[APML]: Takahashi 4" f8 astrophotos?

[Space Boy <astro@cu-online.com>]

The Astro-Photography Mailing List
------------------------------------

I need some references to websites, where there are star-photos taken
with Takahashi 4" f8 @prime-focus.  Preferably the (older) FC100, or the
newer FS102 model.

  I know their reducer (.75x?) works well (pinpoint stars to the edge of
the 35mm frame).  There were some Italians who used this (600mm f6), &
arguably had the best Hale-Bopp photos during Feb. 97 day-in-day-out (as
seen on JPL's Hale-Bopp page).

  Ed Sczepanski claims his 4" f8 (prime focus?) has given him the best
astrophotos he's ever taken.  (Gene Horr corroborates this)  Apparently,
he has done this on medium-format using Mamiya 645.  Q: is the
prime-focus image flat-field?  (i.e., NO field-flattener is required?)
George Greaney originally did his medium-format work with the Tak 5" f8
(great images), before moving up to the AP 6" f7.

  I have a custom-made P6x7 adapter for the Tak 5" f8 focuser.  It won't
fit my 4" f8 FC100 focuser, so I would have to machine an adapter (or
can I buy this off-the-shelf?).  But, I have another P6x7 adapter which
has a 2" accessory adapter (it will fit into the Televue 2" accessory
holder, that now sits in my FC100 2.7" focuser).  However, this wouldn't
give me the *absolute* maximum 50-56mm image circle that is possible, or
am I "splitting hairs"?

  Another Q:  I can insert my 2" AP camera-adapter (which is kinda
longish ~2") into the Televue 2" accessory holder (on the rear of the
FC100 focuser).  I bet this combination causes some vignetting, as
opposed to using Takahashi's camera-angle-adjuster attached *directly*
to the FC100 2.7" focuser?  I suppose I should just try it & see what
happens.


Space Boy

PS

What is the "list price" for the Takahashi .75 reducer &
camera-angle-adjuster?  So, I can find a used one at a decent price.  


Gene Horr wrote:
> Ian Turner wrote:
> 
> > 2. One other comment I have been testing a new FS 102 Tak scope I
> > picked up on a trade is anyone on this list using one for wide field
> > work?
> 
> Ian:
> 
> I've owned one for a couple of years and have recently started
> using it again.  Overall it is a very nice instrument and
> produces very good images.  Ed Szczepanski produces fantastic
> wide field work with his.
> 
> The largest negative is that with the f/5.9 reducer/corrector it
> only produces a ~50mm image circle.  It will not fully illuminate
> a medium-format frame.
> 
> The reducer/corrector and the camera angle adjuster are two highly
> recommended accessories.  The camera angle adjuster in particular
> if you are shooting 35mm.  It allows camera rotation with zero
> focus shift.
> 
> Wide-mount adapters are no longer made by Takahashi for the Tak
> threading.  To maintain thread-to-thread attachment for medium
> format cameras will require either finding a used one or
> fabricating your own.
> 
> I have mixed feelings about the Tak tube holder.  It looks a
> little flimsy to me, although I must admit that I have never
> seen any detectable flexure in the setup.  I still use it,
> however, becuase I have bolted a Losmandy plate to the top
> for the guidescope.  It is easier/lighter than the Losmandy
> double saddle.
> 

LATTANZI, Max wrote:
> 
> Richard
> 
> I basically agree with the comments expressed hereunder.
> 
> One further info: I made an adapter to put my Hasselbad behind the FS-102.
> The field covered is 67mm without the reducer/flattener and some 65mm with
> the R/F.
> 
> The focuser is definitely smoother than AP one (actually is the best focuser
> I have ever used)
> but I would not say that AP is less solid.
> 
> You won't go wrong with either one!
> 
> Hope it helps!
> 
> Max
> 
> > The Takahashi's flourite coated elements do transmit more light
> > than a corresponding AP.  This is why visually they look better:
> > the visual image is brighter with more apparent contrast.
> > Photographically, however, as far as I can tell the performance
> > is identical.  I have never owned an AP refractor but have
> > spent some time viewing through various models and have had
> > chances to spend some time examining photographs taken through
> > two different models.   The focusers and adapters for the
> > Takahashis are (IMO) more solid and the whole system is
> > designed primarily for photography.  This is about the only
> > area where I think Takahashi has an edge over AP.
> >
> >Gene Horr