Questions regarding ATM

Hi!

I hope you don’t mind me asking two questions, regarding amateur
telescope making:



1. How... Ineffective or less “good” is a 6 incher from an 8 inch mirror?

[6 Inch with a F/8 ratio, or 8 inch with a F/6 ratio, hence focal length
isn’t significant].

I am aware that there will be an “effective magnification”

drop from 400x to 300x, but I am unsure as to how that may affect
planetary observing? [I know that aperture is more important, but is say,

240x with some knocked off cos of seeing enough?]

I know that brightness and light gathering will be less for DSO and
planets, but how significant is this? [I.e. 6 inch vs. 8 inch, how much
would I lose? Cos I was gonna make a 8'' but the cost seemed too high for

me, so how sufficient is a 6''? ]



I am also aware that light-gathering and brightness would be reduced in
the 6 inch, but for a first telescope making attempt, is a 6 inch, f/8
too small or insignificant for observing of the cosmos? [Would one be
able to see clouds on Jupiter [small, of course, not like Voyager! ] and

Saturn’s ring(s)]? N.B. I am aware that DSO won’t be in colour or like
pics in books etc. cos of the human retina etc., just wondering how a
planet would look like through a 6 incher].



2. Secondly, I have heard folks comment [and the FAQ!] that making one's
own mirror for cost isn't a good reason for small uns.

Well, I did some comparisons, and found a 6 incher mirror would
cost about £150 to buy, whilst to make it would cost:

£~75 [incl. p+p], including £23 for aluminising + p/p,

£23 for a mirror "kit" [pitch, grit etc.], and £33 for blank incl. p+p+,
roughly]



Well, putting aside labour costs, it seems there is a significant saving?

[If I made an 8 inch one, it would be £40 more tho.]

Have I missed something out significant here in the mirror making
stuff? I know that I'm missing the Tool, but would one be able to make
one cheaply at home?


Any advice would be much appreciated.



Thanks in advance.

#MK.

On Thu, 03 Jul 2003 16:20:17 GMT, in uk.sci.astronomy , #MK
wrote:

Hi!

I hope you don’t mind me asking two questions, regarding amateur
telescope making:



1. How... Ineffective or less “good” is a 6 incher from an 8 inch mirror?

the 8" will gather 64/36 times more light
any flaws in the grinding will be 64/36ths more noticeable.

[6 Inch with a F/8 ratio, or 8 inch with a F/6 ratio, hence focal length
isn’t significant].

the shorter focal length will show a little more aberration I believe.


--
Mark McIntyre
CLC FAQ http://www.eskimo.com/~scs/C-faq/top.html
CLC readme: http://www.angelfire.com/ms3/bchambless0/welcome_to_clc.html


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On Thu, 03 Jul 2003 16:20:17 GMT, in uk.sci.astronomy , #MK
wrote:

Hi!

I hope you don’t mind me asking two questions, regarding amateur
telescope making:



1. How... Ineffective or less “good” is a 6 incher from an 8 inch mirror?

the 8" will gather 64/36 times more light
any flaws in the grinding will be 64/36ths more noticeable.

[6 Inch with a F/8 ratio, or 8 inch with a F/6 ratio, hence focal length
isn’t significant].

the shorter focal length will show a little more aberration I believe.


--
Mark McIntyre
CLC FAQ http://www.eskimo.com/~scs/C-faq/top.html
CLC readme: http://www.angelfire.com/ms3/bchambless0/welcome_to_clc.html


----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

Where is a good place for looking into purchasing kits / elements for a
home made telescope?

I'm interested in building one myself (ex-student you see)

What is the general cost of building a telescope yourself?

Cheers

Kevin Jenner

In message , #MK
writes
Hi!

I hope you don’t mind me asking two questions, regarding amateur
telescope making:



1. How... Ineffective or less “good� is a 6 incher from an 8 inch mirror?

[6 Inch with a F/8 ratio, or 8 inch with a F/6 ratio, hence focal length
isn’t significant].

I am aware that there will be an “effective magnification�

drop from 400x to 300x, but I am unsure as to how that may affect
planetary observing? [I know that aperture is more important, but is say,

240x with some knocked off cos of seeing enough?]

I know that brightness and light gathering will be less for DSO and
planets, but how significant is this? [I.e. 6 inch vs. 8 inch, how much
would I lose? Cos I was gonna make a 8'' but the cost seemed too high for

me, so how sufficient is a 6''? ]



I am also aware that light-gathering and brightness would be reduced in
the 6 inch, but for a first telescope making attempt, is a 6 inch, f/8
too small or insignificant for observing of the cosmos? [Would one be
able to see clouds on Jupiter [small, of course, not like Voyager! ] and

Saturn’s ring(s)]? N.B. I am aware that DSO won’t be in colour or like
pics in books etc. cos of the human retina etc., just wondering how a
planet would look like through a 6 incher].



