Uses of a DSLR for astrophotography

Started Nov 3, 2012 | Discussions
Astrophotographer 10
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Uses of a DSLR for astrophotography
Nov 3, 2012

I am deeply into astrophotography and have been for about 8 years. Generally speaking if you get deeper into astrophotography you will find dedicated astro CCD cameras that are very expensive, expensive telescopes, mounts, filters, filter wheels etc etc.

But DSLRs play a role in this field that dedicated astro cameras have trouble filling and also are very good for getting great images early on.

DSLRs are great for:

1. Widefield nightscapes.

2. Night sky time lapses.

3. Imaging of brighter objects like globular clusters of stars.

They are not well suited to long exposure deep sky objects without being modified but still can do quite well up to a point.

14mm lenses are great for nightscape images of Milky Way, etc. Also for time lapses up to 35mm.

Vixen makes a very clever portable small tracking device called Polarie. It enables you to take longer than 30 second 14mm widefield images at night or use it to create a panning effect for time lapses. It costs about $500.

Most telescope manufacturers have adapters to make various DSLRs fit onto their telescopes (usually called t-thread adapters).

For urban imagers faced with light pollution you'll need a light pollution filter. Hutech sells a range of these and they are reasonably effective.

Deep sky imaging with DSLR usually requires a modified DSLR. Canon 350D modified was popular and a good 2nd hand one can be picked up for around $350. astromart.com is a place to find these things.

The usual UV/IR block filter blocks H alpha light emissions (a pink/red band of light). Nebula unfortunately emit in this band so your standard DSLR will not pick that up so well. Modified cameras (usually Canon EOS's) are very sensitive to that band and improve about 4 or 5X with a different filter installed - often a Baader, now there is an Astrodon replacement filter.

The original Canon 20Da was a model that worked in both daylight and astro imaging. Recently Canon released a 60Da model that is still current.

The mount is one of the most important parts of the setup as you will discover the stars whilst appearing motionless are moving rather fast as the earth rotates. Also being dark they require long exposures. So now we are imaging a dim object that is moving fairly quickly (15 degrees per hour).

Hence a highly accurate mount is going to be the main ingredient to happy imaging. Never skimp on the mount as elongated stars will be your constant battle. Getting round stars is step one. The rest is easy.

Feel free to ask me any question. I have been doing this a long time and know a lot about it and am happy to share my expertise.

Greg

Canon EOS 20Da Canon EOS 350D (EOS Digital Rebel XT / EOS Kiss Digital N) Canon EOS 60Da
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Hotphotons
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Re: Uses of a DSLR for astrophotography
In reply to Astrophotographer 10, Nov 4, 2012

Vixen makes a very clever portable small tracking device called Polarie. It enables you to take longer than 30 second 14mm widefield images at night or use it to create a panning effect for time lapses. It costs about $500.

Most telescope manufacturers have adapters to make various DSLRs fit onto their telescopes (usually called t-thread adapters).

For urban imagers faced with light pollution you'll need a light pollution filter. Hutech sells a range of these and they are reasonably effective.


Greg

Can you elaborate a bit on the light pollution filter? I have the Polarie tracker and have used it a bit but I am in a city and have a lot of light pollution so images have an overall orange glow to them.

I have successfully used a laser to align to the polar star and have captured good round stars with 1 minute exposures but the light pollution spoils the image.

Also what post processing can you do to eliminate the orange glow?

Thanks

Paul

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Astrophotographer 10
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Re: Uses of a DSLR for astrophotography
In reply to Hotphotons, Nov 4, 2012

Paul,

LPS filter by Hutech (IDAS) gets lots of recommendations  or CLS filter from Astronomik.

Astrodon may have some  and perhaps Baader as well.

The red glow is amp glow. Use long exposure noise reduction on all your night shots and it gets removed in camera.

Greg.

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DuncanDovovan
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Re: Uses of a DSLR for astrophotography
In reply to Astrophotographer 10, Nov 4, 2012

Astrophotographer 10 wrote:

Paul,

LPS filter by Hutech (IDAS) gets lots of recommendations or CLS filter from Astronomik.

Astrodon may have some and perhaps Baader as well.

The red glow is amp glow. Use long exposure noise reduction on all your night shots and it gets removed in camera.

Greg.

Do these filters only work properly, when you have a DSLR with the IR filter removed?

