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2" filters with dslr

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#1 cindersash

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Posted 13 July 2015 - 01:26 AM

appologies if this is in the wrong section for some reason. i can delete and repost it somewhere else if needed.

I have a canon eos 60d, and while modifying it sounds tempting, i like to use it for daytime photography aswell. In the future i plan on purchasing a monochrome ccd for narrowband imaging with 2inch filters, but id like to use the filters with my dslr for now.

my question is how exactly would a 2" filter fit in the set up of the dslr, tadapter and tmount on the telescope? i ask this because i dont have the NB filters purchased yet, and have never seen them used in this way. would i require a different adapter then the tmount and tring that i currently have, or could the filter screw in between the two?

Thanks for your help!

Edited by cindersash, 13 July 2015 - 01:34 AM.


#2 cray2mpx

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Posted 13 July 2015 - 07:20 AM

Simple if you have a 2" T-adapter and proper Canon bajonet adapter (or OAG).

See my gallery where I have some pictures.

 

cs, Cray

Attached Thumbnails

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Edited by cray2mpx, 13 July 2015 - 07:24 AM.

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#3 Midnight Dan

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Posted 13 July 2015 - 09:29 AM

It would be helpful if you could mention what kind of scope you have and what kind of focuser it has.

 

If you have a refractor with a 2" focuser, you'd want to get a T-thread to 2" nosepiece adapter.  You'd put the filter on the front of that and then insert it into the focuser.  If you have an SCT, you'd want the same 2" nosepiece adapter, but you'd also need an SCT-to-2" visual back.

 

-Dan



#4 cindersash

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Posted 13 July 2015 - 10:42 AM

It would be helpful if you could mention what kind of scope you have and what kind of focuser it has.

If you have a refractor with a 2" focuser, you'd want to get a T-thread to 2" nosepiece adapter. You'd put the filter on the front of that and then insert it into the focuser. If you have an SCT, you'd want the same 2" nosepiece adapter, but you'd also need an SCT-to-2" visual back.

-Dan


i have a reflector with a 2" focuser. would i get the same adapater as the one you mentioned for the refracter then?

#5 Midnight Dan

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Posted 13 July 2015 - 11:03 AM

That's correct.  A t-thread to 2"nosepiece should do it.  It should end up looking a bit like cary's photo above, but without the OAG hanging off the bottom, and shorter.  It appears that he has an extension tube on there.  For a reflector, you normally want to keep things short so you don't run out of backfocus.

 

-Dan


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#6 cindersash

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Posted 13 July 2015 - 02:02 PM

That's correct.  A t-thread to 2"nosepiece should do it.  It should end up looking a bit like cary's photo above, but without the OAG hanging off the bottom, and shorter.  It appears that he has an extension tube on there.  For a reflector, you normally want to keep things short so you don't run out of backfocus.

 

-Dan

 

Great! and another question in regard to your earlier post, when you say the filter will be put on the front of the nosepiece adapter and inserted into the focuser, does that mean its placed into a 2" inch eye piece holder?



#7 cindersash

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Posted 13 July 2015 - 02:25 PM

also, why would the adapter in the middle out of the three parts of this picture not work for this? it screws onto the camera adapter on the right and then onto the 2" focuser. isnt this just an extremely short version of the nosepiece adapters? because the ones i've looked up seem pretty long.
 
http://imgur.com/eRhOC1W
 
also the part on the left is an eyepiece adapter, returning to the question of if the eyepiece adapter is screwed onto the focuser then the rest of the components are inserted into it.


Edited by cindersash, 13 July 2015 - 02:42 PM.


#8 Midnight Dan

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Posted 13 July 2015 - 08:04 PM

First, let me just say I don't have any newtonion reflectors, so I'm not sure how things attach to the focuser.  

 

But when I talk about a 2" focuser, I'm referring to a focus tube that accepts a 2" nosepiece, and uses one or more thumbscrews to hold it in.  A 2" nosepiece can be the bottom end of a 2" eyepiece, the front end of a 2" diagonal, or a 2" nosepiece that is part of a T adapter arrangement. So when you mention "screwing onto a 2" focuser", I'm not sure what you mean.  My undertanding of a 2" focuser is that you insert 2" attachments, not screw anything onto it.

