What 2nd hand DSLR on tight budget?

[janoskiss]

Seeking advice on what DSLR would be good for dabbling in a bit of deep sky astrophotography. Budget is <$500, but <= $300 would be preferred.

Obviously for that money it'll have to be a relatively old second hand camera, but I have not kept up with developments since the Canon 450D/20Da were new, so I'm not sure what I can realistically expect and should be looking on such a tight budget. I'm also fairly ignorant about all the different makes and models and how wear and tear affects DSLRs (how to assess whether an old camera is still usable for astro). I know Canons are the most popular for astroph., but I haven't got a preference for any make or model. Just after best bang for buck. Camera body only would be fine.

I realise modern cameras are much better with much lower noise and better sensitivity, but I can't spend that much (even if I could get a 10x better camera for 2x the money). It's really just for a bit of fun and to gain some hands-on practical knowledge.

Thanks in advance. :)

[raymo]

You're in luck Steve, not only have DSLRs got quieter, but one of the
best of the budget level models that is eminently suitable for astrophotography falls well within your budget. You should find a used
Canon 1100D including the kit lens [or body only, if you don't need the
lens], for well under $300. Currently Canon are the most popular DSLRs
for astro because there is more software available for them than any other brand. This is changing, but will still apply for a while yet.
You might find a 1200D for under 300 as well.
raymo

[janoskiss]

Thanks for that tip raymo! I was just browsing dpreview.com and checking "completed listings" on ebay for what different cameras have been selling for. I've ruled out Nikons because they seem to demand more on the 2nd hand market than Canons of similar performance. I've just about narrowed it down to the Canon 500D and 550D but I would have missed the 1100D if you didn't mention it. That fits the bill nicely too. I don't want to over-analyse. Now it's just a matter of biding my time and waiting for a bargain to pop up. ;)

[raymo]

I'm pretty sure that the 1100 and 1200 are quieter than the 500 or 550.
raymo

[janoskiss]

I was looking at high ISO comparisons of the cameras and the 1100 seems to be somewhere between the 500 and the 550. Not sure how reliable an indicator these studio shots are of astro performance though... The 1200 is too new: no review or comparisons. I presume it's probably better than all of the rest. The specs seem on a par with the 550D.

[glend]

Any of those cameras will do the job. Obessing about high ISO is not worth bothering about as noise will go up for all if them as ISO goes up. I would not shoot with an ISO higher than 1600 on any DSLR. And if you pick a camera which is easily cooled in a future mod then you gain exceptional capability through very low noise when the sensor is cooled to near 0C. Simply darks start to equal bias/offset frames at that temperature. Remember as well that when new cameras roll out ever karger sensor pixel counts this doesn't necessarily help with astrophotography, it is the pixel size and well depth that you need to be concerned about. Very small pixels in theory give better resolution but only if your scope can provide the high contrast, low obstruction, resolving power to deliver to the sensor.
For someone stafting out in AP with a DSLR, any if the the 12.2mega pixel Canons with Liveview is a good choice, as they are cheap to acquire these days, easiky modded, and have a good pixel size at 5.2. So look from the 450D upward in the model range. Learn to do the filter model, or have it done for you, to gain a full spectrum astro camera.

[Tamtarn]

Steve, I purchased a Canon 600D three years ago new for $425 with full AU Canon warranty.
The reason I decided on the 600 over the newer model 650 was that the reviews showed that the 600 definately had less noise than the 650.
It might be a good idea to check reviews and comparisons on noise before deciding.
Barb

[jamiep]

if you can squeeze a flex screen model in (refractors especially the camera is upside down when your target is at the optimum viewing angle!) - it can be very helpful at the initial stages for framing and focusing with 10x live view.

Less of an issue if you're looking at using something like byeos that can do live view framing on the PC.

Just a thought. Most of the basic canon's though will be fine. Lots of people using 1100d's with great results bang for buck!.

[raymo]

It seems that people have cottoned on to just how good the 1100D
is/was for the price. On ebay the going price for a used one seems to be
nearly $100 more than I paid for mine new, and there's not many of them to choose from.
raymo

[ZeroID]

450D, 1100D and the 1200D are your best options and value. Best low noise performance and the 1200D has 18 megapixels. Get BYEos and use Live View to focus, don't worry about flip screens, you still break your neck and you cannot guarantee good focus.
I can vouch that the 1200D is excellent and my 450D has been hacked and chopped many times and still works. If you can't get a 1200D or the 1100D then the 450D is still a good starting point and possibly cheaper although thye still seem to command a good price over here.

[luka]

While I agree with the others that Canon is a better option (got 1200D myself recently) you could get a brand new the Nikon D3300 body for $256 (https://www.ozbargain.com.au/node/235708). I believe it is a very good performer for astrophotograpy.

