Posts Made By: Paul Boerner

I have some pictures of the sun taken with a Pentax 645 that I'd like to scan at very high resolution. Does anyone know of a professional service for scanning astrophotos that does a good job? Alternately, any good/bad experiences with commercial film scanners for digitizing medium format film at high resolution? (I guess the leading contender is the Nikon 8000ED, but I've heard mediocre reviews of its performance and would like something better than the 4000 dpi it claims to offer). Any advice would be appreciated. Thanks,
Paul Boerner

I'm giving a lecture on telescopes to an introductory astronomy class, and I was looking for a few pictures of really bad telescope ads that I could show for comic relief. You know the ones: the Newtonians pointed at the ground, the "view through the eyepiece" of a comet flying by Saturn, the claims of 1200x magnification...I know I've seen these things, but I haven't been able to find any pictures. Can anyone post any images/links of such ads?

Thanks...sorry if it's a little OT...
Paul

Here are the undisputable rankings of the leading sources of astronomy equipment reviews (after all, if you're going to put up a website full of equipment reviews you ought to be able to take a little criticism...) All rankings are on a scale of 1 to 5 stars, with 1 being Meade-advertising-copy bad and 5 being how incredibly great the reviews would be if I wrote them all.

Cloudy Nights (4/5)
Pro: Very numerous reviews, frequent updates. Reviews written by users; tend to be detailed, entertaining, and useful. Site is well-organized, free of ads (for now...), and popular. Best place to look for a review of a late-model piece of equipment.
Con: technical knowledge and writing ability of reviewers inconsistent. Because most reviews are written by people who own the equipment, and nobody wants to think they own inferior equipment, there's a strong positive bias to most reviews. (They almost always wind up concluding, "It may have some flaws, but it's overall a very good value and I'm glad I bought it.") This is even stronger than the please-the-advertiser bias found in the magazine reviews.

Ed Ting's Scope Reviews (3/5)
Pro: Written by an experienced, knowledgeable observer, with an engaging writing style. Because all the reviews are by the same guy, it's easy to judge his biases. He doesn't own the equipment he reviews (or appear to worry about p!$$!ng off advertisers), and is not afraid to rip it.
Con: Not many reviews posted recently, and therefore becoming increasingly irrelevant. Tends to focus on high-end stuff (big dobs, 6" refractors). Reviews are relatively short and tend to focus on one or two characteristics. Sometimes seems bored with equipment he's reviewing and dismisses it for no apparent reason.

Sky and Telescope (3/5)
Pro: Written by professional reviewers. Long, detailed articles cover most factors that might be relevant (especially ease-of-use). Usually include good pictures.
Con: Generally avoid technical details or comparisons to other products. Even though they avoid technical details, they still manage to be kind of boring to read. Possibly biased in favor of major advertisers in the magazine. Infrequent reviews, focusing on major-brand equipment.

This may be the wrong forum for this post (perhaps there's no right forum for it...), but check out the picture on this ad:

http://www.astromart.com/viewad.asp?cid=183040

Look at the little dust grains on the mirror surface -- it looks like what you'd see if you star-tested a cheap 2" widefield eyepiece on a big f/4 telescope by looking at an open cluster. Well, not really, but I thought it was kinda cool.

Mike,

I don't have the paragon-plus xhd, but I've had the paragon hd-f2 for a while (and am in the process of selling it, though I liked it a lot). It's a great tripod, very sturdy for its price range and lightweight and easy to use. I really enjoyed it. The reason I'm selling it, and the reason that I don't think the XHD model sounds like a good idea, is that the head limits what the tripod can carry. Unlike many photo tripods, the fluid pan head is non-detachable, so you can't use the legs to mount a Giro or Unistar or other astro mount. And the head is not as sturdy as the legs. Even with the lighter hd-f2, I felt like the tripod legs could have supported a bigger load than the pan head was able to handle. The xhd has sturdier legs, but uses the same fluid head, which really doesn't make any sense to me.

