Astro-photo

[thecyclists]

Anyone that has experience with astro-photo?

What I'm looking for are other users experience with using dSLR on a telescope and opinions on which telescope to buy.

BTW - I got Canon dSLR (but I guess all dSLRs can be used).

[bill t.]

It's all about low noise at hi ISO settings and long exposures.  And very, very dark oh-so-distant locations.  And good optics.  Plenty of specialty forums out there with terrific info.

For starts just cobble your camera onto a telescope with a drive motor and try some long exposures through the regular camera lens, not the telescope optics.  Better hurry, we're rapidly loosing the Summer Milky Way which is an astro-photographer's dream come true.  No more majestic sight than the old Milky Way sticking up vertically from the southern horizon.  No need for special equipment, star trails are nice too.  Point your camera at Polaris for some great star rings.

If you're still into it down the road there are some very nice color corrected refractors in the 4" to 7" range with good drive systems that produce excellent quality images at high magnification.  But think $.  Top quality astrophotography is not easy, if you want to produce superb images you need a high tolerance for failure and dogged persistence on a long time scale.  I knew a guy who was really into it, he figured he had to make several 120 mile roundtrips to his observing site to wind up with one truly excellent shot.

Here's some inspiration...
http://www.robgendlerastropics.com/Einstein.html

[Misirlou]

Anyone that has experience with astro-photo?

What I'm looking for are other users experience with using dSLR on a telescope and opinions on which telescope to buy.

BTW - I got Canon dSLR (but I guess all dSLRs can be used).

What objects interest you? How much can you afford? With telescopes, there is no substitute for aperture. The bigger the primary mirror (reflector) or objective (refractor), the more you can capture. It's that simple. Generally, big telescopes are more expensive than small ones. The caveat is the sophistication of the mount and tracking system. A small "go to" scope on a really stable mount will cost much more than a bigger undriven reflector. A large scope with a really good drive system and mount will be extremely expensive.

I know that all sounds rather flip, but astrophotography is an arcane subject. If you were asking someone what sort of car to buy, they might say "get a Toyota Camry" because most people would be satisfied with a Camry. However, if the you wanted to go racing, a Camry would be a very poor choice. In the astro world, you will find many racers, a few joyriders, and almost no commuters. I know a lot of astro photo enthusiasts. Most of them are now well into the five figure range on dollars spent for their imaging rigs. And every one I know is lusting after a bigger scope, a more sensitive CCD, or a custom worm gear drive in their mount, etc. Astrophotography can be a lot like the Dark Side of the Force in the Star Wars movies: Once you start down that path, forever will it rule your destiny.

Assuming you want to stick with a DSLR, rather than some sort of specialized astro CCD rig, your choices will be constrained quite a bit. A DSLR is too big and heavy to work well with a small scope (or more accurately, the drive systems that come with small scopes), but has a sensor that is too small for the really big, specialized imaging rigs. So you'd probably be best served by a mid-size telescope with a solid mount and a good drive. A good choice might be an 8" Schmidt-Cassegrain from one of the big manufacturers (Meade or Celestron). Meade also has a nice 8" Schmidt-Newtonian scope that is a great platform for a DSLR. It's an f/4, vs. the f/10 of the Schmidt-Cassegrains, meaning your exposures can be much shorter (a Very Good Thing for astro - trust me). By the time you're done with the scope, the required adapters, a couple good eyepieces, etc., you'll be into it for $2000 and up for that kind of rig.

As bill t. says though, there's no reason you can't start out with just your camera and a decent prime lens. People cobble up effective little gadgets for doing long duration exposures without a drive. They make some pretty fantastic wide angle views of the Milky Way, etc. I recommend you look for a book called "Star Ware" which can be found in most large bookstores, and many outlets on the net. It lays out the basics of what's needed for any of the major types of astronomy hobby fields. That would be a really good introduction to the whole topic, without spending much money.

[thecyclists]

For starts just cobble your camera onto a telescope with a drive motor and try some long exposures through the regular camera lens, not the telescope optics.  Better hurry, we're rapidly loosing the Summer Milky Way which is an astro-photographer's dream come true.  No more majestic sight than the old Milky Way sticking up vertically from the southern horizon.  No need for special equipment, star trails are nice too.  Point your camera at Polaris for some great star rings.

I got a 500 mm 4 L. Would it do the work if used with a drive motor? And what kind of drive do I need?

[bill t.]

Some guys are using cheap motorized telescope mounts to carry a DSLR for timelapse.  Should also work for astrophotography!