[LightningNZ]

I use the Nikon D5100 which has a very sensitive, low noise sensor. It also has a full swing/tip/tilt LCD which makes it a breeze to use at the scope. If you look at the forums at Cloudynights.com you'll that the days of Canon's monopoly on astronomical DSLRs has been well and truly broken. Lots of people there imaging with Nikon and Sony cameras.
Cheers,
Cam

[janoskiss]

Thank you to everyone for all the excellent advice. I agree with Cam, based on what I've learnt reading up on the topic over the past several days, that the D5100 seem at least as good as any of the Canons mentioned on this thread. But there seem to be fewer of them around and they tend to be more pricey on the 2nd hand market.

Special thanks to Glen for the very practical technical advice, and to Barb and David for the PM with extra useful info.

It is nothing short of amazing what a few $100s get you these days. Progress in camera/detector technology in the past decade or two has been like Moore's law of computing on steroids.

[janoskiss]

Well, I found a Canon 550D with a kit lens for $250 on gumtree from a seller near my place. Looks to be in good nick. Having a basic lens would be nice especially for being able to do much better videos (non-astro) than what I can with anything else I have. I've decided to grab it if it's not sold yet and checks out when I go to have a look at it. If anyone has any tips on what to look out for, it would be much appreciated!

Otherwise that Nikon D3300 body for $256 brand new is hard to pass up. Thanks for that tip, luka! I wouldn't have found it myself.

The only thing that concerns me about the Nikon is that I do all my work in Linux, so compatibility with that OS would be highly desirable (at least as far as being able to use raw format without too many hassles). I gather Canon is better supported in Linux...(?)

[lazjen]

Assuming you're using libgphoto2 or something similar under Linux, you're probably going to be ok with Nikon.

Plus this seems to indicate it's ok: http://indilib.org/devices/ccds/gphoto.html

If you're used to Linux, you can do all your astrophotography there too with tools like INDI/ekos, etc.

[janoskiss]

Thanks Chris, that's great. Sound like I'm sorted either way, Canon or Nikon. :)

[rustigsmed]

550d is a good choice if you are doing planetary as well it has a true video crop mode. :thumbsup:

[janoskiss]

Can you briefly explain what that means please. How does it differ from the D3300? I read the specs and the dpreview details on movie mode but I still can't figure it out.

[rustigsmed]

Hi Steve,

Sorry I should be more specific, 1:1 pixel resolution for video including at 640x480 at 1:1 and at 60fps.

I can't comment on the Nikon. But here is some interesting info on the canons written by Jerry.

http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/Canon_One_To_One_Pixel_Resolution.H TM

That kind of information is hard to come by so not sure if you could find out for the Nikon.

but this is only of value for planetary imaging.

cheers

[janoskiss]

Thanks Russell. I don't think with that many pixels being downsampled to VGA should be a problem. (If anything it should show less quantisation noise...) I can appreciate how downsampling something like 1024x768 or even full HD to 640x480 is going to cause artefacts, but when it's around 100 pixels on the CCD for every pixel on the image, that's gotta be pretty damn good. Or maybe I'm missing something and don't fully understand how these cameras work in video mode.

Anyway, I've decided to go with the Nikon D3300 that Luka recommended. I haven't heard back from the 550D seller, and really for the same money a brand spanking new probably slightly better performing camera vs a 5-6 year old unit is rather appealing. I've read enough reviews on the D3300 to be convinced it's an excellent deal at the current discount price. It's ridiculous. I paid more for an old second hand film SLR 20 years ago and double that for a compact digital 10 years ago (and that's in those days' dollars).

I did the sign up to the HN spam in exchange for the $25 voucher and I was at the checkout ready to buy, but Harvey Norman's final "Proceed to Paypal" button does not work. It's a link to the same page that you're already on. :rolleyes: I sent them a query about it.

The HN special ends at the end of this month and the $50 cashback from Nikon at the end of March. Thanks again Luka for the tip. I should pay you a finder's fee really.

[luka]

Glad I could help. Regarding the finder's fee, post some photos in the deep sky section once you get things working :)

[Windston]

I managed to pull a Canon 600D off gumtree with a 18-55mm and 55-250mm lens for 400$ I would defiantly recommend something similar!

[janoskiss]

I received the new Nikon D3300 and got the latest VR2 18-55mm kit lens for another $70 from a gumtree seller yesterday. Haven't done a lot with it yet but I'm very happy with this camera. I was not expecting to get anything this capable brand new for <$300. (I also bought a second hand Tamron 135mm f/2.8 prime lens off ebay for <$100. Love how current Nikon cameras are compatible with old lenses.)

Here is a single shot of the sky from my place ~10km north of Melbourne CBD (ISO3200, 10s, f/3.5, kit lens at its widest FL=18mm). The camera is aimed south, directly towards Melbourne city, so the prominent feature of the image is a lot of light pollution. I'll try aiming it north instead on the next clear night. (Second image is 100% crop of the unaltered 12MPix JPEG off the camera.)

