Any customer review of new tsn-99? (1 Viewer)

[jcwu88]

Just wondering if anyone got this new scope and share their opinions?

 

[lassa8]

I'm expecting mine to arrive later this week...will post a review once I've had it for a bit!

 

[lassa8]

I'm expecting mine to arrive later this week...will post a review once I've had it for a bit!

Now scheduled to arrive on Friday, so I should be able to put it through some paces this weekend!

 

[Pawellang]

I compared it to Swaro ATX 115 side by side and could not find any difference. It was sunny day, maybe in other conditions I would see it. No CA at all, very sharp image (x70). I bought it.
Before I used Meopta S2 HD and i still own it. When I compared Kowa with it in a cloudy day I could not find big differences neither, so maybe I am blind or Meo is still so good

 

[Baysidevista]

Just arrived today, but i received the wrong tripod and will need to wait for its arrival. Have been using the 773 for about 7 years, and have been very happy with it. Do a lot of phoneskoping of yard box screech owls and i expect the new scope will make viewing even better at dawn and dusk. Will report back once i put the 99 though its paces.

 

[hunt30]

I’ve had mine for a couple of weeks now, but the smoke from California has been so bad I haven’t been able to give it a good test yet. I’ve got an 88 that I can hopefully compare it to soon if the air quality improves.

 

[BoldenEagle]

I just tested two samples of Tsn-99 and found that both had huge spherical aberration, reminding (or even surpassing, not in a good way...) my former scope, Leica Apo Televid82.

The other had slightly triangular rings (on the other side; the other side was just fuzzy, dim sphere with no rings at all), otherwise it looked quite good. Nevertheless the image was lacking contrast at high magnification (I used 1.6x extender to get 112x) and had quite hazy appearance.

The other one had also the familiar yellow vertical prism roof line and distinct astigmatism; it had very poor image quality well before reaching max magnification.

I didn't test resolution and did not any other comparison, just star test with artificial Led light source at about 30m distance.

I know it's just two samples but maybe SA will be a problem with this big objective also with other samples. I will try other samples near future.

Good news is that CA seemed to be very minimal, maybe better than 883 but that's just my quick subjective observation.

Regards, Juhani

 

[henry link]

Hi Juhani,

Two lemons out of two samples is very bad news. As you suggest, it could be that trying to cram a relatively long 600mm effective focal length into a scope body not much longer than the 500mm TSN-88s requires curves for the objective group lenses that are just too radical for low spherical aberration to be readily achieved. Spherical aberration might also be the Achilles' heal of the Swaro ATX-115, although in that case the effective optical focal length itself is quite short at a little below f/5.

I've been unable to find a local Kowa dealer who plans to stock the scope, so at some point I'll order one online from a dealer with a no questions asked return policy. In the meantime I think I'll wait for more star tests and some resolution measurements before I take the plunge. What I want to see is a star test of at least one sample that shows low spherical aberration and a resolution measurement that's diffraction limited.

Henry

 

[Binastro]

Hi Juhani,

Triangular rings could be pinched optics if three sided, but on one side could be poor figure or maybe tilted optics.

These two scopes don't sound good for high magnification.

Were the scopes thermally stabilised, as one sided views could be heat related?

Regards,
B.

 

[Houdiny]

I currently have a specimen of the Tsn-99 here with me at home. I own a Meopta Meostar S2 82 HD, a friend of mine owns a Swaro ATX 85 and another friend owns a Kowa TSN 883. Today we had the chance to compare those scopes side by side. Here are my personal results (concentrating on optical quality only):
1st place: Kowa TSN 883. Crystal clear and brillant image (even at max magnification) with perfect sharpness and color, no CAs at all. Focusing is easy, Eye relief very good.
2nd: Meopta. Also very clear image, with a tiny hinge of a warmish tint. At max magnification, focussing gets more difficult, the image is a bit softer. No CAs, good eye relief.
3rd: Swaro. Slightly visible CAs at height magnifications. Bright image, at low light better than the Meopta.
4th: Kowa 99. At magnifications of 50-70 very soft and almost foggy image compared to the other scopes. Visible CAs. Clearly worse than the other scopes. I might do some star testing tonight, but I am definitely not going to keep this scope.

 

[lassa8]

I received my scope today. Nothing to directly compare it to other than my old (~15 years) Nikon 60mm, but WOW (in a good way).

After an hour of playing around, I didn't have any issues with my model. No CA at all during daytime use no matter what direction I was looking. Higher mags were still bright and crisp. I hope to do some more rigorous testing this weekend, but it seems like based on the other reviews above I've lucked out a bit here with my specimen. No plans (at present) to return this guy.

Edit: to add photo.

 

[henry link]

The more star-tests the better.

That's how we'll find out, not just whether there are good and bad units, but what exactly is wrong with the poor performing ones and what's right with the better ones. It's probably safe to assume that the astigmatism and pinching Juahani observed are sample defects since they occurred in only one specimen, but the "huge" spherical aberration he found in both specimens is more troubling as it might indicate a design limitation. Hopefully "Houdinys" star test can add more information about that and a star test that evaluates the spherical aberration of "lassa8's" presumably better specimen would be very helpful in establishing if there are some units with low spherical aberration.

