SVBony 15mm 70° SWA eyepiece???

[azrabella]

Hi folks - has anyone dared try the "cheap as chips" SVBony 15mm 70 degree eyepiece yet. The specs look OK though words can be cheap. I don't think it's a Chinese clone of anything I am familiar with. They seems top be retailing for around a paltry £46 here in the UK. Is it worth a punt or is it likely to be a poor performer at f/8?

[Louis D]

I wouldn't exactly call $55 cheap as chips.  If it were in the $25 range, I'd agree.  This eyepiece is sold under many other brands such as Apertura and Omegon, so hunt around to see if you can find any feedback or reviews of them.

Regardless, it will probably perform admirably well in an f/12 or slower Mak.  At f/8, expect some astigmatism and possibly field curvature in the outer 25% of the field.  At f/5 or slower, it will probably be a mess beyond 50%.

I have an Orion SWA Centering 20mm, 70 degree eyepiece.  Here's how it looks in an f/6, field flattened ED refractor for reference:

Not very pretty in the outer 25%, is it?  Think of it as a 20mm Plossl with more, but blurrier, outer field for context.  It will look slightly better at f/8.

[scotty38]

Hi @Louis D Can I ask a question about your reports as I am not sure I fully understand them 🙂

Take the last two views, they both show the same eyepiece yet the bottom one is not as good as the one above it, why is that? I realise the bottom one says full view but if you look at the equivalent points on the rule you can see the difference so what am I missing?

 

[Louis D]

3 hours ago, scotty38 said:

Hi @Louis D Can I ask a question about your reports as I am not sure I fully understand them 🙂

Take the last two views, they both show the same eyepiece yet the bottom one is not as good as the one above it, why is that? I realise the bottom one says full view but if you look at the equivalent points on the rule you can see the difference so what am I missing?

 

Sorry to have taken the images out of context where I explained that.  The "Full View" are taken with a 5 MP ultrawide angle cell phone camera so I can capture the entire 70+ degree view in one image.  The regular images are taken with an 8 MP wide angle cell phone camera limited to about 70 degrees on the diagonal.   I then scale up the resolution of the 5MP image to match the linear scale at the center of the 8MP camera.  Due to magnification differences across each camera's field of view, they may not match at each point.  I capture the 8MP edge views by pointing the camera at the field stop so I have a higher resolution view out there for comparison with the center resolution image.

To summarize, there just isn't as much resolution when using a 5MP imager producing a shrunken image.  I'd love to get my hands on an affordable 24MP or more cell phone camera covering at least 110 degrees on the diagonal.

Edited May 24, 2021 by Louis D

[banjaxed]

I have an SVBony 20 mm 68 degree eyepiece which was included with a scope I bought and it is one of my favourites, it is very sharp and I could not fault it.

[Louis D]

2 hours ago, banjaxed said:

I have an SVBony 20 mm 68 degree eyepiece which was included with a scope I bought and it is one of my favourites, it is very sharp and I could not fault it.

In what scopes?  How is center to edge sharpness and flatness of image?

Edited May 24, 2021 by Louis D

[scotty38]

2 hours ago, Louis D said:

Sorry to have taken the images out of context where I explained that.  The "Full View" are taken with a 5 MP ultrawide angle cell phone camera so I can capture the entire 70+ degree view in one image.  The regular images are taken with an 8 MP wide angle cell phone camera limited to about 70 degrees on the diagonal.   I then scale up the resolution of the 5MP image to match the linear scale at the center of the 8MP camera.  Due to magnification differences across each camera's field of view, they may not match at each point.  I capture the 8MP edge views by pointing the camera at the field stop so I have a higher resolution view out there for comparison with the center resolution image.

To summarize, there just isn't as much resolution when using a 5MP imager producing a shrunken image.  I'd love to get my hands on an affordable 24MP or more cell phone camera covering at least 110 degrees on the diagonal.

That’s great really appreciate it and all makes sense now, thanks!

[banjaxed]

12 hours ago, Louis D said:

In what scopes?  How is center to edge sharpness and flatness of image?

I am not an expert by any means but in my 8” Dob an ST 120 it gives very clear images IMO

[Louis D]

5 hours ago, banjaxed said:

I am not an expert by any means but in my 8” Dob an ST 120 it gives very clear images IMO

Maybe I'll pick one up sometime to try.  Does it have enough eye relief for eyeglass wearers?

[banjaxed]

3 hours ago, Louis D said:

Maybe I'll pick one up sometime to try.  Does it have enough eye relief for eyeglass wearers?

Sorry I am unable to give an opinion as I fortunately don’t need to wear glasses for viewing. The particular eyepiece I am referring to is the one with the red band around the barrel

[Louis D]

I've got a SVBONY 20mm 68° on the way.  I'll give it my usual testing and observing runs as time allows.  I'll see how it stacks up against my other 18mm to 22mm eyepieces.  I'm hoping it might work as a pair in my binoviewer if it isn't that great monovision-wise.

[Louis D]

Check out my first look of the SVBONY 68° Ultra Wide Angle 20mm eyepiece:

 

[LDW1]

On 24/05/2021 at 09:56, azrabella said:

Hi folks - has anyone dared try the "cheap as chips" SVBony 15mm 70 degree eyepiece yet. The specs look OK though words can be cheap. I don't think it's a Chinese clone of anything I am familiar with. They seems top be retailing for around a paltry £46 here in the UK. Is it worth a punt or is it likely to be a poor performer at f/8?

Mine performs excellent in all my 5 refractors, f6-f11.4. I like the roll up eye cup as well, its a solid well made ep as are all my other Svbony eps (4) and filters (6).

Edited June 29, 2021 by LDW1