[janoskiss]

Moonshot with 135mm Tamron lens (2x actual size with some sharpening; second image shows the full DX frame with this lens). Thanks again everyone for the good advice. Very happy with the Nikon D3300. Gotta hook this puppy up to a scope. :)

[ZeroID]

You're on your way, watch out for the black hole slippery slope... ;)

[traveller]

Well done Steve on your first shots, it's all down hill from now on with upgrades etc :lol:
I just live up the road from you so feel free to contact me if you want to experiment with a scope at some stage.
Cheers
Bo

[janoskiss]

Yeah, I know what you mean fellas. :lol: Here is a quick Moon shot from this morning using the Intes 6" Mak (photo size reduced 6-fold, green channel only). The camera sure shakes the tripod when the shutter opens. :( I'd better study the manual some more and see if there is anything for it. (I assume mirror lock would be redundant when already using live view...:question:)

[rustigsmed]

if not using it or an intervalometer already - the count timer down feature helps avoid vibrations can help a lot that in conjunction with 10 or so shots helps.

[raymo]

When doing still Lunar work,[ as opposed to video] I use ISO1600,
and a shutter speed of 1/2500 to 1/4000th depending upon the phase of the moon. This way, the exposure is over before the vibrations really get
under way. I can understand mirror vibes being felt through the tripod,
but am a bit surprised that the shutter ones can be felt. I'm guessing
that it is a light duty tripod.
raymo

[janoskiss]

Yes, I do use the countdown timer. I have not tried multiple shots in this instance. I suspect even when in live-view the mirror is lowered and raised again for the shot. Like raymo says the shutter should not shake things that much.

@raymo The tripod/mount is not that bad but after having moved house I still have not found the counterweights, so I shot with the EQ set up in AZ (celestial pole at horizon) but still very off balance.

[raymo]

Yes it is Steve.
raymo

[janoskiss]

I looked at the shutter and the mirror stays locked in live-view and only the shutter is closed and reopened, but there are other mechanicals going clunk-clunk and you can feel the camera body shake a bit if you hold it in your hand.

Three more photos from the same Moon shot: #1. 100% crop of photo which shows chromatic aberration of the Intes MK-65; #2. unprocessed (only contrast stretched and reduced) full frame; #3. same again with moderate sharpening. I went overboard with processing before (unsharp mask and curves) --- I suspect that's a beginner's disease.

[raymo]

My mirror doesn't stay locked, so obviously not all cameras are the same
in that respect. Being as Maks don't suffer from chromatic aberration,
I have to assume that you used eyepiece projection for that shot.
raymo

[janoskiss]

Nah, no eyepiece, just a straight-through camera adapter + helical focusser. The CA is from the Mak. Maks use a front correcting plate and that does have some CA. It's basically a big lens after all.

[glend]

My Mak/Newt does't have any CA but it uses ED glass for the corrector. I suggest it depends on how it's designed and built.

[raymo]

The Mak design was a long time in gestation, and all CA was eliminated in the process.The corrector does cause CA, but the meniscus diverges the
light by the exact amount required to cancel it out. It doesn't matter much what glass is used for the corrector,[ as far as CA is concerned] as the divergence of the meniscus is adjusted to suit whatever glass is used, although admittedly the less CA the corrector exhibits, the easier it is to cancel it out. No self respecting Mak will exhibit any CA at all, even "budget" level models such as the SW 150 and 180 Maks are CA free.
Even a Mak experimented with many years ago with a meniscus not
designed to cancel out the CA showed only very slight CA, owing to its
focal ratio of f/15.
I have owned two Maks [6 and 8] and used a number of others,[for imaging] and have never seen a trace of CA. I have seen a little occasionally [ visual] caused by el cheapo eyepieces.
raymo

[janoskiss]

Well, this is an f/10 Mak, an early model, and not the most sophisticated of the Intes Maks (MK-65, sold in 1994, perhaps made earlier, according to the documentation I got with it). Maybe it's not ideally set up and maybe the collimation is not as good as I thought - though visually it seems to check out alright. Modern SW Maks are better than this scope for sure. Even the central obstruction is quite large on this scope for a Mak (something around 35% from memory).

[raymo]

I am still surprised, because the Mak design was perfected and marketed
back in the 1940s, and with the surfaces being spherical, was fairly easy
to mass produce in smaller sizes [up to 10" or so.]. Maybe it's been
stripped, and the corrector incorrectly reinstalled.
raymo

[janoskiss]

I very much doubt that. As far as I know I'm the second owner and the scope has never been mistreated.

But this is the Moon, at not far off the widest FOV the scope was designed for, and my focus was only so-so. The Moon was also very low in the sky. And it's a 24MPix DX sensor.

Visually I never had issues with CA. The scope could handle planets no probs at up to 300x (though in practice 240x or less is always sharper). It's just that for this particular photo, for whatever reason, using only the green channel made sense.

:shrug: I'm neither alert nor alarmed. :P

[rustigsmed]

if the moon was lowish in the sky it could be some atmospheric dispersion rather than the scope. if you put the photo into RegiStax and choose RGB align (from memory) it can often offer some improvement.

[janoskiss]

I think you may have nailed it. With that telescope the resolution of the camera's sensor works out at about 0.5 arc second per pixel, so atmospherics would be a likely culprit. I thought of aligning RGB but looking at the channels separately (with the G channel showing more detail) and the overall relatively poor quality of the image I did not think it worth the bother.

