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Telescope vs telephoto lens?


Sooty_1 e2
4 1.3k 203 United Kingdom
10 Jan 2013 1:16PM
That solar caveat i mentioned.....

NEVER EVER look at the sun through any magnifying apparatus, including telescopes, camera lenses, magnifiers etc. PERMANENT DAMAGE WILL OCCUR.

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Pete e2
13 18.7k 96 England
10 Jan 2013 1:20PM
Thanks Sooty...I was trying prime focus and found I couldn't focus. I read on one article that you just add extension tubes to get the sensor to the right zone. The problem for me was the other way round. To focus I needed to be closer and I'd reached the limit of the telescope's focus tube (even with the barlow inserted) The only way I could shoot prime focus with the OM-D would be to remove the focusing tube and bodge it. Is that common?
Nick_w e2
7 4.1k 99 England
10 Jan 2013 1:35PM

Quote:One thing you won't ever see with your telescope are the Hubble-esque images on the telescope box!


What's remarkable about Hubble is the following taken from Wikipedia

"The instrument contained eight charge-coupled device (CCD) chips divided between two cameras, each using four CCDs. Each CCD has a resolution of 0.64 megapixels"

It shows how far technology has evoved in under 20 years, and imagine what it would produce even with the sensors available to the mass market, let alone whats probably been developed now within NASA.
oldblokeh e2
3 925 United Kingdom
10 Jan 2013 2:03PM

Quote:It shows how far technology has evoved in under 20 years, and imagine what it would produce even with the sensors available to the mass market, let alone whats probably been developed now within NASA.


Electronics technology for space applications is years behind the earthbound equivalent, because space is such a hostile environment and the chips used have to be ultra-reliable and radiation hardened. If you take the Curiosity Mars rover, for example, it uses a RAD750 computer from BAE Systems. The RAD750 is based on the PowerPC 750 chip once found in Apple’s G3 iMac. That machine debuted in 1997, but it took four more years for the RAD750 to be released, and it didn’t see its first flight until 2005 when Deep Impact was flung comet-ward.

So, while consumers down here got their mitts on Pentium processors back in 1993, that was the year that the HST got *upgraded* to use a 386.
Sooty_1 e2
4 1.3k 203 United Kingdom
10 Jan 2013 4:44PM
Hi Pete,
Yes, there is often a problem with prime focus being out of the focussing range. If slightly too short, you can bodge it by not fully inserting the adapter tube into the eyepiece, or using extension tubes. The problem with longer focus is not being able to get close enough. That's where the Barlow comes in. Sorry, it took so long, but I was looking for this video which explains it (albeit long-windedly!)

http://m.youtube.com/#/watch?feature=related&v=cYTmsfpL0M4&desktop_uri=%2Fwatch%3Fv%3DcYTmsfpL0M4%26feature%3Drelated

Nick
User_Removed 5 4.6k 1 Scotland
10 Jan 2013 5:30PM

Quote:It shows how far technology has evoved in under 20 years, and imagine what it would produce even with the sensors available to the mass market, let alone whats probably been developed now within NASA.

Electronics technology for space applications is years behind the earthbound equivalent, because space is such a hostile environment and the chips used have to be ultra-reliable and radiation hardened. If you take the Curiosity Mars rover, for example, it uses a RAD750 computer from BAE Systems. The RAD750 is based on the PowerPC 750 chip once found in Apple’s G3 iMac. That machine debuted in 1997, but it took four more years for the RAD750 to be released, and it didn’t see its first flight until 2005 when Deep Impact was flung comet-ward.

So, while consumers down here got their mitts on Pentium processors back in 1993, that was the year that the HST got *upgraded* to use a 386.



Absolutely right OldBlokeh.

A friend of mine worked at Ferranti (as was) at Crewe Toll in Edinburgh and drew my attention to this apparent paradox a long time ago. Even some of the defence systems he worked on used what was considered "old technology" at the time. Apparently the Yanks give a lot of contracts to British firms because we are the best at the creative use of proven technology which, apparently, is what they want.

Interested to learn that the next soopa-doopa space telescope will be launched using a European rocket.

.
User_Removed 5 4.6k 1 Scotland
12 Jan 2013 11:39AM
Update:

By chance, the new issue of Outdoor Photography that dropped through my letterbox this morning has a full page advert for astro-photography equipment, including multi-function computerised mounts that can be used to mount a camera and track planets, stars, deep space objects, etc, without having to piggy-back the camera on a telescope.

The web address is: http://www.opticalvision.co.uk/

.
oldblokeh e2
3 925 United Kingdom
12 Jan 2013 11:50AM
Some nice kit in there, but watch out! The alt-azimuth mounts are not good for astrophotography in my opinion. The reason is the problem of field rotation. Celestron, a scope manufacturer, have an explanation of field rotation here .
EsaT 2 21 Finland
17 Jan 2013 4:47PM
Wide field photos like constellations and Milky way are definitely best starting points.
Already because those can be taken with normal photography lenses... thoughoptical qualtiy needs to be good.
You're just going to want big aperture lenses to gather as much light as possible in as short time as possible especially without tracking mount. (Oly's 5 axis stabilizer could do same as Pentax with their astro tracer)
Even with stacking enabled by digital capture it helps to have higher signal in individual images instead of lots of noise with very little signal.

Open star clusters, starting from Pleiades, would be another thing to try.
Nebulaes and galaxies are lot harder because those are wide area objects with low surface brightness.

Really only easy target to shoot through telescope would be moon because of its brightness. (it's in daylight)
Though getting high magnification fine details photos needs very calm atmosphere... unless you've got adaptive optics.


Taking high quality astrophotos needs certain amount of equipment, heck lot more skill and huge amount of patience.
One single photo can easily contain half dozen hours of exposures taken through different filters and bigger wide field mosaic photos basically need something like all clear sky nights of month and some more.
Here are some results of such hobbying: Astro Anarchy
Actually many of those are taken using photography lenses as optics because most nebulas are such large area objects that they don't need focal lengths of astronomy telescopes.

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