[Nemesis6]

http://imageshack.us/f/96/first6.jpg/ <--- This is Vega
http://imageshack.us/f/51/second3.jpg/ <--- This is Sadr

Telescope: Skywatcher 200P
Camera: Canon 1000D
Exposure time: 30 seconds
ISO: 400
Both manipulated in photoshop; adjusting the levels a bit, downscaled and rotated so they're wide instead of tall, height-wise... gah, I fail at explaining stuff, but you know what I mean.
These are my two first astrophotos, and they're basically just test shots to see if I my polar alignment was proper. Turns out, it was!

I still lack some essential components like a remote for the camera so I can use the BULB setting, allowing me to expose for more than 30 seconds, but that's a minor concern at least for now, since my camera is capable of some limited timing stuff. That is to say, I can make it snap up to five shots in succession, so, for example, I have no need to take exposures over 30 seconds, because I can just snap two pictures of 30 seconds exposure and stack them in whatever astrophotography software I choose... so it works out. As it stands right now, though, the camera I'm using has been RMA'd, so I have to wait a few weeks to get it back or get a new one. Anyway, I'm gonna see if I can get a shot of the Etamin(Gamma Draconis) star because... well, you know why!

I don't really know what the point of this topic is. I guess I just wanted to partly share my first photos, and, obviously, my enthusiasm for this hobby of mine, and see if anyone else here is into this.

[Flipside]

Very nice stuff

I'd love to take this up, but I live in the Suburbs of London, which has some of the worst seeing in Europe

[Snail]

Very nice stuff

I'd love to take this up, but I live in the Suburbs of London, which has some of the worst seeing in Europe

Hey look a cloud

[Astronomiya]

Those are nice first shots.  Now for the barrage of advice/questions:

Nemesis6, you'll want that remote; for faint stuff (i.e., anything besides planets and bright stars), you'll need the ability to take one to five minute exposures.  Doing so will add less noise to the picture; dark subtraction and flat fielding can only do so much.  Also, what mount are you using?  Judging by the scope you have, probably an EQ-5, right?  That should be good for a while, but you'll want something better eventually (though "eventually" could mean "years from now").  Losmandy and Vixen make good mounts that would be a nice step up.  Do you know how to drift align?  That will be absolutely essential as you move to fainter targets.

[SirCumference]

Nice pictures!

Wish I had the cash to buy a half-way decent telescope.

[Mika]

Hmmm

Mika ponders about designing his own apochromatic refractor... hopefully that calciumfluoride or fluorite crown glass isn't too expensive!

[watsisname]

Those are great star shots!   If you take requests I'd love to see you try Albireo (Beta Cygni) whenever you have the opportunity.  Not just for being a system used in Freespace but also because it's an absolutely gorgeous double star in real life with strongly colored red and blue components.

I should really drag my scope out again soon, before my climate gets too humid and condensation makes a mess out of everything. D:

[Astronomiya]

Hmmm

Mika ponders about designing his own apochromatic refractor... hopefully that calciumfluoride or fluorite crown glass isn't too expensive!

I... wouldn't use fluorite.  Holy Jesus, is that **** expensive.  At least, that's as near as I can figure the reason why Takahashis are so much more expensive than Astrophysics refractors.  At least you can get one from stock, though!  A cheaper option is something like FPL-53 ED glass.

[rhraziel]

Cool Stuff Nemesis. When I first got into observing I thought, holy ****, I've already heard a ton of these names from Freespace! I bought a Celestron 8 inch Goto back in November, but astrophotography as been pretty intimidating. I just bought a webcam to do some solar system stuff, but I haven't tried it out yet.

Now lets see some of those faint nebulas and galaxies!

[Nemesis6]

Those are nice first shots.  Now for the barrage of advice/questions:

Nemesis6, you'll want that remote; for faint stuff (i.e., anything besides planets and bright stars), you'll need the ability to take one to five minute exposures.  Doing so will add less noise to the picture; dark subtraction and flat fielding can only do so much.  Also, what mount are you using?  Judging by the scope you have, probably an EQ-5, right?  That should be good for a while, but you'll want something better eventually (though "eventually" could mean "years from now").  Losmandy and Vixen make good mounts that would be a nice step up.  Do you know how to drift align?  That will be absolutely essential as you move to fainter targets.

I'm still kind of scared of doing long exposures. The way I understand it, a longer exposure equals more noise, even when stacked and the noise is canceled out. Same reason I stick with a very low ISO setting: The higher settings pronounce both the noise, which is already somewhat of a problem with the 1000D series, compared to for example the 550D. It also amplifies the artificial sky glow. To top all of that off, I'm still learning post-processing. I can manipulate levels and stuff, but when it comes to for example the "curves" function of Photoshop, I'm lost. So for now, the less work, the better. But yes, I am trying to find a proper remote. My big concern is finding one that can force the camera to do mirror pre-firing.

