FRC/BRC vs. Mewlon

[astrotom]

I know the FRCs/BRCs are designed for photography and the Mewlons are more for visual use but I've never understood why. Can someone explain this? More to the point, if put an eyepiece on an FRC/BRC, what would be the drawbacks?

Thanks!

[BT Technologies]

Other than being two different designs the RC lends iteself to be primarly designed to offer a large FLAT field that and a large image circle that can cover a huge ccd or film plane. This design uses a HUGE secondary which usually close to 50 percent obstructed which makes this instrument not ideal for visual use.

The Mewlon is a Dal Kirkham optical design so this instrument can be used for both visually and for imaging. The Mewlon does not have as flat as an image as a RC based design nor is the image circle anywhere near as large as the RC primarly due to the smaller secondary in the Mewlon.

Originally Posted by astrotom

I know the FRCs/BRCs are designed for photography and the Mewlons are more for visual use but I've never understood why. Can someone explain this? More to the point, if put an eyepiece on an FRC/BRC, what would be the drawbacks?

Thanks!

[astrotom]

Yes, I've heard that a large secondary is part of the FRC/BRC design. But, never having used an FRC/BRC or any RC, how does this affect visual use? So, if I were to test a set ep's on an FRC/BRC, what will the drawbacks be in comparison to a Mewlon?

Thanks!

Tom

[BT Technologies]

The biggest problem you would have would be to try to find the right size eyepeice that would work with the FRC/BRC scope. Due to the large size of the secondary you would need to use an eyepiece that would not interfere with the size of your pupil!! With most eyepieces you would get that "hole in the middle" look as you viewed through the eyepiece.

If you were able to find an eyepiece that you found acceptable the next hurdle would be the limited amount of contrast you would get with this scope. Again, since the secondary obstruction is so large using this scope on the planets for example would not yield as asthetically pleasing a view as through an instrument with a much smaller secondary obstruction.

The Mewlon series scopes were designed for visual use and can be used for imaging as well. The RC series scopes were desgined for imaging use and little thought was put into using these scopes visually because very few people if any would use them in that capacity.

Originally Posted by astrotom

Yes, I've heard that a large secondary is part of the FRC/BRC design. But, never having used an FRC/BRC or any RC, how does this affect visual use? So, if I were to test a set ep's on an FRC/BRC, what will the drawbacks be in comparison to a Mewlon?

Thanks!

Tom

[astrotom]

Brian,

Thanks for your excellent help -- I understand now! Is Tak still making Mewlon 300's? I haven't seen one listed for sale for a long time.

Tom

[BT Technologies]

We have several of the Mewlon 300 scopes on order but Takahashi is very slow in producing them. We might see 2-3 M-300's a year and that is when Takahahsi is moving fast!!

Originally Posted by astrotom

Brian,

Thanks for your excellent help -- I understand now! Is Tak still making Mewlon 300's? I haven't seen one listed for sale for a long time.

Tom