RE: [ap-gto] Re: .63 reducer/Cass?


Dec 14, 2005

 


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

#14023 Dec 14, 2005

Would the .63 reducer work on a classical Cassegrain that is a native

f/16? How would it be inserted into the system? It would be coupled to an

ST10/CFW8/Muscle Plate and go into a 2" focuser.



Would it need a specific spacing to the CCD chip to work properly or what?



Thanks,



Mike J. Shade: mshade@...

Director, Sonoita Hills Observatory, Sonoita Arizona

www.sonoitaobservatories.org



See work done at the observatory: c3po.cochise.edu/astro

under the "images & photos" panel on the left of the page



Fight wasteful and obtrusive outdoor nighttime lighting:

International Dark Sky Association: www.darksky.org



"I like the dark, it's cheap." Ebinezer Scrooge



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

#14024 Dec 14, 2005

In a message dated 12/14/2005 8:39:50 AM Central Standard Time,

mshade@... writes:



>

> Would the .63 reducer work on a classical Cassegrain that is a native

> f/16? How would it be inserted into the system? It would be coupled to an

> ST10/CFW8/Muscle Plate and go into a 2" focuser.

>

> Would it need a specific spacing to the CCD chip to work properly or what?

>

> Thanks,

>

> Mike J. Shade: mshade@...

>



We don't make a .63x reducer - that would be a Celestron or Meade product. We

do make a .67x reducer which screws into the 2" nosepiece on the SBIG

cameras. We also make a .75x reducer which is a large optic and requires our 2.7"

focuser attachment. Both of these should work well with an F16 Cassegrain,

assuming that it is well corrected for coma.



Here is an ST10 image taken with the .67x compressor attached to an F14.7

Mak-Cass: voltaire.csun.edu/roland/m51bw.html



Roland Christen





[Non-text portions of this message have been removed]



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

#14025 Dec 14, 2005

Sorry, yes the .67 is what I was referring to...so the spacing to the CCD

chip is not critical?







At 08:33 AM 12/14/2005, you wrote: >In a message dated 12/14/2005 8:39:50 AM Central Standard Time,

>mshade@... writes:

>

>

> >

> > Would the .63 reducer work on a classical Cassegrain that is a native

> > f/16? How would it be inserted into the system? It would be coupled

> to an

> > ST10/CFW8/Muscle Plate and go into a 2" focuser.

> >

> > Would it need a specific spacing to the CCD chip to work properly or what?

> >

> > Thanks,

> >

> > Mike J. Shade: mshade@...

> >

>

>We don't make a .63x reducer - that would be a Celestron or Meade product. We

>do make a .67x reducer which screws into the 2" nosepiece on the SBIG

>cameras. We also make a .75x reducer which is a large optic and requires

>our 2.7"

>focuser attachment. Both of these should work well with an F16 Cassegrain,

>assuming that it is well corrected for coma.

>

>Here is an ST10 image taken with the .67x compressor attached to an F14.7

>Mak-Cass: voltaire.csun.edu/roland/m51bw.html

>

>Roland Christen

>

>

>[Non-text portions of this message have been removed]

>

>

>

>To UNSUBSCRIBE, or for general information on the ap-gto list

>see groups.yahoo.com/group/ap-gto

>Yahoo! Groups Links

>

>

>

>



Mike J. Shade: mshade@...

Director, Sonoita Hills Observatory, Sonoita Arizona

www.sonoitaobservatories.org



See work done at the observatory: c3po.cochise.edu/astro

under the "images & photos" panel on the left of the page



Fight wasteful and obtrusive outdoor nighttime lighting:

International Dark Sky Association: www.darksky.org



"I like the dark, it's cheap." Ebinezer Scrooge



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

#14027 Dec 14, 2005

In a message dated 12/14/2005 10:32:52 AM Central Standard Time,

mshade@... writes:



> Sorry, yes the .67 is what I was referring to...so the spacing to the CCD

> chip is not critical?

>



The spacing only determines the exact power. The lens was designed to go into

the front of the CCD camera nosepiece. The spacing then is what it is for

each individual SBIG camera. They vary slightly from one to another. The

performance will not be affected by different spacings.



