Celestron X-Cel LX eyepieces what would happen if i used them with a shortye barlow (GSO 2,5x barlow)

[LB-10-LB]

Celestron X-Cel LX eyepieces what would happen if i used them with a shortye barlow (GSO 2,5x barlow)

Would the exit pupil come too far out or too close?

Or will it be ok to observe..

[John]

They would barlow OK. The eye relief extends outwards a bit when a barlow is used. The exit pupil will depend on the focal length of the X-Cel LS eyepiece that is being barlowed and the scope it's being used in.

The limits on useful magnification remain when using a barlow of course - barlowing the X-Cel LS 2.3mm with a 2.5x barlow is going to give the equivalent of a .92mm eyepiece - not useful on any scope that I can think of !

[LB-10-LB]

They would barlow OK. The eye relief extends outwards a bit when a barlow is used. The exit pupil will depend on the focal length of the X-Cel LS eyepiece that is being barlowed and the scope it's being used in.

The limits on useful magnification remain when using a barlow of course - barlowing the X-Cel LS 2.3mm with a 2.5x barlow is going to give the equivalent of a .92mm eyepiece - not useful on any scope that I can think of !

Thank you for your reply

[AlexB67]

Hi better late than never.   I would not worry too much since the eye relief is not overly long on those eyepieces to start with AFAIK. The shorty barlow will affect the eye relief more than a longer one though. 

Eyepieces with very long eye relief around 20mm such as the ones I use, if you don't wear glasses and are already using them with the twist cup on the outer most setting you may run out of adjustment range when barlowed. I have to back away from the eyepiece a bit  to avoid blackouts when I use my 2x  barlow with my pentax 10.5 XL.  I can't quite touch the rubber eyecup letting a bit light in from the side, which may be annoying in some situations if not observing from a dark spot. It may perhaps feel a bit uncomfortable for some not being able to hug the eyepiece.  I admit  It is a bit of an odd sensation when I compare the barlow/pentax combo to my 5mm orthoscopic eyepiece straight after that offer similar mag,  where it is all about hugging the eyepiece and very short eye relief   

In any case, the increase in eye relief is more drastic with long focal length eyepieces, so it is there you may find it to be most bothersome ( if at all).

I imagine if it was a 20mm focal length or greater eyepiece with 20mm eye relief it may become a bit too much for me, and my barlow is a fairly standard medium length one as well. The Delos 14mm I own has an extra fold up rubber cup, as well as a huge adjustment range on the eyecup so even when barlowed there is enough adjustability there. 

Your mileage in comfort may vary depending on your combo