Any customer review of new tsn-99? (3 Viewers)

[henry link]

Thanks for the photos, Baysidevista. I can see only one area that contains useful information about the quality of the TSN-993. That's in the upper background of photo #6 (Little Blue Heron) where there are many accidental images of defocused point sources of light returning from glitter points of the sun reflecting from grass blades. They form doughnuts with a bright outer ring and a dark interior. That suggests the presence of spherical aberration, but exactly how much can't be determined from that one image.

Henry

 

[BoldenEagle]

Haven't heard anything specific but from a source I personally trust: out of six samples two were optically defective, I don't know what was causing them to be so bad but I guess one could bet at least for an enourmous SA...But anyway, the most interesting thing was that among the other four samples there were told to be one "extremely good" sample. Exactly how good, well, we may hear from it at some point...

At least I got new hope from this information as I was already giving up on this 99, because hearing mostly about bad samples and testing two bad samples (or one; I guess the other better one could be also described as "mediocre" or "average" sample if taking into account how many bad samples Kowa puts out...) myself...

Regards, Juhani

 

[Pawellang]

Could you elaborate on that a bit?

I printed out a file (resolution diagram) from the forum, I set it at 30 meters and all lines where visible at all magnifications starting from 30 to 120 using extender.

 

[henry link]

Thanks, but I think we still need more clarification about your result. I"m leaving now, but I'll try to get back to you later tonight or tomorrow (if nobody else does).

Henry

 

[jcwu88]

I think it’s really tough comparing pictures from the 2 scopes, but when looking through the 99a it is a very clear/sharp image. I am noticing it being an improvement over my 773. It should also help considerably with dawn/dusk with screech owls. I will include some good shots to see if you notice any differences. First time adding pictures, so I’m not sure if this size works. First 4 with the 773 and next 4 with the 99.

Thank you for sharing the photos. To me these photos are good especially the last one. The focus on eye and the feathers color contrast is great.
It is not easy to evaluate scope by phone photos due to pixels limit and phone’s automatic settings (it varies on each photo). DSLR is more controllable but it is the other story.
Seeing through the scope is the best way to judge: If you like it, it works for you.

Happy birding!

 

[Tringa45]

Hi,

thanks for the result... if you use an artificial star like you made, you need sufficient distance or you will see SA which is not really there...

30m or more are a good rule of thumb for a small refractor.

Joachim

Hi Joachim,

Just a thought, if a little late: for star tests or resolution measurements one would need high magnifications, which are often achieved with astronomical eyepieces.
Some of these require lots of in-focus or will not reach infinity focus on spotting scopes (e.g. 7,5 mm Baader Eudiascopic and 6 mm Vixen NLV on Kowa 883). If used at short distances indoors the scope's focus setting would be at a more typical outdoor setting and its performance would not be compromised.
Conversely, if using eyepieces requiring little in-focus (many from Televue) one could clamp them a few millimetres out of the astro adapter to simulate a distant focus setting for the scope.
Btw, I recently made another futile attempt at measuring the resolution of my binoculars on a backlit Edmund Optics USAF 1951 glass slide at about 6 m. Using 3x and 6x monoculars to boost the image, the limitations of my own eyesight (floaters) and the loss of contrast at the small exit pupils made any assessment impossible.
I then set up my 883 and at 60x (TE-11WZ) and had a wonderfully defined image of element 3,6 (14,3 line pairs/mm). Now this is something over 2" and well below the capabilities of my 883 (I measured at least 1,42" years ago) but nevertheless very impressive.

Regards,
John

 

[jring]

Just a thought, if a little late: for star tests or resolution measurements one would need high magnifications, which are often achieved with astronomical eyepieces.
Some of these require lots of in-focus or will not reach infinity focus on spotting scopes (e.g. 7,5 mm Baader Eudiascopic and 6 mm Vixen NLV on Kowa 883). If used at short distances indoors the scope's focus setting would be at a more typical outdoor setting and its performance would not be compromised.

