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Kowa TP-95FT filter (1 Viewer)

If you really need the protection (for seawatching?) then I don't think the filter would noticeably degrade the image. However, it's not a very good idea of Kowa (or Swarovski) to put the filter thread in the objective hood instead of the scope body.

John
 
If you really need the protection (for seawatching?) then I don't think the filter would noticeably degrade the image. However, it's not a very good idea of Kowa (or Swarovski) to put the filter thread in the objective hood instead of the scope body.

John

Why's this, John? Can you explain please what the issue is with this? Does this mean on an 883/Swaro that if you extend the hood the filter moves away from the objective lens?
 
Does this mean on an 883/Swaro that if you extend the hood the filter moves away from the objective lens?

Exactly that. Take a look at the video Marriusz linked. I have never used a filter but the threads are on the objective hoods of both my Kowa 883 and my Swarovski ATM 65HD. Silly isn't it? IIRC my first scope, a Zeiss Diascope 65 had the filter thread in the scope body. No idea if Swarovski have seen the light with the ATX/STX.

John
 
Same with ATX/STX, unfortunately. The threads are on the hood only and hence next to useless. I guess this is Swarovski's and Kowa's educational approach to keep us away from evil, image-degrading UV filters.
 
Kowa got it right on the 774 - the filter screws on to the body of the scope and the hood slides out over it.
 
Same with ATX/STX, unfortunately. The threads are on the hood only and hence next to useless. I guess this is Swarovski's and Kowa's educational approach to keep us away from evil, image-degrading UV filters.

Of course two additional air/glass surfaces are going to increase the risk of ghosting and flare, but when one considers the number of elements in scope and eyepiece, the effect of a high quality filter will be negligible.
See: https://photographylife.com/lens-filters
Perhaps Kowa's and Swarovski's decisions to put the thread on the objective hoods was influenced by the availability of different filter sizes and that the mount of a filter on the scope will require a somewhat larger diameter objective hood and consequently larger scope body.

John
 
@dogbreath I cannot open the link you sent.
https://www.birdforum.net/showpost.php?p=3725586&postcount=4

I think Kowa and Swarovski are wrong in placing the filter thread on the hood:
1) The further the filter is away from the lens he worser for ghosting and flare.
2) The hood cannot shade the filter against sunlight, hence unnecessary reflexes appear.
3) The hood cannot protect the filter against water spray, branches, finger tips etc.

But I doubt that they took proper filter use on their scopes into consideration. A Swarovski rep told me: "The front lens coating is hard as well as water and dirt repellent. You don't need a protective filter, not on the sea, not elsewhere, it would degrade the image only. The front thread is there for the lens cap solely."
Maybe, but I'd like to make my own decisions. In the end, it is *my* scope.
 
Last edited:
@dogbreath
I cannot open the link you sent.

The link was to a post by Brett Richards. I couldn't get it to open just now. Sorry - not sure what has gone wrong. I have copied and pasted the relevant bit:

"Thanks Richard,

I sent an email to Kowa enquiring about this and got the following reply

"Hello Mr Richards,

Thank you very much for your recent service enquiry.

You are correct, the thread fits the hood only.
The inner thread that you see is for assembly purposes only, you will notice that there are special tool marks that precludes the use or fitting of a filter.

The only place that you can fit the filter therefore is the shade, the filter is properly multi-coated and has hydrophobic coating (our Kowa proprietary KR coating) that repels water and other liquids.
This also cleverly protects the front optics and the shade from potential damage from the ingress of salt spray and/or sand.
If the filter was in the position you hoped, it wouldn’t have this extra further protective effect.

I hope this answers your question.

Yours with best regards,"

At least this answers my query, but I still think it would be better on the end of the 'scope body. I will have to make some sort of extension from a pop bottle or something as you suggested.

Brett"
 
https://www.birdforum.net/showpost.php?p=3725586&postcount=4

I think Kowa and Swarovski are wrong in placing the filter thread on the hood:
1) The further the filter is away from the lens he worser for ghosting and flare.
2) The hood cannot shade the filter against sunlight, hence unnecessary reflexes appear.
3) The hood cannot protect the filter against water spray, branches, finger tips etc.

But I doubt that they took proper filter use on their scopes into consideration. A Swarovski rep told me: "The front lens coating is hard as well as water and dirt repellent. You don't need a protective filter, not on the sea, not elsewhere, it would degrade the image only. The front thread is there for the lens cap solely."
Maybe, but I'd like to make my own decisions. In the end, it is *my* scope.

I too wanted to make my own decision. Swaro's explanation would seem to be similar to Kowa's. I accept the potential for a degraded image. I will live with that with a filter (in my case a Hasselblad one bought secondhand, so likely to be a good filter). I am much more comfortable cleaning a secondhand filter than the front element of my scope and if the filter gets damaged it is cheaper and easier to replace thana flourite front element.
 
I am much more comfortable cleaning a secondhand filter than the front element of my scope and if the filter gets damaged it is cheaper and easier to replace thana flourite front element.

Fluorite was used (possibly still is) for the front element of some astronomical refractors but because of its fragility it is not used for the front element of the Kowa 550 and 880 scopes. The fluorite elements in their objectives are internal.

John
 
I looked into the Kowa filter before getting my 883, but instead got a Hoya UV filter for a fraction of the price. I actually ordered the filter before I ordered the scope. I also agree that it's a lot cheaper to replace the filter, then sending the scope in for repair, and then being without the scope for an extended period of time. The day I received the scope, I first viewed without the filter, and then with...and both views were equally amazing!
 
I leave my filter on my 823 all of the time. I notice a slight image degradation when using my 50x eyepiece, in which case if the weather's ok I temporarily remove it. With the 30x, for seawtaching etc., the difference is barely noticeable, so I tend to leave it on as default. Mine is also a Hoya.
 
Some early Hoya filters were pretty awful. I have several examples of these.
Modern ones are likely good.
But B and W (Schneider), Hasselblad, Nikon, Canon, Minolta and Russian ones are high quality.

However, camera filters are probably not up to the quality of a high magnification scope. 60x is pretty low for a scope.
My 12.5 inch or slightly bigger optical window for my 12.5 inch aperture Dall Kirkham was good up to 600x or more.
The Russian MTO 1000 Maksutov filters are O.K. at 100x although the instruments all seem to have temperature problems, maybe from the tube material or the design of the instrument.

It would not surprise me if there are fake Hoya filters also.

The bigger the filter the more difficult it is to get good quality.

If I had a cherry example of a Kowa 88mm scope I would not put a Hoya filter on it, unless it were a specified high quality Hoya filter.
 
I leave my filter on my 823 all of the time. I notice a slight image degradation when using my 50x eyepiece, in which case if the weather's ok I temporarily remove it. With the 30x, for seawtaching etc., the difference is barely noticeable, so I tend to leave it on as default. Mine is also a Hoya.

Filters are a bother, especially in cold and damp conditions. Moisture condensing on the filter inside gradually blurs things.
A good hood normally protects more effectively, without impacting the view.
 
Filters are a bother, especially in cold and damp conditions. Moisture condensing on the filter inside gradually blurs things.
A good hood normally protects more effectively, without impacting the view.

My experience hasn’t proved particularly bothersome!
 
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