aperature stop

fizzy123 · Post by **fizzy123** » Sat Feb 21, 2004 7:48 pm

When I was separating my department store scope one day, I noticed a disc at the center of scope, is it a aperature stop? If I remove it does it affect image quality.

:roll:

Post by **Airconvent** » Sat Feb 21, 2004 9:58 pm

fizzy123 wrote: When I was separating my department store scope one day, I noticed a disc at the center of scope, is it a aperature stop? If I remove it does it affect image quality. :roll:

can you elaborate? what scope do you have?
I'm assuming you bought a Toys R Us Newtonian..if that's the case, then the disc is your secondary mirror and that's needed!
Else I cannot think why a refractor will have such a disc...

rich

fizzy123 · Post by **fizzy123** » Sun Feb 22, 2004 9:13 am

It is a refractor. The disc is located in the miidle of the tube.

ChaosKnight · Post by **ChaosKnight** » Mon Feb 23, 2004 8:25 pm

Sounds like a baffle to me......

Post by **Airconvent** » Tue Feb 24, 2004 2:23 am

ChaosKnight wrote:Sounds like a baffle to me......

that's what I thought so too but he said "disk"...so does not seem likely...
baffles are located along the length of the scope with an opening in the centre.
also, dept store scopes will not be so good as to have baffles...!

rich

harlequin2902 · Post by **harlequin2902** » Tue Feb 24, 2004 2:28 am

Hm, yup. I think it might be a baffle. My very first Tasco 60mm had one somewhere in the middle of the tube too. In this case, you should leave it alone because some manufacturers of department store scopes use baffles to help reduce the effective size of the objective and this is meant to conceal the true nature of the (already) poor optics.

Did your Refractor come with a finderscope ? If it did, the finderscope would probably have a baffle inside also. If it's easily removable, try removing it and compare the before / after views of a lighted street lamp at night through the finderscope. You should be able to detect a degrading of the image quality with the baffle removed. The same would likely apply to your scope itself.

ChaosKnight · Post by **ChaosKnight** » Tue Feb 24, 2004 6:08 pm

Airconvent wrote:
ChaosKnight wrote:Sounds like a baffle to me......
that's what I thought so too but he said "disk"...so does not seem likely...
baffles are located along the length of the scope with an opening in the centre.
also, dept store scopes will not be so good as to have baffles...!

rich

Well.....certain discs like compact discs have a hole in the middle too.... 8)

Post by **weixing** » Tue Feb 24, 2004 10:23 pm

Hi,
I have check my department store scope before I give it to someone else. I also notice a disc in the middle of the scope tube and I think that it act as a baffles to block out stray light.

Have a nice day.

Post by **Airconvent** » Wed Feb 25, 2004 12:13 am

weixing wrote:Hi,
I have check my department store scope before I give it to someone else. I also notice a disc in the middle of the scope tube and I think that it act as a baffles to block out stray light.

Have a nice day.

Hi Weixing,
As I have mentioned, some discs with holes would be more correct for removing stray light or maybe even flocking but a disc in the centre?
Would it not behave like a newtonian with central obstruction, and hence, lesser contrast?

rich

Post by **weixing** » Wed Feb 25, 2004 1:14 am

Hi,

Would it not behave like a newtonian with central obstruction, and hence, lesser contrast?

To stop the confusion, it is actaully a disc with a big hole in the center. The hole is around the size of the scope aperture, so it won't block the lens.

Have a nice day.

SingAstro

aperature stop

aperature stop

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