2. Secondly, I have heard folks comment [and the FAQ!] that making one's
own mirror for cost isn't a good reason for small uns.

Well, I did some comparisons, and found a 6 incher mirror would
cost about £150 to buy, whilst to make it would cost:

£~75 [incl. p+p], including £23 for aluminising + p/p,

£23 for a mirror "kit" [pitch, grit etc.], and £33 for blank incl. p+p+,
roughly]



Well, putting aside labour costs, it seems there is a significant saving?

[If I made an 8 inch one, it would be £40 more tho.]

Have I missed something out significant here in the mirror making
stuff? I know that I'm missing the Tool, but would one be able to make
one cheaply at home?


Any advice would be much appreciated.



Thanks in advance.

#MK.





--
Kevin Jenner

Kevin Jenner wrote:
Where is a good place for looking into purchasing kits / elements for a
home made telescope?

I'm interested in building one myself (ex-student you see)

What is the general cost of building a telescope yourself?


All the info you may need is linked to from:
http://astunit.com/tonkinsastro/atm/beginner.htm

Best,
Stephen

--
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books +
+ (N51.162 E0.995) | http://www.astunit.com +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Kevin Jenner wrote:
Where is a good place for looking into purchasing kits / elements for a
home made telescope?

I'm interested in building one myself (ex-student you see)

What is the general cost of building a telescope yourself?


All the info you may need is linked to from:
http://astunit.com/tonkinsastro/atm/beginner.htm

Best,
Stephen

--
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books +
+ (N51.162 E0.995) | http://www.astunit.com +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Where is a good place for looking into purchasing kits / elements for a
home made telescope?

I'm interested in building one myself (ex-student you see)

What is the general cost of building a telescope yourself?

Cheers

Kevin Jenner

In message , #MK
writes
Hi!

I hope you don’t mind me asking two questions, regarding amateur
telescope making:



1. How... Ineffective or less “good� is a 6 incher from an 8 inch mirror?

[6 Inch with a F/8 ratio, or 8 inch with a F/6 ratio, hence focal length
isn’t significant].

I am aware that there will be an “effective magnification�

drop from 400x to 300x, but I am unsure as to how that may affect
planetary observing? [I know that aperture is more important, but is say,

240x with some knocked off cos of seeing enough?]

I know that brightness and light gathering will be less for DSO and
planets, but how significant is this? [I.e. 6 inch vs. 8 inch, how much
would I lose? Cos I was gonna make a 8'' but the cost seemed too high for

me, so how sufficient is a 6''? ]



I am also aware that light-gathering and brightness would be reduced in
the 6 inch, but for a first telescope making attempt, is a 6 inch, f/8
too small or insignificant for observing of the cosmos? [Would one be
able to see clouds on Jupiter [small, of course, not like Voyager! ] and

Saturn’s ring(s)]? N.B. I am aware that DSO won’t be in colour or like
pics in books etc. cos of the human retina etc., just wondering how a
planet would look like through a 6 incher].



2. Secondly, I have heard folks comment [and the FAQ!] that making one's
own mirror for cost isn't a good reason for small uns.

Well, I did some comparisons, and found a 6 incher mirror would
cost about £150 to buy, whilst to make it would cost:

£~75 [incl. p+p], including £23 for aluminising + p/p,

£23 for a mirror "kit" [pitch, grit etc.], and £33 for blank incl. p+p+,
roughly]



Well, putting aside labour costs, it seems there is a significant saving?

[If I made an 8 inch one, it would be £40 more tho.]

Have I missed something out significant here in the mirror making
stuff? I know that I'm missing the Tool, but would one be able to make
one cheaply at home?


Any advice would be much appreciated.



Thanks in advance.

#MK.





--
Kevin Jenner

http://www.dhinds.co.uk/frames.html

6" mirror £40
in "for sale- used products"

Colin Smith

Somerset
Telephone: 01458 440366
E-Mail:
Mobile No: 07860 825942

Price: £ 40





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http://www.dhinds.co.uk/frames.html

6" mirror £40
in "for sale- used products"

Colin Smith

Somerset
Telephone: 01458 440366
E-Mail:
Mobile No: 07860 825942

Price: £ 40





---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.496 / Virus Database: 295 - Release Date: 03/07/2003