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Astro Eyepieces for Kowa 883 Scope

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#1 portauto

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Posted 13 September 2021 - 11:55 AM

Hey Guys, I’m brand new to the forum and hoping for some advice. I currently use a Kowa 883 spotting scope (25x to 96x magnification), mostly for bird watching and looking up at the Moon, Jupiter and Saturn. I’ve purchased an astro adapter, and I’m looking for some recommendations on astro eyepieces,

 

Current system consists of:

 

- Kowa TSN-883 Spotting Scope
- Kowa 25-60x Eyepiece (TE-11WZ)
- Kowa 1.6x Extender (TSN-EX16)

- Kowa iPhone X Phone Adapter (Kowa TSN-IPX RP)
- Kowa Astro Eyepiece Adapter with Knurled Screws (TSN-AS1.25K)

- Manfrotto MT055CXPRO3 Tripod

- Manfrotto MVH500AH Fluid Head

- B+W 95mm Clear UV Haze Filter (010M)

 

What would be your suggestions on potential astro eyepieces that would work well with this system?

 

Cheers,

Portauto



#2 fftulip

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Posted 13 September 2021 - 12:07 PM

How about the Pentax/Ricoh XW series?  They have a good balance of eye relief and wide field, and have been used for both astronomy and spotting scopes.

By the way, how is the Kowa TE-11WZ zoom eyepiece?  It has excellent specifications (one of the best for zoom eyepieces) and I was wondering how it would perform for astronomy.



#3 Jeff Bennett

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Posted 13 September 2021 - 12:53 PM

The XWs are a good choice, especially since they are sealed to be waterproof and fog proof as are most spotting scopes, IIRC.

 

They are a bit large, and if you like something a bit smaller and lighter, I would suggest the TV Delites.  I have used them in my Meostar S2 spotting scope and found them quite nice.  Their AFOV is a bit smaller than the XWs, but they have good eye relief.



#4 portauto

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Posted 13 September 2021 - 01:44 PM

Thanks gents! This has been my first spotting scope so I wouldn't be able to compare the performance of the TE-11WZ eyepiece for astronomy.

 

As far as the XW series, I see there's a wide variety of options. Do you have any suggestions on which eyepieces will be the best to start with? 40mm, 30mm, 20mm, 14mm, 10mm, 7mm, 5mm, 3.5mm

 

When I previously owned an inexpensive 102mm refracting telescope, I recall I was using a Plossl 25mm for moon observation, and 12.5mm with 2x Barlow lens for planets, but it left much to be desired.

 

Cheers,

Portauto



#5 DRodrigues

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Posted 13 September 2021 - 02:16 PM

...

 

As far as the XW series, I see there's a wide variety of options. Do you have any suggestions on which eyepieces will be the best to start with? 40mm, 30mm, 20mm, 14mm, 10mm, 7mm, 5mm, 3.5mm

 

...

Pentax XWs 30 and 40mm are 2" and will not reach focus.

For birding, I recommend 1.25" eps with >=70º AFOV. At https://www.birdforu...orums/kowa.298/  you will find some posts about using astro-eps on your scope. One post mentions the use of a no longer produced Docter 12.5mm, that reached focus with the shorter adapter and should result on awesome views!

About using astro-eps of about 5mm for birding you can look at http://www.pt-ducks....f 5mm eyepieces but not with your scope...
 



#6 fftulip

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Posted 13 September 2021 - 03:13 PM

The birdforums link above has some good information about using astro eyepieces with the Kowa.  Be aware that there are several astro adapters and some eyepieces won't reach focus with certain adapters.  Many users were able to use the Pentax XW's but it is not clear with which adapter - please read those birdforums posts carefully.   About which eyepiece to use, as pointed out above, it needs to have a 1.25 inch barrel.  It looks like the maximum recommended magnification is around 177x, though this depends on seeing and how good your spotting scope's optics happen to be (some report being able to use >200x).  The magnification will depend on the focal length of the eyepiece and also the adapter (apparently they have different magnifications).  So mag = adapter mag x scope focal length/ep focal length.


Edited by fftulip, 13 September 2021 - 03:14 PM.


#7 hoes

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Posted 13 September 2021 - 03:18 PM

I’ll just add that the adapter that uses set screws provides a little more in focus.

It’s worth having both adapters.

Steve

#8 j.gardavsky

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Posted 13 September 2021 - 03:59 PM

Hello Portauto,

 

you already reach a high magnification of 96x on your Kowa 883 when you mount the zoom on the 1.6x extender.

Herewith the question would be, which short focus astronomy eyepiece to take instead of using the extender.

And possibly, you wold like to have a comfortably wide field, I mean more than your zoom offers.

 

The Pentax XW are well suited for the fast refractors, and so I can imagine that the 5mm and 7mm might work fine on your Kowa. According to my opinion, the Pentax XW 5mm and 7mm are the best of the series, when leaving aside the 30mm and 40mm.

