Re: [tec-scopes] Re: TEC 140 flat field


Jul 20, 2004

 


----------------------------

#5128 Jul 20, 2004

For comparison, I clipped two corners from two of my images: one

taken at native F/7, and the other at F/5.6 with the AP reducer and

ST10.



You can see the difference here (both images enlarged 4x):



pk.darkhorizons.org/images/tips/TEC140coma.jpg



Regards,



-Paul

--- In tec-scopes@yahoogroups.com, "Paul K" paul@p...> wrote:

> Hi Steve,

>

> I don't use a digital SLR, but my ST10 ccd chip is already slightly

> too big for the flat field of the TEC140: the stars at the edges

are

> just starting to show a very slight coma. The detector size is

> 10x15mm, so anything larger than that will likely show a lot more

> distortion at the edges without a FF. I believe the 300D has chip

> size of 23x15mm, so I think you'll really want a FF with it.

>

> I've recently been using ST10 with the AP 0.75x reducer, and it

seems

> to completely correct the coma at all the different compression

> ratios I've tried so far. Don't really know if it'll correct a much

> larger chip than 10x15mm, though...

>

> Regards,

>

> -Paul

>

>

>

>

>

>

> --- In tec-scopes@yahoogroups.com, "sryde2000" sryde@o...> wrote:

> > Hi,

> >

> > Has anyone out there been using their TEC 140 with a digital SLR?

> In

> > particular, a Canon digital SLR?

> >

> > Also, a question for Yuri:

> >

> > With the 6 megapixcel and bigger digital SLR cameras coming on

> line,

> > do you need to use the field flattener with the TEC 140 or is it

> > more for larger format film cameras?

> >

> > Cheers,

> >

> > Steve



----------------------------

#5134 Jul 21, 2004

Thanks Paul,



Most interesting!



Steve

----- Original Message -----

From: "Paul K" paul@...>

To: tec-scopes@yahoogroups.com>

Sent: Wednesday, July 21, 2004 12:30 AM

Subject: [tec-scopes] Re: TEC 140 flat field





> For comparison, I clipped two corners from two of my images: one

> taken at native F/7, and the other at F/5.6 with the AP reducer and

> ST10.

>

> You can see the difference here (both images enlarged 4x):

>

> pk.darkhorizons.org/images/tips/TEC140coma.jpg

>

> Regards,

>

> -Paul

>

> --- In tec-scopes@yahoogroups.com, "Paul K" paul@p...> wrote:

> > Hi Steve,

> >

> > I don't use a digital SLR, but my ST10 ccd chip is already slightly

> > too big for the flat field of the TEC140: the stars at the edges

> are

> > just starting to show a very slight coma. The detector size is

> > 10x15mm, so anything larger than that will likely show a lot more

> > distortion at the edges without a FF. I believe the 300D has chip

> > size of 23x15mm, so I think you'll really want a FF with it.

> >

> > I've recently been using ST10 with the AP 0.75x reducer, and it

> seems

> > to completely correct the coma at all the different compression

> > ratios I've tried so far. Don't really know if it'll correct a much

> > larger chip than 10x15mm, though...

> >

> > Regards,

> >

> > -Paul

> >

> >

> >

> >

> >

> >

> > --- In tec-scopes@yahoogroups.com, "sryde2000" sryde@o...> wrote:

> > > Hi,

> > >

> > > Has anyone out there been using their TEC 140 with a digital SLR?

> > In

> > > particular, a Canon digital SLR?

> > >

> > > Also, a question for Yuri:

> > >

> > > With the 6 megapixcel and bigger digital SLR cameras coming on

> > line,

> > > do you need to use the field flattener with the TEC 140 or is it

> > > more for larger format film cameras?

> > >

> > > Cheers,

> > >

> > > Steve

>

>

>

>

>

> Yahoo! Groups Links

>

>

>

>

>

>

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>

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>

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