The mount is a Skywatcher-specific EQ5 "deluxe"(they've got some nerve to claim that it's deluxe) mount. As far as drift aligning goes, I'm still reading up on that. I've read about it, but I haven't quite gotten the idea yet, so I'll read up on that. One thing that is a bit hard sometimes is focusing, which is why I've set my sights on a 200mm Bahtinov mask -- That ought to make things a whole lot simpler.

[Mika]

I... wouldn't use fluorite.  Holy Jesus, is that **** expensive.  At least, that's as near as I can figure the reason why Takahashis are so much more expensive than Astrophysics refractors.  At least you can get one from stock, though!  A cheaper option is something like FPL-53 ED glass.

The point is, I want to try it myself. FPL-53 ED seems to have mainly better scratch and environmental resistance compared to CaF2, but I suspect price-wise the difference isn't significant. S-FPL53 is listed  around 15 to 20 times the price of N-BK7 category... The price of CaF2 is nowadays mainly related to the manufacturing phase, it has to be ground and polished slowly. Calsium fluoride has better performance in the UV range and seems to work better batch by batch, since index and Abbe number of ED glass like S-FPL53 likely needs to be measured by each molded batch - that is to say, according to my understanding.

In other news, I actually checked out the design process of apochromatic refractors with a not-so-serious case study of an F/5 500 mm focal length (4 deg FFOV with a 35 mm sensor) at work for giggles to see what's the big deal. Answer: higher order aberrations. This one would likely call for aspheres, or field lenses close to the sensor. Conveniently, the first element just happened to be fused silica, of which there are off-the-shelf aspheres available - hmmmmm...

With an aperture ratio of F/8, I got it diffraction limited for two thirds of the field, though.

EDIT: I have HAD it with these m********ing indefinite articles in this m*******ing language

[Mika]

I'm still kind of scared of doing long exposures. The way I understand it, a longer exposure equals more noise, even when stacked and the noise is canceled out. Same reason I stick with a very low ISO setting: The higher settings pronounce both the noise, which is already somewhat of a problem with the 1000D series, compared to for example the 550D. It also amplifies the artificial sky glow. To top all of that off, I'm still learning post-processing. I can manipulate levels and stuff, but when it comes to for example the "curves" function of Photoshop, I'm lost. So for now, the less work, the better. But yes, I am trying to find a proper remote. My big concern is finding one that can force the camera to do mirror pre-firing.

Yes, typical CMOS sensor indeed accumulates noise during longer exposure times, this type of noise is called dark noise. CCD sensors do that too, but fare slightly better in comparison, and for longer exposure times most of the sensors are cooled to keep dark noise under control. Typical astronomical instruments tend to use cooled sensors to allow longer exposure times.

Now that you mentioned it, I need to check if my Canon 20D supports long exposure mode. I think two different versions of that camera exist, and the other one of them has a specific feature for star viewing that allows direct user control for the mirror down, allowing extended exposure times. If I recall right, they dropped this property in 30D, but I'm not sure of further developments.

Does anyone know why Digital SLR manufacturers push for insanely fast ISO options like 3200? My personal observation of this 20D is that anything above ISO800 is pretty much useless due to shot noise, and even then the image quality at ISO800 is questionable.

[Astronomiya]

I'm still kind of scared of doing long exposures. The way I understand it, a longer exposure equals more noise, even when stacked and the noise is canceled out. Same reason I stick with a very low ISO setting: The higher settings pronounce both the noise, which is already somewhat of a problem with the 1000D series, compared to for example the 550D. It also amplifies the artificial sky glow. To top all of that off, I'm still learning post-processing. I can manipulate levels and stuff, but when it comes to for example the "curves" function of Photoshop, I'm lost. So for now, the less work, the better. But yes, I am trying to find a proper remote. My big concern is finding one that can force the camera to do mirror pre-firing.

The mount is a Skywatcher-specific EQ5 "deluxe"(they've got some nerve to claim that it's deluxe) mount. As far as drift aligning goes, I'm still reading up on that. I've read about it, but I haven't quite gotten the idea yet, so I'll read up on that. One thing that is a bit hard sometimes is focusing, which is why I've set my sights on a 200mm Bahtinov mask -- That ought to make things a whole lot simpler.

