Filters in stock ship usually ship within 3 weeks.
You may click the “Get an alert” button to be notified when an out of stock filter is back in stock. It is necessary to pay for back-ordered filters immediately to reserve your spot in our wait list. Often we have more orders for out of stock filters than we have incoming filters. Many Astrodon filters are perpetually out of stock for this reason.
Standard sizes are 1.25″, 31mm, 50mm round, and 50mm square. The 1.25″ is 27.5 mm of filter glass mounted in a 1.25″ filter cell. The 31mm is 27.5mm of filter glass mounted in a 31mm ring. More information here:
Unlike other Astrodon filters, the Photometric filters (Johnson-Cousins and Sloan) do not come as 36mm of unmounted glass. For those who want 36mm round for use in a 36mm filter wheel, 27.5 mm of filter glass can be mounted in our 36mm adapter. More information on 36mm mount here:
We also have a limited quantity of 12mm and 25mm (call for pricing and availability). All Astrodon Photometric filters are 100%-Coated for long-term durability and consistency of research with the highest throughput.
NOTE: In Astrodon part numbers we pronounce the ‘ character (apostrophe) as “prime” and the _ character (underscore) we pronounce as “sub.” So u’2_27R should be read as “u prime 2 sub 27 R.”
However, our dinosaur website software software chokes on ‘ (apostrophes) if they are in a SKU field part number. So we have replaced ‘ with ! in these places. So the above part number (when used in a SKU field) on our website will appear as u!_27R. But it is really u’_27R. Again, this is due to our dinosaur software, but if you Google Astrodon you will find that Astrodon was a dinosaur with star shapes in the fossils…so appropriate, eh? In any event, forgive our software, move on, and be happy.