2inch filters

[Earl]

Are 2 inch filters 48mm thread size?

[Elp]

1 hour ago, Earl said:

Are 2 inch filters 48mm thread size?

Yes, I use them on the front of camera lenses with the appropriate step down rings.

[Louis D]

And I use 48mm photographic filters directly threaded onto my 2-inch eyepieces.

[Earl]

cool thanks

 

[Don Pensack]

48mm x 0.75mm thread.

[globular]

35 minutes ago, Don Pensack said:

48mm x 0.75mm thread.

While they are all 48mm, they are not all 0.75mm pitch.

Baader claim to have come up with a pitch that works with a wide variety of the pitches out there in the market. This is what they say on the matter:

Our 2" filters have a M48 male (and M48 front female) thread.
Both thread sizes come with our proprietary pitch - which is not the same for the female and male threads.
This is our own proprietary "emergency solution" for uniting a world were manufacturers all over the world copy from each other - to the point that there are almost a dozen different pitches in use for male and female threads. Traditionally US-companies used to do a UNF-based pitch and the rest of the world went for metric threads - but these do vary from 0.5 to 0.75.
For this reason it does not make sense to publish our non standard pitch because our pitch is made to cope with all existing metric and US-pitch standards - and as said - our solution has evolved from sheer necessity. It is a mixture of a queer pitch and under-/over-dimensioning . We will not want to declare this as a standard and get bashed up for it. It works for us and is a result of 20 years adaptation to fit our filters onto all crazy threads we have seen. And inspite of this - every now and then there comes another "dragonboat-eyepiece" were even our filters may not fit

[Elp]

It's true the pitches may be different, but from my experience having used Baader, Optolong, Astronomik, Svbony, they all fit the same M48 photographic thread and M48 filter drawers. More of a glaring issue is the cell thickness (critical when using filter drawers) and glass thickness for calculating backfocus requirements.

 

[Don Pensack]

15 hours ago, globular said:

While they are all 48mm, they are not all 0.75mm pitch.

Baader claim to have come up with a pitch that works with a wide variety of the pitches out there in the market. This is what they say on the matter:

Our 2" filters have a M48 male (and M48 front female) thread.
Both thread sizes come with our proprietary pitch - which is not the same for the female and male threads.
This is our own proprietary "emergency solution" for uniting a world were manufacturers all over the world copy from each other - to the point that there are almost a dozen different pitches in use for male and female threads. Traditionally US-companies used to do a UNF-based pitch and the rest of the world went for metric threads - but these do vary from 0.5 to 0.75.
For this reason it does not make sense to publish our non standard pitch because our pitch is made to cope with all existing metric and US-pitch standards - and as said - our solution has evolved from sheer necessity. It is a mixture of a queer pitch and under-/over-dimensioning . We will not want to declare this as a standard and get bashed up for it. It works for us and is a result of 20 years adaptation to fit our filters onto all crazy threads we have seen. And inspite of this - every now and then there comes another "dragonboat-eyepiece" were even our filters may not fit

I have found that Baader's proprietary thread pitch doesn't fit a lot of commercially available 48mm threaded accessories.  Just like Orion's proprietary thread pitch, their accessories thread it part way and jam.

I have checked a lot of threads, and the most universal is 48mm x 0.75mm.  I just wish the world would standardize.

[Louis D]

I've got over a dozen 2" photographic and astronomic filters, and I've never had issues with threading them onto any of my 2" eyepieces, or into my M48 step rings to get to other thread sizes.

I can't say the same for the 2" SCT visual back thread size.  I have yet to find a 2" SCT to M48 step ring for my 2" GSO diagonal that do not bind.  And yet, my 127 Mak to SCT thread ring screws all the way into the GSO diagonal with no binding at all.  I've tried both Agena's Blue Fireball and Baader's step rings, and both brands bind.

Does anyone know of a non-binding 2" SCT to M48 thread adapter that works with GSO diagonals so I can get a more secure threading with my TSFLAT2 and M48 spacer ring(s).  Thanks!

[Elp]

If you have a thread pitch gauge at hand you can measure them yourself, but usually such practice it helps to have a mating part with said measured thread to test.