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Old Monday 15th May 2017, 14:33   #1
Dante Shepherd
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Thoughts on Kowa TSN-602 with TE-9Z 20-60x eyepiece

Hello, I recently bought a Kowa TSN-602 with a TE-9Z 20-60x eyepiece and a waterproof case all together on eBay for 250. The scope is due to arrive in the next week or so and is an upgrade from my very old Nikon D=60 P. What can I be expecting?

Thanks in advance, Dante
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Old Monday 15th May 2017, 15:15   #2
jring
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Hi,

I don't know this model but extrapolating from the earlier TSN-1 which also has non-ed glass, I would expect a very good view up to 45x or so. If this will be an upgrade regarding your Nikon, I can't tell... was this a 60mm ED III?

If you really got the current TE-9Z zoom with the twist-up eyecup, this alone costs 250 quid new. You might want to get the 30x wide EP later which will be brilliant in this scope - the zoom is always a bit narrow.

Joachim, happy owner of an old TSN-3
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Old Monday 15th May 2017, 15:31   #3
Dante Shepherd
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Thanks Joachim,

Probably the main reason I bought it was because it had the TE-9Z eyepiece included (which I think is a huge upgrade from the older Kowa zoom eyepieces?). Do you know if the higher end of the zoom will be good enough to read distant colour rings on gulls?

This is the scope I am using at the moment: http://www.birders-store.co.uk/used-...-eyepiece.html
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Old Monday 15th May 2017, 16:40   #4
jring
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Thanks Joachim,

Probably the main reason I bought it was because it had the TE-9Z eyepiece included (which I think is a huge upgrade from the older Kowa zoom eyepieces?). Do you know if the higher end of the zoom will be good enough to read distant colour rings on gulls?

This is the scope I am using at the moment: http://www.birders-store.co.uk/used-...-eyepiece.html
Hi,

the current TE-9Z is a lot better than the terrible 90s Kowa zoom with the rubber eyecup, but when I tried it in my TSN-3 in a store, the Opticron SDLv2 I already had (but could have returned at the time) was nicer, mainly due to field flattening. The SDLv2 probably won't fit your 602 though due to the protective glass in front of the prisms...

We tried a fellow birders TSN-1 with my SDLv2 and the Kowa 30x wide EP instead of the old Kowa zoom she used and views were comparable to my TSN-3 up to 45x or so.

Past that the image got a bit harder to focus correctly on the TSN-1 - a typical effect of longitudinal chromatic aberration when not all colors focus at the same point and the depth of focus cannot compensate any more.

If and at what distance one could read rings on gulls with your example is hard to say for me - we don't have a lot of ringed gulls here to try.
I have read a numbered ring on a grey heron with my TSN-3 with the zoom at 52x at 170m or so rather easily, but that ring was a bit larger than usual...

Joachim
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Old Monday 15th May 2017, 16:58   #5
Dante Shepherd
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Thanks once again. What do you mean by field flattening?
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Old Monday 15th May 2017, 21:41   #6
jring
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Hi,

short focal length refracting telescopes like spotting scopes suffer quite a lot from field curvature - especially at low magnifications, which is not an optical aberration but rather a fact even for perfect optics. The the shorter the focal length, the more field curvature is visible in a scope.

This is counteracted by the depth of focus, which depends on the focal ratio and is small in fast instruments like spotting scopes.

This results in field curvature to be visible in spotters and even more so in binoculars with even shorter focal lengths and faster focal ratios.

If the edge of the image is not sharp when the center is in focus and you can adjust focus so the edge is sharp and the center isn't, it's field curvature.
If you can't adjust the focus so the edge gets sharp, it might be other aberrations like coma or astigmatism or a mixture oft the two with or without field curvature.

This can be corrected with extra lenses, either as a part of the telescope, as an extra field flattener attachment or as part of the eyepiece.

Joachim

Last edited by jring : Monday 15th May 2017 at 21:44.
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Old Monday 15th May 2017, 22:42   #7
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Cheers. Is there anyone who has experience with the 601/2 or with the TE-9Z on a 600/660 series scope?
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Old Tuesday 16th May 2017, 05:40   #8
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Cheers. Is there anyone who has experience with the 601/2 or with the TE-9Z on a 600/660 series scope?
I have the zoom on a 663M and I really enjoy using it. Image quality at the top end of the zoom depends greatly on atmospheric conditions. When it is very gloomy or hazy it can be a struggle to get a very clear image at 60x, although it is usually still good enough to be able to ID something. However it is very unlikely that you will be using the scope constantly at 60x, I would estimate that 75% of my viewing time is spent with the eyepiece at 20x at which it is very good. Nice and bright, very sharp and with great contrast. FOV is not spectacular but not something that particularly bothers me except when seawatching.
Kowa make great optics, I'm sure you'll be happy with your scope.
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Old Tuesday 16th May 2017, 17:06   #9
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I'll mostly be using the scope between 20-30x as well. Obviously the 602 will be worse compared to the 663M as the objective lense is smaller and it does not have ED glass but I am still expecting good things. Do you have the 30x wide eyepiece?
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Old Tuesday 16th May 2017, 19:23   #10
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I'll mostly be using the scope between 20-30x as well. Obviously the 602 will be worse compared to the 663M as the objective lense is smaller and it does not have ED glass but I am still expecting good things. Do you have the 30x wide eyepiece?
I have not looked through a 602 so can't say what it will be like, but it will not be as bright due to the objective size, as you have mentioned.
I don't have the 30x but I plan on getting one in the future, I have heard very good things about that eyepiece.
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Old Tuesday 25th July 2017, 19:43   #11
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I have both the 601 and the 664 and the 884 come to that. The 664 and te-9z make a good combo when I don't feel like taking the big gun. The 30X lives on my 601 and is handy to throw in a suitcase if i'm flying some where and birding isn't the main purpose of the trip. How I wound up with all three was because Ben at Eagle Optics kept giving me deals I couldn't pass up. the 884 about five years ago (not long after the 25X60 eyepiece came out ) I got the 884 with that eyepiece and fitted cover for about two thousand total. The other two were demod and were very cheap as well
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Old Wednesday 26th July 2017, 17:10   #12
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Hi, i use a kowa tsn 663M with the TE-9z (20x60) and the TE-14wd (30x), Chris murphy the 60x zoom is dark and loses a bit of sharpness but below this focal point is very sharp (i would like Try a Opicron SDL2) the prominar optic makes the colors very good. The Eyepiece 30x is a show, a broader field and a relaxation for the eye. Giorgio
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