Hi John,

while it is correct that the recommended magnification for a star test is that at 1mm exit pupil (so around 90-100x for the large Kowas), one can easily see major defects when star-testing at 60x (like the 1/2 wave criterion stated by some Leica tech and cited somewhere in here lately).

Also a star-test is not affected by your visual acuity or your photography skills... which is a major advantage to resolution testing.

Joachim

 

[paperweight]

I phoned a German retailer today whose predominant business is selling astronomic gear. He told me he has had a couple of TSN-99 coming in that he all put to the test (artificial star). Up to now, he has not found a "lemon" as he told me.
Tonight, I'll try my 883 with the TE-11 on an artificial star in our garden. Thanks @jring for the instruction of how to proceed.

That dealer was very helpful and open in discussing the subject 883 vs 99 and 1.6 Extender vs astronomic eyepieces. In the end, you will gain some light which will be helpful in the dawn for terrestrial use (birds, nature, wild-life etc.) For astronomic use, the gain will not be huge, and everybody will have to decide if he is willing to spend about 3200 EUR for the 99 (without an eyepiece).

I had already offered my 883 in German classifieds but have withdrawn the offer: my 883 in fact deserves a "2nd chance".

 

[henry link]

I printed out a file (resolution diagram) from the forum, I set it at 30 meters and all lines where visible at all magnifications starting from 30 to 120 using extender.

Sorry for the late reply. I thought I could continue to participate here while I was on vacation, but it turned out I couldn't.

So, here are a few questions based on the information you supplied above.

What "resolution diagram" did you use?

What was the number of line pairs per millimeter of the smallest group on your resolution chart?

I'm perplexed by your statement that "all lines were visible at all magnifications starting from 30 to 120 using extender." Does that mean you were unable to resolve any smaller line pairs at 120x than at 30x?

What was the resolving power of the scope expressed either in line pairs per mm at 30 meters or in arc seconds?

Thanks,

Henry

 

[samwise2010]

I have owned a 99A for 2 weeks now and I haven’t had any sharpness/image quality issues, at full 70x zoom it’s still tack sharp, outresolving my eyes anyways.

My only gripe is that with the 1.6 extender it’s easier to lose the image of you aren’t looking at the correct angle to the lense. I haven’t had any experience from other scopes so maybe that’s common with extenders.

Overall I love it. Maybe the 883 is just as good for 98% of time vs the 99A

Sam

 

[paperweight]

Three days ago, I had the chance of comparing three 883 (including mine) to a demo TSN-99 provided by Kowa Germany. I fully agree with Sam: it's not a huge step from the 883 to the 99, but there is a discernable difference in the amount of light that reaches your eyes. Especially the new eyepiece TE-80 XW was impressive. At 70 and at an early stage of cataract, every little amount of light is welcome.
The three 883 performed with an identical positive result at 60x magnification.
I sold my 883 today including the earlier zoom eyepiece, the 20-60x TE 10, and consider getting the new 99, even though I'm still aware of the ambivalent discussion in this thread.
It will take 4 to 6 weeks to hold it in my hands, so I will have the option of thinking it over. On the other hand, I have the TE 11, two 1.6 Extenders and the DA4/DA10 for digiscoping, so the 99 will fit in nicely.
Regarding the contrasting reviews in this thread I phoned Kowa Germany and asked about how they check the new 99 before delivery. I was told each and every 99 is tested and inspected individually on a collimator before being shipped to its first owner.
Nonetheless, I think the new scope might fail in a star test, but instead of being able to compare several 99 at Kowa I must live with the fact that there is a huge backorder and such a comparison might only be possible in a couple of months.
I talked to a Kowa representative about the problems a star test might bring and he answered that Kowa rather puts a focus on contrast and colour instead of a perfect performance in astronomical situations. They told me the 99 is not intended for astronomical purposes in the first place.

