Dumb question (possibly..) regarding focusing DSLR with 80ED

[Jarndyce]

Well, I succumbed to temptation - an 80ED for a little over £200 from the nice people at FLO was just too much, and it arrived today.

Thrilled with it, however, when I fit my Nikon onto the T-ring in place of an EP, and try to focus on a distant object, the focus tube is almost completely extended - almost drops off the rack, and then will only just reach focus.

Now I haven't tried it on anything in the sky - cloud cover has knocked that on the head - only chimney pots around 100M away, so this may be a factor.

Am I being really dumb, or do I need to add some sort of extension tube?

Anyone else use a DLSR with an ED80 and have similar issues?

[George]

You will need one of these

BTW there's no such thing as a dumb question, we have all asked these questions at one time or another

[EA2007]

I just asked this question in the 'Equipment Help' section..........I might need an extender for my Olympus E-400.

[Jarndyce]

Aha!

Cheers George.

I'll give FLO a call tomorrow.

50 or 80mm?

I take it that these extension tubes replace the 1 1/4" EP adaptor and they are threaded to take a T ring?

[George]

80mm is what I use with my DSLR and ED80

You wont need the diagonal but you will need a 2'' nosepiece that fits into the 80mm extension tube.

[Jarndyce]

Cheers George.

Just so I'm completely clear, when you say '2" nosepiece', do you mean the EP adaptor that steps down from 2" to 1.25"?

This is the bit supplied with the 80ED that is threaded for the T ring.

Can this be fitted into the extension tube?

Obviously, I won't use the diagonal.

[George]

This is what you need to fit into the 2'' extension tube, using the 1.5'' will induce vignetting as its not big enough for the FOV of the dslr.

[jgs001]

There are 2 ways to do this... One is to use a normal 1.25" nosepiece on the T thread and fit it into the 2' to 1.25" adapter. Oddly the t thread fitting just won't quite reach focus. The extra distance of the 1.25" nosepiece works perfectly. The other choice is to remove the 2" to 1.25" adapter and use a 2" extension tube and either a t thread and 2" nosepiece of one of the MaxDSLR adatpers. I was unable to reach focus with a 50mm extention tube and the 2" to 1.25" adapter fitter. Of the two choices, I'd suggest the second one, as this will allow a wider light path to the camera and reduce vignetting.

[Jarndyce]

Thank you very much guys. You are both patient and knowledgeable.

I think you're both saying the same thing. Sorry to appear dumb - "nosepiece" is not a term I'm familiar with...

So I remove the 1.25 EP adaptor.

Fit the 80mm focus extension tube.

Add the 2" T mount camera adaptor to the extension tube (not sure how - is it threaded?)

Fit my T ring to the adaptor.

My Nikon will then fit the T ring, achieve focus and no vignetting...

[jgs001]

The nosepiece (might be using the wrong term ) is the bit that is fitted into the diagonal or the 1.25" adapter.

I'd suggest this fitting (check the fitting screws are tight, I read somewhere that they worked lose the the t thread seperated from the body) and the 50mm extention tube. This is the combination I'm using with my C80ED. I'm not sure the 2" fittings remove all vignetting, but it's a lot better than using 1.25" fittings.

[Jarndyce]

Thanks John.

The Max DSLR adaptor looks good.

One last question: is it screwed into the 50mm extension tube? It's not clear from the photos.

[jgs001]

Nope, the 2 inch nosepiece bit (not the Nikon attachment) fits into the extention tube and it's clamped with thumb srews... Give me five minutes... and I'll post a piccy or three

[jgs001]

As promised... Here you go. The Tube I have has a brass compression ring with a single thumbscrew fitting.

The 50mm ext tube and the MaxDSLR seperately

Aligned as they would be used

And fitted together

[Jarndyce]

John, you are the man, as they say.

A picture's worth a thousand words.

The photo of the adaptors on FLO doesn't show the thumbscrews, though it does mention the compression ring.

This is now crystal clear.

Thanks for that. From previous posts, I'm not the only one asking this question, so I think your pics will be most helpful.

Thanks again!

[jgs001]

You're welcome. I actually keep a Skywatcher 2" LP filter on the MaxDSLR adapter, but leave them off the scope when not in use. I put the diagonal back in after an SLR imaging session (I can point the eyepiece hole of the diagonal downwards, with the objective also pointing downwards and uncap both ends, allowing any dewing to clear and with them pointing down, minimising the liklihood of things getting into the OTA. Not foolproof but it works.

[tinvek]

one other option since you've already tried fitting your tring to the thread on the focusser is to use a t thread extension either http://firstlightoptics.com/proddetail.php?prod=AEexttubeset

or

http://firstlightoptics.com/proddetail.php?prod=BaaderT2ext

i use the first as it gives me a bit of flexability on length and just leave the exension screwed to my t ring and then screw the whole lot on when i want to attach the dslr