Kowa 99 Update? (3 Viewers)

[DRodrigues]

...
I know this is far from being scientific at all, I just wanted to give you an impression of how a Kowa TSN 99a works with different steps of magnification compared to a good camera (which I think the Sony RX 10 IV is).

Thank you for your test but there are 2 errors:

• last photo has less magnification than the one before;
• both last photos haven't 1.6x factor increase from the previous...

My guess is that you used zoom on of the mobile phone when taking the photos so these don't show true magnification increases. Please redo you test without using the phone zoom and repost the correct photos.

 

[paperweight]

@DRodrigues: you are certainly right that using the iPhone's zoom factor is not helpful in such a comparison. But what I can say is that the second last photograph was made with the TE 11 at full zoom plus one Extender 1.6 and the last one with the TE 11 at full zoom plus two Extenders 1.6.
I will soon do a second test without the iPhone's zoom.

 

[paperweight]

A lot of rain coming, so I had to be fast in the cold outside (4° C). So here's the second series without any adjustment in the iPhone 13 nor cropping of the picture in Mac "Preview". The 99a was angled at about 30° upwards. I wanted to get off that porch with its vibration and inevitable blur and shoot from the ground directly which resulted in some vegetation being in the way unfortunately.
I will do a comparison later with an object that allows a straight view.

TSE 99a, TE 11 full zoom (70x)



Kowa TSN 99a, TE 11 full zoom, Ext 1.6 (118x)



Kowa TSN 99a, TE 11 full zoom, 2x Ext 1.6 stacked (118x)

 

[DRodrigues]

Thanks.
The AFOV increase with the extenders or is the eye-relief?
With only the zoom, the black area of the photo is much bigger...

 

[paperweight]

@DRodrigues: I cannot answer that question because I do not know which part the iPhone's camera plays. What I can say is that watching with two extenders stacked is much more difficult than with just the TE 11 because of the absolutely small exit pupil.

 

[cncbits]

A lot of rain coming, so I had to be fast in the cold outside (4° C). So here's the second series without any adjustment in the iPhone 13 nor cropping of the picture in Mac "Preview". The 99a was angled at about 30° upwards. I wanted to get off that porch with its vibration and inevitable blur and shoot from the ground directly which resulted in some vegetation being in the way unfortunately.
I will do a comparison later with an object that allows a straight view.

TSE 99a, TE 11 full zoom (70x)

View attachment 1613911

Kowa TSN 99a, TE 11 full zoom, Ext 1.6 (118x)

View attachment 1613912

Kowa TSN 99a, TE 11 full zoom, 2x Ext 1.6 stacked (118x)


View attachment 1613913

I find it particularly interesting to watch such comparisons. I just want to check if it's a typo 118× with one extender and the same 118x with two extenders?
Shouldn't it be like in the previous comparison: 112x with one extender and 180x with two extenders?

By the way, I didn't know that you can use more than one extender. And can you use 3 or 4 extenders? Would it make sense to do that?

 

[KBHC73]

I find it particularly interesting to watch such comparisons. I just want to check if it's a typo 118× with one extender and the same 118x with two extenders?
Shouldn't it be like in the previous comparison: 112x with one extender and 180x with two extenders?

By the way, I didn't know that you can use more than one extender. And can you use 3 or 4 extenders? Would it make sense to do that?

Yes i reckon pushing 200x with the 2 extenders. You could stack more but the light & quality will massively suffer. I have an 883 & i had 2 1.6x extenders at one point. With both i could get a sharp image on a cool fine day but i found i wasn't using both enough to warrant keeping one so i sold it on & don't miss it. One extender is enough & even that sits in the bag nost of the time! All the best.

 

[Gzoladz74]

Yes i reckon pushing 200x with the 2 extenders. You could stack more but the light & quality will massively suffer. I have an 883 & i had 2 1.6x extenders at one point. With both i could get a sharp image on a cool fine day but i found i wasn't using both enough to warrant keeping one so i sold it on & don't miss it. One extender is enough & even that sits in the bag nost of the time! All the best.

I agree with this...even if you get enough like, the depth of field will be so shallow that focusing will be a challenge. Still nice for experimenting.

 

[paperweight]

I find it particularly interesting to watch such comparisons. I just want to check if it's a typo 118× with one extender and the same 118x with two extenders?
Shouldn't it be like in the previous comparison: 112x with one extender and 180x with two extenders?

By the way, I didn't know that you can use more than one extender. And can you use 3 or 4 extenders? Would it make sense to do that?

Sorry for my mistake. It was supposed to be 180x with 2 extenders. Counting is quite easy. The Kowa 99a offers a max magnification of 70x with the TE 11. One 1.6 Extender will blow it up to 112x, a second, stacked 1.6 Extender will push magnification to 179,2. As pointed out above, a third extender will not make much sense.

 

[DRodrigues]

...
By the way, I didn't know that you can use more than one extender. And can you use 3 or 4 extenders? Would it make sense to do that?

It could make sense for astro use but my tests with the Moon (light availability isn't a problem...), showed to me that 2 extenders wouldn't result on a real gain in resolution, both with the Swaro X95 and the X115...
Someone can do the same test with the Kowas.

 

[KBHC73]

The more extenders you use the harder it is to get a decent sharp image. I found it tricky using 2 as it's such a fine margin.