Burgess/TMB Planetary + Pentax XW 7mm comparoo

[Starkler (Geoff)]

Originally Posted by janoskiss

Geoff, it sounds to me like you have the eyecup adjusted too high. I found that the eyecup needs to come up less than half way out from the lens, otherwise I'd get the sort of blackout and eyeplacement problems you are describing.

I have just been outside with the 10" and viewing jupiter in average seeing in the twilight.

My perceptions are still the same:

1. This eyepiece is sharp, no problems there
2. Eye placement is tricky, especially if your eye moves to look to the field edge . This is not a public viewing eyepiece and takes some getting used to.
3. field appears to be sharp edge to edge at f5 . More testing needed to confirm.
4. Its not a premium top shelf offering , but its not far behind it and is EXCELLENT value for money
   

I would really love to do a side by side with a televue radian as this ep strikes me as being the poor mans radian and would be the closest competitor.
This range is currently top selling in the US and its easy to see why.

[davidpretorius]

thanks geoff

[janoskiss (Steve H)]

Originally Posted by Starkler

I would really love to do a side by side with a televue radian as this ep strikes me as being the poor mans radian and would be the closest competitor.

From memory, my impression of the Radian 5mm was better. It has less scattered light than the Burgess (virtually none of that sort of scatter...), a full 60-degree FOV, and more generous eye relief: very comfy. Feels like a premium EP too. The Burgess is a bit rough around the edges, esp with the twist-up eyegard action. Burgess maybe has less false colour off-axis. Given the choice I would opt for the Radian but next to the Burgess the TV offering certainly looks way overpriced.

I did not notice the eye placement issue with either EP but settled in quicker with the Radian. Geoff, I experienced the sort of thing you are describing with the 17mm T4.

[janoskiss (Steve H)]

I should add that if anyone is looking for a similar EP near the 12mm or 8.5mm mark the Pentax XFs are absolutely brilliant! 60-degree FOV and 18mm eye relief. They are priced between Burgess and Radians and worth every cent and then some. My 8.5mm performs as good as the 7 and 10mm XWs, right down to f/4. I have not tried the 12mm but I hope to be getting one soon.

[Starkler (Geoff)]

I gave the 7mm a bit of workout tonight at my favourite semi dark sky haunt.
My intention for this eyepiece was for high power dso viewing and it performs quite well for this. 47Tuc was awesome, as was the closeup view of the ring nebula.
With the uhc filter viewing the saturn neb I could see the faint whispy wings in averted vision which gives it its name.

Regarding edge correction, I detected a small amount of star bloat (field curvature?) away from centre (f5 scope). Its certainly much less than I get from the 14mm XL so its not a deal killer for me. I didnt detect any astigmatism (seagulling).

Now for the bad bit. If you use Baader or Celestron filters you might strike a bit of trouble. THe Baader OIII filter doesnt have a very long threaded section and it seems that the TMB/Burgess might have a taper to the thread start at the end of the barrel.
The upshot is that i couldnt get the OIII filter to hang on which for me was something of a dissapointment. However my Lumicon UHC with its longer threaded section hung on fine.

[janoskiss (Steve H)]

Geoff, maybe buy a cheap 1.25" colour filter, remove the glass/plastic and use as an adapter for your OIII.

[davidpretorius]

thanks geoff