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02-23-2014, 09:04 PM - 5 Likes   #1
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Basic astrophotography for peasants.

Yes, as in the poor working class (that's me) who have zero chance of affording any fast lenses other than a 50mm and will never see a fancy moving star tracking mount or extra software or even a good telescope with an adapter.

This is more of an educational comment (by an uneducated commenter) to bump others ahead based on my fumbling trial and error with frozen fingers rather than a question, but if anyone wants to add their own 2 cents all is welcome. There are many sites on astrophotography but most of them seem to be how to do it properly with all the right gear and tend to be really long.
I can tell you this won't lead to any really cool shots, those take fancy stacking and tracking for the most part.

I got bored and wondered what your average person without expensive lenses could do taking pictures of stars and whatnot. This is for stuff other than the moon which is far brighter and a totally different thing to do.

The best I came up with was taking my used K5 with its excellent high ISO ($390), my Pentax A50 1.4 with square hood (frequently under $150 if you wait and watch), my cheap tripod ($50), and heading out into the freezing dark. All stuff most of us have already.
I do have the advantage of being fairly far from a major city, though there is still sky light from several towns and its not true rural darkness. I can't actually clearly see the milky way here which I have been able to from other places farther out.

What I found:
Shoot it in raw and edit it in the program that comes with the camera (PDCU4 for me), I would think astrophotography baffles the auto corrections during JPEG conversion. In the software which I don't know a thing about I moved the +/- (black ball and white ball picture) slider 2 notches to the right and the half black half white circle slider below it full right as my only edits, I wanna say it was contrast and brightness but the idiot who designed that horrible software didn't even label the buttons. This got rid of the high ISO sky glow and then brought back the stars without blowing them into light blooms. It did dim out some of the weakest stars (there were a crap ton) I also unchecked all three noise reduction boxes.

ISO 3200 seems to work best on a K5 for max light without fuzzing everything out.

I had to stop my F1.4 lens down to at least F2 or I got nothing but light blooms, I may have gone slightly more in the example pic, exif is all there. That means that a cheap 50mm F2 would be too slow and the F1.7 would be marginal. Stick with the A series as you can read the back lit top LCD to see aperture among other settings and use the wheels to adjust settings. Fumbling with an M lens in the dark would seriously try my patience, especially in the cold since you can operate the front and rear dials with thick gloves (ISO button not so easily but it can be done).
Also with a lens that fast and the stock focusing screen I was able to use the normal viewfinder to see what was in the frame, that was after constantly blinding myself with the top LCD and chimping on the rear screen to see what I got. I have heard others say that is not possible. Dunno what live view would have shown. It really helps to know your camera well enough to operate it in the dark by feel.

Shutter speed was a bother to decide on and I settled on 6 seconds as the max with my 50mm without the stars visibly elongating too much but still getting a long enough exposure to see something.

My cheap tripod works fine, but I quickly discovered that when the angle is cranked way up the tripod creeps almost imperceptibly on occasion, so I had to make sure the tensioner knob was properly tight.

Chimp a whole lot and use the rear wheel to zoom in until you can clearly see if the individual points of light are stretched at all, that's how I caught the tripod slipping issue which I thought was just earth rotation at first (till I realized that would require a 90 degree earth axis shift), and judged the limits for various settings.

Here is the rather not impressive shot I ended up with, I just picked the brightest constellation that didn't have trees in the way which happened to be Orion. That also happens to be the only constellation other than the big dipper I can identify thanks to his belt. This is only part of the original image, but if I shrank the full image down to the forum size you wouldn't be able to see anything. Too bad because things like Orion's red star head got cut out.
I kept one neat thing in the crop, 2 satellites crossing each others paths (one is really faint), there is a ton of traffic up there you can't see with your eyes. I think better editing on color among other things from the DNG would help.




Last edited by PPPPPP42; 02-25-2014 at 06:32 PM.
02-23-2014, 09:23 PM   #2
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Good work for basic sky shooting! It is amazing/sad just how often a man-made streak passes through my field of view.
And if your tripod sags too often, a concrete slab with a brick to point the camera skyward is quite stable, and nearly as cheap as many tripods
02-23-2014, 10:00 PM   #3
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Congratulations. Your photo is good. And your post too.
02-24-2014, 05:01 AM   #4
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Nice post, nice photo. Thanks for your elaboration, for me as a(nother) beginner your post is most useful!

02-24-2014, 09:13 AM - 1 Like   #5
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Thanks all.
Some bricks would indeed be cheaper than the tripod but I didn't want to lay in the snow and it worked fine when I tightened it properly, it has probably been slipping in all my shots and I just didn't notice clearly.

I forgot to mention I just left the camera on infinity focus as it seemed rather obvious but you never know. A camera lens with a questionable infinity would have issues with this then I guess. I have actually had this lens completely apart to fix a lumpy rough focus after it want crashing into concrete from a toppled tripod on my K20D and had to reset focus myself with distant power lines, but it seems to be correct (I think). Its possible the lens isn't perfect any more and a person could shoot slightly wider open with a better copy.

If I were rich I would love to try this with the 50mm 1.2 or the 135mm F1.8 (especially on that nebula in the pic). I have heard of people using the much more affordable 135mm F2.8 but I think they use that more for stacking as its wide open setting is slower than what I took the above pic at. I will try other lenses on brighter stuff to see if I can see anything with a longer focal length (105 end of my A35-105 F3.5), but I am not especially hopeful without software stacking help or something to track the stars through a longer exposure. Even 6 seconds might be too long with double the focal length which I would guess shows even slight movement better. I also want to try the moon next time its around though that's kinda been done to death with normal lenses.