 

[BoldenEagle]

Hi Juhani,

Triangular rings could be pinched optics if three sided, but on one side could be poor figure or maybe tilted optics.

These two scopes don't sound good for high magnification.

Were the scopes thermally stabilised, as one sided views could be heat related?

Regards,
B.

Hi Binastro,

That triangular form was three sided but it was not very strong and mostly disappeared when unfocused further.

I didn't even thought about thermal stabilising. Would it have that strong effect if scope was brought from room temperature (or storage) to outside where it was +13°C? I spend about 15 minutes with the better sample and I didn't notice anything change during that; I checked the light point couple of times and viewed some tree leaves, buildings etc. in between. I have star tested my 883 multiple times brought from room temperature and I remember sometimes in winter there was some fuzzines and currents inside the scope but it must have been well below zero on the outside. Even then I don't at least recall seeing differences on just one side of the focus point.

It's probably safe to assume that the astigmatism and pinching Juahani observed are sample defects since they occurred in only one specimen, but the "huge" spherical aberration he found in both specimens is more troubling as it might indicate a design limitation.

Maybe I will try to clarify that "huge" term a bit further: the worse side did show a bright tiny central point but outside of that, there was not any rings, just fog-like sphere which was clearly dimmer than the central point, the outer edges were diffuse. Both of these 99-samples were identical in this regard. If not accounting the bright central spot, it looked the same or maybe even worse than what I saw with my Leica, because it at least had some weak outer ring and inside that just same kind of fog or fuzzy mass.

Regards, Juhani

 

[Houdiny]

I tried star testing the scope, but I’m not really experienced in that regard. Please see my attached photos, maybe you guys understand more than me.
I had some trouble finding those rings when out of focus in the one direction, in the other direction they were a lot clearer to see.

Martin

 

[dipped]

I got the chance to very briefly do an artificial star test on a 99A too recently and also found a lot of spherical aberration. The rings on one side were ok but the other side were indiscernible. This was done in a shop so the distance to the target may have been borderline acceptable but I felt somewhat underwhelmed by the image, and have seen better star results from cheaper scopes in the same shop. If I get a chance I will compare it to the Swaro ATX95 next time.

 

[Binastro]

Hi Juhani,

Heat currents cause the air to rise up mainly and this can be seen.
Also the objective subtly changes shape.

Different scopes cope differently.

Usually refractors cope better than reflecting scopes.

But fast refractors cope less well than slow refractors.

I mentioned elsewhere the Zoomar 2000mm f/14 odd mirror lens for movie use.
The one I had never achieved thermal equilibrium even with a tiny change in temperature.
It was awful optically visually.

Also a not so good scope is more easily affected by heating effects than a cherry example.

The triangular pattern suggests pinched optics.

I had a 500mm f/5.6 Zeiss East lens for Pentacon Six that had terribly pinched optics. I should have unscrewed it and carefully screwed it back. The optics must not be tightly held.
The lens looked great with excellent multicoating. It was oversize, maybe f/4.8.

Maksutovs can take an hour to cool.

My 123mm f/5 refractor takes about twenty minutes, but still shows some effects if there is a big temperature change.

Regards,
B.

 

[henry link]

I tried star testing the scope, but I’m not really experienced in that regard. Please see my attached photos, maybe you guys understand more than me.
I had some trouble finding those rings when out of focus in the one direction, in the other direction they were a lot clearer to see.

Martin

Looks like your photo technique will work well, but the ones you posted are too far out of focus (too many rings). Try defocusing to only about 4 rings on each side of focus (or to the same size disc on the side of focus that has no visible rings). I think that will show us what we want to see.

Henry

 

[henry link]

Maybe I will try to clarify that "huge" term a bit further: the worse side did show a bright tiny central point but outside of that, there was not any rings, just fog-like sphere which was clearly dimmer than the central point, the outer edges were diffuse. Both of these 99-samples were identical in this regard. If not accounting the bright central spot, it looked the same or maybe even worse than what I saw with my Leica, because it at least had some weak outer ring and inside that just same kind of fog or fuzzy mass.

Regards, Juhani

That sounds like a classic description of very high spherical aberration, which is almost certainly the cause of the hazy image.

 

[lassa8]

I had the scope out for a few minutes tonight and was able to zoom in (70x) on just a couple stars (one mid horizon, one near the zenith) before the clouds came in really thick. Was pleased to see absolutely pinpoint stars with no readily apparent aberrations regardless of where I put the star in the field of view.

 

[BoldenEagle]

Looks like your photo technique will work well, but the ones you posted are too far out of focus (too many rings). Try defocusing to only about 4 rings on each side of focus (or to the same size disc on the side of focus that has no visible rings). I think that will show us what we want to see.

I don't want to jump to conclusions but; trusting on these pictures, this sample looks like having a much better weaker side than the two samples I tested: at least there is weak outer ring just to be detected and I imagine to see some faint inner ones also. The bright central point I saw is also lacking in these pictures.

For sure one can see the vertical prism roof line in these both pictures, in the first one there is also traces of dark bands both sides of the yellow line (looks just the same as in my 883).

Allthough too far defocused, isn't there already astigmatism showing also? That could also be from camera positioning though.

Very interesting to see little less defocused patterns but thank you Martin already for sharing these ones!

Regards, Juhani