Strongest practial Barlow lens for 8" SCT (e.g., x5?)

[Sedna]

I have a Celestron 8SE (8" SCT) and am wondering what the strongest practical Barlow lens is that can be used with my scope? I already have a 2x but recently saw a 5x on Amazon and wondered if this is worth buying? Or is it too powerful? Thanks! 

[knobby]

The 8se is 2000mm focal length, wouldn't really use a Barlow as it's already high mag, unless planetary imaging or you have poor eye relief maybe.

What eyepieces do you have ?

[John]

Is this for visual observing or for planetary imaging ?

For visual observing even a 2x barlow is not going to be much use with a scope that is already 2000mm in focal length.

 

[Sedna]

This would be for planetary imaging. I already have 32 mm, 25 mm, 17 mm, 13 mm, 8 mm, and 6 mm eyepieces.

[Merlin66]

For visual it would be of limited use....

If you consider imaging - lunar/ planets the optimum focal ratio is x5 the pixel size in micron.

For a typical small CMOS with say 3micron pixels, this infers f15, a x2 barlow on the f10 C8 is almost overkill.

The x5 barlow would be of more use on a f4 or f5 scope.

Just my 2c.

 

[Ibbo!]

For imaging I have used my x5 successfully about 3 times in the 10 years I have had it.

 

The x2.5 powermate is my normal plan of attack on planets but this year from home I have not had much sucess as the planets have been so low.

[Ruud]

https://starizona.com/tutorial/planetary-imaging/ suggests an image scale of 0.1 to 0.25 arcseconds per pixel. 

[Demonperformer]

As you increase magnification the image gets bigger (obviously) and fainter (double the magnification = 1/4 the brightness). As a consequence you end up having to use longer exposures which increases "blurriness" as you are capturing more atmospheric movement - the very thing you are trying to avoid. With my 8SE, I had a 2x barlow (which worked quite well) and bought a 3x in the hope of getting better results ... wrong! They ended up being MUCH worse. OK, my camera at the time was not the best, but I think the comparison is valid and so would stick with 2x.

[PeterCPC]

As above but I have used a 5X Powermate quite successfully with my C9.25 and Canon. Gives a nice wide field FOV of Jupiter and its moons.

Peter

[Cosmic Geoff]

12 hours ago, Sedna said:

This would be for planetary imaging. I already have 32 mm, 25 mm, 17 mm, 13 mm, 8 mm, and 6 mm eyepieces.

I normally image using my C8 and a ASI120MC without a Barlow lens.  I tried using a x2 Barlow and found that under the prevailing conditions the images were no better and I was giving myself twice as much grief in aiming the telescope.  I suspect that a x5 would be totally useless.

[Sedna]

Ok, got it, stay clear of the x5 Thanks all!