globular
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Posts posted by globular
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First thing to check is that you have the GPC correctly oriented. The convex face of the GPC should point towards the object / away from the binoviewer. The GPC should help correct colour fringing - but if positioned incorrectly it can make it worse.
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If you want to make it 2" exclusive and have 48mm threads too, you could use one of these...
https://www.firstlightoptics.com/adapters/baader-low-profile-eyepiece-adapter-for-steeltrack.html
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oooo congratulations
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I think this question is similar to eyepiece jumps. For eyepieces I, broadly speaking, went for gaps of 1.4x, i.e. the next EP 40% longer focal length than the one below. This 1.4x is actually √2 and means that you double the area in each step. This seems to give a meaningful jump in FOV and exit pupil at the lower power end, and sensible magnification jumps at the high power end.
Applying to telescopes would suggest jumping from a 6" to 8.5", an 8" to 11.3", a 10" to a 14.1", 12" to 16" and so on.
And in the very low aperture refractor world, 60mm to 85mm, 80mm to 113, 100mm to 140, 120mm to 160mm and so on.In practice I ended up with slightly more EPs (so slightly less than √2 gaps) and I think I'd go for slightly larger jumps when it comes to telescopes. I think @Paz's "strong improvement" of 1.5x is what I'd aim for.
All that said, in reality other considerations like weight, length, mountability, aesthetics, whether you a 'collector', observing preferences, sky conditions, finances, etc, etc all come into play - often to greater extent than any "meaningful noticeable difference" argument.
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Eyepiece focal length equal to scope f ratio is just another way of saying exit pupil of 1mm.
So your question becomes "is 1mm the smallest usable exit pupil".
For me, the answer is no - I regularly go to 0.5mm. And with binoviewers even lower on the right targets.
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Generally speaking*, the casing can be placed either in the binoviewer or in a diagonal.
Placed in the bino gives lower magnification and gives back less back focus.
Placed in the diagonal gives higher magnification and gives back more back focus.
It's a personal preference / choice (or necessity if you are very short of back focus) - but which ever you choose you have to place the lens within the casing orientated so that the convex surface faces away from the binoviewer.
So if the lens is orientated in the casing as in your picture, the casing should be inserted into the binoviewer.*some GPCs are cemented in their case and can not be re-orientated.
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1 hour ago, IB20 said:
What is on OWL? Optical white light? OTA with lickables?🦉
I'm guessing, but I think it's Ohara With Lanthanum.
i.e. it is a doublet with Ohara FPL-53 glass and a lanthanum element.-
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17 hours ago, Sunshine said:
Anyone know what this symbol means?
Symbols like this usually mean it was manufactured for foreign export (to America) and not for the local Japan market.
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I see that FLO have just added them to their web site.
I imagine this was in response to you asking them if they can get them for you.... but if it wasn't, now you know here is that option too.
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I have the 7, 10, 16.5 and 40 XWs. They are all fabulous.
I didn't get the 23 because I already have a very nice N22T4.
I haven't got the 3.5 and 5 (yet) because I don't (yet) have a scope that would make regular use of them. I will get them when I do.-
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Looks HUGE....
Looks the perfect size...
Looks wonderful. Hope you enjoy it
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oops, sorry.
Good luck
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Don't know why but I thought you only wanted the latitude one.
They do them both as a set too - also in stock.....
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Pierro Astro have it in stock. I think they deliver to UK.
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Looks a bit like one of these... ??
Which was on a John Browning telescope....
https://jasonclarkeantiques.co.uk/products/mid-victorian-astronomical-telescope-on-stand-by-john-browning-63-the-strand-london-
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This is great - thanks very much for sharing.
On 11/07/2023 at 17:09, Richard N said:I suspect that there will be one or two mistakes (I have already spotted one) but I will issue an update in a few months
I think Santa is secretly getting me a copy of the Duplex Moon Atlas - so I can't check it for myself as yet. If you have an update (to the .pdf in particular) that would be fantastic.
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5 minutes ago, badhex said:
we would not be able to say which planet was dominant
Under current 'rules' I think neither would be a planet. But more likely we'd come up with some new rules that fit what we 'want' if such a system existed.
Rogue planets and exoplanets don't need to fulfil the 'cleared their neighbourhood' rule, so why solar system ones? But then I guess you could argue that we can't measure things that well for other systems.
As I hinted at earlier - it would be interesting to see what an alien race (or rather us but with without the historical baggage of our gradual technological improvements and, most importantly, our local bias) would come up with as a definition.
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24 minutes ago, badhex said:
L4 and L5 can in theory support a planet sized object sharing an orbit
Planet sized maybe - but it can't be called a planet.... because it hasn't 'cleared it's neighbourhood' - being held in the other 'planets' lagrange point means it isn't dominating the neighbourhood.
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I position my 8" SCT on the very end of the bar and can slew anywhere without anything catching the mount.
If you've already tried it in this position then a photograph of your set-up might help us help you.
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If aliens ever pop by to say hello I suspect our first argument with them will be over this.
"What do you mean you're on the 3rd of 8 planets? Can't you count you fools there are way more than 8."-
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37 minutes ago, mikeDnight said:
Even the expert planetary observer Edward Emerson Barnard found that 180X is around the ideal power for Jupiter
I've had some lovely views of Jupiter at high power (350x-450x) - when conditions are right its lovely to see a huge image.
However for picking out details I find dropping the magnification to 150x-200x shows more of what's on offer.My observation notes from a session back in 2021....
"tried ES92/12 with 2x powermate (354x). amazingly stable. lots of band detail. bet there is more to be had at lower power, but still very nice, especially the size! swapped the ES92 for N22T4 still in powermate (195x) wow! the detail! io, europa, ganymede and callisto on show too. stunning!"-
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1 minute ago, Stu said:
Make that North Somerset! Clear here, but seeing is pretty bad unfortunately.
I can't even see the seeing here - so any old Somerset will do 🌧️
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Wind here is gusting at 30mph and there is near horizonal rain. I really must look into moving to the Somerset area 🤔
MaxBright II BW colour fringing - is it expected?
in Discussions - Scopes / Whole setups
Posted
Bader make two versions of the 1.7x GPC, one facing the binoviewer and one facing away. Which ever one you have you can turn it into the other one by removing, flipping and reinserting the lens within the housing.
In other words the key is not whether you put it in the bino or the diagonal, but whether the lens is orientated correctly within the housing for your choice of bino or diagonal placement.