Yes, a longer exposure does mean some more noise, but it is less than is gained from a bunch of shorter exposures all stacked together.  The noise you get from that stacking process is harder to account for than that in a single long exposure, although of course there are limits either way.  You should look up dark frames and flat fields; those are the two most basic steps to reducing astronomical images.  Here's the basic idea behind darks though:

Every digital sensor randomly has pixels fire due to their own thermal radiation; this generates what is known as dark current.  If you take an image even with the shutter closed, you'll notice noise.  The idea is take a bunch of these frames with the same exposure times as your images.  Then average these frames (since dark current is random) and subtract the averaged dark frame from each image you took that night.  You will immediately notice a large reduction in noise.

Does anyone know why Digital SLR manufacturers push for insanely fast ISO options like 3200? My personal observation of this 20D is that anything above ISO800 is pretty much useless due to shot noise, and even then the image quality at ISO800 is questionable.

Because you can take quick images in poorly lit locations.  On really good DSLRs like this Nikon model I remember reading about, you can get usable shots at ISO 16000 or something equally ridiculous.  This is very nice for showing everything in a dimly lit boxing arena or something in only one quick shot.

The point is, I want to try it myself. FPL-53 ED seems to have mainly better scratch and environmental resistance compared to CaF2, but I suspect price-wise the difference isn't significant. S-FPL53 is listed  around 15 to 20 times the price of N-BK7 category... The price of CaF2 is nowadays mainly related to the manufacturing phase, it has to be ground and polished slowly. Calsium fluoride has better performance in the UV range and seems to work better batch by batch, since index and Abbe number of ED glass like S-FPL53 likely needs to be measured by each molded batch - that is to say, according to my understanding.

In other news, I actually checked out the design process of apochromatic refractors with a not-so-serious case study of an F/5 500 mm focal length (4 deg FFOV with a 35 mm sensor) at work for giggles to see what's the big deal. Answer: higher order aberrations. This one would likely call for aspheres, or field lenses close to the sensor. Conveniently, the first element just happened to be fused silica, of which there are off-the-shelf aspheres available - hmmmmm...

With an aperture ratio of F/8, I got it diffraction limited for two thirds of the field, though.

I know you want to try it yourself.  Fluorite being really expensive is the only reason I can think of why Takahashi refractors costing so much more than the AP apos, despite being available from stock (AP stuff has like a 10-year waiting list or something now).  The performance for visual and amateur level photographic work is honestly almost exactly equivalent.  Hence why I suggested just going for the cheaper option.  Neither ED glass nor CaF is by any means cheap, but the ED glass is cheaper to manufacture.  You could even use something like FPL-51, but the 53 grade is somewhat better.

As for an f/5, yeah, you will probably need to grind aspheres to be diffraction-limited over the entire range, but I don't see a major problem with that.  Sure, spheres are easier, but somehow companies like Takahashi and TMB Optical found a way to do that and make their scopes $6-7k and under.

[Mika]

Because you can take quick images in poorly lit locations.  On really good DSLRs like this Nikon model I remember reading about, you can get usable shots at ISO 16000 or something equally ridiculous.  This is very nice for showing everything in a dimly lit boxing arena or something in only one quick shot.

I haven't been following on the image quality of current crop of DSLRs, but the image quality in mine just doesn't cut it. I would understand the high ISO rating when shooting a movie, shot noise doesn't seem to bother eye that much if it's random, check old black & white films for reference. But in a single photograph, I don't know. On second thought, I tend to take photos with a philosophy of "If you can't print it and be happy with it, why bother in the first place?"

I know you want to try it yourself.  Fluorite being really expensive is the only reason I can think of why Takahashi refractors costing so much more than the AP apos, despite being available from stock (AP stuff has like a 10-year waiting list or something now).  The performance for visual and amateur level photographic work is honestly almost exactly equivalent.  Hence why I suggested just going for the cheaper option.  Neither ED glass nor CaF is by any means cheap, but the ED glass is cheaper to manufacture.  You could even use something like FPL-51, but the 53 grade is somewhat better.

As for an f/5, yeah, you will probably need to grind aspheres to be diffraction-limited over the entire range, but I don't see a major problem with that.  Sure, spheres are easier, but somehow companies like Takahashi and TMB Optical found a way to do that and make their scopes $6-7k and under.