Easy way to settle it is to take more shots with the Moon nearer to zenith, which I will certainly do.

PS. I don't even need to do that. Closer look at the photo reveals colour shifted uniformly across the whole photo: up for the blue end and down for the red end of the spectrum. It could still be miscollimation but it would be a little bit of an unlucky coincidence if the miscollimation matches up with the up-down direction in the sky.

[raymo]

I had another look at your image after my last post, and realised that it
couldn't be CA because I could see yellow as well as violet in and around the craters. The violet was also too intense. So I came to the same conclusion, but Russ beat me to it.
raymo

[janoskiss]

You were right raymo (& Russ), there is no CA from this scope even at the edge of frame. Here are a couple of the Moon in RGB through thin clouds at around 70 degree altitude (with a counterweighted and roughly SCP aligned mount with tracking on).

[rustigsmed]

that's good news :thumbsup:

[raymo]

:thumbsup:

Raymo

[thegableguy]

Keen to hear your thoughts on the D3300. I just ordered one purely for AP - figured it was better to stick with Nikon, for which we have about $8000 worth of lenses, rather than needlessly start down the Canon path. It worries me slightly how very cheap it is; is it okay?

[janoskiss]

You have nothing to fear but fear itself. :P The camera is fantastic value for money. It's classed as a "beginner's" DSLR because it's lacking fancy features and "only" has 11 AF zones. :rolleyes: (First thing I do with any camera for normal use is change AF to centre only; almost always shoot by aiming at what I want in focus first and getting AF to lock in on it.)

The "Effects" mode and all the effects therein are very gimmicky (childishly so) and just removing that from the dial altogether would already make the camera seem more professional. But who cares! The other thing about the whole beginner vs pro camera thing is that you have to go into the menu to change things that on more expensive cameras are more immediately accessible. But again for astrophotography, for the most part, who cares!

As far as the performance of the sensor goes it's only within a couple of f-stops (2-4x ISO) of some fairly recent pro cameras costing several $1000. It's within about one f-stop / 2x ISO of the Canon 5D Mk II & III in terms of low light performance and noise. At least they're my initial impressions (friend of mine has a 5D Mk II). But maybe on long exposures the thermal noise will get worse with the smaller DX sensor. But still, for <$300 one can't complain. And it's great that you don't need to be so precious about it because it's inexpensive. It's small and light as well.

For the money, you cannot go wrong; in fact you could do a lot worse for a lot more. But you really should be asking these questions before buying the camera. :poke: :lol:

If you already have so many lenses then it's a no brainer. Even if you don't the F-mount is probably the most backward compatible mount ever made. There are tonnes of decent old film camera lenses available on the cheap. The DX sensor format is especially kind to lenses designed for 35mm film.

[thegableguy]

Glad to hear it!

I guess I worry about noise. We had a D7000 years ago and I was fairly unimpressed with its low light ability; I expect the D3300 to be less adept, being significantly cheaper. But then I know how remarkably far cameras have come in the past five years, so maybe it'll be better. DxO Mark suggests it is, though I always take DxO with a grain of salt.

Yeah, even the D750 has the gimmick modes in there - Sketch Mode, Miniature Mode... what on earth were Nikon thinking? Who is there spending $2k on a body who wants that nonsense? Our cameras have never been off Manual mode shooting RAW anyway. And I'm with you on the focus points, I switch all ours to 11 points regardless of how many they come with.

Either way, it'll be fun to have a little DX again - and this way I avoid having to learn my way around a Canon for a while longer...

[janoskiss]

You can check out the very non-astro comparisons between the D3300 and D7000 yourself: http://www.dpreview.com/reviews/nikon-d3300/11

It looks like the D3300 has a tad more noise but it's spread over more pixels and overall there is nothing in it really. I read and watched a lot of reviews before buying it and the consensus seemed to be that the D3300 offers the same raw performance as the D7200 but it's not as feature packed.

But features are lost on me. Just give me a sensor, exposure, aperture, focus and maybe a light meter (what luxury!). Then get out of my way and let me drive my own camera while I collect some photons. Basically I'd be more than happy with a decent Praktica that has a CCD in place of where the film used to go.

I do understand the need for more features for pro photographers who need to be on and always ready to shoot, but I don't like how the industry uses that to manipulate public perception and sell the same gear at hugely inflated prices. Case in point: D3300 body going for around $300; D7200 for $1200. It's basically the same camera apart from the window dressing! But maybe I'm wrong and someone more knowledgeable will put me in my place. I'm all ears. Don't hold back folks. It's the only way I'll learn.

[thegableguy]

Well... most recent models (the D5500, D7100, D7200, D750, D810) are ISO invariant, which is a fairly big deal and worth paying considerably more for - particularly when it comes to low light photography.

