Help with filter sizes, please.

[Seanelly]

I ordered an IDAS LPS D2 2" filter yesterday for my Canon DSLR 50mm lens, but I'm now worried it may not fit, and is only for a telescope eyepiece.

I thought the 2" was equivalent to the 58mm marking on the lens, but upon further research I see that this is not exactly so.

I think I may have jumped the gun on this order and I'd like to alter it if necessary before it ships, and I think that is still possible because of the Christmas hours and subsequent delay in shipping.

A rookie mistake, if it be so!

[happy-kat]

You just use step down rings or step up rings, I use a 2" filter on my different lens.

 

My lens range from 52mm to 58mm so have a variety of step rings.

I get mine from crocked imaging but there are other suppliers, just make sure you get the right step up or step down that you need.

Edit: though that is a UK supplier.

Amazon sell them

[Seanelly]

30 minutes ago, happy-kat said:

You just use step down rings or step up rings, I use a 2" filter on my different lens.

 

My lens range from 52mm to 58mm so have a variety of step rings.

I get mine from crocked imaging but there are other suppliers, just make sure you get the right step up or step down that you need.

Edit: though that is a UK supplier.

Amazon sell them

Thanks for responding. Just to clarify, does the 2" filter fit telescope 2" eyepieces as well as lenses using the correct adapter?

[happy-kat]

I would imagine so, though I don't have any 2" eyepieces.

[Waldemar]

15 hours ago, Seanelly said:

Thanks for responding. Just to clarify, does the 2" filter fit telescope 2" eyepieces as well as lenses using the correct adapter?

Yes, it does... 
Your lens may get slower because of the smaller aperture of the filter, though.

[Seanelly]

1 hour ago, Waldemar said:

Yes, it does... 
Your lens may get slower because of the smaller aperture of the filter, though.

I appreciate your input, but it still leaves me confused. I asked if the stated 2" filter fits a telescope 2" eyepiece and also an adapted lens, and you said yes it does, and then went on to say that my lens may become slower due to the smaller aperture of the filter, though. I'm now wondering if you meant that yes the 2" fits scope eyepieces, but aside from that if I was to use it with an adapter my lens will become slower; or if you meant that the 2" fits both eyepiece and 58mm lens; or only the lens with an adapter, albeit more slowly.

Since I can get an adapter for the lens, it has become mostly a matter of curiosity as to what fits what in what way, because it will take at least ten days to get the filter and maybe longer if I can catch the order before it ships to add the adapter. That said, if I don't need an adapter and I can change the order before shipping, I will save a few bucks and not end up with a useless (for me) piece of equipment, because this rig is entirely for prime focus and 50mm/250mm lens imaging, since I have a dob for visual.

As it is, I have contacted the supplier, who(m?) have yet to confirm the order (placed three days ago) shipped, I suppose because of Christmas hours, etc., and told them to hold the order until I know for certain what exactly I need, but they haven't contacted me yet about shipping or my concerns.

All this I could hane avoided if my EF-S lenses would fit in the DSLR with my IDAS LPS D1 clip-in filter in place, but they do not, as apparently only the EF type lenses fit with an LPS filter (Grrrr), so I've had to buy an LPS filter for the lenses for camera-only wide-field imaging, and will have to look into the future to purchase those costly EF lenses. $$$$$!!!

If you finished this whole spiel, thanks for listening, and if you can clear up any of my confusion, I'd appreciate it.

[Waldemar]

I'm now wondering if you meant that yes the 2" fits scope eyepieces, but aside from that if I was to use it with an adapter my lens will become slower; or if you meant that the 2" fits both eyepiece and 58mm lens; or only the lens with an adapter, albeit more slowly.

The 2" filter will fit 2" eyepieces and with an adapter it will fit the frontside of your lens, too, but if the aperture of the filter is smaller than the lens opening, it will make your lens slower at full aperture ?

[Seanelly]

5 minutes ago, Waldemar said:

I'm now wondering if you meant that yes the 2" fits scope eyepieces, but aside from that if I was to use it with an adapter my lens will become slower; or if you meant that the 2" fits both eyepiece and 58mm lens; or only the lens with an adapter, albeit more slowly.

The 2" filter will fit 2" eyepieces and with an adapter it will fit the frontside of your lens, too, but if the aperture of the filter is smaller than the lens opening, it will make your lens slower at full aperture ?

Gotcha. Thanks a bunch. Your responses are ever so much quicker than my supplier's!

Merry Christmas!

[happy-kat]

But if you do need to use a step down ring for the filter to fit the lens it does work as a slight aperture mask and thereby suppress/minimise any aperture related star spikes.