 

[henry link]

I talked to a Kowa representative about the problems a star test might bring and he answered that Kowa rather puts a focus on contrast and colour instead of a perfect performance in astronomical situations. They told me the 99 is not intended for astronomical purposes in the first place.

A star-test has absolutely nothing to do with astronomy. Any point source of light can be used. What the test does is to provide a picture of the wavefront errors of a telescope. Those errors will affect the image quality of everything that's looked at through the scope, bird or star, day or night.

This isn't the first time a representative has either misunderstood what a star-test is or has understood it well enough to hope he can say something to make it go away.

 

[paperweight]

I did the "star test" with my equipment (883, TE 11, DA4/DA10, Sony RX 100 II) at 60x/30m and will show the results here. The first four pictures (focus/back focus/front focus) were done with an LED, a pin-point-hole through aluminium foil, a Gitzo tripod and an AOK Swiss Ayo mount.



The second series of pics were taken with the same gear, this time a star in Cassiopeia.



I'm neither experienced nor up to standards in such a testing procedure, and I can't judge the "human factor". I sent the pics to Kowa and were told they could not judge the 883 from a distance from just watching the pictures.
As I said: the three 883 I saw on Tuesday (including mine) were crystal sharp at 60x and about 30m when watching natural objects like branches, trees etc. At least 3 pairs of eyes had the same experience.
Thanks to jring who was kind enough to help with the basic information of how to do such a test.

 

[Hauksen]

Hi Henry,

This isn't the first time a representative has either misunderstood what a star-test is or has understood it well enough to hope he can say something to make it go away.

I once had a girl friend who worked in corporate "communications", and she said the game was to respond in a way that didn't tell the other person what he'd like to know.

By the way, some industry representative once pointed out that he didn't trust star tests because they are, to a degree, subjective. I thought it was Gerold Dobler in an interview posted by Lee, but I failed to find the exact quote. Do you believe he was "smoke screening", or does he have a point? I presume Dobler is expert enough not to have fallen for a simple misunderstanding.

Regards,

Henning

 

[mskb]

Thanks @paperweight. I very much look forward to the insights from other experienced users on the scale and effects of the aberrations here. But to me, it looks like both astigmatism and spherical aberration are present based on the pictures you have listed. The images have low resolution so I am unable to check for the diagonal prism lines if any (came across them with the 883s).

 

[paperweight]

Hi mskb, I chose "fine" for quality in the menu of the Sony RX 100 II and cropped the pics. I have just downloaded them once again, this time directly from the SD card, and have put them in a folder of their own. This is a link to the folder. I guess this won't help much because they are still jpgs, but it's at least worth a try:

Dropbox - File Deleted - Simplify your life

www.dropbox.com

 

[mskb]

Thanks @paperweight. I tried looking through the pictures you have uploaded - like you guessed based on the resolution, I am unable to add more. Thank you and I am eagerly looking forward to the discussions around these.

 

[jcwu88]

I got many advice from birdforum friends and was impressed by looking through a birder’s tsn-99 in the field. I decided to purchase tsn-99A. When I received the scope, I took tsn-99a with Nikon ED82 to the field- the bay wetland with flocks of birds.

I have Nikon Fieldscope ED50 and ED82 for many years and they are excellent scopes. I have compared my ED82 with friend’s Swarovski ATX 85 and found they are on par with image quality. For ED82 I use DS 30x wide and MC II zoom eyepiece. DS 30x is wide and sharp; and MC II is a bit sharper and with more contrast than DS 30x.
Since tsn-99a comes with zoom eyepiece, I compared with ED82 with MC II zoom. As a birder, I evaluated scopes by viewing birds in the fields, observing details and color of feathers, searching birds from bush and under shade.

1) Zoom eyepieces: at lowest magnification Kowa FOV is much wider than Nikon; both scope have bright, crisp, sharp images from center to edge, and Kowa is brighter. Magnifications at 40-60x, Kowa still has sharp images and relaxing view. At highest magnification, both scopes hold up sharp images. I didn’t feel Kowa dark at 70x, and ED82 at 70-75x is noticeable darker.
Brightness difference makes sense for objective difference of 99mm and 82mm; it is more pronounced at overcast and dusk.