M = (304 - S) / 304 where M is the magnification, 304 is the focal length of

the compressor, and S is the spacing.



Roland Christen





[Non-text portions of this message have been removed]



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

#14028 Dec 14, 2005

Hi Roland,

Just curious if you have tried the reducer with a SBIG STL11k? I was

wondering how flat the image would be in the corners.

I usually use the Field Flattener with the STL11k and the images are

excellent in the far corners.

There are two reasons why I would ask this question and want to use

the reducer.

1. The first is to change the FOV to get a slightly larger FOV for

large objects.

2. The second to to remove the distance dependence (set distance from

field flattener to sensor) so that I could use such items as camera

rotator, and auxillary filter wheels in between the camera and the

scope. I don't know of any way to use these devices with the existing

setback distance constraint when using the filed flattener.

Thanks, Rick

--- In ap-gto@yahoogroups.com, chris1011@a... wrote:

>

> In a message dated 12/14/2005 10:32:52 AM Central Standard Time,

> mshade@t... writes:

>

>

> > Sorry, yes the .67 is what I was referring to...so the spacing to

the CCD

> > chip is not critical?

> >

>

> The spacing only determines the exact power. The lens was designed

to go into

> the front of the CCD camera nosepiece. The spacing then is what it

is for

> each individual SBIG camera. They vary slightly from one to

another. The

> performance will not be affected by different spacings.

>

> M = (304 - S) / 304 where M is the magnification, 304 is the focal

length of

> the compressor, and S is the spacing.

>

> Roland Christen

>

>

> [Non-text portions of this message have been removed]

>







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

#14030 Dec 14, 2005

Hi Rick,

Unfortunately, it's very unlikely that the "clear aperture" of

the .67 reducer will allow for use with the STL11000...way too much

obstruction I believe. Wonder what others have to say about this.



Regards,

Randy Nulman





--- In ap-gto@yahoogroups.com, "Rick Wiggins" rickwiggins@e...>

wrote: >

> Hi Roland,

> Just curious if you have tried the reducer with a SBIG STL11k? I

was > wondering how flat the image would be in the corners.

> I usually use the Field Flattener with the STL11k and the images

are > excellent in the far corners.

> There are two reasons why I would ask this question and want to

use > the reducer.

> 1. The first is to change the FOV to get a slightly larger FOV for

> large objects.

> 2. The second to to remove the distance dependence (set distance

from > field flattener to sensor) so that I could use such items as

camera > rotator, and auxillary filter wheels in between the camera and the

> scope. I don't know of any way to use these devices with the

existing > setback distance constraint when using the filed flattener.

> Thanks, Rick

>

> --- In ap-gto@yahoogroups.com, chris1011@a... wrote:

> >

> > In a message dated 12/14/2005 10:32:52 AM Central Standard Time,

> > mshade@t... writes:

> >

> >

> > > Sorry, yes the .67 is what I was referring to...so the spacing

to > the CCD

> > > chip is not critical?

> > >

> >

> > The spacing only determines the exact power. The lens was

designed > to go into

> > the front of the CCD camera nosepiece. The spacing then is what

it > is for

> > each individual SBIG camera. They vary slightly from one to

> another. The

> > performance will not be affected by different spacings.

> >

> > M = (304 - S) / 304 where M is the magnification, 304 is the

focal > length of

> > the compressor, and S is the spacing.

> >

> > Roland Christen

> >

> >

> > [Non-text portions of this message have been removed]

> >

>



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

#14031 Dec 14, 2005

In a message dated 12/14/2005 1:00:47 PM Central Standard Time,

rickwiggins@... writes:



> Hi Roland,

> Just curious if you have tried the reducer with a SBIG STL11k? I was

> wondering how flat the image would be in the corners.