Natural fluorite seems to be of order 1.2 $ / g. If this number is used in the cost estimation, the diameter of that fluorite lens would be about 100 mm, and thickness about 10 mm. With the specific weight of 3.18 g/cm^3 the material itself nets about 300 $ - however, this doesn't have any guarantee of any sort of material homogeneity. Add on top of that the Knoop hardness of the material is around 160, while for BK7 it is about 560. So CaF2 is about four times softer than BK7, which results in considerable amount of time in the grinding and polishing to get it in the right shape. S-FPL53 hardness is around 350, which makes it easier to process (this is not to say it wouldn't still be sensitive to temperatures, it is). It isn't only the material cost - synthetic CaF2 is cheaper, this goes under the name Lithotec-CaF2 by Schott - it is the grinding and polishing process itself that is significantly more costly than with typical glasses, even with ED glasses.

But it is true that S-FPL53 might be more sensitive approach for this purpose.

This would be another project to add on top of the earlier idea of doing a F/0.7 lens and combining it with Hamamatsu's back-thinned CCD for the meanest low light level camera produced. I actually might be crazy enough to pull this off one day. But it won't happen quickly, doing that kind of lens would probably take well over year assuming one lens per two months rate...

[Astronomiya]

I haven't been following on the image quality of current crop of DSLRs, but the image quality in mine just doesn't cut it. I would understand the high ISO rating when shooting a movie, shot noise doesn't seem to bother eye that much if it's random, check old black & white films for reference. But in a single photograph, I don't know. On second thought, I tend to take photos with a philosophy of "If you can't print it and be happy with it, why bother in the first place?"

This Nikon is fairly recent; I think I read about it last year, right about the time it came out.  DSLR sensors have improved a lot in time since the 20D came out.

[newman]

Nemesis, I was wondering just what exactly and in what detail you can see with that 200mm reflector? Planets? Can you discern Saturn's rings? Can you see it's satellites? What about DSOs, nebulae, etc (in addition to the pics you posted) I was looking into getting a scope myself and scopes larger than 200 start going into the "huge" category. I'm also looking at SkyWatcher scopes, and since I'm more interested in observation than astrophotography I was considering a dobson mounting with a larger scope. Skywatcher has those retractable 254 and 305mm reflectors on dobson mounts that take surprisingly little space when retracted - but I'd like to know what exactly you can and can't do with that 200mm of yours because it's definitely a lot more practical to use. I don't feel like juggling 20kg components for an hour every time I want to do some stargazing..

[Nemesis6]

Nemesis, I was wondering just what exactly and in what detail you can see with that 200mm reflector? Planets? Can you discern Saturn's rings? Can you see it's satellites? What about DSOs, nebulae, etc (in addition to the pics you posted) I was looking into getting a scope myself and scopes larger than 200 start going into the "huge" category. I'm also looking at SkyWatcher scopes, and since I'm more interested in observation than astrophotography I was considering a dobson mounting with a larger scope. Skywatcher has those retractable 254 and 305mm reflectors on dobson mounts that take surprisingly little space when retracted - but I'd like to know what exactly you can and can't do with that 200mm of yours because it's definitely a lot more practical to use. I don't feel like juggling 20kg components for an hour every time I want to do some stargazing..

As far as Saturn goes, it's quite clearly visible with both my smaller 130mm scope. I haven't had the 200mm scope out for some time now as I'm waiting for my camera to be returned after some clumsyness on my part resulted in a dead USB interface. But even with the 130mm, you can see both the rings, the space between the rings, and obviously the planet itself, quite clearly. The moons of Saturn are visible, though they look more like stars, although the color can be made out easily, with Titan being obviously red-yellow. As far as DSOs and nebulae, that will be very hard no matter what telescope you have as far as I understand. The M42 nebula for example is the most visible nebula in the night sky, and even that one is only barely visible when using averted vision, so as far as a telescope for observation purposes goes, if you really want to see the more spectacular stuff like globular clusters and nebulae, you're generally not gonna be able to see anything. That's my experience at least. One thing you need to take into account is also the increased size -- The bigger the scope, the harder it obviously is to set it up. I'd say stay with something below a 200mm telescope, unless you plan on getting one of those fancy Schmidt-Cassegrain telescopes.

[newman]

Actually I was considering a retractable newtonian 300mm on a dobson mount - something like this: http://www.skywatcher.com/swtinc/product.php?id=140&class1=1&class2=106. Alternatively that same model only a 254mm one. I can make an enclosing to basically always keep it in the same place all the time. When I want to stargaze I just pop the enclosing open and extend it. Then again there's something to be said for portability. Thanks for the info, in any case!