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Hotphotons
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Re: Uses of a DSLR for astrophotography
In reply to Astrophotographer 10, Nov 4, 2012

Astrophotographer 10 wrote:

Paul,

LPS filter by Hutech (IDAS) gets lots of recommendations or CLS filter from Astronomik.

Astrodon may have some and perhaps Baader as well.

The red glow is amp glow. Use long exposure noise reduction on all your night shots and it gets removed in camera.

Greg.

Thanks Greg, I forgot about the in camera noise reduction I will try that.

How would light pollution show up in an image what would it look like?

Would you be able to give a link to one of the filters?

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Astrophotographer 10
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Re: Uses of a DSLR for astrophotography
In reply to DuncanDovovan, Nov 5, 2012

No they work with standard cameras.

Greg.

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Astrophotographer 10
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Re: Uses of a DSLR for astrophotography
In reply to Hotphotons, Nov 5, 2012

Light pollutions shows up as too bright a sky. Or a yellow glow coming up from the horizon.

http://www.sciencecenter.net/hutech/idas/lps.htm  for Light pollution filters.

Greg

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allcart
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Re: Uses of a DSLR for astrophotography
In reply to Astrophotographer 10, Nov 13, 2012

Hi Greg, could you possibly try to explain the difference between canon's modiffications and the mods done by the likes of gary Honis. Is the end result the same.

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Astrophotographer 10
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Re: Uses of a DSLR for astrophotography
In reply to allcart, Nov 16, 2012

Gary Honis mod is removing the AA filter in front of the 350D, 20D type Canon's and installing a Baader UV/IR cut filter or Edmunds Optics clear glass (same thickness). 20Da, 60Da are more of a AA filter that has been tuned to allow more Ha light to pass where it is normally blocked.

I think the main difference would be the 20Da and 60Da would work fine for terrestial shots as well whereas the modded one has a bad red bias (with clear glass the red bias is very strong and makes the camera useless without a correcting filter like Xnit CC1 filter).

With the Xnite CC1 filter colour was restored to close to normal. Not sure about later Canon models for modifications as they become more complex with dust shakers etc.

Greg.

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PC Wheeler
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Re: Uses of a DSLR for astrophotography
In reply to DuncanDovovan, Nov 17, 2012

DuncanDovovan wrote:

Do these filters only work properly, when you have a DSLR with the IR filter removed?

No. Can be used in standard or modified camera. I have an Astronomik CLS clip-in LP filter for use in my Canon 60Da. Goes behind the lens, in front of the sensor. Works only with EF lenses, not with EF-s lenses (which protrude into the space required by the filter).

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PC Wheeler
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Re: Uses of a DSLR for astrophotography
In reply to Astrophotographer 10, Nov 17, 2012

Astrophotographer 10 wrote:

I think the main difference would be the 20Da and 60Da would work fine for terrestial shots as well whereas the modded one has a bad red bias (with clear glass the red bias is very strong and makes the camera useless without a correcting filter like Xnit CC1 filter).

Right. I have a 7D and a 60Da. The 60Da works fine for daytime shooting, and its articulated LCD is a real plus for AP use.

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Trollmann
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Re: Uses of a DSLR for astrophotography
In reply to PC Wheeler, Nov 18, 2012

Got myself a pair og Canon 60Da's (beeing a Sony shooter when it comes to terristial scenes), and I am very happy with the cameras. Had a SBIG ST-8300 that never worked properly, had to give up the whole damned thing.

What surprised me most with the 60Da is how well balanced the colors are for astrophotography (use AstroArt and Photoshop), and how easy it is to post process the results.

Advice to RAW Canon astrophotographers:

Use the cameras at ISO 400 to record as faint nebulosity as possible. At higher ISOs and longer exposures than about two minutes, we start losing dynamic range! Remember that the RAW images are mostly a result of total light captured, so a bit dark jpg's do not indicate disaster. The cameras are calibrated for terrestial use, not fine tuned for astronomical use. At ISO 1600 we loose about two steps dynamic range in RAW compared to ISO 400 (optimum setting) - but the image is of course boosted by gain (tweaking ISO is of course simply a function of adding gain and adjusting the contrast to best fit).

If in doubt, try for yourself with ISO 400, 800, 1600, 3200 and exposures exeeding two minutes...

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wfektar
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Re: Uses of a DSLR for astrophotography
In reply to allcart, Nov 19, 2012

allcart wrote:

Hi Greg, could you possibly try to explain the difference between canon's modiffications and the mods done by the likes of gary Honis. Is the end result the same.

