Widefield eyepiece for f/6 SW 200P

[russ.will]

You

Quick update: ordered from Explore Scientific in Germany last Thursday, they were shipped on Friday and arrived today. Looks like stock/ordering issues I'd read about in other Maxvision threads seem sorted now.

Even though I'd read quite a few things about it and was aware of the size, still a little shocked when I actually saw the 24mm UWA . The 16mm next to it (and the rest of my eyepieces for that matter) look like toys!

Hoping to try them out tonight, fingers crossed the skies stay clear

You should see the 40mm....

http://img.tapatalk.com/d/13/07/19/vu5equ6a.jpg

Russell

[TwoPi]

That's just silly!

[AlexB67]

This type of thread pops up so often, and people spending a fortune on eyepieces and what not trying to get that best field of view across the FOV when a sky-watcher 250 costs < 500 pounds. There should really be a market for a sky-watcher f/6 - f6.5 at 10 inches aperture ?. I wonder what the reason is for sticking to that same length of 1200mm OTA in the 200 and 250 models. For sure if there was a f/6 version I'd buy it in a heartbeat over the f/4.7, it would still be short enough for most people to use comfortably without needing steps.

Sure, you can argue the pros and cons of faster versus slower scopes, but anyway. I'd feel it would sell and that a gap exists in the market there, or is it just me ?

[Moonshane]

it's almost certainly down to container filling. different length boxes means less efficient filling of a container and given the (low) prices of these things, reduced shipping costs per unit will be a not insignificant contribution to the profit margin I expect.

[AlexB67]

Yes, that makes sense, I mean I suspected it would be very fine margins with such mass produced products and that there is probably a reason something like you pointed out, but anyway, may be they need to think about their container lengths and designs carefully, and perhaps it would pay off in the long run. I mean 10 boxes at length X or 8 boxes of length Y can come to the same packing container, granted you'd ship less scopes in one go.

After all, they also sell bigger scopes like 12, 16 inch that are longer anyway. Perhaps it will happen at some point in the future I suppose it would always be a risk to try and market something new, but hey I want one

[Moonshane]

Indeed. another issue is their design of alt bearing might not work with such a long OTA in terms of adequate balance for e.g. 10" f6. might be wrong of course as I don't have one :0) I do agree though that this would be a really nice focal length in terms of height of eyepiece, focal ratio and eyepiece choice etc.

[AlexB67]

I suspect weight/balance can be sorted, granted it could all add to the price though and see the difficulty that could bring in profit margins. The law of diminishing returns probably kicks in quickly with every little thing you have to consider and add.

Perhaps time to write some letters and get them signed by uhhmm ... let's say brain Cox. I doubt it will change anything. I'll even offer to try out the first prototype for free and I will not complain . I'll see how far that will get me, not far me thinks

[AlexB67]

One more thing of course with slower scopes, Sky-watcher will still want to charge for the more expensive peripherals and eyepieces and earn that way. If a f/6.5 or whatever slower ratio would sell more compared to a f/4.7 that could possibly go against business ethics. They wouldn't want every one to be a cheapskate on eyepieces ( like me for example who can only afford reasonably priced top gear car type eyepieces right now, and also see slower scopes as being of one benefit to get around that to some degree )

[Laurie61]

I was in the same position a few years ago and was looking for an EP, for a f6 scope, with wide field. Ended up with a Williams Optic Swan 2" 40mm. The outer field was not good but on axis was fine so fitted a bigger field stop and turned it into a 2" 52dg 40mm plossl :smiley:Exit pupil still within useful range and goods contrast. http://www.firstlightoptics.com/william-optics-eyepieces/william-optics-swan-eyepiece.html

This type of thread pops up so often, and people spending a fortune on eyepieces and what not trying to get that best field of view across the FOV when a sky-watcher 250 costs < 500 pounds. There should really be a market for a sky-watcher f/6 - f6.5 at 10 inches aperture ?. I wonder what the reason is for sticking to that same length of 1200mm OTA in the 200 and 250 models. For sure if there was a f/6 version I'd buy it in a heartbeat over the f/4.7, it would still be short enough for most people to use comfortably without needing steps.

