Pentax XF 6.5mm - 19.5mm zoom - update with PST

[Mark at Beaufort]

Well the new Pentax zoom arrived today so sorry about weather. I placed the Pentax zoom into my 4" Astro Tech APO frac and looked at a distant electric pylon. The initial view showed that it was sharp across the whole FOV with no apparent CA.

Next I did a comparison test using my Baader Hyperion zoom and the 10mm TeleVue Delos. With all 3 EPs set to about 10mm I again viewed the pylon. The Pentax and the Baader were the same but the Delos was sharper and brighter.

I bought this Pentax to use as a possible EP in my binoviewers so I tried them in the BV to test focus. The Pentax zoom is quite small and placing a similar sized EP in the other BV slot showed me that I would not have a problem with IPD if I went along this route.

So I now really need to test this zoom on the night sky and in my PST. Depending on how it goes I might buy another - time will tell.

[Luke]

Mark, I think this is the first first light report of an eyepiece I have read where the target was an electric pylon! Congrats on the new piece of glass!

That's interesting that the Pentax is quite small, I haven't given up yet on the idea of getting a nice zoom, light and compact would be a definite plus as it would be used a fair bit on a portable giro mount setup.

[John]

Ahh, the old pylon test ! 

Congratulations on the new zoom Mark, I'll be interested to hear your thoughts on it. Since getting the Mk III Baader zoom I've been more impressed with it each time I use it despite being somewhat dubious about zooms for a long time. I wonder if the Pentax will outperform it ?

[Mark at Beaufort]

The Sun has come out so I have been able to test this Zoom EP on the PST.

The zoom is lightweight with a good rubber eye cap which gives eye relief of between 11mm and 15mm. I don't wear glasses to observe but this might be a problem if you do. The Zoom ring is smooth but does not have click stops and is not parfocal.

The view of the Sun in the PST at the 19.5mm is excellent - very sharp and very good contrast. As you zoom in you need to refocus but I still obtained a sharp view at the 9.8mm setting. The FOV ranges from 42 at the 19.5 setting to 60 at the 6.5 setting. In fact the view at 6.5mm still showed the whole solar disc.

I still need to test further but the Sun has gone behind thick cloud. My initial thought was the view was better than the Hyperion zoom but I need to test some more.

Anyway first astro test seems that this zoom is ok. I will try and take a photo of the zoom on the PST but in the meanwhile I attach some official info on the zoom.