[Astronomiya]

Nemesis, I was wondering just what exactly and in what detail you can see with that 200mm reflector? Planets? Can you discern Saturn's rings? Can you see it's satellites? What about DSOs, nebulae, etc (in addition to the pics you posted) I was looking into getting a scope myself and scopes larger than 200 start going into the "huge" category. I'm also looking at SkyWatcher scopes, and since I'm more interested in observation than astrophotography I was considering a dobson mounting with a larger scope. Skywatcher has those retractable 254 and 305mm reflectors on dobson mounts that take surprisingly little space when retracted - but I'd like to know what exactly you can and can't do with that 200mm of yours because it's definitely a lot more practical to use. I don't feel like juggling 20kg components for an hour every time I want to do some stargazing..

You can all of those things you mentioned quite easily with a 4-inch or larger scope; many will be visible in binoculars (I can usually just make out that Saturn has rings in my 10x50's).  An 8-inch (200 mm) or larger will show you more, more, more.  If you can get to a dark site (unfortunately, with you being in the UK (?), dark-ish is the best you'll get without heading to rural Wales or Scotland), an 8-inch will show you stars down to mag 14, and most DSOs down to about mag 12 or so, depending on their surface brightnesses.  Even from relatively light polluted areas, an 8-inch will show you enough to get you through years of observing.  It's the minimum size I'd advise getting if you are at all serious about the hobby; contrary to your initial belief, 8 inches is actually relatively small for an amateur reflector (go to a serious star party, and if you don't see at least one half-meter class instrument I'd be surprised).  For Europe, Skywatcher (Synta) dobs are the best ones to get from a price/performance standpoint; they don't have the best optics, but they are very, very good for the price.  In the US, go Orion (basically Synta's US outlet at this point) all the way.

The M42 nebula for example is the most visible nebula in the night sky, and even that one is only barely visible when using averted vision, so as far as a telescope for observation purposes goes, if you really want to see the more spectacular stuff like globular clusters and nebulae, you're generally not gonna be able to see anything.

No offense, but I really want to know what you're doing to reach that conclusion.  M42 is clearly visible with direct vision in binoculars even in most urban areas, and to the naked eye everywhere else.  Saying you can just make it out in a 5-inch seems ludicrous.  What magnification/eyepieces are you using?  If you can see Titan (mag 8.5-9, and you're seeing color!), M42 should be easy pickings at mag 4 total.

You do make a good point about portability, however; newman, I'd advise going to see one of these scopes in person before getting one.  It can be surprising how big they are, but 8 to 10 inches is eminently manageable for just about everyone in my experience (I started with an 8, and now have a 10-inch Orion dob).

Newman, I also would not store your scope outside.  To protect it from the elements, especially rain, wind, and snow, it needs to be in an enclosure of some kind, even just an unheated garage.  You'll need to take it out every time you want to observe, but a Dob makes it so your setup time is two or three trips and about five to ten minutes, even in the dark.

[watsisname]

The M42 nebula for example is the most visible nebula in the night sky, and even that one is only barely visible when using averted vision, so as far as a telescope for observation purposes goes, if you really want to see the more spectacular stuff like globular clusters and nebulae, you're generally not gonna be able to see anything.

No offense, but I really want to know what you're doing to reach that conclusion.  M42 is clearly visible with direct vision in binoculars even in most urban areas, and to the naked eye everywhere else.  Saying you can just make it out in a 5-inch seems ludicrous.  What magnification/eyepieces are you using?  If you can see Titan (mag 8.5-9, and you're seeing color!), M42 should be easy pickings at mag 4 total.

I agree with Astronomiya, there's no reason why visual observation of DSO's would not be possible, as there are a fairly large number of them that are bright enough.  I'd say there's at least a dozen, maybe two dozen Messier objects that can be picked out through an 8" scope under urban skies.  Even from my home (just 3 miles outside DC), I can pick out M42 as a vague fuzzy spot with unaided eyes (at least on very transparent nights, which is usually the case over the winter months when Orion is visible).  With binocs I can discern its overall shape, and with my 8" scope it looks almost exactly like this sketch, just a little fainter overall.



If you're able to get out to a dark observing site then you'll be able to spot a large number of the fainter nebulae and galaxies, and the brighter ones will also gain a great deal of definition.  With an 8" scope M42 will be just as clear and bright as the above sketch.  And if you can't get to a dark site then there are still other options.  For observing nebulae you can use narrowband filters that transmit only the wavelengths that those nebulae emit, thus cutting out most of the unwanted sky glow and dramatically improving the view.  For galaxies and star clusters though you'll need to use astrophotography to get more detail.

Anyway, those are my thoughts on visual observing of DSO's.  I've seen a lot of people look through a scope at a nebula or galaxy for the first time and be really disappointed -- like they were expecting to see something from out of a Hubble image gallery.   With astrophotography you can create images like that, but there is still a whole lot you can see with just your eyeballs and scope.