# Weathersealing a non-weathersealed lens / Dust Donut



## ahsanford (Oct 8, 2013)

Great people of CR,

I know that there is more to weathersealing a lens than just the rubber gasket, but I thought it might be a good idea to gasket my non-WS glass if it was a non-permanent thing (i.e. considering resale).

So I found this kickstarter:
http://www.kickstarter.com/projects/77243737/dust-donuttm-add-a-weather-seal-to-the-mount-of-an?ref=live

It looks like it was funded, but I don't see a storefront on Google anywhere. Did he just make a production run to cover the backers and then shut down? It would be a pity if so.

Any thoughts in general on the upsides/downsides of such an idea? Does anyone have one of these?

Thanks,
A


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## neuroanatomist (Oct 8, 2013)

Great for the 100-400L and the 400/5.6L, which are weather sealed _except_ for the lacking mount gasket. Pretty useless for other lenses, IMO, since they lack sealing at the switches, focus/zoom rings, etc., and once water has an ingress, it will find it's way into the body anyway.


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## 1kind (Oct 8, 2013)

I had contacted them awhile back for review samples when the Kickstarter program was still running. They said no problem once the project is completed. Project is funded and I contacted them awhile back. Never got a reply back.


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## neuroanatomist (Oct 8, 2013)

1kind said:


> I had contacted them awhile back for review samples when the Kickstarter program was still running. They said no problem once the project is completed. Project is funded and I contacted them awhile back. Never got a reply back.



Crowdfunding is the new pyramid scheme.


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## ahsanford (Oct 8, 2013)

Neuro, do you feel the same way about the limited value of this if only dust & sand were concerns? I'm in Southern Cal, so water is not a concern for me unless a sprinkler goes off in a park.

And while you are at it, I did not know this about partial weathersealing -- I presumed all L lenses were completely or not at all weathersealed based on whether they had a mount gasket or not.

Offhand, if you know, what is the extent of weathersealing on my L lenses?

100 F/2.8L IS
24-70 F/2.8L I
24-70 F/4L IS
70-200 F/2.8L IS II

All are mount-gasketed, and I filter the front elements as I believe that all of them are not front element gasketed. I thought only the "non-front-filterable" longer lenses had front element gaskets. Please set me straight if I've got that wrong.

- A


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## 1kind (Oct 8, 2013)

neuroanatomist said:


> 1kind said:
> 
> 
> > I had contacted them awhile back for review samples when the Kickstarter program was still running. They said no problem once the project is completed. Project is funded and I contacted them awhile back. Never got a reply back.
> ...


Its been successful for Custom SLR and Peak Designs


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## hpmuc (Oct 8, 2013)

This has already been discussed ....

http://www.canonrumors.com/forum/index.php?topic=12416.0


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## neuroanatomist (Oct 8, 2013)

1kind said:


> Crowdfunding is the new pyramid scheme.


Its been successful for Custom SLR and Peak Designs
[/quote]

Sure - there are legitimate products there. But not all of them...and whether it's intentional fraud or just overpromising/underdelivering, some of the funded products seem to fail to result in an actual product being produced. The money goes somewhere.....



ahsanford said:


> Neuro, do you feel the same way about the limited value of this if only dust & sand were concerns? I'm in Southern Cal, so water is not a concern for me unless a sprinkler goes off in a park.



I feel pretty much the same, particularly for extending zoom lenses - those are going to move air in and out, and whether it moves through the mount or the zoom ring, if there aren't dust seals the dust will come in with the air. 'Sealing' the mount just means the air comes in through the other openings.



ahsanford said:


> And while you are at it, I did not know this about partial weathersealing -- I presumed all L lenses were completely or not at all weathersealed based on whether they had a mount gasket or not.



Pre-1999 white L lenses have sealing at the switches and zoom/focus rings, but lack the mount gasket. For example, the 100-400L and 28-300L are the same basic barrel design, but the latter has the mount gasket and so is a sealed lens. The info on the partial sealing came from an email discussion I had with Chuck Westfall (Canon USA's technical mouthpiece).



ahsanford said:


> Offhand, if you know, what is the extent of weathersealing on my L lenses?
> 
> 100 F/2.8L IS
> 24-70 F/2.8L I
> ...



I suppose Canon would call the sealing equivalent, but I'd bet it's better on the 100L and 70-200 II. To put it another way, the sealing probably is equivalent, but it's more effective with a non-extending lens design, since they don't pump air in and out of the lens as you zoom.

Reading the Canon manuals, only the lenses with 'internal' but exposed moving barrels require a filter to complete the sealing - among current lenses, that's the 16-35L II, 17-40L, and 50/1.2L. For the others, there's no stated requirement for a filter to complete the sealing. However, in that same email exchange with Chuck Westfall, he recommended using a front filter on all lenses which accept one.


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## ahsanford (Oct 8, 2013)

hpmuc said:



> This has already been discussed ....
> 
> http://www.canonrumors.com/forum/index.php?topic=12416.0



Good forward, thanks! Looks like my lenses are not in the 'partial sealing' camp (besides the front element).

But I still would like a read on the viability of this concept for just dust and sand. Again, moisture isn't a concern for me.

- A


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## Mt Spokane Photography (Oct 9, 2013)

ahsanford said:


> hpmuc said:
> 
> 
> > This has already been discussed ....
> ...


 
There are going to be those who swear by it, and there will be skeptics like Neuro and I.

The fact is that there is no reliable data, so if it makes you feel safe, get it. Its not likely to cause any problems other than a loss of your money.


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