 

On the other hand,

like some others, I am using the spotting eyepieces from Leica, Swarovski, and Zeiss, on my 6" F/5 achro, as the views through these eyepieces are to my eyes better than through the astronomy eyepieces.

 

To each his own,

JG



#9 dcosmar

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Posted 28 October 2021 - 12:30 PM

I've taken a couple of different routes with this scope for looking at planets, etc. I had two 1.6x extenders stacked with the TE-11WZ and that gave a range of ~64-156x. On average/better than average nights of seeing, that top end of 156x was very good for Jupiter and Saturn. When Mars was at opposition, I had 3 extenders stacked and had very good results to around 175x. I have since sold the extenders. The reason being that the internal reflections, glare and scatter (particularly on Jupiter) were a problem for me with the zoom. I now use a Takahashi TOE 3.3 for planetary. With the TOE, the reflections are also still there, but the control of them is much, much better. The Tak TOE 4mm was also very good for this. The AFOV is smaller, but I use a geared head for precision tracking so it doesn't bother me.

 

Here are some things I've found with 2 years of experimenting with the Kowa TSN-883:

 

- Any of the Ethos lineup that have the 2" skirt will give you issues--you'll run into problems getting the eyepiece to drop into the focuser deep enough to reach focus. The 4.7/3.7 should reach focus because they have a removable skirt and I do believe I had the 4.7 a couple of years ago and it reached focus, but the APM HDC XWA are a cheaper good performer for 100deg. However, the APM 13mm (I think technically 13.3 to 13.5mm) does not reach focus. I wanted it to reach focus so badly that I sacrificed one to the machining gods and cut the 1.25" threads off the bottom to try and gain a few more mm to see if it reached focus (it wasn't enough). The 9, 5 (4.77) and 3.5 do reach focus. I haven't tried the 7mm. 

 

- The TV 3-6 zoom won't reach focus to infinity. I think the barrel is longer and the focal plane is higher up. Many spotters have a focal plane right at the back of the scope so if you hunt down eyepieces that are nice enough to show diagrams of where the focal plane is, you can eliminate some options if they have planes further up the eyepiece. I've got a PDF document from the US Kowa rep that shows 30+ eyepieces they tested and which adapters worked (knurled or grub) or if it didn't reach focus. Some notable Tele Vue eyepieces that *do* reach focus with the knurled screw adapter are: Delos 12mm-3.5, Delite 18.2mm-5mm (3mm unconfirmed); Nagler Type 6, 16mm-2.5mm, 24 TV Panoptic. 

 

- Binoviewers wont reach focus without a barlow or using the 1.6 extender. I used a 5x powermate with the celestron binoviewers and two Baader Mark IV zooms and it worked. It's a matter of stabilizing the weight of all that to enjoy the views. Some of the linear binoviewers like the Orion/Omegon/TS will create problems with the image being inverted, so that is not great for daytime viewing, and also dont focus to infinity without a barlow. The stack of the powermate, along with longer eyepieces, will make vibration issues a problem, but there are some ways to stabilize it with longer arca swiss plates and foam supports under the focuser. 

 

- Putting UHC-type filters on a 40mm plossl, or 24ES68 results in the eyepiece being pushed too far out to be able to use them with the UHC filter. The only 24/68(ish) eyepieces I've been able to use with a UHC filter attached to the barrel so far are the APM/Celestron 24 UFF and TV 24 Pan. The 24UFF just barely gets there and only with the grub screw-type adapter. 24mm eyepieces will likely cause vignetting. The clear aperture of the scope's prism is somewhere around 23.45mm so you're going to get vignetting with field stops greater than that (you can also see a fuzzy field stop in the TE-11WZ at ~50x setting as well).

 

- The same focusing issues that exist for eyepiece focal planes, exist for trying to use prime focus night vision devices with the Kowa TSN-883. You can use a 40mm plossl for 7mm exit pupil for max brightness in the afocal configuration, but again you can't put an h-alpha or long pass filter on the eyepiece and will need to have that on the lens of the NV device or afocally attached to the business end of the eyepiece. I rigged up an adapter to do this when I was doing NV.

 

- There are many eyepieces that don't reach focus to infinity in the knurled screw-type adapter because of the extra ~6mm it pushes eyepieces out. The grub screw adapters sink into the scope and you need that in many cases. The 1.6 extender probably creates more usefulness with the knurled adapter if it pushes the focal plane of the scope out enough to where that ~6mm doesn't matter anymore. One thing to note about the astro eyepieces/adapters, is that the scope probably isn't technically waterproof when using the adapters.


Edited by dcosmar, 29 October 2021 - 11:19 AM.

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#10 DRodrigues

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Posted 28 October 2021 - 05:16 PM

...