Some of the other features are worth having, too. The higher quality LCD display is one. The major lack of controls on the D3300 is going to be very hard to get used to. No aperture preview is a bit annoying. And no ISO button!! Argh!! I know I can assign the Fn button, but I usually use that for spot metering for (I do a lot of stage & live performance photography; admittedly I'm not planning to with this camera, but the lack of proper controls is a definite drawback).

Then there's the fact it's 12 bit instead of 14. The smaller battery & shorter life. The single SD card slot. Etc etc. All this in addition to a clearly inferior sensor - seriously, the sensor in the D750 is insanely good; I wouldn't be surprised if the D750 at ISO 12,800 is better than the D3300 at ISO 3200.

On the other hand, I don't care about the lack of AF motor - I don't own vintage lenses or ever plan to. I look forward to the small size and light weight. It's got the nice new processor and all the video capability of its bigger brothers. Its sensor should (hopefully) do the job. Most of all, the thing costs so little, there's really no right to complain - of course it'll come up short when compared to cameras costing five times as much!!

Anyway. Looking forward to using it, and to seeing some more of your results! Hopefully you're getting clearer skies down there than we are in Sydney...

[janoskiss]

Thanks, you make good points.


Can you briefly explain what "ISO invariant" means?

[raymo]

Okay Chris, ISO invariance is most definitely not a big deal; noise is the
astrophotographer's biggest enemy, and invariance has no effect on that,
and even causes a slight loss of detail in the shadows[with the 750D]. As far as astro imaging goes, all the user reviews show it as pretty much a non event. As far as battery life is concerned, less than $20 buys a 240v adaptor, eliminating the need for a battery. Why would you need more than one SD slot for astro imaging? What does a higher quality LCD screen do for astro imaging? it has zero effect on the images you produce.
raymo

[janoskiss]

I'd still like to know what "ISO invariant" means.

The battery life of the D3300 is supposed to be exceptionally good (one of the claimed main improvements over the D3200). This guy reckons it "lasts for ever": https://www.youtube.com/watch?v=r8Ksuc7T-VQ --- claims 700 x 20s shots. I have not used it enough to have anything more to say about it. But in any case I would definitely like to get a spare battery to have on standby.

[janoskiss]

I read this article on ISO invariance: http://improvephotography.com/34818/iso-invariance/

I get it but it would seem you'd need a lot more than 14 or even 16 bit resolution in RAW. Basically each ISO step (e.g. ISO 1600 to 3200) needs an extra bit (because you're halving the intensity or photon count, if you like, going from 3200 to 1600). So if you want to shoot at ISO 100 and then boost it to ISO 6400 in post-processing and still want say 12-bit colour at ISO 6400, then you'll need 12 + log_base2(6400/100) = 12 + 6 = 18 bit colour.

It's the same as if you want to record audio but don't want to worry about levels. You record in 24-bit to capture quite (-45dB) signals at 16-bits for the final master.

So I don't see how this ISO invariance could work as well as amplifying the signal as it's collected at the sensor. :shrug:

[thegableguy]

Raymo, I'm not talking specifically about AP here. I'm talking about the differences between the absolute entry-level DSLRs and the pro models, which is what Steve and I were discussing. Surely we all agree that DSLRs and the comparisons between them are meaningless when compared to purpose-designed CCDs. We're talking about what you get for your money when you go beyond the absolute cheapest DSLRs on the market.

ISO invariance, to summarise, basically means that you can underexpose a shot by several stops and not lose any detail (how many stops largely depends on the bitrate). It's explained reasonably well here:

http://improvephotography.com/34818/iso-invariance/

Raymo I know you're a big fan of the entry-level Canons, but I'm gonna just go ahead and disagree with you on their superiority over the ISO invariant Nikons. There's simply no way they can compete with the likes of the D750, or even come close.

[thegableguy]

Steve - yes, it's similar to headroom in digital recording. That's precisely why studios do record in 24 bits in preparation for mastering in 16 bits. It's a good idea.

I actually don't know how it transfers to usage in AP to be honest. Haven't tried it yet, I'm waiting on scope and mount to arrive. But I've used both types extensively in regular photography and I can say it's a relief to be able to deliberately underexpose shots with the knowledge that detail isn't actually lost.

But claiming that battery life doesn't matter because you can just plug it in... yeah I totally and utterly disagree there.

Anyway. Raymo and I probably aren't destined to agree on this. My own experience and reading leads me to different conclusions than his experience and reading has. What's more, it's all beside the point! We're all shooting with entry-level DSLRs. We should be united in fist-pumps for the little guys of the camera world.

[janoskiss]

You must have been typing your message while I posted mine. Yes I've read the article but I'm skeptical for reasons I stated in the above post. I can already do this anyway if I'm happy with 8-bit colour. Shooting at ISO 200 and then upping the gain in post processing by a factor of 8 will give me a virtually identical result to shooting at ISO 1600 = 8 * 200. (I don't actually use a "factor of 8" in practice; that's just theoretical; I just contrast-stretch/normalise each photo.) And that works because I have 4-bits to spare between 12-bit RAW and 8-bit final. So I could even go as high as ISO-3200-equivalent from ISO 200.