 

The only piece I recongnize in your photo is the part on the right.  That appears to be a T-ring which attaches to a DSLR on one side, and has a female T-thread (?) on the other.  I can't really see the other side so I don't know for sure.

 

The part on the left might be part of a 2" focuser.  The top of it looks like it might accept 2" attachments like and eyepiece, diagonal, etc.  But I'm not sure what the bottom attaches to.  Perhaps it attaches to a focuser mechanism on a scope, which is why I'd think of it as possibly part of a 2" focuser.

 

I'm not sure what the middle piece is.

 

But again, what I think of as a normal arrangement would be, from camera to scope:

 

1) Camera

2) T-ring (camera mount on one side, female T-thread on the other)

3) Male T-thread to 2" nosepiece adapter.  Example: http://agenaastro.co...pter-ff145.html

4) 2" Filter - screws into the end of the 2" nosepiece

5) 2" focuser tube (accepts 2" nosepiece)

6) Scope

 

-Dan


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#9 cindersash

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Posted 13 July 2015 - 09:21 PM

thank you for clarifying with that last list. sorry that my image was a bit confusing but ill try to explain it a bit better. 

 

http://imgur.com/Tdj...Wddo,HiwTTn0#0 

 

the first image in the link shows the left part from my first imgur link, which does attach to the focuser and accepts 2" accessories. the second image in the link shows the middle part and the right part (camera t-ring). the middle part came with my scope when i purchased it, and could be unique to it. this part is what i use to attach my camera's t-ring to the focuser. it is a t thread to 2" thread. this part and the 2" focuser part (that accepts nosepieces) are interchangeable via a thread within my focuser (as in, the parts can be screwed and unscrewed at the top of the focuser). this is my first telescope, so I was just as confused (but probably more so) than you might have been. 

 

i now see that the t thread to 2" thread part will be out of the mix when i use the filters, as it is not made to accept 2" accessories, only to accept the camera's t-ring.

 

thanks so much for helping me understand and for trying to understand a dunderhead like me! I'm very surprised to find people as helpful as you have been on a forum.



#10 Midnight Dan

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Posted 14 July 2015 - 08:45 AM

No problem, happy to help. :grin:

 

I'm still not sure that the middle piece in your first photo is actually a 2" to T-thread adpater.  The sizes of the 2 threads should be closer than they appear in your photo.  Here is a link to a 2" to T-thread adapter sold by Agena Astro. You may have to click on the image to get a larger view:

http://agenaastro.co...apter-t-05.html

 

If you look at your part, it seems like either the 2" side is too large, or the T side is too small.  Since it screws into your focuser mechanism in place of the 2" tube, I'm guessing that the screw thread on that side is not a standard 2" thread, but is instead something a bit larger that is specific to your focuser.

 

If I'm mistaken, and that larger side actually is a 2" thread, then a 2" filter should be able to screw on between the middle piece and your focuser mechanism.  That would allow a shorter arrangement and would ensure that you can reach focus.  Using the 2" nosepiece could end up putting your DSLR sensor too far away to reach focus.  That's a common problem with newts.

 

-Dan



#11 cray2mpx

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Posted 17 July 2015 - 09:31 AM

That's correct.  A t-thread to 2"nosepiece should do it.  It should end up looking a bit like cary's photo above, but without the OAG hanging off the bottom, and shorter.  It appears that he has an extension tube on there.  For a reflector, you normally want to keep things short so you don't run out of backfocus.

 

-Dan

Yes, its an extension to place the DSLR sensor at exactly 133 mm from the SCT flange. That's the spec the built-in corrector/flattener of the Edge HD C8 scope requires to work at optimum.

 

cs, Cray



#12 Lew Chilton

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Posted 17 July 2015 - 09:02 PM

Baader-Planetarium sells a DSLR T-adapter with built-in 2-inch filter holder for your choice of filters for the Canon EOS series and I think also for the Nikon. Check out the AgenaAstro Products website.

 

http://agenaastro.co...r-2958550l.html

 

But first check out the Astronomics website to see if it carries this item.




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