 

- Binoviewers wont reach focus without a barlow or using the 1.6 extender. I used a 2.5 powermate with the celestron binoviewers and two Baader Mark IV zooms and it worked. It's a matter of stabilizing the weight of all that to enjoy the views. Some of the linear binoviewers like the Orion/Omegon/TS will create problems with the image being inverted, so that is not great for daytime viewing, and also dont focus to infinity. The stack of the powermate, along with longer eyepieces, will make vibration issues a problem, but there are some ways to stabilize it with longer arca swiss plates and foam supports under the focuser. 

 

...

I don't think that a 1.6x OCA/GPC would be enough to reach focus. Even a 2.6x one might not be enough. Nice to know that powermate 2.5x work!...waytogo.gif
 


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#11 dcosmar

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Posted 28 October 2021 - 06:37 PM

I don't think that a 1.6x OCA/GPC would be enough to reach focus. Even a 2.6x one might not be enough. Nice to know that powermate 2.5x work!...waytogo.gif
 

Yes, and now that you say that, it was the 5x powermate I used and not the 2.5x. I didn't have the 2.5 when I was testing it. That gave around 106x to start with on the BHMKIV zooms.



#12 dcosmar

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Posted 19 July 2022 - 07:56 AM

Just adding into this thread a list of 1.25" eyepieces that have either been confirmed to work by myself, or by the US Kowa rep, for the TSN-883...

 

Kowa Grub (G) and Knurled (K) Screw 1.25" Adapter Options
*Knurled screw adapter pushes eyepiece out additional ~6mm causing focus issues on some eyepieces

*Any eyepiece that comes to focus in the (K) also comes to focus with a (G) in many cases

*When stating "will not come to focus"--this relates to focus to infinity

APM UFF = 24 (G)
APM HDC = 9, 4.7, 3.5 (G). 13 will not come to focus
APM HiFW = 12.5 (G)
Baader Hyperion = 5, 17 (G)
Baader Mark IV 8-24 Zoom = (G) but the 2.25x barlow does not come to focus with this eyepiece
Baader Morpheus = 17.5, 14, 9, 6.5, 4.5 (G)
Binoviewer (Celestron) = (K) needs 5x Powermate to reach focus. Likely operating at 7-8x due to BV light path

*Orion/Omegon/similar linear BV invert image and did not focus to infinity. Possibly would with 5x Powermate
Celestron Omni = 40 (G)
Celestron 8-24 Zoom = (G)
Docter 12.5 = (G)
Explore Scientific = 24/68 (G)
Masuyama 35 52* = Does not come to focus
Pentax SMC XW = 20, 14, 10, 7, 5 (G). 3.5 will not come to focus for me, although Kowa rep listed it as being able to focus
Takahashi LE = 2.8, 5, 12.5, 24 (G)
Tak Abbe = 6, 12.5 (G)
Tak TOE = 4, 3.3 (G)
TV Delite = 18.2, 15, 11, 9, 7, 5 (K)
TV Delos = 17.3, 14 = (G); 12, 10, 8, 6, 4.5, 3.5 (K)
TV Ethos = 4.7, 3.7 (G); Anything else = 2" non-removable skirt that won't sink in deep enough to focus
TV Nagler = 16T5, 13T6, 11T6, 9T6, 7T6, 5T6, 3.5T6, 2.5T6 (K)
TV 3-6 Zoom = Does not focus
TV Panoptic 24mm  (K)
Vixen HR = 2.4 (G)
Vixen SLV = 12 (G)
Vixen SSW = 3.5, 5 (G)

 

*Night Vision M703E, PVS-7 and PVS14 did not come to focus using prime focus and 1.25" adapters to ENVIS lens.


Edited by dcosmar, 19 July 2022 - 09:28 AM.

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#13 Mark9473

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Posted 19 July 2022 - 08:54 AM

Thanks. Am I correct that the Baader zoom you tried is not the version IV which needs less infocus?

#14 dcosmar

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Posted 19 July 2022 - 09:21 AM

Thanks. Am I correct that the Baader zoom you tried is not the version IV which needs less infocus?

I updated that entry to make it more clear, but I used the Mark IV zoom. The Mark IV zoom, itself, came to focus, but with the 2.25x barlow that comes with some packages, it did not come to focus with the barlow lens attached.


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#15 DRodrigues

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Posted 19 July 2022 - 01:32 PM

... The Mark IV zoom, itself, came to focus, but with the 2.25x barlow that comes with some packages, it did not come to focus with the barlow lens attached.

It probably will reach focus with the 2.25x Baader barlow if you will use the Baader 1.25" extension tube with 18.5mm length as I did at https://www.cloudyni...1#entry11950099 - by the way, the APM zoom will not reach focus on your Kowa without a barlow...

 

Do you have a linear BV? I know a way that it might reach focus, zoom and have the image not inverted...

 



#16 n2dpsky

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Posted 19 July 2022 - 01:41 PM

I use Explore Scientific 82 deg eyepieces in my Pentax spotter.  They're waterproof and offer excellent field of view and eye relief. 




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