Anyway, like I said, I've never used the XHD tripod, so maybe you should hear from someone who has. But I'd recommend against it. A photo pan head isn't really what you want for a heavy scope anyway, and if you have a small, light scope or binoculars then the smaller tripod would handle them just as well. I'd either go with the HD-F2, or get a bigger tripod with a detachable head (like a bogen 3033) and a true altaz mount to put on top.

pb

The 1 hr labs won't do it, but a high-end photography store probably could (they might have to send it out), or you could try one of these online places (eg www.timelessphoto.com; I've never used them, but it might be worth calling and finding out what process they use on B&W film).

It'd be best to take it somewhere where you can explain to the people who'll be doing the developing (and especially the printing) if you've got astrophotos, as sometimes the negatives don't look like much and they decide not to print anything.

In any case, it's probably best not to mention if you've got hypered film. It doesn't really make any difference in how it should be processed, but I've had some stores get nervous about accepting any film that's been "tampered with" by the customer.

Hope this helps...Good luck,
Paul

Canon 10x30 IS. You can get them for <$300, they're more portable than 10x or 7x50s and, thanks to the IS system and very sharp optics, will show you more in the night sky from most sites. Not to mention the fact that they're vastly better for daytime viewing. Try out a pair if you get a chance; I doubt you'll want 10x50s after that.

Paul

Here's a rough estimate: The angular diameter of Saturn's rings is ~45 arcseconds (you can look up the exact number, which varies). If that occupied a quarter of the Radians' field, then you were magnifying a 45 arcsecond object so that it appeared about 15 degrees across. Convert everything to arcminutes:

0.75 arcmin X magnification = 900 arcmin

So magnification = 1200x

Either the seeing was ridiculously good, or you've overestimated the fraction of the apparent field occupied by Saturn's rings, or you were magnifying waaay more than is usually recommended (though if you liked the way it looked, I guess that doesn't matter).

Does that agree with what you'd calculate?

Paul

Hi Bruce,

I own a GM8 (for my C9.25 and Pentax SDHF76), and I like it, but I still think you made the right choice. Here are the strengths and weaknesses of the two, as I see it:

GM-8 advantages:
- Carries more weight; the specs I've seen claim 22 # for the GP-DX vs. 30 # for the GM8, and that sounds about right to me. It's a more solid mount.
- Astrophotography: the included drive system has features like PEC, TVC, and autoguider input that I dont think you get on the GP-DX without upgrading to their Goto system. Also, my impression is that the gears and motors on the GM8 are a little smoother (not enough to notice visually, but a factor in astrophotography; you see a LOT more good astrophotos taken on GM8s than on GP-DXs).
- I think it's better looking, but that's just me.
- The slip clutches are nice, in that you don't have to worry about stripping the motors or unlocking them before slewing to a new object.

GP-DX advantages:
- Substantially lighter (though not exactly light)
- Probably is easier to rebalance quickly, thanks to the clutch levers instead of the slip clutches
- The annoying part about the GM8 is that there's no manual slow motion; you either have to push it around by hand (making it hard to make fine changes) or use the motors (which, even at top speed, are painfully slow when you're acquiring an object using your finder or a wide-field eyepiece). The slow-motion knobs on the GP-DX offer a good middle speed.
- While it's not quite as strong or as smooth as the GM8, it's plenty strong enough to handle your C8, and plenty smooth enough to track at high power; the difference probably only matters if you're trying prime-focus astrophotography.
- You can get the SS2k goto system a lot cheaper than the Losmandy Gemini Goto, if you're interested in upgrading.

There's a good comparison of the GM8 vs. a super polaris on Cloudynights, which you've probably already read; you can extrapolate his comments on the SP to the GP-DX. Anyway, I think the only reason to go for the GM8 is for astrophotography (that goes double for the Tak; it would really be a waste to spend that much extra on a mount where the main improvements were intended for photographers, if you're not doing photography).

Hope that helps.

PB

Maurice,

Check out www.inconstantmoon.com; they have a reversed map, as well as a lot of other links and features (and the site plays the Moonlight Sonata for you while you browse).

PB