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Beginner's Astrophotography: Can I use my unmodified DSLR?
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Beginner's Astrophotography: Can I use my unmodified DSLR?
It is often recommended to modify DSLR's for deep sky photography. It may be one of the first topics a beginner comes across and sometimes the recommendation sounds like modding is an absolute necessity. There are good reasons not to do it, for example the camera is used for daytime photography as well or the budget does not allow either to have an existing camera modified or get a modified one. I don't want to go deeper into it. I'm also not opposed to modified cameras. I just would like to show what can be done with an unmodded relatively low priced DSLR if modding is not an option. All images have been taken from Germany under Bortle 4-5 skies from my backyard with an unmodified Canon T3i or T7i. Theses are sold under the name 600D and 800D respectively in Europe.
Near Earth Objects
Any object in close proximity to our home planet is a pure broadband object. Our natural satellite the moon is one and it can be imaged with a telephoto lens from a static tripod.
The Moon. Canon T3i, Sigma 50-500 at f/8, 1/80sec, ISO 100, single image
Taking a photo of the international space station is demanding and requires a long focal length, much longer than what was to my disposal. A modified camera however is neither required nor beneficial.
ISS. Canon T7i, GSO RC8 at f/6, 1/2000sec, ISO 400, 7 images
Comets light up and develop the fantastic tales when they are close to our sun. They too do not benefit from a modification.
Comet Neowise 2020.
Canon T7i, TS 65mm Imaging Star, f/6.5, 40x30sec, ISO 400
Star clusters reside near or in our own galaxy. Older globular clusters contain old yellow stars that are not burning hot enough to make hydrogen glow. This holds for all globular clusters in the Messier catalog.
M13. Canon T3i, GSO RC8 at f/6, 29x2min, ISO 800
Some open clusters are located in hydrogen clouds and make the cloud glow red. We will see this in a bit. Others are not. The famous Pleiades reside in a blue reflection nebula that does not benefit from a modification either.
M45. Canon T7i, TS 65mm Imaging Star, f/6.5, 19x4min, ISO 400
The Double Cluster in Perseus comes without any nebulosity and little variation in star color. Still many regard it as one of the most beautiful sights in our night sky.
h and Chi in Perseus.
Canon T7i, TS 65mm Imaging Star, f/6.5, 31x4min, ISO 400
Galaxies consist of stars mainly but galaxies also have star forming regions that typically show strong Ha emissions. In some cases the galaxies are so far away that it is impossible to resolve such small regions from earth. For example all the galaxies in the Coma Cluster will probably have Ha regions but we cannot resolve them.
The Coma Cluster. Canon T7i, GSO RC8 at f/6, 158x5min, ISO 400
If a galaxy is nearby the Ha regions can be resolved. They show up as pink dots in the spiral arms. When imaged with an unmodified camera these dots are blue. This does not necessarily ruin the image. Galaxies often show plenty of color in broadband. The stars near the center are the oldest. Only if a star burns at low temperatures it can become old thus the center is often a yellow or golden color. New stars are formed in the spiral arms in areas of high density. Many of them burn hot which gives the spiral arms a blue color. Between the stars there is interstellar dust that shows up as brown clouds. So even without the Ha regions the images do not suffer from lack of color.
M51 and NGC 5194. Canon T7i, GSO RC8 at f/6, 88x7min, ISO 400
M101 and M33 are among the largest and brightest galaxies. Thus they are suitable for beginner setups with a moderate focal length.
M101. Canon T7i, GSO RC8 at f/6, 120x5min, ISO 400
M33. Canon T7i, TS 65mm Imaging Star, f/6.5, 41x5min, ISO 400
O-III emission objects
The emission line of double ionized oxygen is a blueish green or teal color. It can be picked up easily by any unmodded camera. Many emission objects are so dim that only a cooled astro camera can pick up the faint signal. But there are brighter objects. Often objects emit Ha and O-III. With an unmodded camera only little of the Ha is picked up. Unlike galaxies with only tiny parts of Ha now larger parts may be missing in the image. Does that mean you must not image it? When the central star in the Ring nebula in Lyra shows up you can be proud of what you have achieved in terms of good focus and good guiding.
M57. Canon T7i, GSO RC8 at f/6, 57x2min, ISO 400
M27. Canon T3i, GSO RC8 at f/6, 51x2min, ISO 800
Bright Ha emission objects
An unmodded camera is not totally blind at 656nm. As a rule of thumb removing the filter enhances the sensitivity by a factor of two or three depending on how the IR filter is designed. In photographic terms this is just 1 to 1.5 f-stops. There are plenty of bright Ha objects. Probably the most famous one in the northern hemisphere is the Great Orion Nebula. When imaged together with the nearby Running Man nebula an unmodded camera can even be superior because it dims the bright Orion Nebula down a bit so that the blueish running man appears brighter in the image.
M42 and Running Man.
Canon T7i, TS 65mm Imaging Star, f/6.5, 27x2min, ISO 400
But this is by far not the only emission nebula suitable for unmodded cameras. The Trifid Nebula comprises a blue reflection nebula next to a red Ha emission area.
