Stellalyra Kitakaru 40mm & 45mm Eyepieces

[John]

7 minutes ago, badhex said:

Honestly, no joke - I wrote this yesterday without reading the review. Have now seen the review itself - 4/5 score 😂

I wonder what they have to do to get a 3/5 in S@N ? 😬

[vlaiv]

12 hours ago, Louis D said:

It looks like you don't quite have the camera's entrance pupil lined up with the eyepiece's exit pupil.  I generally keep an index finger and thumb between the top of the eyepiece (with eyecup rolled down or removed) and the back of the phone to maintain a steady alignment and distance.

What phone are you generally using for this?

There is a chance that phone is not the best of tools for taking images like that. Most phones have small fast lens. Here, emphasis is on small diameter. If lens diameter is smaller then exit pupil, phone will act as aperture stop and it might render better image than it actually is for observer.

Say you use iPhone 13, it has following specs:

• Primary: 12 MP sensor, 1.9µm pixels, 26 mm equivalent f/1.5-aperture lens, sensor shift OIS, Dual Pixel AF
• Ultra-wide: 12MP sensor, 13mm equivalent f/1.8-aperture lens, PDAF, 2cm macro
• Tele: 12 MP sensor, 77mm equivalent f/2.8-aperture lens, OIS

You use primary camera. It has 26mm equivalent at F/1.5. Sensor is 12MP with 1.9um pixel size. Let's say that ratio of the sensor is 16x10 for sake of argument square root of(12MP / (16x10)) = 274px per 1 unit, so it will be

16 * 274  x 10 * 274 = 4384 x 2740px sensor

It has diagonal of ~5170px and at 1.9um that is 9.8mm sensor size. That is about 43.2 / 9.8 = 4.4 crop factor, so 26mm equivalent lens will actually be 26 / 4.4 = 5.9mm lens.

It has aperture ratio of F/1.5 so actual aperture size is 5.9mm / 1.5 = 3.9mm

Any exit pupil recorded with this lens will be stopped down to 3.9mm exit pupil, so long focal length eyepieces that produce larger exit pupil will be rendered better then they are in reality.

[badhex]

3 hours ago, John said:

I wonder what they have to do to get a 3/5 in S@N ? 😬

Genuinely curious to know the answer to that! If the optical components of a given item are installed backwards? 

Bit off topic, but joking aside I do feel it undermines trust somewhat when known excellent products and distinctly average products both get 4/5, sometimes in the same review. It's not even as if the reviewers are just random people, some impressive names in there often. 

Edit: I should add, that I am nonetheless very grateful for the existence of S@N and there is plenty of excellent content in the magazine. 

Edited August 19, 2023 by badhex
Added more info

[Louis D]

4 hours ago, vlaiv said:

What phone are you generally using for this?

For most of the images, I use a Samsung Galaxy S7's rear camera.

For complete ultrawide images as in the SAEP/CAEP comparison collage and for the older "full view" images, I used the ultrawide camera of the LG G5.  The screen died on this one recently, so it's been retired.

I recently switched to the ultrawide camera on the LG G6 for higher resolution and sharper images just before the G5 screen died.  I'll have to either get another used LG G5 for new SAEP photos or retake all of them with the L6.

I haven't noticed that low power eyepieces are rendered sharper, but I have noticed that the depth of field of these cameras renders eyepieces as having much flatter fields than they have in reality.

Here's the longest eyepieces comparison image.  The Meade 5000 Plossl 40mm looks worse than the Meade 5000 SWA 40mm both to the eye and in the image at f/6 in a 72ED.  If the camera is making it look better than reality, it isn't by much.

Here's a side project image that I haven't updated in years showing performance in a 127 Mak with many of the same eyepieces:

In this image, even the Rini Erfle 42mm is sharpening up nicely at the edge, just as it appears to the eye.

And here's the 29mm - 30mm comparison image showing how "flat" the Agena UWA 80° 30mm is.  In reality, you have to refocus quite a bit for the edge to get that same sort of sharpness:

Again, some of the same eyepieces in the 127 Mak:

Here, even the awful Rini 29mm and Kasai 30mm look usable.  Even to the eye, they are both much improved.

All I'm saying is that if the combined pupil is being reduced, I'd expect the images at f/6 to move somewhat noticeably toward the f/12 images, but they don't seem to move much if at all compared to what I'm seeing with my eye.  It's not like I'm ignoring any mismatch with reality because I do see the massive flattening of curved fields in the camera images.

[dweller25]

23 hours ago, John said:

They work very well with scopes under a night sky though, I hardly ever look at rulers with my Nagler 31 these days 😉

 

I do the same as a rule 🥳

[John]

With my old 12 inch dobsonian, the closest focus I could get (without a ridiculously long extension tube) would be around 100 metres away. It would have been interesting to find out what my neighbour a few houses down the road would have said if he had caught me nailing a ruler up on a tree in his back yard. I guess the phrase "It's OK, I'm an astronomer" would have explained everything 🙂

[JeremyS]

2 hours ago, John said:

With my old 12 inch dobsonian, the closest focus I could get (without a ridiculously long extension tube) would be around 100 metres away. It would have been interesting to find out what my neighbour a few houses down the road would have said if he had caught me nailing a ruler up on a tree in his back yard. I guess the phrase "It's OK, I'm an astronomer" would have explained everything 🙂

I think he’d say he’d got the measure of you, John 🤣

[F15Rules]

On 18/08/2023 at 22:12, Louis D said:

It helps if you can wedge your butt up against a wall to steady your whole body while doing this, or use a sitting position.

The mind boggles!! 😂😂

Dave

[F15Rules]

On 19/08/2023 at 19:16, JeremyS said:

I think he’d say he’d got the measure of you, John 🤣

Yep, he's got it taped Jeremy..🙃

[JeremyS]

1 hour ago, F15Rules said:

Yep, he's got it taped Jeremy..🙃

He’s inching towards perfection.

[John]

 

I like jokes about stationery but rulers are where I draw the line 😁

 

 

 

[JeremyS]

9 hours ago, John said:

 

I like jokes about stationery but rulers are where I draw the line 😁

 

 

 

You are going to great lengths with this one!

[badhex]

1 hour ago, JeremyS said:

You are going to great lengths with this one!

The caliper of these jokes is getting worse with each post

[Mr Spock]

You folks need to stop using weapons of math destruction 

[Louis D]

What have I started with my ruler photos?!?!?

[JeremyS]

55 minutes ago, Louis D said:

What have I started with my ruler photos?!?!?

Perhaps you were hoping to divide and rule 😊

[badhex]

44 minutes ago, JeremyS said:

Perhaps you were hoping to divide and rule 😊

He's a smooth operator