You might find this interesting.

http://www.cloudynights.com/item.php?item_id=2805

To Da owners: These sound like an excellent choice for dual-duty cameras. But if you already have a general purpose camera, what do these offer that a converted camera doesn't? It seems like you could get, say, a Nex-5n with that excellent Sony sensor and convert it with a fair chunk of change to spare for the cost of a 60Da. Provided, of course, that you already have a general purpose camera.

To converted camera owners: This is really a question regarding Bayer filter throughput so it might depend a bit on specific camera, but if you went with full-spectrum, is it useful with other filters, say UV or SII?

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PC Wheeler
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Re: Uses of a DSLR for astrophotography
In reply to wfektar, Nov 19, 2012

wfektar wrote:

To Da owners: These sound like an excellent choice for dual-duty cameras. But if you already have a general purpose camera, what do these offer that a converted camera doesn't? It seems like you could get, say, a Nex-5n with that excellent Sony sensor and convert it with a fair chunk of change to spare for the cost of a 60Da. Provided, of course, that you already have a general purpose camera.

We have two Canon DSLRs because we both shoot. One is a 60Da for astro use; the other is a 7D. While I can use an EVF (have owned Sony A55 and Panny GH1/GH2) I find composing for motion (like flying birds) much faster with an OVF. My wife hates the EVF for some reason.

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PC Wheeler
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Re: Uses of a DSLR for astrophotography
In reply to Trollmann, Nov 19, 2012

Trollmann wrote:

Got myself a pair og Canon 60Da's (beeing a Sony shooter when it comes to terristial scenes), and I am very happy with the cameras.

OK, I'll bite: Why two 60Da?  Stereo astronomy?

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Trollmann
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Re: Uses of a DSLR for astrophotography
In reply to PC Wheeler, Nov 19, 2012

Have two 60Da's because I am twice as stupid as most buyers...

One is for my astro shed (love small refractors and autoguiders and pretty good mounts, so there you have one of the 60Da's - glued to the telescope).

The other one is for me and my well beeing (love to be outside in the chill of the night, so the other 60D'a is glued to my AstroTrack, which I move around my house simply to be able to aim my lenses in all the four cardinal directions - and keeping me in the lovely outdoors).

Then I can cover narrow field and wide field astrophotography every clear night (living in Norway, usually under a deck of clouds) - twice as much fun when the stars shine! Also feel privilleged to be able to own two cameras for astrophotography only...

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eyeport
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Re: Uses of a DSLR for astrophotography
In reply to Astrophotographer 10, Nov 22, 2012

Astrophotographer 10 wrote:

I am deeply into astrophotography and have been for about 8 years. Generally speaking if you get deeper into astrophotography you will find dedicated astro CCD cameras that are very expensive, expensive telescopes, mounts, filters, filter wheels etc etc.

But DSLRs play a role in this field that dedicated astro cameras have trouble filling and also are very good for getting great images early on.

DSLRs are great for:

1. Widefield nightscapes.

2. Night sky time lapses.

3. Imaging of brighter objects like globular clusters of stars.

They are not well suited to long exposure deep sky objects without being modified but still can do quite well up to a point.

14mm lenses are great for nightscape images of Milky Way, etc. Also for time lapses up to 35mm.

Vixen makes a very clever portable small tracking device called Polarie. It enables you to take longer than 30 second 14mm widefield images at night or use it to create a panning effect for time lapses. It costs about $500.

Most telescope manufacturers have adapters to make various DSLRs fit onto their telescopes (usually called t-thread adapters).

For urban imagers faced with light pollution you'll need a light pollution filter. Hutech sells a range of these and they are reasonably effective.

Deep sky imaging with DSLR usually requires a modified DSLR. Canon 350D modified was popular and a good 2nd hand one can be picked up for around $350. astromart.com is a place to find these things.

The usual UV/IR block filter blocks H alpha light emissions (a pink/red band of light). Nebula unfortunately emit in this band so your standard DSLR will not pick that up so well. Modified cameras (usually Canon EOS's) are very sensitive to that band and improve about 4 or 5X with a different filter installed - often a Baader, now there is an Astrodon replacement filter.

The original Canon 20Da was a model that worked in both daylight and astro imaging. Recently Canon released a 60Da model that is still current.

The mount is one of the most important parts of the setup as you will discover the stars whilst appearing motionless are moving rather fast as the earth rotates. Also being dark they require long exposures. So now we are imaging a dim object that is moving fairly quickly (15 degrees per hour).

