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  #61  
Old 24-03-2016, 02:22 PM
raymo
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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
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  #62  
Old 24-03-2016, 02:32 PM
raymo
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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
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  #63  
Old 24-03-2016, 03:40 PM
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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.
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  #64  
Old 24-03-2016, 03:45 PM
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rustigsmed (Russell)
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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.
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  #65  
Old 24-03-2016, 04:19 PM
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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).
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Last edited by janoskiss; 24-03-2016 at 04:42 PM.
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  #66  
Old 24-03-2016, 07:55 PM
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thegableguy (Chris)
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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.
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  #67  
Old 24-03-2016, 11:18 PM
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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.
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Last edited by janoskiss; 25-03-2016 at 01:00 AM.
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  #68  
Old 25-03-2016, 02:51 AM
glend (Glen)
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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/...mance.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/48...better-for-ap/

Last edited by glend; 25-03-2016 at 08:45 AM.
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  #69  
Old 25-03-2016, 10:52 AM
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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?
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  #70  
Old 25-03-2016, 11:14 AM
glend (Glen)
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Backyard EOS has a Nikon version now but I can't comment on it operationally.
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  #71  
Old 25-03-2016, 12:08 PM
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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!
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  #72  
Old 25-03-2016, 12:37 PM
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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.
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  #73  
Old 25-03-2016, 12:55 PM
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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.
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  #74  
Old 25-03-2016, 02:01 PM
glend (Glen)
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Quote:
Originally Posted by thegableguy View Post
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.n.
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.
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  #75  
Old 25-03-2016, 02:42 PM
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Quote:
Originally Posted by thegableguy View Post
Just FYI - I got my new D3300 with 18-55mm VR II kit lens for $429 through DWI Digital Cameras.
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.
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  #76  
Old 25-03-2016, 08:31 PM
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Quote:
Originally Posted by glend View Post
Backyard EOS has a Nikon version now but I can't comment on it operationally.
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.

Last edited by John0z; 26-03-2016 at 09:28 AM. Reason: digicamcontrol
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  #77  
Old 26-03-2016, 11:26 AM
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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!
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  #78  
Old 26-03-2016, 05:25 PM
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Originally Posted by thegableguy View Post
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!
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
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  #79  
Old 05-04-2016, 07:17 AM
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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.
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  #80  
Old 05-04-2016, 07:53 AM
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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
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