You can't really see it on this crop, but another odd thing that shows up clearly when you are trying to get single points of light in focus all across the frame is the fact that towards the edges of the frame the stars stretch outwards towards the edge slightly (almost all appear to be moving away from the center) even when the center area is perfectly clear. Even with a good lens like this one I guess that's how edge distortion shows up or something. You don't really notice it in normal photos and I suppose you can't even see it on these until you zoom in at least somewhat. At first I thought it was just the slight star movement, but its too radial a pattern and the center area doesn't seem to show it. I can actually zoom in and scroll up one edge and tell you exactly when I am at the middle of the edge by the angle the star is stretched at. Not really a big deal since most things with a 50mm are wide enough to chomp out the middle and just use that for posting it online, but it might matter on high magnification stuff where it fills the frame.
02-24-2014, 12:01 PM   #6
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Those long star at the edge come from an aberation called coma (coma means comet in latin). So, when the stars look like comets, you have that aberation. I tried with Pentax M 50mm f2, wide open and it has coma. I close it to f4, and the coma was almost gone. At f5,6, there was no coma at al.

One friend of mine has a 50mm f1.2. Not a Pentax, something else, but he told me that he can't use it wide open from the same cause.

A cheap tracking system for this can be made from an old mechanical clock. Coupling the hourly axis to another solid - built by you - axis by a 1/2 reducer, put it with this axis as good is posible in the direction of the Pole Star, and you have a cheap equatorial mount. Of course, probably you will cannot make an hour long exposure. But much longer than 6 seconds, for sure.
02-24-2014, 09:23 PM   #7
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Thanks for the explanation of coma aberration, I had heard of it but didn't know what it looked like till now. I will experiment with stopping down a bit more next time. I didn't know stopping down helped with coma.
You really have to zoom in to see it at F2.2 (what I took the above picture at) with the lens at F1.4 it turned all the stars into fuzzy blooms of light which was far worse. I just assumed that was normal but if not the lens might have gotten banged around harder than I thought when I toppled it over a long time ago.
I think the main advantage to a F1.2 lens would be that even my max of F1.4 would be stopped down one stop for that lens.

That equatorial mount sounds very interesting I will have to try to look it up.
02-24-2014, 09:34 PM   #8
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QuoteOriginally posted by PPPPPP42 Quote
Yes, as in the poor working class (that's me) who have zero chance of affording any fast lenses other than a 50mm and will never see a fancy moving star tracking mount or extra software or even a good telescope with an adapter.


Awesome pics , great pointers and lots of inspiration....

02-25-2014, 03:57 PM   #9
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Nice image. You captured the Flame nebula also, half-way up from M42 at app.11 o`clock.
http://http://en.wikipedia.org/wiki/Flame_Nebula
You really should try the DeepSkyStacker.
02-25-2014, 06:56 PM   #10
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I had no idea the flame nebula existed (or that the Orion nebula is called M42) until you pointed it out. Its odd that in other pictures online it seems to be surrounding that one belt star, while the most visible part in mine is up and to the left. Its more visible in some of my other pictures now that I look, but not really any better of an image.

I see deep sky stacker is free, I will be looking into that.

If this keeps up I might someday consider an equatorial mount, still looking into building one.
I think the thing that has always prevented me from seriously investing in this stuff is the atmosphere being in the way to make everything all fuzzy even with top equipment. The best will always be seriously handicapped.
Maybe I need to move to rural Colorado or something for more dark and less atmosphere above me.
02-26-2014, 08:44 AM   #11
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You might want to consider building a barn door tracker. They can be built pretty cheaply, and are very effective.
The tracker can be mounted to a 4x4 in the ground instead of on a tripod. That keeps one from having to spend big bucks on a super duty tripod to start out.
02-26-2014, 06:04 PM   #12
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+1 on the barn-door.
2 straight pieces of wood, nice and tight piano-hinge and a 1/4-20 screw with a handle, 11.47" from the hinge-pin, will get you started, as far as compensating for earths rotation goes. You will need other bits to get the camera mounted and pointed.

Last edited by Ex Finn.; 02-26-2014 at 06:12 PM.
02-26-2014, 08:48 PM   #13
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I had actually look up the plans for the barn door which had another odd name too as i recall. It seemed a bit crude to operate both accurately and smoothly without creating vibration in the camera since you have to keep turning a bolt to make it work.

I even considered that old clock idea, but the complexity of the mount and building it heavy enough so the weight of the camera and lens wouldn't throw the timing way off sounds like a headache.

Still reading up on different ideas when I have time.
02-27-2014, 07:45 AM   #14
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They are far from crude. When turned as required, there will be no vibration.
I have built several with and without clock drives. I never spent more than $20.00.
The threaded rod should be run back and forth several times to be sure no crud in the threads cause a hang up though.
When using a 50mm lens, the rod does not have to be turned at a perfect speed. Advancing the rod every ten seconds will suffice.
02-27-2014, 04:50 PM   #15
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I suppose I will have to give it a shot.

This seems to be a pretty clear picture of whats involved. I will have to get a tall ball tripod head, seems the most practical way to do that part. I do have an old non removable head aluminum tripod that will probably work well for the base mount though.
A Beginner's Guide to DSLR Astrophotography
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