50mm finder, filter mod

[Moonshane]

Yet another innovative use for the ever popular Baader fine tuning ring!

I have been meaning to do this mod for ages and on a whim did it just now. The only refractor that has a permanent place in my heart and my kit boxes is the humble 9x50mm right angle correct image finder. This mod works (I presume) with any 50mm finder.

Whilst I love my three scopes, their Achilles heel is that they give a really narrow field compared with those short tube fracs that people keep banging on to me about Talk of lovely wide field views with the whole Veil system and North America Nebula / Pelican in the field made me think of a way I could do the same thing.

I therefore struck upon the idea of using a 14mm Baader fine tuning ring (FTR) and gluing this into the end of my 50mm finder. I could then add any of my 2" filters to the finder for ultrawide (5 degree or so) fields where I could hopefully see these targets from dark sites.

Here's a few pics which show what I did. I used araldite (or similar) and happened to have a spare 2" eyepiece cover so that helped. There's no weight being held really so I doubt the glue will be stressed at all and the field of the finder seems unaffected.

Hope this is a useful mod for others.

[John]

Nice idea Shane - I'll give that a try

[Moonshane]

cheers John

I cannot see why it won't work, especially from better skies than at home. at a cost of nil (I had all the bits) it's worth a shot!

[Moonshane]

well, it works. I think........I had been out under clear skies for maybe one minute when the clouds rolled in. must be a record.

even though I was straight out from a lit room, I am sure I could seen nebulosity in the Veil area. once adapted and in better skies this could be a winner!

[estwing]

fantastic! Shane very clever....

[Moonshane]

ha ha cheers Calv.

must avoid the fracs somehow

[John]

I manged to see the eastern Veil with 15x70 binoculars on really good night last summer and that was without a filter so I reckon 50mm of low power aperture with an O-III should do it.

[TwoPi]

As I said in the other thread Shane, great idea. At some point I will try this too.

[nicks90]

it will be interesting to see what the true fov will be with this finder now - any chance you could post up the results if we ever get a clear night?

my 70mm widefield frac is just a touch too heavy to use as a finder on my new dob, which is a shame cos it was brilliant on my eq mounted newt - 10x70 finder with 4.7deg Tfov is a lovely thing, but if your mod gets close enough then i'll be giving this a stab.

[Stu]

I'm in the middle of putting together an 80mm mega finder :-). Having decided that the 20 x 80 binos I put together from parts very cheaply are unlikely to get used much, I've taken them apart and am using one objective as part of a finder. I currently have a 45 degree erecting prism so can fit 1.25" eps in it and am in the lookout for a 90 degree to make it easier to use. I have an Orion Ultrablock filter and SW OIII which I can try out in it, should be handy and will post up when I've finished it.

Stu

[Moonshane]

cool. I had a bit of a go last night and I think the aperture is just a little small from home. the field is approx 5 degrees though so it's a nice wide vista. I am hopeful from darker skies it will be better but I'll certainly report back when I have had more of a chance. neighbours constantly turning on lights does not help!