Nikon T2 ring for Skywatcher Explorer 250PDS

[ZiggyStardust]

Hello. I have an order of Skywatcher Explorer 250PDS and it should arrive within a month or so. I also have a Nikon D40 camera and I was wondering what kinf of adapter must I purchase to make sure it will work with my new 'scope. Are there more than one type of T-ring adapters for camera/telescope combination or are they all of same standard? Would this thing do? I never had one and just want to be 100% sure it will work fine and that I don't buy something that will not work.

[Hornblower]

Hello. I have an order of Skywatcher Explorer 250PDS and it should arrive within a month or so. I also have a Nikon D40 camera and I was wondering what kinf of adapter must I purchase to make sure it will work with my new 'scope. Are there more than one type of T-ring adapters for camera/telescope combination or are they all of same standard? Would this thing do? I never had one and just want to be 100% sure it will work fine and that I don't buy something that will not work.

That is the T ring which fits into the camera body's bayonet mount in place of a lens. The front of the ring is threaded to take a T-adaptor, the front end of which mates to the telescope. To complete the system you need a T-adaptor that fits into the focuser on the scope in place of an eyepiece. I just looked here:
http://www.green-witch.com/acatalog/T-Adaptors.html
I was hoping to see one with a 2" barrel, since your scope will take 2" eyepieces. The only ones I can see are 1.25".

[ZiggyStardust]

So I need two parts, T-ring and T-adapter. My local astro shop doesn't have the adapter at the moment, but this ring will work on all Nikon cameras will it not? So I could order it now and look for the adapter bit elsewhere.

[glappkaeft]

That is the T ring which fits into the camera body's bayonet mount in place of a lens. The front of the ring is threaded to take a T-adaptor, the front end of which mates to the telescope. To complete the system you need a T-adaptor that fits into the focuser on the scope in place of an eyepiece. I just looked here:
http://www.green-witch.com/acatalog/T-Adaptors.html
I was hoping to see one with a 2" barrel, since your scope will take 2" eyepieces. The only ones I can see are 1.25".

That is probably bad advice. Most Newton telescopes lack enough back-focus to reach focus with the combination of a T-adapter and a DSLR camera. Usually you need to unscrew the entire eye-piece holder and mount the T-ring directly on the focuser.

[edit to add]: Although the T-adapter is useful if you want to use a barlow lens.

Patrik

[ZiggyStardust]

This gets complicated.
Is there just one standard T-ring for Nikon cameras and also just one T-adapter for 2-inch focusers? In other words, if I buy a T-ring for my Nikon D40 camera and a 2-inch T-adapter, they will work just fine with no incongruities due to brand- or maker-specific reasons?

[Hornblower]

That is the T ring which fits into the camera body's bayonet mount in place of a lens. The front of the ring is threaded to take a T-adaptor, the front end of which mates to the telescope. To complete the system you need a T-adaptor that fits into the focuser on the scope in place of an eyepiece. I just looked here:
http://www.green-witch.com/acatalog/T-Adaptors.html
I was hoping to see one with a 2" barrel, since your scope will take 2" eyepieces. The only ones I can see are 1.25".

Addendum: For most if not all of the adaptors I have seen, I cannot see any way the focal plane of an SLR body will reach the Newtonian focus. You would need eyepiece projection with the eyepiece or perhaps a Barlow lens inside the adaptor, if such is possible. I cannot tell from the online brochure what might be workable. There must be some alternative out there, because the manufacturer of the scope specifically said that prime focus photography can be done.

My only experience with SLRs and T-adaptors is with my Celestron 8 Schmidt-Cass. Celestron sold me a T-adaptor that mounts directly to the back fitting on the scope, which is well corrected when focused on the camera's focal plane. It is easier to balance than a Newtonian without overloading the mount, and it gave good results on film with snapshots of the Moon and a close conjunction of Mars and Saturn.

[glappkaeft]

This gets complicated.
Is there just one standard T-ring for Nikon cameras and also just one T-adapter for 2-inch focusers? In other words, if I buy a T-ring for my Nikon D40 camera and a 2-inch T-adapter, they will work just fine with no incongruities due to brand- or maker-specific reasons?

Yes, the "T" in T-adapter and T-ring refers to the T-thread standard (metric M42-0.75mm thread). If the makers didn't botch their product they are guarantied to fit each other. There could be other problems like the one I mentioned earlier about not being able to reach focus but the adaptors should fit.

I'm no expert on Nikon (I use Canon 400D myself) but IIRC the current Nikon-bayonett has been in use for a long time (all digital SLRs and the autofocus enabled film SLRs). There are some older film Nikon cameras that use another bayonett (and would require a different T-ring) but all digital ones use the modern variant.

[glappkaeft]

Addendum: For most if not all of the adaptors I have seen, I cannot see any way the focal plane of an SLR body will reach the Newtonian focus. You would need eyepiece projection with the eyepiece or perhaps a Barlow lens inside the adaptor, if such is possible. I cannot tell from the online brochure what might be workable. There must be some alternative out there, because the manufacturer of the scope specifically said that prime focus photography can be done.

As I already said above, the T-adapter is usually not necessary for Newton telescopes. If you remove the 1 1/4" eyepiece adapter you can fit the T-ring directly on the focuser. This allows for the camera to be mounted significantly closer and almost all Newtons with 2" focusers use a T-thread for the 1 1/4" adapter for precisely this reason.

[Hornblower]

As I already said above, the T-adapter is usually not necessary for Newton telescopes. If you remove the 1 1/4" eyepiece adapter you can fit the T-ring directly on the focuser. This allows for the camera to be mounted significantly closer and almost all Newtons with 2" focusers use a T-thread for the 1 1/4" adapter for precisely this reason.

Thanks for the information. That should give ZiggyStardust a good sturdy mount.

[glappkaeft]

It's a really nice scope for photography assuming Ziggy ordered the telescope with the (looks like - standard) EQ-6 mount. I have a 8" Newton on a Celestron CG-6 mount and that's just a little too much scope for that mount (for astrophoto) but the EQ-6 has a load capacity of 25 kg.

[ZiggyStardust]

Unfortunately the EQ6 is just too expensive for me, I ordered an EQ5. EQ6 alone was worth almost as much as the telescope and EQ5.

[glappkaeft]

I have no experience with the EQ-5 and there are several variants (plain, HEQ-5, HEQ-5 Pro, etc) with different characteristics but I suspect you will have problems with wind gusts (I certainly have with my setup). Photography puts much higher demands on the mount than visual use (at a typical ~1 arcsecond/pixel the error margin is slim indeed). There is a rule of thumb that the load capacity for photography is half that of the load capacity for visual use and experienced astrophotographers know that there is no such thing as an overmounted telescope.