I'm selling my EQ6 and SXV-H9. Have decided to get a H-EQ5 as they have impressed me. I think they perform better than the EQ6's from what I've seen. I will also be getting a DSLR, probably the 1000D. I will then have a set-up that is more portable and practical and also one-shot colour so less messing around. Hoping to have it all in time for Kelling Heath.
Cool! DSLR imaging is a great way to get multi-megapixel imaging at a reasonable price.
Mark
And a whole new learning curve...
Quote from: RobertM on Mar 07, 2011, 10:14:21And a whole new learning curve...
True, but it's been so long since I did any serious imaging that I would have had to re-learn things anyway.
Anyone know if the 1000D is a good choice of DSLR? Any other recommendations?
You'll probably need this at some stage -
http://www.ghonis2.ho8.com/rebelmod450d1.html (http://www.ghonis2.ho8.com/rebelmod450d1.html)
Quote from: Mike on Mar 07, 2011, 10:46:20
Quote from: RobertM on Mar 07, 2011, 10:14:21And a whole new learning curve...
True, but it's been so long since I did any serious imaging that I would have had to re-learn things anyway.
Anyone know if the 1000D is a good choice of DSLR? Any other recommendations?
Depends on your budget. EOS1000D body only is approx £210 on EBay whereas 450D ~ £310, 550D varies a lot ~£410+ and if you really want to push the boat out there is the EOS 5D full frame camera...
Yes but any ideas on which of the Canons would be most suited for astrophotography? Bearing in mind I have an ED80 and ZS66.
Mike,
First of all get the proper SkyWatcher flattener for the ED80 - the William Optics ones aren't such a good match.
As for the camera, do you intend to use it solely for astro? Do you intend to mod it? Will you mod it yourself - if so stick to the cheaper end of the scale - you don't want to wreck an expensive camera (speak to Mick - he has experience!).
Some things to consider:
EOS 400D and 1000D are only 12bit
450D, 500D and 550D are 14 bit
none of the above suffer from the amp-glow which plagues the 300D and 350D
Regarding Quantum Efficiency http://www.sensorgen.info/ has some useful info and so does this thread http://forums.dpreview.com/forums/readflat.asp?forum=1019&thread=34516718&page=1
The figures are "reverse engineered" from data provided by http://www.dxomark.com/index.php/Camera-Sensor/All-tested-sensors using the methodology documented here: http://www.sensorgen.info/Calculations.html
Summarising some QE figures:
350D 27% - this is the camera I am still using
1000D 32%
400D is probably similar to the 1000D
450D 30%
500D 36%
550D 40%
The figures above have been calculated on a consistent basis so they give a good indication in the gradual improvement in QE.
I used to think that small pixel sizes invariably meant noisier images but I am gradually coming to the conclusion that small pixel sizes are not an issue as long as QE does not suffer and as long as read noise reduces in proportion to the area of the pixel.
I think the important criteria are the following:
1) Read noise (measured in electrons, not ADUs)
2) Dark current - especially over a long duration imaging session of hours
3) bit depth (14bit is preferable to 12 - it means there's less need to bracket exposures to prevent the highlights saturating)
4) Overall QE
5) QE for H-alpha wavelength in particular
6) other useful features such as liveview (which helps focusing) and such as shooting video
The problem is that no-one publishes all these figures.
For the 1000D, 450D, 500D, 550D Gary Honis has done some experiments of how noise increases over a long imaging session: http://ghonis2.ho8.com/rebelmod550duncooledcomparison.html
So I reckon the jury is still out on the 500D/550D - their noise seems to climb faster and higher.
I think I would go for the 1000D (fairly cheap) or the 450D (14 bit) if I hadn't already bought a cheap second-hand 400D off eBay. This 400D will shortly become my "workhorse" camera - my tests show it has a better overall QE than the 350D; much lower dark current (after 2 hours imaging) with no amp glow; the read noise and H-alpha sensitivity is only marginally worse than the 350D. It would be good to thoroughly test the 1000D and 450D at some point also.
Hope this helps.
Mark
I'm not sure I've previously published the results of my 3 way test between the 300D, 350D and 400D - so here they are - all at ISO 800:
(http://www.markshelley.co.uk/webdisk/threewaytest300_350_400D.jpg)
The 3 camera simultaneous thermal test was done at room temperature 21C - I took a continuous sequence of 5min frames over a period of 2 hours - though the battery expired on the 300D partway through. The graph scale shows electrons/pixel/second against frame number.
