RE: [APML] 35 mm Camera & Focuser

["Serge Theberge" <serge.theberge@wti.on.ca>]

Hi Stuart,

You might want to consider the STI Stiletto Series IV for the Nikon.  You
get both the knife edge and a 300-line Ronchi screen.  Very easy to use and
if the calibration is not perfect, it is easy to refine the calibration.

Serge

-----Original Message-----
From: astro-photo-bounces@seds.org [mailto:astro-photo-bounces@seds.org] On
Behalf Of Stuart Heggie
Sent: Saturday, December 13, 2003 8:36 AM
To: Discussion of Film Astrophotography
Subject: Re: [APML] 35 mm Camera & Focuser


Bradley, thanks for this. I actually have a DW-2 and it is GREAT for
composition / framing but it is not so easy to focus with (and not
recommended for this by experts I'd read so far). The trick with the DW-2 is
you have too many variables first of all and its focus is very dependent on
your angle of view so stuff swims in and out of focus as you move your head
- not so easy. I sense from what I've read that the most success seems to
come from people who are putting an eyepiece or loupe on the focus screen
directly and studying the tightness of the star's image on the matte portion
of the screen. I think!

For my camera lenses, I put a two-hole mask over the objective and then took
a series of 30 second shots, recording the focus position at each shot and
slowly stepped through the range on each side of infinity and found critical
focus for the lenses that way. With prime focus, you have no way to lock the
scope down permanently (unless you never plan to look through it I guess).

PS - don't be surprised if those DW-2's go for a lot more by the time the
auction closes - they are fetching upwards of $200 typically.

Stuart
----- Original Message -----
From: "Bradley Hope" <bradley@thorngarden.net>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Saturday, December 13, 2003 7:28 AM
Subject: Re: [APML] 35 mm Camera & Focuser


> ----- Original Message -----
> From: "Stuart Heggie" <stuart.j.heggie@sympatico.ca>
> To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
> Sent: Saturday, December 13, 2003 3:04 AM
> Subject: Re: [APML] 35 mm Camera & Focuser
>
>
> > John, for those of us with cameras with removable pentaprisms, would
this
> > thing plunked directly down onto the focus screen work? I'm still
shooting
> > piggyback so I've focussed using the the Hartmann mask technique but
when
> I
> > finally make the jump to prime focus, I think I'll need something 
> > better than what I've got.
> >
> > Anyone else, I've got two Nikon F2's so if there is another means 
> > that
> works
> > for sure on this camera, I'd love to know it - mostly what I read is
that
> I
> > buy a loupe and file it down to fit into the top of the camera and 
> > rest
on
> > the focus screen - if I get one that is adjustable, is that better 
> > so
that
> I
> > don't have to fine tune the filing job for height?
> >
> > Stuart
>
>
> Stuart;
>
> I would suggest the Nikon DW-2 finder. It's 6X and has an adjustable
focus,
> full frame viewing of the focus screen. There are a couple available 
> on Ebay, both ending today, currently $27.50 and $99.00. There's 
> nothing
wrong
> with the one for $27.50 except it's missing the name plate.
>
>
http://search.ebay.com/search/search.dll?query=dw+2&catref=C3&socolumnlayout
=3&lotr=1&from=R2&sacategory=625&BasicSearch=
>
> Bradley
>
> _______________________________________________
> Astro-Photo mailing list
> Astro-Photo@seds.org http://seds.org/mailman/listinfo/astro-photo
>

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