Barlow Advice Please

[andyrawlins]

Hi all. I have an 8" reflector which I use visually mainly with Vixen LV 5&12mm objectives. I also have a 'no name' 25mm and a no name 2xBarlow that came with the telescope. 

The Barlow seems OK. If I visually compare the 5mm on its own with the 12mm plus Barlow there is little if any difference in quality on Moon or planets. 

However, I have started imaging with an ASI 224mc that I believe is ideally used with a 2.5x Barlow (reflector is 1200mm f6)

So to my question: does the fact that I can't see any obvious image degradation visually with the Barlow mean that it is good enough for imaging too?  What is the difference between an ok Barlow and a premium one?  Should I upgrade to a better one or a Powemate?  Recommendations gratefully received. 

Cheers in advance 

[bomberbaz]

Not sure what your trying to achieve but the 224MC is primarily seen as a planetary camera hence why a barlow might be useful although specifically a 2.5, Not sure where that comes from. The type of barlow magnification would depend as much upon the focal length of the scope it is attached to as well as the camera itself. 

A 200p gives the two images of Jupiter with and without barlow when using the 224mc. The 2x would be a reasonable image to me but others may want to try and get some more out of it.

A camera will pick up a any poor image quality far more than your eye ever can when an image of "an object" is made and your looking at it on a screen. So to be honest it might be better just trying your barlow out and seeing what's what. If it's no good, you could consider buying something better. (There is always the classified section on these forums)

Tele extenders (a type of  barlow) are preferred by some or a traditional 3 glass element (or more) barlow are generally better quality but I am not an expert.

[newbie alert]

Regarding the Barlow try what you have first, then if you feel that you want a better quality one then you can at a later date

Not too sure if you're aware but in most capture softwares there will be a function where you can use ROI( region of interest)  this enables you to  capture just the target if that's you're interest and it has the added bonus of keeping the file size smaller and therefore increasing your FPS( frames per second)

Edited October 1, 2022 by newbie alert
Added info

[sorrimen]

1 hour ago, bomberbaz said:

Not sure what your trying to achieve but the 224MC is primarily seen as a planetary camera hence why a barlow might be useful although specifically a 2.5, Not sure where that comes from. The type of barlow magnification would depend as much upon the focal length of the scope it is attached to as well as the camera itself. 

A 200p gives the two images of Jupiter with and without barlow when using the 224mc. The 2x would be a reasonable image to me but others may want to try and get some more out of it.

A camera will pick up a any poor image quality far more than your eye ever can when an image of "an object" is made and your looking at it on a screen. So to be honest it might be better just trying your barlow out and seeing what's what. If it's no good, you could consider buying something better. (There is always the classified section on these forums)

Tele extenders (a type of  barlow) are preferred by some or a traditional 3 glass element (or more) barlow are generally better quality but I am not an expert.

He’s likely talking about optimum planetary sampling. 4*pixel size yields f/15 and a 2.5x barlow (though 4x should arguably be 5x). 2x barlow would be fairly significantly undersampling, though depending on whether his set up is tracked it may end up being favourable. Image scale is essentially irrelevant for planetary as you can scale it up in post, as well as using ROI, so focal ratio is the focus instead of focal length. 

Still, sound advice to just try out the barlow and camera first. If the set up is tracked, moving up to a 3x gets you to optimum sampling. If it’s untracked, it would be wise to stick with the 2x and change camera to smaller pixels (asi462 or something). 

[andyrawlins]

Thanks all.  I'm using my current Barlow and it seems OK.  My question is really whether a 'premium' Barlow will make an appreciable difference over a 'standard' one.  I have only ever used the one I have and would be prepared to spend £100 or whatever if its going to make a big difference, but don't want to waste my money if it won't.  I have nothing to compare it to. vlaiv recommended 2.5x here 

 

[Guest]

Eyepieces come and go but a good barlow will be with you forever.  I have 3 telecentic barlows and i wouldn't trade them for anything. 

[andyrawlins]

On 04/10/2022 at 01:02, Mike Q said:

Eyepieces come and go but a good barlow will be with you forever.  I have 3 telecentic barlows and i wouldn't trade them for anything. 

I had to look that term up but thanks