[janoskiss]

:lol: We're posting out-of sync. Thanks for the feedback anyway. Being new to DSLRs I have much to learn. I'll read your last response now.

[janoskiss]

Yeah, I have no experience but I'd be worried about electronic noise and heat interfering with the sensor.


:thumbsup: I like the idea of pushing the limits on a budget and working on things that make the hobby and even some of the science accessible to more people. I found glend's recent posts on de-Bayering (http://www.centralds.net/cam/?p=8561) and how old cheap DSLRs can be turned into high-performance astro-cameras most interesting:
http://www.iceinspace.com.au/forum/showthread.php?t=139719
http://www.iceinspace.com.au/forum/showthread.php?t=144032

[glend]

Re the last post, batteries do produce heat as they are used and their presence inside the camera contributes to heat build up. If you are shooting a series of long subs, you can feel the warmth in a battery when you remove it as it gets down to lower power after some time at imaging. It is better imho to use a battery eliminator (like the Orion ones), as it does not create heat nor hold it inside the camera. It also makes cooling and sealing a camera much easier as you don't have to open it to change batteries. In my experience heat build up comes not just from the sensor itself but as much from the camera processor. The more 'work' being done by the image processor the more heat it generates. By processing work I am referring to is any programmed feature such as internal dark generation for each image, internal noise reduction, video processing is perhaps the worse, etc etc. Setup for astro imaging varies by camera make and model but you want to minimise the camera doing work that you intend to do in post-processing and through dark, Bias, flat capture. Also watch out for EXIF temperature data that is included in RAW file data, as it is not the sensor temperature itself but is actually captured at the processor. Some modern DSLRs actually have muliple processors, and these generate more heat than single processor cameras. I cannot comment on Nikons or Sony's as I have no experience with them.

[raymo]

Chris, At no time have I said that the budget Canons can compete with
pro level cameras; I have only said that they are amazingly quiet for a
budget level camera. A number of other members have posted the same
sentiments over the last two or three years. When the 1100D came out
it was quieter than many mid level cameras, let alone budget ones. Of
course, time and technology have caught up with it since then, and now
there are more lower end cameras that are probably just as quiet, or
even quieter.
raymo

[raymo]

This thread started out looking at cameras for astro imaging, and that is
what I have been dealing with in my posts. I still maintain that for astro
battery life is not that important because 240v at low current draw such
as a camera needs, is easily and cheaply available at home or on site.
raymo

[janoskiss]

It's all good folks. You're teaching me good stuff.

@glend Thanks Glen, that makes a lot of sense. I'll see how I go with the camera as is but external battery sounds like a good idea in the long run.

@Raymo If my battery went flat I would not hesitate to plug her in and keep shooting instead of packing up disappointed on a good night. But my camera did not come with an AC adapter and it's not a standard plug. It came with an external charger only. So I guess I'd be more inclined to buy another battery than the AC adapter. But I'll look into Glen's suggestion also. Maybe I can use 18650s (have a fair few of those) with an external battery pack.

[rustigsmed]

one of the main reasons the "lower end" dslr's are great for astro work is because they have larger pixels. physics over internal wizardry!
that is partly why the A7s is king of the low light, newer sensor and only 12mp full frame.

[janoskiss]

Well, the D3300 does not really qualify with 24MP. Binning the data from 2x2 pixels, thereby reducing the image size to 6MP, certainly helps reduce the noise. But I imagine a native 6MP sensor of the same size could be made less noisy still and for less cost. But the market keeps driving the pixel count up and up.

I still have and don't intend to upgrade my old 6MP Fujifilm F30 compact. The series reached a pinnacle for low-noise/low-light performance with that model. Subsequent models traded off low noise for more Mpixels. I blame the consumer more than the manufacturers (although some educational marketing to help keep a good thing would not go astray). For a compact the 10 y.o. F30 still does all right even today. I've got two of them. (The first one was $430 new, the second one $30 second hand off ebay.) Here is a 2007 McNaught shot I took with it, ISO 800, f2.8, 15s (no dark frame - I should have though, because it does help).

[thegableguy]

Stunning shot of McNaught!! I was floating around on a cruise ship somewhere, as I so often was at the time, which meant I didn't even know about and wouldn't have been able to see if it even if I had. Hopefully something similarly wonderful will come by soon now that I'm (almost) ready for it...

Just wanted to post a photo from my D750 at ISO 25,600. I understand that ISO invariance doesn't necessarily mean low noise - it's simply a different signal path which lends itself to underexposing. Nevertheless, this is an amazingly low-noise sensor. Whether or not that's because of ISO invariance is for people who care more than I do to decide!

Regarding resolution, I respectfully disagree. Resolution has advanced at pretty much the same pace as noise reduction. I loved our wonderful old Nikon D700s at 12MP, superb cameras... until we got a bunch of clients' prints from our first 24MP camera. For large prints there's no denying 24MP is much, much better. We upgraded both our D700s as soon as we received the first print. Newer sensors have better resolution AND lower noise. It's not a trade-off, as is so often suggested. The top DSLRs of ten years ago could only dream of the low-light performance the humble D3300 or 1200D manage these days - and they've tripled the resolution at the same time.