(http://www.markshelley.co.uk/webdisk/thermaltest300_350_400D.jpg)
One other thing - when taking a sequence of images with the 400D (and probably other cameras as well) it is very important to switch off the rear LCD during exposures otherwise it heats up the CCD and the dark currrent goes through the roof!
Mark
Thanks Mark. This further leans me towards my choice of the 1000D as the 550D was the other option. The 1000D certainly seems to be one of the less noiser cameras at higher temperatures and it's a decent price.
Mike,
The 550D has a lot of video circuitry on the sensor so that may well explain the extra noise to a degree.
Although ideally you want a camera with low read noise and high dynamic range you can work around that. Use low iso (higher read noise) where LP is bad (you can't use low read noise to advantage) and use higher iso (and lower read noise) for dark sky sites where read noise might be a contributing factor. If Nikon hadn't buggered up their D7000 by monitoring the shutter with an IR lamp it would have been the best camera by miles (ultra low read noise through the range up to max ISO).
Hopefully I'll have time tonight to get on with the 1000D/450D comparison and that should give you a bit more information.
Robert
Quoteit is very important to switch off the rear LCD during exposures otherwise it heats up the CCD and the dark currrent goes through the roof!
Hmmm didn't know about that, maybe that's why I have such a lot of noise in my images. Must find out how to do it.
Carole
Quote from: Carole
Quoteit is very important to switch off the rear LCD during exposures otherwise it heats up the CCD and the dark currrent goes through the roof!
Hmmm didn't know about that, maybe that's why I have such a lot of noise in my images. Must find out how to do it.
I only accidentally found this out by experiment. I questioned why the noise was rising so fast from frame to frame. I let the camera cool then repeated the expt with the LCD off and it made a huge difference.
Mark
QuoteI questioned why the noise was rising so fast from frame to frame. I let the camera cool then repeated the expt with the LCD off and it made a huge difference.
Yes I noticed that the warmer the camera got the paler some of the images got too and did the same thing on a long run, shut it down to give it a break. I was told to switch off live view because of noise, but I thought that was live view on the laptop and always switch that off now, but hadn't thought about the LCD screen on the actual camera which I don't really need).
Sorry we've highjacked your thread a bit Mike, but it's all useful info for you if you're going over to DSLR.
Good tip.
Carole
H-EQ5
QHY5
Canon D1000
All ordered and on the way :D
You should be well set up for Kelling Heath then ...
Just need to learn how to use it all now.
H-EQ5 arrived today.
...followed closely by the QHY5 :D
Great service from Bern at Modern Astronomy as usual.
The QHY5 was a bit of a pig to set up. Took several goes of installing and reinstalling different types of drivers before it was recognised by PHD. Got there in the end.
Haven't tried it in MaximDL or AA yet.
Gosh, Mark, that was some info you posted, you are a very helpful chap!
I always use the QHY5 Ascom Driver.
QuoteThe QHY5 was a bit of a pig to set up
Yes I'd conclure with that. I've done it twice now on both laptops.
Carole
Canon 1000D arrived today :D
Now I just need to learn how to use it all !!
Excellent, is it modded yet or will you break it later ;)
I went down the lazy route of buying a pre-modded one from astronomiser. Simply because I know it has been done properly and is still covered by warranty. It's got the Baader filter in it.
Same as mine Mike
Wise choice Mike
One of the other items I got from Bern was an adaptor to allow the QHY5 to be connected directly into the ED80 Finderscope. I think it's a great idea and cuts down on complexity and weight a lot:-
(http://www.earthshineelectronics.com/Images/astronomy/finderadaptor.jpg)
Beats cutting the end off your finderscope as I did with my Meade. But that was mostly so I could get it to focus with a webcam where the CCD is set back inside the housing a cm or more.
BTW Flocking (http://forum.orpington-astronomy.org.uk/index.php?topic=6294.msg38590#msg38590) the inside of the finder/guide scope greatly improved contrast and allows me to pick out faint stars when no easy ones are visible with my QHY5 (or use shorter exposures).
so do you use that as your guidescope Mike?
I will be yes, once these bloody clouds go away!!! :!
