I have a Zhumell Z12 f/4.9 1500mm focal length, with some nice Televue nagler eyepieces (5mm, 9mm and 20mm) and a couple of Explore Scientific 82 deg eyepieces as well (13mm and 30mm).
I presently use a Zhumell 2X barlow, but it seems to make images "fuzzy", especially at higher magnifications (300 - 600 range, using the 9mm and 5mm eyepieces).
I do not do astro photography, just vieiwing, and would like to get a quality barlow-like accessory.
Is the Televue Powermate overkill (and over-paying: around $330 US) for my use? If so, what are some recommendations?
In my opinion, the Powermates are worth the price. I'd also suggest the Televue 2X "Big Barlow" as a great visual observing aid, and much lower cost.
However, what you're most likely experiencing is inadequate seeing for the magnification employed.
Generally, even "good" seeing will limit you to around 250X maximum unless you're observing from altitude. The unsteadiness of our atmosphere is normally the limiting factor with today's optics.
I routinely observe at a very dark-sky site on the Texas Plains, near the southeastern corner of the Panhandle (Comanche Springs Astronomy Campus). The altitude is about 1,500 ft. at this Bortle Class 2 site. On most nights even at this great site, I must stay below 300X.
I occasionally observe at McDonald Observatory, a Bortle Class 1 site, from an altitude at about 6,200 ft. The difference is amazing. With 10" to 12" consumer-grade telescopes, you can employ magnification up to 400X easily. With the observatory's 82" scope I've reached 1,700X on a couple of occasions.
I live near Dallas, and have been able to observe fine detail on Mars at 500X exactly once in 30 years of observing there. We have about three nights a year, generally in September, when the air is clear and steady enough for high-power visual planetary observing.
That said, you can often employ magnification of 300X or more if you're willing to wait for those fleeting seconds of stable air out of many minutes of roiled seeing. This is how planetary and double-star observers operate at magnifications other observers consider unworkable. It's also how we manage to make decent lunar and planetary images using small telescopes and webcams: the high video frame rate allows us to use software during post-processing to select a few dozen clear frames from several hundred blurry frames.
It's all down to seeing ...
The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane
Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.
www.3rf.org
Does this make a case for smaller scopes? If the seeing limits me to, lets say 200x, is there a reason to purchase a 12" telescope?
Darren in Tacoma If the seeing limits me to, lets say 200x, is there a reason to purchase a 12" telescope?
If the seeing limits me to, lets say 200x, is there a reason to purchase a 12" telescope?
Yes, for the bigger light grasp, and the larger scope shows more detail at the same magnification compared to a smaller scope. Always get the largest scope you can handle and afford. That could be an 80mm alt-az but the reasoning is the same.
TS 8x40 Wildlife - TS 10x50 Marine - Fujinon 16x70 - TS 80mm f6 triplet & Sky-Watcher EQ-3 mount - TS 2" 99% diagonal - Celestron C5+ on DIY tripod - 5" homemade Bahtinov - Sky-Watcher 6x30 right-reading finders - 12" GSO dob - Baader Hyperion 24,13,10mm 68° - TS Expanse 17mm 70° - Celestron Ultima 2x barlow - Astronomik UHC-E nebula filter - Baader Astro Solar 5" filter - Sky Atlas 2000 - Rükl's Moon Atlas - Canon 400D - 5mW green laser
Darren,
Have a look at www.skyandtelescope.com/.../3305656.html
It's been my experience that poor seeing and light-polluted skies are not valid reasons to avoid larger apertures. Cost, ease of setup and use, and transportability are valid factors.
Dave Mitsky
Sic itur ad astra!
Chance favors the prepared mind.
A man is a small thing, and the night is very large and full of wonders.