DSLR Questions

[Radar]

Hi People,

What modifications are needed to a DSLR for Astrophotography? Can you just get one straight off the shelf and start shooting DSO's or do they need to be modded?

Also, what other (non-essential) mods can be done? I see people doing all kinds of mods with them now.

Ta

Radar

[Noel Carboni]

No mods are strictly necessary with the latest crop, though they will cut out more of the Ha emissions than most astrophotographers would like.

There is a filter Canon mounts in front of the imager that de-emphasizes reds as a side effect of blocking infrared light, which can ruin daytime images if it comes through too strongly.

However, this is not all bad... I've seen some DYNAMITE astroimaging work done with an unmodified Canon EOS-20D, and the fact that it brings out the blues and other colors more than we see in typical astroimages helps to differentiate one's work from the crowd.

Some people remove this filter. I myself have chosen not to modify my own dSLRs. I just need a dark site to be able to go really deep now.

Here are several recent 20D shots (not done by me) that I think you might find impressive.

http://forum.ourdarkskies.com/index.php?showtopic=16468&hl=

http://forum.ourdarkskies.com/index.php?showtopic=16338&hl=

http://forum.ourdarkskies.com/index.php?showtopic=16431&hl=

http://forum.ourdarkskies.com/index.php?showtopic=16337&hl=

http://www.ourdarkskies.com/gallery2/v/Nighthound/

Besides removing/replacing the filter, other mods I've heard about are to add a cooler to the imager chip, which really digs into the camera deeply and may make it impossible to use for other than astro work. However, the dSLR images really don't have all that much noise in them, so it's not a necessity. The one thing that the Canons do that was a little difficult to deal with during image processing is that they could make banding noise in the darkest parts of an image. That's a bit less of an issue now that I have banding noise reduction actions in my set. :) If you have dark enough skies and good enough tracking that you can stretch the exposure time out to many minutes, noise is a complete non-issue. Note some of the fairly short cumulative exposure times listed in the above links.

-Noel

[Dusty]

Radar, grab yourself a Canon 350D/400D and go for it.
No need for modding it.
See how you go, I'm sure you'll love it, then as you progress you can think about doing mods to it.

Also I'd recommend using good quality lenses if you want to do piggyback imaging.

[Radar]

Hmm, okay, thanks guys. :thumbsupmate:

[h0ughy]

do yourselfa favour and get a very cheap 300d. apply the russian hack so you can get the mirror lock. should be achievable under 500. then if your feeling brave you can mod it yourself (heaps of tutorials around for this one). the 350 is another good start andthe 400 is even better noise wise. but if you can afford a 5d - get one. hunt around for a 20Da canon - older but oh so nice, but not cheap.

[Noel Carboni]

The 300D idea has merit, cost-wise, but the advancements in the sensor design between the two are significant.

I own a 10D (same sensor as 300D), and a 20D, and the 20D is by far the better astro camera. Thermal noise is much less, and long exposures are cleaner of hot pixels by quite a bit too.

I do agree with h0ughy about the 20Da. I'd have one if they only cost an arm; can't do without a leg.

-Noel

[Radar]

Cheers Houghy / Noel.

Do the numbers on DSLR's represent anything? I notice that the better cameras seem to have a higher number, Just curious if this relates to something technical.

[h0ughy]

Cheers Houghy / Noel.

Do the numbers on DSLR's represent anything? I notice that the better cameras seem to have a higher number, Just curious if this relates to something technical.

Naaa, just a product number

[Dusty]

Cheers Houghy / Noel.

Do the numbers on DSLR's represent anything? I notice that the better cameras seem to have a higher number, Just curious if this relates to something technical.
With the Canon DSLR range you'll find the old "filum repricosity" mentality.
The smaller the model number the better the camera is..........:Chessy_Smile:

[h0ughy]

With the Canon DSLR range you'll find the old "filum repricosity" mentality.
The smaller the model number the better the camera is..........:Chessy_Smile:


Thanks Mr Dusty for that information, but you just keep adding fuel on that film fettish these guys seem to have. I bet you use film too:hmm:

[Dusty]

Thanks Mr Dusty for that information, but you just keep adding fuel on that film fettish these guys seem to have. I bet you use film too:hmm:



No Sir, haven't used it since.....:hmm:...........oh boy I'm getting old, just look at my avatar. :crying23:

[Noel Carboni]

With the Canon DSLR range you'll find the old "filum repricosity" mentality.
The smaller the model number the better the camera is..........:Chessy_Smile:

That's generally accurate, if a bit oversimplified.

There are several lines of Canon brand dSLRs:

Pro models - the '1' series: 1D, 1Ds, 1D mark II, 1Ds Mark II, 1D Mark III).

Semi-pro model: 5D.

Prosumer models - the 'x0' series: D30, D60, 10D, 20D, 30D.

Entry level models - the 'xx0' series: 300D, 350D, 400D aka the digital Rebel line).

The 1Ds, 1Ds Mark II, and 5D have full frame 36mm x 24mm sensors, the 1D, 1D Mark II, and 1D Mark III have 1.3x crop 29mm x 19mm sensors, and the rest have 1.6x crop 22mm x 15mm sensors (APS-C sized).

The 20Da is externally identical to the 20D, but with a different filter over the sensor, and different software inside to attempt to facilitate both daytime shooting and astrophotography.

-Noel

[Dusty]

That's generally accurate, if a bit oversimplified.