Hence a highly accurate mount is going to be the main ingredient to happy imaging. Never skimp on the mount as elongated stars will be your constant battle. Getting round stars is step one. The rest is easy.

Feel free to ask me any question. I have been doing this a long time and know a lot about it and am happy to share my expertise.

Greg

Hi Greg,

I am a newbie for astrophotography and wondering about what equipments (lens/telescope, tracking amount, tripod) to get to get started. Besides doing wide sky galaxy shots I am strongly interested in deep sky. But first to get a quality sword of orion shot will make me really happy. I really appreciate your advice.

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DuncanDovovan
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Re: Uses of a DSLR for astrophotography
In reply to eyeport, Nov 22, 2012

eyeport wrote:

Astrophotographer 10 wrote:

I am deeply into astrophotography and have been for about 8 years. Generally speaking if you get deeper into astrophotography you will find dedicated astro CCD cameras that are very expensive, expensive telescopes, mounts, filters, filter wheels etc etc.

But DSLRs play a role in this field that dedicated astro cameras have trouble filling and also are very good for getting great images early on.

DSLRs are great for:

1. Widefield nightscapes.

2. Night sky time lapses.

3. Imaging of brighter objects like globular clusters of stars.

They are not well suited to long exposure deep sky objects without being modified but still can do quite well up to a point.

14mm lenses are great for nightscape images of Milky Way, etc. Also for time lapses up to 35mm.

Vixen makes a very clever portable small tracking device called Polarie. It enables you to take longer than 30 second 14mm widefield images at night or use it to create a panning effect for time lapses. It costs about $500.

Most telescope manufacturers have adapters to make various DSLRs fit onto their telescopes (usually called t-thread adapters).

For urban imagers faced with light pollution you'll need a light pollution filter. Hutech sells a range of these and they are reasonably effective.

Deep sky imaging with DSLR usually requires a modified DSLR. Canon 350D modified was popular and a good 2nd hand one can be picked up for around $350. astromart.com is a place to find these things.

The usual UV/IR block filter blocks H alpha light emissions (a pink/red band of light). Nebula unfortunately emit in this band so your standard DSLR will not pick that up so well. Modified cameras (usually Canon EOS's) are very sensitive to that band and improve about 4 or 5X with a different filter installed - often a Baader, now there is an Astrodon replacement filter.

The original Canon 20Da was a model that worked in both daylight and astro imaging. Recently Canon released a 60Da model that is still current.

The mount is one of the most important parts of the setup as you will discover the stars whilst appearing motionless are moving rather fast as the earth rotates. Also being dark they require long exposures. So now we are imaging a dim object that is moving fairly quickly (15 degrees per hour).

Hence a highly accurate mount is going to be the main ingredient to happy imaging. Never skimp on the mount as elongated stars will be your constant battle. Getting round stars is step one. The rest is easy.

Feel free to ask me any question. I have been doing this a long time and know a lot about it and am happy to share my expertise.

Greg

Hi Greg,

I am a newbie for astrophotography and wondering about what equipments (lens/telescope, tracking amount, tripod) to get to get started. Besides doing wide sky galaxy shots I am strongly interested in deep sky. But first to get a quality sword of orion shot will make me really happy. I really appreciate your advice.

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Regards,
Felix Wu
Creationheart Photography
www.creationheart.com
Canon 1Dx, Canon 5D Mk3, 16-35L II, 35L, 85L, 100L, 135L, 70-200L IS II, 580EXII x2, PWplus3 x3, ThinkTank Airport Takeoff, Thinktank Retrospective LC3, Shootsac

I'm also a beginner. I want to learn the process of long exposing and noise reduction via stacking first using tripod wide angle shots.

I've also bought a Polarie tracker, that should enable me to make longer exposures or more towards tele.

As a next step I'm considering a Celestron 11" SC telescope, that would allow me to make photos at the view piece and, but also use Hyperstar to mount the camera in front of the telescope to do wide aperture wide photos. My NEX-7 is so small, that I think it will not block the view dramatically.

But at the moment I'm trying without a telescope first. When I see the pictures here in this forum that are being made with 50mm for example, I think there is a whole landscape of things to discover.

Deep Space does not always mean telescope, it can also mean long exposure without a telescope to make faint details visible.

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I'm a peaceful person looking for clarity and harmony and willing to help. If you believe my post had the intention to harm you in some way, you are probably wrong. =;-) Please verify first before assuming something bad happened to you. I can be a bit too brief at times. =;-)

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