Svbony 8-20 Super Zoom

[Louis D]

1 hour ago, Second Time Around said:

Don, isn't that just because of exposure?  On my phone I can see more detail in the highlights on the zoom compared with the Delite?

You bring up a good point.  At 11:00, Bogdan is comparing contrast.

However, we have no idea if he locked down exposure between the two images or not.  It appears the DeLite image is exposed about 1/3 stop to 2/3 stop more than the SV230 image which would account for the appearance of lower shadow contrast and highlights being slightly washed out.

However, I'm seeing much higher sharpness and detail in the DeLite's dead, brown, shadowed branches to the right of the flagpole.  Notice how much easier it is to pick out the limb structure in the DeLite image.  I suspect the lighting also changed in the shadow area between images based on the different pattern of lit leaves mixed in the shadow area.  This also makes comparisons difficult.

I'm also noticing a yellow-green cast to everything in the SV230 (especially in the flag's blue squares).  Again, is this due to transmission differences across the spectrum between eyepieces, or is it due to white balance differences?

[LondonNeil]

I'll definitely be keeping an eye out for either a stunning svbony discount or more reviews before buying as although it seems likely it'll better an Hyperion and one zoom wins for convenience..... when you've several scopes out you need several eps so the current 17% off making £262 is still too much.   

Double the discount and bring it under £200 and I'd be very tempted to get a couple with the resale of set of Hyperion largely covering the cost of one.

[Louis D]

47 minutes ago, LondonNeil said:

Is it me,  or does the delite show slight distortion near the edge?  Looking at the roof edge it seems slightly bowed. It's perfectly straight on the zoom.  

You are correct.  This is what I meant by the SV230 having low rectilinear distortion.  However, this is not necessarily a good thing for astronomy aside from planetary, lunar, and solar observing when letting the object drift across the FOV.

Compare the distortion relative to the Svbony SV171 zoom at 8mm (@11:17).  It makes the roof lines look like something out of a cartoon:

 

Straight lines are bent everywhere you look in the SV171 on the right.  Notice how the chimneys no longer have vertical edges.  If this were grid paper being photographed, you'd see a pincushion pattern similar to this:

Edited Friday at 21:23 by Louis D

[Louis D]

21 minutes ago, Louis D said:

However, I'm seeing much higher sharpness and detail in the DeLite's dead, brown, shadowed branches to the right of the flagpole.  Notice how much easier it is to pick out the limb structure in the DeLite image.

I'm not so certain now that I looked at the SV171 contrast comparison image at 11:19 below:

The SV230 is now showing good detail in the shadows very similarly to the SV171 at 8mm and the Delite 9mm.

Edited Friday at 21:22 by Louis D

[LondonNeil]

Yes,  spherical aberration isn't it?  And while the delite isn't going to be a problem,  surely it's a small plus for the zoom.

[Louis D]

1 minute ago, LondonNeil said:

Yes,  spherical aberration isn't it?  And while the delite isn't going to be a problem,  surely it's a small plus for the zoom.

No, pincushion distortion.

Spherical aberration is when all the light isn't focused to a point as in with a spherical mirror as compared to a parabolic mirror:

Or with a lens:

[Mr Spock]

I'd prefer to see a picture of the moon or Jupiter to make an assessment. Terrestrial images just aren't any good.

[Don Pensack]

1 hour ago, LondonNeil said:

Is it me,  or does the delite show slight distortion near the edge?  Looking at the roof edge it seems slightly bowed. It's perfectly straight on the zoom.  

The delite does have slightly better  ca, and sharpness in those later images,  still prefer the svbony for colour but overall it's picking hairs.   I sense my set of Hyperion for my mak127 and c8 may be hitting sales Corner. 

ok.

There are two forms of distortion.

Rectilinear distortion keeps images the same size in the field but causes straght lines to  curve in the outer field.  That's fine for astronomy but not great for terrestrial use.

Angular magnification distortion keeps straight lines straight but causes objects to change size as they cross the field.  That's not great for astronomy, but works fine for terrestrial use.

Spotting scopes are used for terrestrial use, so that probably indicates the source for the design of the zoom.  Zooms represent 99.9% of all spotting scope eyepieces, so the factory was probably thinking about mixed use.

[Ratlet]

13 hours ago, Mr Spock said:

I'd prefer to see a picture of the moon or Jupiter to make an assessment. Terrestrial images just aren't any good.

Ditto.  The only images through an eyepiece I know I can trust to be reproducible are @Louis D reviews.  I'll hold out for Ernst on the bench test.

Ultimately I'm desperately hoping that @Mr Spock gets a lottery win tonight and drunkenly orders one and shares his opinion.  I think it's a bit pricey for me to have a boat in the race on getting one, but there is so much to when 'good is good enough' that whilst the images are helpful to an extent photons to eyeballs are where the rubber hits the road. 

But the price being so high kind of begets the analysis it is receiving.

Got to say though, I love the discussion it's generated.  You get spoiled sometimes with eyepieces generally being pretty good that I forget how complicated optics actually is.

[Mr Spock]

7 minutes ago, Ratlet said:

Ultimately I'm desperately hoping that @Mr Spock gets a lottery win tonight and drunkenly orders one and shares his opinion.

It will be a sober decision  It will also be a lottery win - my pension doesn't quite cover extravagant astro purchases 

[LondonNeil]

The thought came to me last night that I really value the comments of many of the excellent and experienced amateur Astronomers that are part of this community and commenting here.  Don, Louis, Spock and others.  Really useful to a novice like me who doesn't yet know readily what differing performance traits mean in the real world and have the patience to answer basic questions.  So first off,  thank you gents!

Secondly I'm sure I'm not alone being interested in this ep but thinking I should wait for their comments once they've seen and used it.   With that in mind,  would it be practical for a bunch of us to buy one for these gents to review?  Could that work?  If ten people paid £30 each there would be plenty to buy the ep and to post it between a few reviewers.   Then,  I dunno,  a raffle for who gets to keep it? Is that just a daft idea from Mr Impatient,  or worth considering?