M20. Canon T7i, GSO RC8 at f/6, 29x4min, ISO 400
Coming back to open clusters that may or may not be associated with an emission nebula. The Rosette nebula is famous example of a star cluster and a Nebula but not the only one.
Open Cluster NGC2237 and Rosette Nebula.
Canon T3i, TS 65mm Imaging Star, f/6.5, 71x2min, ISO 800
M8. Canon T7i, GSO RC8 at f/6, 43x2min, ISO 400
M16. Canon T7i, GSO RC8 at f/6, 51x2min, ISO 400
Large Ha areas in the Milky Way
This group overlaps with the last one. All the objects shown in the last section are located in the Milky Way. I decided to put the next objects in a separate group because they are so large that the images are powdered by stars. You can easily find 20,000 stars and more in one image. The size of the object allows to shoot them with a moderate telephoto lens in case you do not own a telescope. Most beginners are troubled by the amount of stars that distract from the nebulae. When the stars are reduced in size during post processing the objects show up more clearly.
Heart and Soul. Canon T7i, Askar FMA180 at f/4.5, 54x3min, ISO 200
Sadr region. Canon T7i, Askar FMA180 at f/4.5, 60x5min, ISO 200
North America Nebula.
Canon T3i, TS 65mm Imaging Star, f/6.5, 18x5min, ISO 800
You can find many of these images on my website 'elf-of-lothlorien.de'. Many of them are composite images that contain Ha data from a mono camera. These have been reprocessed for this article without the use of Ha data. Of course there are more objects suitable for unmodded cameras like dark nebulae or planets but alas I do not have any image of those.
It is perfectly possible to take decent images of the night sky with an unmodified camera. If you don't want to modify your camera for whatever reason be encouraged to use it as it is!
- F.Meiresonne, markb, hendric and 26 others like this
if someone whats to take a closer look on the image there is an html verion with links to fullHD sized images here:
clear skies and Happy New Year!
I think your images are amazing even without a modified camera.
I would be very happy with those images myself
Very nice work
Wonderful explanation and demonstration, Elf. I think it shows two things: one, how sensitive and productive "ordinary" digital cameras can be and two, how easily we can convince ourselves that unless we use the "latest and greatest and totally optimized", we won't get "good enough" results. To my mind, the results you have in this article show that for all intents and purposes, most people would likely be highly satisfied with "good enough" results on a wide range of astronomical subjects. Indeed, I suspect even expert imagers might be hard pressed to discern differences between images captured with an "ordinary" DSLR and LRGB images with high-end gear. I suspect it is much like a blind wine-tasting between bottles costing a few euros or dollars and those costing 10 times the price. Not everyone will be able to "taste" a difference and even if they do, taste is a very personal opinion. And for subjects well suited to "ordinary" DSLR capture (as you point out, lots of them available!), the image is not only created by the camera but also significantly by the post-capture processing. It reminds me of the similar discussion about golf clubs. You can buy cheap ones or ones that will set you back almost as much as top-end astrogear. But a duffer will still be a duffer with the most expensive clubs. Tiger (or Rory, or pick your favorite pro) will still beat the pants off of mere mortals using your grandfather's castoffs.
Hopefully your article will encourage those contemplating getting started in astroimaging to go ahead and use the "ordinary" DSLR that they already have, without feeling obligated to either modify it or purchase a dedicated camera. That may come later, but you have very ably demonstrated that high-qulaity results are certainly within their reach.
Well written! This article should be a must read for all beginners (like me) as there is a fair amount of hand wringing that will be obviated by the really illustrative point hits home.
I have not modded my camera yet, and probably defer that for some time now thanks to this beautifully written vote of confidence.
Thank you. I'm absolutely not opposing camera modding. I just would like to show that there is a life before the mod. I'd also like to point out that on the long run the question is not whether or not to modify the DSLR. The question is whether to go for a modded or for an OSC astro or for a mono astro camera. The mono can be used to take Ha only and mix it into the color data taken with the DSLR or OSC. One needs to know all options to make the right decision. It often appears like using an unmodded camera isn't an option. That's just not true. Also it often sounds like the only way to use a mono is LRGB and narrowband. It is perfectly fine to use a mono for Ha only without a filter wheel and an OSC or DSLR to capture all the colors in one go. It's all about knowing the options.
Thanks for the article and the link. Beautiful images on that webpage.
I both bookmarked and printed it, as inspiration and also a really nice target list to point the scope at.
Love your article! I am one of the newbies to astrophotography and am still trying to figure out the details for photographing DSOs. Until I get the scope, auto guiding, ISO speed and exposure times right with my unmodded Nikon D750, I should not splurge on a dedicated CCD/CMOS camera for the purpose. Your article has given me hope that I can do a lot with my existing setup! Thanks for posting!
