Modulation Transfer Function

I think that is all that I can contribute to this

3 hours ago, Sunshine said:

I'm sure that will buff out and they'll have it ready in a snap.

Reminded me a little of this:

"I think you had it there a while back Ted"

While the Taks are light compared to some, they thrive on high and very high magnifications so the mount choice needs to be able to deal with that.

I didn't think that I would use my Nagler 2mm-4mm zoom all that much but it's very frequently used with my Tak.

29 minutes ago, duncanjameshill said:

That is what I hoped (and feared) to hear 😁. I was under the impression I would need a hefty mount for the ED120? I'm thinking about an SW equatorial but, obviously, not sure which one yet. Costs go up so quickly but I'm worried about under buying and having to upgrade soon after buying.

For visual observing the Skytee II or Giro Ercole (in my pic) does very well. An EQ5 is fine or Vixen GP. For imaging something heavier duty though. 

I have put the scope on an AZ4 and it was OK for low to medium magnifications. Bit wobbly at higher powers though.

16 minutes ago, johninderby said:

Wouldn’t you like to win the lottery and call up FLO and say send me one of every scope you have. 😁😁😁

Just at the moment, that might not be many

Take it to The Repair Shop ?

Spectacular though !

5 minutes ago, duncanjameshill said:

I think maybe I'm trying to cover too many bases in one and should forget about imaging for now - really it's just the visual I'm after. I would love for someone to tell me the 120ED could be described as a grab and go........?

On an alt-azimuth mount it's a readily portable scope and quick to set up . I can pick this whole setup up and move it around the garden. I take it out of the house in 2 parts (tube + mount / tripod). Cool down time is about 20 minutes for best high power viewing.

Whether that is fully "grab and go" depends on the definition of that term I suppose. There is not an official definition !

53 minutes ago, Tiny Clanger said:

Yep, it is a far heftier chunk of solid aluminium than the illustrations make it appear to be : that disc you see at the top with the skywatcher logo on is 6cm thick, and the two curvy arms which connect to it fix to opposite sides of it, which is not at all obvious in pictures. I don't have the stat. to  hand, but I was most surprised by the weight of the thing

Yes, I had a play with one when it was first launched

43 minutes ago, Robindonne said:

How nice would it be if shops send out “try before you buy-versions” of these small items to well known customers.   All these dilemmas would be gone. 

It does happen

Reminds me of this by Chesley Bonestell

7 minutes ago, Jasonb said:

Exactly, why put an Aluminium tripod under an AZ5? Though I don't know if it's Skywatcher or FLO that are making that pairing. And to be fair to FLO, you can easily buy the AZ5 and they sell a separate steel tripod that would fit it. Didn't know you had the AZ5 Heather, I take it you're happy with it?

It will be Skywatcher's choice. I seem to recall that FLO were selling the AZ5 as just a mount head at one point but it is not listed that way now.

21 minutes ago, Jasonb said:

That's true John, but sometimes all I have to go on from sites etc. is the figures they have, like Payload. That said, if you had an AZ5 and put it on a steel tripod, I'd expect it's capacity to increase.

The AZ4 was one of the most portable mounts I've ever owned. It was my "go to" mount for outreach events in remote sights where I had to carry the equipment some way. When we can do such things again, I'll probably get another one.

10 minutes ago, Deadlake said:

I went with the phenolic tube as you mention not wanting to get my hands frozen to the tube...

Highly resistant to dewing as well - objective included

12 minutes ago, Captain Magenta said:

Before I got to this post I had precisely the same question bouncing around my head. And seeing @John’s reply my heart sank ... I so wanted the answer to be “no no no FAR too heavy”.

Magnus

I ought to qualify my reply by saying that was without the 2 Rowan 3.8 kg counterweights that I needed for the scope that I was using to test the mounts operation.

Also I guess I ought to add that "Your Mileage May Vary". We are not all the same shape, size and capacity as humans !

4 minutes ago, Jasonb said:

That's interesting, I looked at both of those (of course, just looking, not buying!) and the AZ4 comes with a steel tripod and is listed with a payload capacity of 6.8Kg and the AZ5 comes with a Aluminium and a capacity of 5Kg. Seems weird the AZ5 is 'worse' than the AZ4?

 

I don't think the he mount head of the AZ5 is quite as solid as the AZ4. Also aluminum tripods don't generally have the stiffness and solidity of the steel tripods, although there are better ones about eg: Vixen.

I'm rather cautious about translating loading capacity figures into relattive "real world" capacity because the characteristics of the scope can make a major difference ie: the physical tube length and the focal length. The weight capacity is just one part of the equation.

1 minute ago, Deadlake said:

I have an APM LZOS 130 mm / F6 on order. F6 due to being able to use it with a televue compressor for NV in case you where wondering why not go for the 9.2. 

Fantastic scope !

I have the F/9.2 and the optical quality is outstanding. The F/6's are just as good despite their faster focal ratio I've heard. The build of the scope generally is really excellent as well.

I use an AP Maxbright diagonal with mine but I'm mulling over a Baader BBHS prism in the 2 inch size as an alternative.

When I had those early AZ100 units to try out I had them on an Uni 28 and found that I could carry around the mount / tripod in one piece, with some care and, as John says, I would not have wanted to negotiate stairs with it.

Does this spell the end of the dielectric dominance of the diagonal world ?

57 minutes ago, acercon3 said:

Hi Nik

When viewing Alnitak I thought that I could see a very dim object to the west of it, barely visible . Could this have been what I was searching for ?
 

Alan

This is quite a good representation of Alnitak through a 101mm refractor

It can be quite a tough one though if the seeing is unsteady, scope not quite cooled, etc ,etc.

The only issue that I've seen people run into when replacing the focuser on the ST80's is making sure that the replacement unit is of a suitable optical length so that eyepieces will come to focus when a 2 inch diagonal is used. A 2 inch diagonal has a longer optical length than a 1.25 inch.

The great thing about the ST80 is that even with the stock 1.25" focuser you can get a 4 degree true field with a 24mm super wide eyepiece such as the ES 24 / 68 or Panoptic 24 or a 32mm plossl

I'm not bothered about having a mirror in the system, as long as it's a good one.

Likewise, I'm happy to use lens based eyepieces in my 12 inch dobsonian

28 minutes ago, Carbon Brush said:

..Once bitten twice shy. Since then I have only ever bought 2nd hand Orion kit. I would never trust them with a new order.

 

That's how I feel about OO as well