I love living in the future.

[janoskiss]

Nice one, Chris. I think that checks out with what I wrote earlier: that these cheapies are about two f-stops from the big boys in terms of noise performance (i.e., ISO X cheap ≈ ISO 4X expensive).

Re attached: ISO 6.4 & 25.6k, basic kit lens, zero skill, JPEG only, 8-bit levels and resize in GIMP, no processing hocus-pocus, wysiwyg; the Exif data is still there if you want to have a closer look at what you're getting. But if you're still worried about the noise for your ~$300 worth, I recommend getting some earplugs from your local chemist. :P

[glend]

It would be worthwhile to consider the Quantum Efficiency of any potential DSLR purchased for astrophotography work. Here is a link to an old study by DPReview that covers the older Canon models (typically used by those of us that modify them):

http://www.dpreview.com/forums/post/34516718

Under this review the 450D delivered a QE of 30.4%, the Nikon D3 at 40.2%.

There is another very useful link here:

http://www.clarkvision.com/articles/digital.sensor.performance.summary/

This link by Roger Clark for Clarkvision, covers everything pretty well and includes a useful "Sensor Full Well" chart by camera model, and SNR over pixel pitch, and sensor read noise charts. The typical Canon models disucssed showed significantly less Read Noise than the Nikon's tested, but I think the Nikon D3 was actually the best in this category grouping in with the Canons. Importantly the CMOS sensors all showed less read noise than the CCDs examined, including the venerable KAF-8300.
From the Dynamic Range chart, it is clear that Dynamic Range drops as ISO goes up. Clark observes that "ISO is simply a post sensor gain followed by digitisation. ISO settings are needed mainly to compensate for inadequate dynamic range of downstream elecronics".
The Thermal Noise from Dark Current Chart is informative, clearly showing the benefits of keeping the sensor cooled; and this backs up research under taken by rchesire (Rowland) here in his thread on IIS on Cold Finger Cooled DSLRs in the DIY forum. Rowland showed through Dark and Bias Frame comparisons that cooling a 450D sensor (with 5.2 micron pixels) to 0C produced the best solution for elimination fo Dark Current Noise; this was also confirmed by my own comparisons on my cooled 450D.
This indepth study by Clark is good holiday reading and provides a tutorial to all the terms of reference in DSLR performance.

BTW, this thread topic was also the subject of a Cloudy Nights thread here:
http://www.cloudynights.com/topic/489149-are-new-dslrs-really-better-for-ap/

[John0z]

You guys got me interested in the Nikon D3300 also. I see that Kogan has a 20% off on ebay at the moment (until 26 March), which makes it cheaper than their web price.

My question is - there is lots of software to control Canon EOS cameras, what about for Nikon?

[glend]

Backyard EOS has a Nikon version now but I can't comment on it operationally.

[thegableguy]

That article by Clark does look great, very in-depth and technical. I had a quick skim and the only problem I could see was that it was talkig about cameras that are 7 years old. Newest one I can see is the Canon 7D, released in 2009. Things have progressed a lot since then. The principals remain the same, I'm sure, but there have unquestionably been significant advances.

Anyway - proof of the pudding is in the tasting. Should have my new D3300 next week, along with my first mount (NEQ6) and first refractor (ED80), and I will be starting by shooting with Nikon D750, D610 and D3300 through 18mm f/3.5, 50mm f/1.4 and 200mm f/2.8. Lots and lots to learn and I can't wait. I'll report back my findings.

Cheers all!

[glend]

Yes that article details on models were older ones but the definitions and explanations remain current for new cameras, think of it as a primer on the subject. Current camera sensor specs can be found at sensorg.info I believe. The Nikon D3300 does look very cost effective through Kogan, even his Canon body prices seem ok. I have too much invested in Canons to switch to Nikon now. I'd like to find that sort of price on a Sony A7S, just to play with.
According to that lng Cloudy Nights thread 'if you debayer a colour sensor the QE is suppose to increase substantially', so i look forward to getting some images on my mono 450D.

[thegableguy]

Hehehe - that's why I went with the Nikon, too expensive to start down the Canon path now! I'm glad there's Back Yard Nikon now - hopefully the Canon monopoly in DSLR astrophotography will start to diminish and we won't feel like we're on the fringe...!

Just FYI - I got my new D3300 with 18-55mm VR II kit lens for $429 through DWI Digital Cameras. They're grey market, which means it takes a week or so to ship and if you have a warranty issue it's a lot more hassle to resolve (you have to post it overseas)... but we've saved literally thousands of dollars over the years through DWI.

Having said that, yeah looks like Kogan is the cheapest local option.

[glend]

I think Canon will be the preferred platform for the DSLR astro modders for a long time, there are years of research and work that have gone into cooling solutions, full spectrum mods, etc. Even the pro mod companies like CentralDS are Canon solutions. If your never going to be tempted to open it up to mod it then, yeah, Nikon, and Sony will be good choices.

