Pentax XW 7mm or 5mm

[vlebo]

Hi all 

After an extremely long lay off from stargazing I'm soon  planning on getting a new setup which will be purely visual.

I'm planning on getting a Skywatcher 300p Dob .

I ,wisely , kept my eyepieces , which consist of Pentax XW30 , 20 and 10mm and I'm looking to add one more , either the 7mm or the 5mm . 

Can't decide between the two ....... any suggestions greatly appreciated 

Chris 

 

 

Edited August 10, 2020 by vlebo

[michael.h.f.wilkinson]

At 1500 mm, the XW 5 mm will give 300x magnification, which can certainly be useful in a 12" instrument, although sky quality must be good (under good conditions I frequently use 290x using the XW 7 in my C8 (2030 mm focal length)). The 7mm will give 214x which will probably see more use, and is a gentler step up from 150x with the XW 10. However, ultimately, I would advise getting both (you know you want to ), as they are both very useful EPs..

[iPeace]

16 minutes ago, vlebo said:

either the 7mm or the 5mm

 

7 minutes ago, michael.h.f.wilkinson said:

The 7mm will give 214x which will probably see more use

In my own case, most definitely.

[John]

The 7mm will see more use although my my 12 inch F/5.3 I find 6mm the "goldilocks" high power much of the time. I do use the 5mm XW quite often to tease out the finer lunar details though.

I hesitate to say "get both" though because it's so easy to spend other peoples money !

[Geoff Barnes]

Thinking long term when the planets rise much higher in your northern skies in a few years, I think you will be glad to have both.

Down here in Oz the planets are almost directly overhead and although I don't have any Pentax EP's, I have a Vixen SLV 4mm and SW 4mm and 5mm Planetaries and they are the ones I find I use the most on the major planets when seeing is good with my SW 12 inch F4.9 Dob.

[F15Rules]

Get the 7mm and a decent used Barlow lens like Baader x2.25 or similar. Then you can turn your 7mm into a 3-3.5mm for exceptional nights, and much cheaper than buying both EPs👍🌝

Dave

[Louis D]

I've got the 7mm XW and 5.2mm XL in an 8" Dob and tend to use the 5.2mm more.  However, given your longer focal length, the 7mm would probably make more sense.  You could get a 5mm BST Starguider  as temporary stop-gap to see if you need that focal length as well later on.

[Alan White]

I as a fellow XW owner also suggest the 7 mm will see more use.
I have a new 7 mm XW on its way to me this week for use in my 10" Dobson.
 

[vlebo]

I think it’s gonna be the 7mm for now ! I’ll use it for a while and see how it goes with thoughts of getting the 5mm at a later date ! Thank you so much for all your feedback 

Chris 

[michael.h.f.wilkinson]

Getting the XW 7 makes sense. If you want to push more, but not break the bank, the Vixen SLV 5mm is essentially an XW5 with smaller FOV. Really great EP. The 6mm might be more useful, given John's input.

[Timebandit]

 

Go for both

Get the 7XW first as you will probably use it more

And then go for the 5XW

Then you will need the 3.5XW too 😁

I have the small Pentax XW set , 10, 7, 5, 3.5 XW all keepers 👍

 

 

 

[rwilkey]

Hi Chris, I agree with John above, get the 7mm, it will give you just over 200x which is perfect for planets and the Moon (and what more would you want besides this as the seeing will not always be perfect!)