TV Plossl 10.5mm & TV 2.5X BARLOW ?? good deal???

[stringpickin]

I can get these two items for 150 u.s.  delivered..   do you think that is a good deal?  

and would the 2.5x barlow and this plossl most likely work well in my 4.5 dob,,   440/ f/4  

Thanks for your input..   

TELE-VUE Plossl 10.5mm Ocular EYEPIECE & 2.5X BARLOW Lens Lenses

[Joves]

I wasn't aware the TV Plossl's came in a 10.5mm... I thought it went from 8mm to 11mm?! Here in Oz, the 8mm and 11mm each cost $115 Aussie dollars, so I'm imagining the 10.5mm, if it exists, would be a similar price. This would be about $105 US, so you'd be getting a 2.5x TV Barlow for only $45 US. Seems like a reasonable enough deal to me.

[ronin]

The 10.5mm TV is one of the older models, at some time they modified/rationalised the focal lengths and it seems made them more along the lines of integer values. Nothing wrong with them, just the focal length now are fractionally different (or at least that is what the numbers on the side imply as 10.5mm is close to 11mm)

The TV plossls are designed to operate to f/4 but that is the limit. How it will work at the limit I have no idea. Could be a case of it works and you can view but starting to lose the edges.

I have no idea if the barlow will operate at f/4, do not hear much of them over here which is a bit odd. If TV have followed through the performance criteria then it should, but again it wil be at it's limit.

One thing to remember is the eye relief, you will have about 6-7mm eye relief, and this will be from the centre of the lens not the top face, if you wear glasses then it might be tight.

[RikM]

I use a TV 2.5x Barlow with my f/4.7 Dob sometimes with an old smoothside 13mm TV Plossl. Optically it is a fine combination but not as comfortable to use as the same Barlow with my 14mm Pentax XW (5.6mm equivalent) This is currently my main 'planetary' combo. Occasionally, depending on seeing, I can use the 10mm XW for a 4mm equivalent.

[Stardust]

I have a pair of the TV 10.5mm plossls, not much in the way of eye relief so don't know how comfortable they would be barlowed. 

[Naemeth]

The 10.5mm TV plossl is excellent, I use mine with a removable rubber eye cup which puts the eye exactly in the right place. I'd say it's a good deal .

[andrew63]

I used a tv 10.5 plossl with an ultima barlow - but as pointed out in another thread -  tv plossls have soft edges when barlowed due to  the design. So some of the edge of field is lost  -  the quality of view was very good however.

andrew