[janoskiss]

Nikon still have $50 cash back offer on the D3300 till the end of the month afaik. Go to Nikon AU website to claim it. They'll want a purchase receipt / tax invoice --- scanned or electronic is fine, but they were a bit fussy: I had to ring Harvey Norman and get them to email me a proper tax invoice. I sent Nikon a screenshot and then they were happy and I got my $50 in the bank within a few days.

[John0z]

Just checked, Backyard Nikon doesn't currently support the D3000 to D3300 due to lack of SDK.

[Edit] Found some free software called digicamcontrol that will at least do live view, video recording - so have bit the bullet and ordered the Kogan special on ebay.

[thegableguy]

Oooooh. That's annoying. I didn't even think to check.

Ah well. Intervalometers are only $20 or so. Not the end of the world. Wonder why they don't do SDKs for the 3000 series though.

Looking forward to comparing D3300 results in the weeks ahead!

[John0z]

Maybe, the D3000 series is just too new and they haven't yet produced the SDK. Anyway, I just have to wait a few weeks until it comes in.

-John

[John0z]

My Nikon D3300 kit came in yesterday morning. Now I need a T adapter, but will try it out with visual first to get the hang of it and see how it compares with my Sony a300 and Nex 5 - it certainly is small though.

[Camelopardalis]

The entry level Nikon and Sony models only use a 12-bit ADC whereas the Canons use 14-bit. As soon as you move away from the native ISO you lose dynamic range. You may not care about this in suburbia but out at a dark site it makes a difference. I figure, why start with fewer stops in the first place?

The read noise isn't all that different between most DSLRs at this point. Older models such as the Canon 1100D hold up surprisingly well in this respect, despite their age.

Differences in QE of 10% aren't that noticeable with a OSC camera out at a dark site. You still need to learn to expose the image correctly. Likewise ISO invariance...it's a bit of a red herring for AP, as if you don't expose sufficiently you're going to have a problem bringing the signal out of the read noise floor. My suggestion to deal with that is to take a shot a couple of stops higher than native gain and look at the histogram, then scale it back to native gain for the real shots.

The thermal dark noise is the great divider for astrophotography. The problem with making objects such as cameras smaller is that there is less opportunity to dissipate the heat generated by the internal electronics when exposing for several minutes time after time. This causes sensor/electronics heat-up which makes the dark noise worse.

I recently did a lot of research on this as I had the (rare) opportunity to upgrade and had to choose between all the great models available now. I went with the Canon 6D, a 4-year old design! I read a couple of reviews comparing the 6D and the Nikon D750 and it wasn't that the D750 was bad, it just didn't do a better job than the Canon. On top of that, the Nikon/Sony models that were theoretically more interesting were way out of my budget. The plus side is that my lenses still fit and there's no change required to my astro software ;)

[glend]

Dunk I think camera choice is a bit like car loyalities. Cameras may do much the same thing but its the operations side, and particularly the software control and mod ability that influences DSLR choices. Canons are a 'safe' choice for astro work, and a Canon buyer will get a lot of help here with any issues they have just because there are so many being used, modded, etc.
As you point out, recent DSLR releases can be smaller form factor, higher heat generation, and un-modifiable platforms, which while fine for normal consumers but not what astro photographers are looking for. I don't have a problem with industry trends other than there is no product stream that really is aimed at dedicated astro work. Sure we get the occasional 'special' model like the 6DA, and others, but they disappear very quickly because they are no 'mass market' enough to attract the volume that manufacturers want to continue a line. Astro people would be all over a modern design that provides deep spectrum capability, and electronics that can map pixels to colour profiles ( think of this as an electronic form of a Bayer Matrix). The processing power is available these days, why not be able to select pixel filtering as you can white balance. I might want to shoot mono one night, and colour the next using the same camera and sensor. I would gladly pay a premium for this feature. I believe true narrow band would still require filters but mono with pixel colour profiling is doable now.

[Camelopardalis]

In my case, the brand loyalty factor was minimal to none...I tried to look at the "upgrade" as objectively as possible as the upgrade fund was precious and it's not like I'm a professional photographer with a lot of lenses.

The more I looked into it the more I started to see through the marketing and technological fluff. For the most part, most of the units for sale are in the same ball park. There are differences for sure, some might show prettier pictures on their LCD screen, but that doesn't necessarily give a better end result...each come with their own set of pros and cons as an imaging platform, and it's up to the "artist" to understand their equipment, play to its strengths and make what they will of the results.

My modded 1100D will still play an active role...I'm planning mod v2 even :lol: for what it cost me, and the enjoyment of working on the little beastie, it's worth the entry price.

FWIW, my point-and-shoot is a Fujifilm X-E1 which has excellent low-light behaviour, and I do use it for nightscapes and ultra-wide shots, but the lack of automation (besides an intervalometer) precludes it from becoming part of the next step in my imaging. It also happens to take stunning daytime shots ;)