2) Image sharpness: side by side comparison at the same magnifications, Kowa showed more feather details of cinnamon teals from close 10m to far 500m. I used 70x to observe radio antenna tower on mountain from 10 km, Kowa show more details of antenna and building structure.
When I searched American coots from dense plants and green-winged teals resting under shade, Kowa did better job for better sharpness and contrast.
Reading small texts and car plates from signs at 500m distance under good condition (no heat haze), I can identify smaller texts and icons from Kowa when both scopes were at 70x. Maybe I will test by using USAF resolution charts later as I tested camera lens, and for scopes I found pretty consistent results of reading plates/signs from distance.
I have to say that my ED82 is excellent and sharp to edge and only side by side at the same condition can tell difference.

3) Color Aberration (CA): Kowa does great job at CA control. I chose objects at high contrast environments: branches against blue sky, egrets standing dark water background, power cables with white cloud background and I can’t find CA from the center to 90% of FOV from Kowa. Only 70x at far edge ~97% of FOV showed trace of CA. ED82 has good CA control but Kowa is better.

4) Color: both scopes provide vivid and saturated color. There’s slight difference to my eyes: Kowa has overall warm tone with a little enhanced yellow and red; Nikon (with MC II) has warm tone with a little enhancing red.

5) Eye relief (ER) of Kowa zoom is 17mm at 30x and it’s comfortable for me (I wear glasses). The ER reduces a bit at higher magnification and I still can see full FOV at 70x. Nikon zoom at 25x ER is okay. Nikon ER at 40-75x is short (10-12mm) so I need to press my eye onto eyepiece in order to see the image.

6) I like Kowa dual knobs focus system. It is very precise especially at high magnification.

In summary, I am satisfied with optical performance of tsn-99a. For me the wide FOV at low magnification and comfortable view at higher magnifications for long period of time are the key attributes. It is a big plus for sea watching and long distance birdwatching.

Jay

 

[b-lilja]

My 883 is flat out spectacular. I say that having owned excellent Nikon EDs of various configs, including the 82. The 883 is a whole different deal, often breathtaking. I did sample two at purchase, and the one I kept was clearly a bit better (the second was still excellent).

The 883 is the outer limit of what I'm willing to schlep on my shoulder for a mile or two; if I were doing stationary seawatch stuff all the time, I would certainly be curious about the 99.

 

[henry link]

Hi paperweight,

I'll have to give a brief response now. I'm sure other star testers will be coming along soon.

I think the most useful photos are the second, third and fourth on the second line of photos. If you take the fourth photo and place it between the second and third you have a progression from about 2 rings inside focus (assuming the scope is undercorrected) to almost perfect focus (but overexposed) to maybe 3 rings outside of focus (hard to say since there are no rings except for the 1 bright outside one).

As "mskb" mentioned it's easy to see the classic pattern of astigmatism, which causes the out of focus patterns to form ellipses instead of circles, with the long axes of the ellipses changing by 90 degrees from one side of focus to the other. The best focus image forms a little diamond shape, which would be a cross of it weren't overexposed. In a perfect scope the rings would be circular and would appear to be identical on both sides of focus and the best focus would be a little white disc surrounded by one dim diffraction ring.

Some amount of spherical aberration appears to be present, but I think it might not be quite as bad as it looks because some of the problem with that image probably results from air turbulence (it always looks worse on that side of focus), which causes the gaps in the outer ring and probably distorts and diminishes the appearance of whatever dim inner rings might be there. It's hard to make a clear photo of outside focus diffraction rings in the presence of even a little turbulence which might just look like a slowly rolling clear image at the eyepiece.

That's all I have time for now. If nobody beats me to it I'll post some speculations tomorrow about why you and three others might think this is a "tack sharp" telescope.

Henry