1.5X Barlow for Planetary camera

[bluesilver]

Hi,  I have been doing a bit of searching around and have yet to really find an answer for this question.

I am trying to find or convert a barlow to get to a 1.5X barlow.

I have read that on a 2X barlow,  you can basically unscrew the bottom of the barlow and screw this into the bottom of an eye piece to give you roughly 1.5X

But is also true for planetary cameras?

I have a f11 scope and the pixel size is 2.9µm which roughly mean that i need a 1.5X Barlow.

Any advice would be appreciated.

Thanks.

 

[CraigT82]

Yes… the less distance between the Barlow lens and the camera sensor the less the power increase of the Barlow lens. Assuming you can actually unscrew the lens and it’s not fixed that is.

I can’t say that screwing a 2x Barlow lens directly onto the nose of a camera will give you exactly 1.5x, as that will depend on the Barlow itself.  You might need to do some experimenting to figure out the power of the Barlow you have when used like this. Otherwise some Barlow manufacturers post charts or formulas to allow you to calculate the power based on the distance between lens and sensor - I know Baader do for their VIP Barlow, perhaps Televue too but I’m not sure. 

 

[vlaiv]

8 hours ago, bluesilver said:

I have a f11 scope and the pixel size is 2.9µm which roughly mean that i need a 1.5X Barlow.

I don't think you really need a barlow at all.

2.9um pixel is optimally sampling 500nm with F/11.6. Even if we go for lowest wavelength of 400nm (although in reality it makes almost no difference as shorter wavelengths are more affected by seeing) - we get F/14.5 - which is still smaller than F/11 * 1.5 = F/16.5

[bluesilver]

Thanks for the replies and advice, I have a few spare one that i can play around with.

I might also just give it a go without the barlow also and see what the results are.

It is not quiet planetary time here yet,  so just getting things organized before hand.

All very much appreciated.