Quote from: Mike on Mar 10, 2011, 22:00:07
The QHY5 was a bit of a pig to set up. Took several goes of installing and reinstalling different types of drivers before it was recognised by PHD. Got there in the end.
I'm surprised to hear that, the drivers on the CD normally work first time.
I'd like to make using these cams as easy as possible so:
Was this a fresh install, ie no previous drivers?
Did you follow the instructions, or just go for it?
bern
Having bought my QHY5 secondhand I have no experience of the CD
When searching for suitable drivers on various forums, I don't recall anyone saying "this is what you need, works first time"
QHY do not seem to make life easy
I got the latest drivers and firmware update from the QHY website recently. Uninstalled the previous installation and re-installed no problem. Don't know what all the fuss is about! I use the "ASCOM v5 Camera" option in PHD 1.12.3.
Note: if you are using a USB hub, power it. The QHY5 seems to like it's milliamps fresh.
Went out last night, of course, to test the new kit.
Setting up was nice and easy and took half the time it used to with the EQ6 and SXV-H9. The use of the finder-scope as a guide scope makes life a lot easier and also makes the rig a lot lighter. Was up and running in 15 mins.
GoTo worked first time and was spot on. Well impressed.
Guiding was also spot on. PHD worked first time using the default settings. Also well impressed.
(http://www.earthshineelectronics.com/Images/astronomy/guidetest.png)
This is a 5 minute test shot for guiding. There is some slight distortion at the corner. The camera was obviously not inserted into the scope straight enough. The crap rear end of the ED80 might be to blame for that. Will have to replace it with a compression focuser. Still , it shows guiding was spot on.
(http://www.earthshineelectronics.com/Images/astronomy/guidetest5mins.jpg)
Using the camera was easy enough. I tried both MaximDSLR and DSLR Rremote Pro. Noisy images but then that is to be expected compared to using the SXV-H9. I will now have to get used to doing bias, dark and flat frames.
It was a terrible night for imaging with the full moon and also a lot of moisture, but great for testing and I am well chuffed with the new gear. :)
Excellent results Mike, looks like it's coming together well
Blimey Mike
Quoteup and running in 15 mins
I don't even manage that with an obsy.
and even when my guiding is working, I've never seen a graph that looks as smooth at that, even on forums where every-one is comparing their graphs.
Carole
Well done Mike, nice to see you getting going again
Carole,
Do you force a calibration routine before your guiding session?
Also, is your camera oriented correctly, i.e. with the light at the top (presuming you use a QHY5 also) ?
QuoteDo you force a calibration routine before your guiding session?
What do you mean by force a calibration routine?
I go throught the normal calibration routine before it will guide. I have picked up some tips from the Stark labs website though on problems with Dec calibration failure which seems to be a common problem, and I did increase the calibration steps last night to 1200 from 500 which Craig Stark suggested and that made calibration work thanks goodness but the guiding was not too good. The other idea he suggested was moving the mount Northwards before checking backlash had finished and before the N calibration started which apparently can often help.
Quoteis your camera oriented correctly, i.e. with the light at the top (presuming you use a QHY5 also) ?
Yes I have a QHY5, can't remember where the light is, but I have it orientated vertically and horizontally with the handset up/down/left/right pad.
Carole
The guiding looks good Mike, I'm not sure compression rings are any good at all, they allways seems to move the attachments about, but I guess if there a good back for the scope then why not.
I'm assuming your not using an ED80 flattener to the camera, if not then you will not get round stars, if you do you will not need compression rings, the flattener crews onto the back of the draw tube and the flattener comes with an EOS adaptor, a perfect solutioin.
Chris
Yes I have a SkyWatcher field flattener and a low profile EOS adaptor.
Looking good Mike but something isn't square in your imaging train. The stars are more squiffy towards the bottom left.
Robert
Nice results. I agree with earlier comments.
Also, do you think the finderscope will be held tightly enough to prevent flexure?
Put something in place to hold the USB lead tightly in the camera - if it falls out it can potentially wipe out the firmware - as I found, to my cost.
Mark
Quote from: RobertM on Mar 19, 2011, 22:41:19
Looking good Mike but something isn't square in your imaging train. The stars are more squiffy towards the bottom left.
Yeah, hence the comment about the standard rear end of the ED80. It's not very good quality. I may replace it.