New telescope - Founder Optics Draco 62mm refractor

[Elp]

This might be an interesting short FL refractor, 5 element 300mm FL so it can frame lots of targets well, can be reduced from native f4.8 to 3.9 for imaging purposes with the x0.83 reducer so 249mm FL which is even better for AP framing large emission targets, waterproof and apparently fogproof? According to WS also user collimation possible.

Topic is now open for discussion.

 

https://www.founderoptics.com/index.php?action=news&id=12

https://www.widescreen-centre.co.uk/founder-optics-draco-62-5-element-ed-refractor.html

Edited February 8 by Elp

[Elp]

Can a scope be waterproof or fogproof, I know certain spotter ones are designed as such but an astro telescope?

[DirkSteele]

Widescreen Centre has reportedly the first example in the country at AstroFest last weekend. I picked it up and it was quite a chunk of metal and glass. Should be available in March / April.

[Elp]

It seems to do a lot of things nicely. But I'm interested whether you'd need dew heaters with it regarding the fogproof claim, or I assume that applies to internal surfaces only?

[Richard_]

When fitted with the reducer, this looks like a much more affordable alternative to the WO Pleiades telescope!

https://www.firstlightoptics.com/william-optics/william-optics-pleiades-68-f38-astrograph.html

I wonder what grade of glass is used as it just says ED.

Regarding water proofness, I would guess that the nitrogen purging and  coatings on the lens elements inside the telescope would be to prevent/stop fungus growing inside the telescope. I think it would still be a good idea to use dew heaters to prevent dew from forming on the outer surface of the lens.

[ollypenrice]

15 minutes ago, Richard_ said:

When fitted with the reducer, this looks like a much more affordable alternative to the WO Pleiades telescope!

https://www.firstlightoptics.com/william-optics/william-optics-pleiades-68-f38-astrograph.html

I wonder what grade of glass is used as it just says ED.

Regarding water proofness, I would guess that the nitrogen purging and  coatings on the lens elements inside the telescope would be to prevent/stop fungus growing inside the telescope. I think it would still be a good idea to use dew heaters to prevent dew from forming on the outer surface of the lens.

At a first glance, the RASA 8 blows this out of the water. It has a 100mm longer FL but is nominally  3.6 times faster, though rather less given the central obstruction. Even so, it will cover the same FOV in far less time and, I think, with perceptibly better resolution. The RASA is not diffraction limited but it doesn't need to be when considering its competitor refractors of comparable focal length.

The RASA is entirely dew-proof without heaters, in my experience. Camera heat and fan deals with the problem.

Olly

[Elp]

For some reason I can't quite nail down, I much prefer setting up refractors than my F2'd SCT even though both take a similar amount of time. I use my Z61 in hand with the faster scope to supplement the data. I think this scope offers a decent spec for those looking for something small but the proof will be in the pudding.

But yes, once you've done F2 at a decent aperture, everything else is kind of too slow.

[Richard_]

16 minutes ago, ollypenrice said:

At a first glance, the RASA 8 blows this out of the water. It has a 100mm longer FL but is nominally  3.6 times faster, though rather less given the central obstruction. Even so, it will cover the same FOV in far less time and, I think, with perceptibly better resolution. The RASA is not diffraction limited but it doesn't need to be when considering its competitor refractors of comparable focal length.

The RASA is entirely dew-proof without heaters, in my experience. Camera heat and fan deals with the problem.

Olly

Is that also with a dew shield fitted or not? I imagine having heat from the camera mounted on the lens helps a lot!

Whilst I don't disagree with what you're saying regarding the RASA being faster, I imagine you need a lot more mount (eg EQ6-R pro) for the RASA unlike these lighter, 60-70mm aperture refractors.

Plus, you need specific narrowband filters for very fast optics right? My Antlia filters are good down to around f/3, so that's one less thing I'd have to consider upgrading if I moved to one of these fast* refractors.

*I mean fast by refractor standards 🙂

[ollypenrice]

11 hours ago, Richard_ said:

Is that also with a dew shield fitted or not? I imagine having heat from the camera mounted on the lens helps a lot!

Whilst I don't disagree with what you're saying regarding the RASA being faster, I imagine you need a lot more mount (eg EQ6-R pro) for the RASA unlike these lighter, 60-70mm aperture refractors.

Plus, you need specific narrowband filters for very fast optics right? My Antlia filters are good down to around f/3, so that's one less thing I'd have to consider upgrading if I moved to one of these fast* refractors.