>



Well, the .67x is not flat to the corners because it doesn't cover the

corners. The lens is only 45mm diameter, and at .67 the field size will be .67 x

45mm = 30mm. No two inch compressor will cover the STL11000. It does cover the

ST10 nicely. The larger .75x compressor does cover the STL11000 with good

corrections into the corners. That, of course assumes that the imaging scope is

coma-free. I have taken images with my 160EDF using this telecompressor, and the

star images are quite nice and tight right into the corners. Lots of people

have used this with their RCs to take excellent images. Again, this

telecompressor requires the 2.7" focuser drawtube.



Roland Christen





[Non-text portions of this message have been removed]



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

#14038 Dec 16, 2005

Hi Roland,

Thanks for the response. I figured it might not work, but had to ask.

I have the 4 inch focuser, so I guess there currently is not a

solution for me.

Thanks, Rick

--- In ap-gto@yahoogroups.com, chris1011@a... wrote:

>

> In a message dated 12/14/2005 1:00:47 PM Central Standard Time,

> rickwiggins@e... writes:

>

>

> > Hi Roland,

> > Just curious if you have tried the reducer with a SBIG STL11k? I

was

> > wondering how flat the image would be in the corners.

> >

>

> Well, the .67x is not flat to the corners because it doesn't cover

the

> corners. The lens is only 45mm diameter, and at .67 the field size

will be .67 x

> 45mm = 30mm. No two inch compressor will cover the STL11000. It

does cover the

> ST10 nicely. The larger .75x compressor does cover the STL11000

with good

> corrections into the corners. That, of course assumes that the

imaging scope is

> coma-free. I have taken images with my 160EDF using this

telecompressor, and the

> star images are quite nice and tight right into the corners. Lots

of people

> have used this with their RCs to take excellent images. Again, this

> telecompressor requires the 2.7" focuser drawtube.

>

> Roland Christen

>

>

> [Non-text portions of this message have been removed]

>



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

#14039 Dec 16, 2005

In a message dated 12/16/2005 10:41:21 AM Central Standard Time,

rickwiggins@... writes:



> Thanks for the response. I figured it might not work, but had to ask.

> I have the 4 inch focuser,



I don't know what you mean by "the 4" focuser". If it is one of ours, or one

of the large Feathertouch focusers, then the .75x compressor will certainly

fit nicely.



Roland Christen





[Non-text portions of this message have been removed]







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

#14040 Dec 17, 2005

If it is one of our focusers, use the 4" to 2.7" reducer to simulate the 2.7" drawtube.



Marj Christen

Astro-Physics, Inc

11250 Forest Hills Road

Machesney Park, IL 61115

Phone: 815-282-1513

Fax: 815-282-9847

www.astro-physics.com

Please include this e-mail with your response.





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

From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]On Behalf Of

Rick Wiggins

Sent: Friday, December 16, 2005 10:39 AM

To: ap-gto@yahoogroups.com

Subject: [ap-gto] Re: .63 reducer/Cass?





Hi Roland,

Thanks for the response. I figured it might not work, but had to ask.

I have the 4 inch focuser, so I guess there currently is not a

solution for me.

Thanks, Rick

--- In ap-gto@yahoogroups.com, chris1011@a... wrote:

>

> In a message dated 12/14/2005 1:00:47 PM Central Standard Time,

> rickwiggins@e... writes:

>

>

> > Hi Roland,

> > Just curious if you have tried the reducer with a SBIG STL11k? I

was

> > wondering how flat the image would be in the corners.

> >

>

> Well, the .67x is not flat to the corners because it doesn't cover

the

> corners. The lens is only 45mm diameter, and at .67 the field size

will be .67 x

> 45mm = 30mm. No two inch compressor will cover the STL11000. It

does cover the

> ST10 nicely. The larger .75x compressor does cover the STL11000

with good

> corrections into the corners. That, of course assumes that the

imaging scope is

> coma-free. I have taken images with my 160EDF using this

telecompressor, and the

> star images are quite nice and tight right into the corners. Lots

of people

> have used this with their RCs to take excellent images. Again, this

> telecompressor requires the 2.7" focuser drawtube.

>

> Roland Christen

>

>

> [Non-text portions of this message have been removed]

>













To UNSUBSCRIBE, or for general information on the ap-gto list

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