Take a look at this.  Haven't done it myself.  The motors in these things aren't all that strong so the main issue would be getting your camera + lens balanced well so the center of weight was near the center of the rotation axes.  Might want to have the center of balance shifted just a little forward or backward from the "perfect" point to take up any backlash.

http://www.youtube.com/watch?v=Ni89TBOTCUA

You need to mount the contraption "equatorial style" with azimuth (left right) axis tilted on the support to an angle equal to your latitude.  The axis of the left right rotation should point to Polaris.  If you use the alt-azimuth orientation (with the left-right axis pointing straight up) you will get some star streaking around the center of the image for exposures longer than a couple minutes.

[DaveCurtis]

You are probably best to ask in an Astrophotography forum

I'm using a Meade LX200 12" and a 1DSM3.

First of all DSLRs aren't the best choice for astrophotography. They are fine if you already have one but I wouldn't buy one "to do astrophotography".
The main problem is they don't record HII light very well. (pretty red nebula) The IR filter in the DSLR creeps into the red and filters a large portion of it out.

If you can afford one buy a dedicated astro CCD camera.

Telescopes. Well the new high res cameras really take the optics to task. Depending on what kind of objects you want to image I would suggest looking at the new fast high quality refractors that have popped up in recent years.

[agavephoto]

I have done a fair bit of astrophotography, and I hope I can offer some insight, too.

I think the astro-CCD vs. a DSLR can really go either way: it all depends on what you want to do really.

IF you want to end up doing actual research with your setup, an astro-CCD is the way to go. DSLR research can be done, but the bayer matrix in front of the sensor greatly increases your workload to get useful data out of it. One has a lot more work and planning to get a good colour astro-CCD shot . . . since one must take separate photographs for R, G, and B to get colour. There are some full colour astro-CCD's out there, but do the research before buying it. Those will need power from significant batteries vs. what you need for a DSLR.

For just pretty photographs, I would honestly say a modern DSLR can be not only a good choice, but a great one. More than one company will modify DSLR cameras to completely remove the IR filter, or replace it with one that allows a LOT more of the deep red hydrogen alpha light to reach the sensor. At least one company also modifies the DSLR's to  include a cold finger under the sensor which GREATLY reduces overall noise. http://www.centralds.net for more information if you care to go that route. Post processing can be half the battle, and there are lots of good software packages dedicated just to astrophotography.

That said, you can do amazingly good work with just a DSLR and lens on an equatorial mount that will track the sky.

As an example, this shot is straight from my camera (which has NOT been modified, btw) . . . meaning no dark frame reduction (LENR was OFF), no colour corrections, and no levels adjustment: just a resize and a conversion to JPEG. This is the full frame using a 200mm lens. I think I can get a result I'm really proud of with some processing . . . but I'm pretty happy to start with since this is straight from the camera!

[attachment=16272:M20_M8.jpg]

Your 500mm lens will work on a tracking mount as long as the mount can handle the weight. The better the mount, the more wind you will also be able to deal with before it becomes an problem, too. I would advise starting out with wide angle to low telephoto lenses as you learn how to properly align a tracking mount. The longer the focal length, the more apparent tracking error will be.

Hope this adds something helpful to your thoughts.

[PierreVandevenne]

Anyone that has experience with astro-photo?

What I'm looking for are other users experience with using dSLR on a telescope and opinions on which telescope to buy.

BTW - I got Canon dSLR (but I guess all dSLRs can be used).

Here is a shot I took last week of the Andormeda Galaxy. (colour/greyscale/procesessed for punch)

http://www.datarescue.com/life/kepler/20090823/

The camera used was a Canon 40D with a 520mm 2.7 optical train, from my suburban backyard in Belgian (very very poor skies).

A few pointers

- Canon cameras are great choices for astrophotography.
- you should shoot RAW at all times.
- while the cameras have an optimal ISO, especially as far as read noise is concerned, if you shoot RAW and do a proper calibration, you don't really care. I've used 100 and 1600 with roughly equivalent results.
- most deep sky objects are dim. You'll need to take long exposures, 5 mins per shot is a good choice.
- you'll need to take bias and equivalent dark frames wich you will average and then substract from the individual shots.
- you'll have to align and stack your shots to increase the SNR

A very good and easy to use program for this purpose is DeepSkyStacker 3.3

As far as practical issues are concerned

- you'll need a very good mount, or at least a mount you can guide accurately.
- if you shoot with a DSLR and a relatively large sensor, you'll need a decent optical system.
- if you spend $10K plus on the mount, you can probably do 5 mins unguided exposures (that depends on the focal length of course). If you have a dark sky, you can do really nice things with smallish lenses on a primitive mount.
- if you have an average mount, you'll have to guide.