*I mean fast by refractor standards 🙂

Yes, a shot dewsheild to camera height.

You're right about the mount and the RASA is not my idea of portable since it's a vulnerable setup when assembled. It's also fickle and best left alone once sorted. It is also best seen as an OSC instrument in my view, though this makes the tri-band filters an option. Pure narrowband would be an expensive palaver.

Olly

[Kyuss]

Searching for a small refractor and that seemed to check all the boxes. Then Cuiv kinda ruined it with the pinched optics:

 

 

[Elp]

The thing with pinched optics, when people mention them they don't go into it further as it could be attributed to a number of things. I believe the new Askar triplets can suffer from it, it's temperature related and you have to wait for thermal equilibrium, some people have used dew heaters further past the objective to heat the internal mounted lenses.

[jjohnson3803]

Have to admit that I like the color.  🙂

[Kyuss]

10 hours ago, Elp said:

The thing with pinched optics, when people mention them they don't go into it further as it could be attributed to a number of things. I believe the new Askar triplets can suffer from it, it's temperature related and you have to wait for thermal equilibrium, some people have used dew heaters further past the objective to heat the internal mounted lenses.

But do you really want all that trouble with your newly acquired scope? Not to mention that pinched optics can be a design flaw also.

[Adam J]

On 11/02/2024 at 20:11, ollypenrice said:

At a first glance, the RASA 8 blows this out of the water. It has a 100mm longer FL but is nominally  3.6 times faster, though rather less given the central obstruction. Even so, it will cover the same FOV in far less time and, I think, with perceptibly better resolution. The RASA is not diffraction limited but it doesn't need to be when considering its competitor refractors of comparable focal length.

The RASA is entirely dew-proof without heaters, in my experience. Camera heat and fan deals with the problem.

Olly

Yeah it but the RASA is 2.9x the cost normally (although it is on sale), the RASA is hardly a portable scope and where this will sit just fine on something as cheap as a SA GTI the RASA is going to need a approx. 2k mount. 

 

All said and done your are comparing a bulky £4.5k setup to a £1.4k grab and go / mobile imaging setup, making a comparison between apples and oranges. 

 

Adam 

Edited April 3 by Adam J

[Elp]

1 hour ago, Kyuss said:

But do you really want all that trouble with your newly acquired scope? Not to mention that pinched optics can be a design flaw also.

Of course not, here due to moisture in the air you need to use dew straps anyway so it's part of the process, allowing scopes to acclimatise is essential regardless of using dew straps or not. It could be manufacturing fault but statistically more glass and more likelihood of issues, so other triplets, quads, petzvals all could potentially suffer similar, the venerable SW Esprit, one of the best refractors for imaging suffers from it too.

[Adam J]

13 hours ago, Elp said:

Of course not, here due to moisture in the air you need to use dew straps anyway so it's part of the process, allowing scopes to acclimatise is essential regardless of using dew straps or not. It could be manufacturing fault but statistically more glass and more likelihood of issues, so other triplets, quads, petzvals all could potentially suffer similar, the venerable SW Esprit, one of the best refractors for imaging suffers from it too.

 

On 02/04/2024 at 17:23, Kyuss said:

Searching for a small refractor and that seemed to check all the boxes. Then Cuiv kinda ruined it with the pinched optics:

 

 

He is actually wrong it's not pinched, pinching will show that effect across the entire frame including the centre of the field. It's actually a sign that the corrector design is not working well at full frame.

It's a common effect in the corners of large sensors as the reducer effectiveness breaks down. I can't find a spot diagram for this scope. However for example this is a Askar scope. 

Note the bottom right star 22mm spot shapes, when pixel sampled this ends up looking like a cross. 

Edited April 4 by Adam J

[Kyuss]

8 hours ago, Adam J said:

 

He is actually wrong it's not pinched, pinching will show that effect across the entire frame including the centre of the field. It's actually a sign that the corrector design is not working well at full frame.

It's a common effect in the corners of large sensors as the reducer effectiveness breaks down. I can't find a spot diagram for this scope. However for example this is a Askar scope. 

Note the bottom right star 22mm spot shapes, when pixel sampled this ends up looking like a cross. 

I see your point!!! Seems to fit the case in the video.

[Adam J]

2 hours ago, Kyuss said:

I see your point!!! Seems to fit the case in the video.

yeah, take it as supporting up to APSC and you will be fine.