Hi yu Ken,
Its a knife edge focuser.....
Makes focusing for imaging easy.....thats the theory anyway!!
you substitute the camera you use for imaging with this unit....you focus up using special screens, then take it off and put the camera back.....and away you go!!
In the 'swap in, swap out' video he is pretty rough with it. I wonder if it still kept focus after he took it out. The focuser seemed to move a fair bit!
yep I have one for the pentax, tried to use it once and I had no idea whether or not I was using it right. been in the box ever since. Now I use the canon most of the time maybe I should get the adapter for that??????
Good news - it works! I use mine for the Pentax *ist DS DSLR. Care is required when mounting the stiletto, then uncoupling it and replacing it with the DSLR. All adapters, couplings, focusers, etc much be tight or locked to avoid any play or movement, otherwise there is the potential to disturb the precise focus position.
Every time I have thought that I had a precise focus using just my eyeballs through the viewfinder of the Pentax, the stiletto has always proved me wrong when I fitted it, delivering a sharp, focused image.
I did have a problem once when I used a cheap T2 ring and it wobbled in the stiletto which is useless - it should be firmly engaged.
I went the cheap and versatile option. A long time ago I had a 201xt autoguider that I couldnt get to decent focus for autoguiding. I bought the ronchi screen focuser for the 201xt and guess what it worked perfectly first time right out of the box, but then I did something sneaky. You can use it to test your opticss like any ronchi screen and with an eyepiece parfocal ring set it up for your DSLR. I found perfect focus for my dslr, then used the parfocal ring on the ronchi focuser to get the correct spacing. Now it takes 10 sec to get perfect , repeatable focus for the dslr.
A very neat looking gadget Harb and it works with a DSI as well.
Hmmmm thinking how I can sneak it past the wife and then say it's been there all the time. Nope I'd never get away with it.
If it's not personal, how many children did have to sell to buy that.
Auctually was about $500AU I think..........I have a hopless memory.....
It has 2 adaptors one for Nikon Mount stuff and one for The DSI, but they have them for everthing.
This is the delux version with the box etc....
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Very tempting for my film cameras 
Nope I'd never get away with it.