You're absolutely right Noel, I was just having a bit of a joke. :yesplease:

The 5D and the 20Da are wonderful cameras for astro work and of course the 5D is really designed for terrestrial shots.
This model has an amazingly low noise ratio even better than the 20D series.

:thumbsupmate:

[AstroTasmania]

The big advantages with digital versus film, is of course, that you have so much control over the final result, ie, removing vignetting, pollution gradients, as well as all the other aspects of image manipulation/tweaking. A digital system is approx 10 faster than a film based system.

Film really falls down with increasing exposure of dim objects. It is a case of diminishing returns due to the "reciprocity law" failure. (Equal exposure does not result in equal density). So, Radar, maybe you are wasting 15 minutes out of every 20 you are glued to the guide scope!!!

Film emulsions designed for normal photography are designed to accept an exposure range between (approx) one second to one thousandth of a second. For astro work, special emulsions were developed, which are designed for long exposure and not very good at short exposure.

There are many articles which discus silver halide response to photons and the latent image formation as development centres on those crystals, so no need for me to expand on that here.

My move to digital has reduced my exposure to a variety of chemicals in my darkroom, which is a big plus. Some newcomers will probably ask "what is a darkroom?"

With the new full 35mm size sensors now available, achieving big print enlargements is easy. The cost of these sensors will continue to fall, it is one of the great factors with digital, over time, quality goes up and price comes down.

Clear skies...

[Radar]

Hey Shev, yeah I have read that film is slower. I look at some of the stunning images done with CCD and DSLR these days and I amazed at how short the exposures times were. Technologoy has come far to say the least.

I want to explore film a bit more though before I start learning digital. I feel I still have some travelling to do with film. Currently, I enjoy the way film feels. I also really enjoy using the old camera bodies for some reason. I don't know what it is, I just love the old equipment. :duh:

I do enjoy the prospect though of one day buying a good CCD camera. CCD is like a giant Xmas present just waiting for me under the tree. :Chessy_Smile:

[Noel Carboni]

For what it's worth, there are some amazing dedicated astro cameras that put dSLRs to shame. Keep in mind the dSLRs, while good for astrophotography, were designed for daylight photography. The dedicated astro cameras with big imagers are coming into their own, and amateurs are now producing imagery that only pro observatories could do only a few decades ago.

Also, there are monochrome and full-color cameras to consider... A monochrome camera is sensitive to a wide spectrum of light, while a color camera has the little red, green, and blue microfilters on the photosites just as a dSLR or other full-color digital camera has.

There will be those who will tell you the monochrome camera, with appropriate filter sets, is better, but it's not that simple.

In my own processing of astroimages I've come to realize that the full color cameras have some advantages. While exposure time may be longer to achieve the same level of depth, it's good to get all the planes (red, green, blue) exposed at the same time. Gradients are simpler to deal with, the exposure levels are always consistent between channels and so the color is more accurage, alignment is easier... The list goes on. And the neatest thing is that with stacking of multiple exposures and imperfect mount tracking (a given) the resolution is really just as good as with the monochrome camera.

One downside to the dedicated astro camera... They're expensive. As expensive as or even more expensive than even the best dSLRs.

By the way, a very capable model my chief collaborator uses, and which I recommend, is the Starlight Xpress SXVF-M25C full color 6 megapixel APS-C sized sensor camera.

-Noel

[AstroTasmania]

Hi Radar,

Back to your original question, check out these links, it will give you an idea of the short image times with a cheap introductory Canon 350D- modified, (XT is the USA designation for the same camera) a non modified camera lets you retain a camera for everyday use as well as astro and no waiting for the film to be processed, results posted on the web within a short time of taking the shots, important aspect re your Russian rocket debris image. first reported usually gets accredited with the discovery too.

A non modified camera passes approx 27% H-alpha, a modified one around 98%.

A future S&S Magazine will open your eyes.

http://tinyurl.com/2zl3jp

http://mail.synergyitg.com/mike/feb-07/hh-35x180-800-full-l.jpg

http://tinyurl.com/ytboxn

Clear skies...

[Radar]

Hmm?

Noel, I thought I'd already posted in response to this, but I must have forgot to press the save button. I'm easily distracted when using the net.

What exactly is an astro camera. I thought you were referring to DSLR's, but this is obviously not the case.

Hey Shev, those are awesome shots for an entry level DSLR. You are right, that an Aper should always have a DSLR on hand for those unexpected events that may pop up from time to time. I tried to capture the sperical shape of that Rocket with my Sony Cybershot, but I really didn't give myself enough time. I took some shots, but I should have changed the ISO settings, aperture and exposure time. I'm so rusty with digital at this stage. But it's an awesome avenue I have yet to take.

[Noel Carboni]

Depending on which of my posts you read, I've referred to both dSLRs and cameras specifically made for astrophotography.

There are some things about a dSLR that do not suit astrophotography well, such as a physical shutter (read: vibration), and as you might imagine there are specialty camera makers who build imagers into assemblies that are optimized for astro work.

The best thing I can do is point you to some of the web sites where specific models are described:

http://www.starlight-xpress.co.uk/SXV-M25.htm

http://www.sbig.com/sbwhtmls/online.htm

These are just two with good names, there are others.

-Noel

[Radar]

Hi Noel, in your earlier posts I thought you were referring to some other kind of camera. Like some special DSLR made for astrophotogrpahy. Now I understand. :duh:

[Johatin]

hey radar, just browsing through here.....my camera is the canon DSLR 350D..
no mods...off the shelf....and i like the results....nebula is blue-ish-green, and some red.........especially with M8....the only problem i can say i have is FOCUSING......what a chore....