There's really a lot to say about this field. The forums of www.cloudynights.com are a very good place to start. There's also a very good intro to "photon counting" by Craig Stark on the front page.

Enjoy!

[agavephoto]

- if you spend $10K plus on the mount, you can probably do 5 mins unguided exposures (that depends on the focal length of course). If you have a dark sky, you can do really nice things with smallish lenses on a primitive mount.

I would add that one doesn't have to spend NEARLY $10K+ on a mount to get good tracking for 5 minutes or longer unguided.  

[PierreVandevenne]

I would add that one doesn't have to spend NEARLY $10K+ on a mount to get good tracking for 5 minutes or longer unguided.

Depends on what you aim for and your focal length. Sub arc second tracking is generally what you want and what you get with guiding, but you can get away with 2" precision.

A perfectly aligned paramount will get you there, with PEC, for about 14500$ plus accessories. There are other choices from Takahashi or Astro-Physics.

http://www.bisque.com/sc/shops/store/Hardw...aramountME.aspx

My current Vixen Atlux (around 5000 EUR) will get +/- 3" unguided when its PEC has been trained. At 550 mm focal length, around 2" per pixel you'll get a drift of 3 pixels if everything else is perfect.
For example, this assumes of course that you are aligned with 1' of the true pole. This level of precision is, unfortunately, unacceptable.

Which specific mount do you use or recommend that provides "good" unguided tracking for 5 minutes or longer? Or what do you define as good tracking?

Anyway, here is a shot of the area you imaged earlier, taken through an 80/400 refractor, with a guided mount.

http://www.astromatt.com/NebulaPages/Images/M8+M20+More.jpg

[agavephoto]

Depends on what you aim for and your focal length. Sub arc second tracking is generally what you want and what you get with guiding, but you can get away with 2" precision.

A perfectly aligned paramount will get you there, with PEC, for about 14500$ plus accessories. There are other choices from Takahashi or Astro-Physics.

http://www.bisque.com/sc/shops/store/Hardw...aramountME.aspx

My current Vixen Atlux (around 5000 EUR) will get +/- 3" unguided when its PEC has been trained. At 550 mm focal length, around 2" per pixel you'll get a drift of 3 pixels if everything else is perfect.
For example, this assumes of course that you are aligned with 1' of the true pole. This level of precision is, unfortunately, unacceptable.

Which specific mount do you use or recommend that provides "good" unguided tracking for 5 minutes or longer? Or what do you define as good tracking?

Anyway, here is a shot of the area you imaged earlier, taken through an 80/400 refractor, with a guided mount.

http://www.astromatt.com/NebulaPages/Images/M8+M20+More.jpg

Hahaha, apparently my comment offended you. It was not intended to suggest spending lots of money for better equipment is bad, unjustifiable, or the wrong way to end up going if so desired. My post was to the OP to show what can be done with pretty simple means and to show what a result may look like straight from the camera as it most likely won't look like your processed images or my processed images do. Posting that isn't what I view this thread to be about.

My personal mounts of choice are from Takahashi, though my posted image was not taken using one. I would actually very loosely define good tracking to mean round stars in the resulting image. Yes, this will be dependent on focal length, exposure times, and even the environmental conditions like wind and seeing. The desired photo and tools used on the mount should dictate how big the mount should be and how well it needs to track.

I am quite familiar with the Paramount ME: I've used around 20 of them with scopes ranging from 4" APO's to a 20" RCOS. It is indeed capable of good work, too.

I see some good astrophotography on the web . . . not all of these people are using $10K+ mounts.

Why post somebody's image of the same part of the sky? Was that supposed to be some sort of put down to me? I stated my single image was literally out of camera, and the other image is processed from many images.

And just for the record, the image from the person's site you linked to was using a Meade LX200 w/ super wedge as the mount . . . and those are well below $10K (even for the whole telescope and mount set!). Were you pointing out that image as unacceptable because it didn't cost enough to track well? That was also using a CCD camera dedicated for astrophotography; the OP pretty clearly stated a desire to use a DSLR.

[thecyclists]

One of the models I have been looking at is a Sky-Watcher  100 ED Pro with a HEQ-5 SynScan. There is also a better one (120 ED Pro).

A EOS adapter can be bought to both models.

Any comments on this models?