Yes, you can do a lot with your existing setup. The trick for a good first image is to pick an object that is large and bright. Going to a dark place helps much more than any fine tuning of settings. The D750 can be operated at low ISOs. I'd use ISO 400. Ask other users what they do. For exposure time refer to this table:
You have to refer to the black numbers and multiply by 3. If you don't know what Bortle scale you have clearoutside.com will give you an estimation. Very likely your first processed image will not look like a Hubble image. Beginners cannot know if that is caused by flaws in the data or lack of processing skills. Thus I strongly recommend you upload your first stack to dropbox or Google drive and send a link in the forum. Friendly people will take a look at your data and give you feedback. Looking forward to your first image!
Possibly because they have plenty of time to think up good stories
Nice comet pic
Ooooops! Spelling is not my strong side.
Thanks for the tips! In early Nov 2020, I photographed Orion Nebula wide field with my 102mm f/7 refractor at ISO 125 for 30s and it turned out pretty okay for my first try. I can't seem to upload it to my Cloudynights account or this article, to get feedback, but the stars seem far from pinpoint when magnified. My experience with Bahtinov masks is not great and I can't seem to get good focus with the one that I have. But now that I have a better idea about the parameters to shoot with, I'll give that a try the next time the skies are clear near Seattle.
We are getting off topic. As it is my post I dare:
Bahtinov masks work great for long focal length scopes. With 1000mm + you only need something like 10 bars. If you go for a shorter focal length you need a mask with more and smaller bars. In the 200mm region and below they are no longer helpful. Without a B-mask use live view on the camera display and go for 10x mag and reduce exposure time until the star is dim. That is like 1/500s or so. I minimum change in focus makes it disappear. You can focus very accurate to maximum intensity with this method for a short focal length. For a longer focal length you have to correct focus now and then because a few degrees temperature change can bring you out of focus. I refocus after 1 hours and after that when the temperature has change more than 5°C with my longer ones. The short one does not need refocus at all.
Informative and professional.
Wanted to ask you, why didn't you add a link to a good site that explains what the modding is all about.
Well, the topic of the article is what you can do with an unmodded camera. Isn't a link to modding somewhat misplaced here? Anyway, I do have a link to an excellent video that shows the process of modding:
As a newbie, this is very interesting to me. Are these pictures achieved by using a camera mounted on a drive to track the object?
Great pics by the way!
Nicely written article with excellent examples of what can be achieved with an unmodded DSLR.
A. Brott, the images are taken on a German Equatorial Mount, a Skywatcher EQ6-R with auto guiding. There is very little you can do from a static tripod.For deep sky objects you need a mount or a tracker.
Thanks for the article! I was surprised that even a traditionally "hard" subject like the Horsehead comes out pretty well with an unmodified camera. These are from my first real attempt at DSOs with my setup I bought years ago. https://hendric.smug...rop/i-cFb7P7W/A
nice images. Under dark skies you have a good chance to see dim objects. Alas many of us live under light polluted skies.
Thank you for the excellent explanations of why many objects do not require modding. You are quite correct that modding is not required for great astrophotos. I think that dark skies, good focus, and good tracking/autoguiding are more important. In urban skies however, I have had to resort to narrow band filters (H-alpha and OIII), and then H-alpha sensitivity (increased several fold by modding) becomes more important.
great article. I have used an unmodded Canon 7D Mark II for awhile and am quite pleased with its results on H alpha, even without using a CLS clip in filter. Will I ever modify my camera? No, I will not. I primarily use camera lenses, and they are optimized for unmodified cameras.
Thanks for this encouraging article! Now I won't be overly concerned with my stock DSLR. And these images you share in the post become my next targets to try out.
On a different note, are there any negative effects in imaging celestial objects, other than for daytime photography, which DSLR modification (IR cut filter removal) could bring. I don't have a camera lens for daytime photos, so I'm still wondering if I should mod my DSLR just for astrophotography. But I don't hope to see problems this may bring which I have to compensate with more accessories, software, or modification.
There is a known issue. Modern lenses have electronics for autofocus and stabilization inside. The electronics glows in infrared. In some cases you see a flare in the image. In this thread a few lenses known for this problem are listed.
The solution is to go for fully manual lenses. Some recommend not to fully attach the lens so that the contacts do not engage. In that case you cannot set the aperture and there is a chance of dropping the lens. As telescopes are pure manual devices you won't run into that trouble with a telescope.
If you replace the camera filter with a different filter you'll be fine. If you remove the IR filter without a replacement the optical length changes. That is because in glass the effective way appears to be about 1/3 shorter. As a result you can no longer focus on infinity with some lenses. If the lens has enough travel beyond infinity it works. Again, no problem with a telescope. If you go for a full spectrum mod the chromatic aberration of UV and IR will blur your image when you have a refractor. You have to use a clear L filter (UV/IR blocker) in that case. In full spectrum mods you loose the sensor cleaning in Canon models. Don't know about other brands. The mod may or may not void warranty depending on your local law. Some professional modders have an agreement with some brands that warranty does not void. If you mod an old camera this is no longer a problem. If you try the mod yourself you can ruin the camera.
I recommend you get a used modded camera or get a new one from a professional store. Use it with telescopes only and you have no trouble.