Sure, you can argue the pros and cons of faster versus slower scopes, but anyway. I'd feel it would sell and that a gap exists in the market there, or is it just me ?

I must admit that when I started to look for a 12" scope I thought you would be able to buy an, of the shelf, f6-7 and was surprised to find none were available. Although if you want a 10", OO make one as a standard production model. When I bought my first decent scope in 78 longer f newt's were common place. I ended up having one made but not the cheapest option. I would love to see somebody like sky watcher make an 8" f8, I reckon it would sell like hot cakes

[John]

I'd certainly like to see slightly slower 10" newtonians from the mass producers. I suspect that Shane's point re: container length is what lies behind the tube length though with the larger aperture scopes occupying a higher price point which can absorb slightly less efficient shipping costs. I occasionally wonder if the 8", 10" and 12" Flextubes were introduced as much because of shipping efficiencies (= more profit) as much as demand from astronomers

I really like my Orion Optics 12" F/5.3 but that did not have to be shipped halfway round the world !

[russ.will]

I was about to agree with the container filling theory, when I remembered the sheer (over) size of my SW Dob base....

Russell

[Moonshane]

but the bases are flat packed?

[AlexB67]

I guess there could be a number of reasons they are not doing it, with the ever improvements in eyepieces also for the price perhaps that is a factor in the overall decisions ?

Apart from coma correctors, I never read up on them to see how they work, but if I understood the theory rightly, coma cannot be cured, it is inherent part of the scope and goes as the cube of f ratio or something like that, so that the coma free field is going be better in the slower instrument, no matter the eyepiece ( or may be I need to read up on that again and refresh myself )

I would have thought by now they would have made my dream f/6.5 or slower scope if they intended to, however, if anything the tendency has been for them to get faster, ( I want slower, jumps up and down on floor while typing )

[russ.will]

but the bases are flat packed?

Yes, but it's one hell of a flat pack and second, they weigh a huge amount.

Russell

[John]

I guess there could be a number of reasons they are not doing it, with the ever improvements in eyepieces also for the price perhaps that is a factor in the overall decisions ?

Apart from coma correctors, I never read up on them to see how they work, but if I understood the theory rightly, coma cannot be cured, it is inherent part of the scope and goes as the cube of f ratio or something like that, so that the coma free field is going be better in the slower instrument, no matter the eyepiece ( or may be I need to read up on that again and refresh myself )

I would have thought by now they would have made my dream f/6.5 or slower scope if they intended to, however, if anything the tendency has been for them to get faster, ( I want slower, jumps up and down on floor while typing )

At some point it might be worth you having a look at the maksutov-newtonian design. They have 70% less coma than a traditional newtonian and tend to come in focal ratios between F/5 and F/8.

[AlexB67]

a 10 inch in that type don't think will happen any time soon, cost, in an ideal world yes . Who knows, in years to come that may well be my scope of choice as you point out, but under the circumstances, I rather buy 10 inch of aperture for 500 pounds with some extra coma instead of a fraction of aperture in that design and less coma.

[John]

a 10 inch in that type don't think will happen any time soon, cost, in an ideal world yes . Who knows, in years to come that may well be my scope of choice as you point out, but under the circumstances, I rather buy 10 inch of aperture for 500 pounds with some extra coma instead of a fraction of aperture in that design and less coma.

Watch out on UK Astro Buy & Sell for a used Orion Optics 10" F6.3 optical tube - I managed to pick up the 12" F/5.3 for a very low price and one of our members built me a great dob mount for it (both items came to less than £500). These slower scopes show much less coma and the OO ones are really surprisingly portable for their aperture. Great optics too.

[AlexB67]

Thanks, will do John, will keep my eyes open for next year or if something turns up, did not realise they could be had that cheap second hand, but who knows, perhaps a good value dob will also turn up by then, for sure worth considering. I suppose cooling is a issue when they really get to that size, and dewing need some extras too.