Congratulations Andrew, the comet is still quite visible BTW, don't do what I did and forget to take darks, I used in camera long exposure mode which automatically subtracts darks but the raw is not subject to that and very noisy without a dark frame.
Hey Andrew - me too about 2 weeks ago, suggestion get an external DC adapter if you plan to image long term somewhere nears main power - about $100 if you shop around.
Right now I've downloaded the 30 day trial versions of MaximDL, MaxDSLR, DSLR Focus and DSLR Shutter and am busying reading manuals!
I understand for long duration photography you have to enable the Bulb function, which it seems you can't do in any software operating via the supplied USB cable????? (serious software design oversight there). So I am busy waithing for a ShoeString DUSB USB shutter cable to arrive - as I have read in online forums that most software seems to work with that.
I say most and not all because I hear the renown DSLR Focus doesn't, even though it specifically supports the 5D, 20D, 300D and 350D! I've written to Chris twice now asking if there is a workaround or any idea when a release may add support for the 400D - no reply in over 10 days...
I'd be curious to know what settings you use for photography. So far I have tended to use the supplied Canon EOS utility with the camera directly attached to a scope and the control wheel set to Av settings, set ISO to 800 or 1600, and take 30 second snaps for nebula, down to 4-5 seconds for bright planets like Saturn. I set the Bias is it to +2 - it gives the best results for the faint dust in nebulae.
My shots seem to have a green tinge to them, for instance M42 below, which I understand should look pinkish (after photshop?). So I guess you need to adjust the RGB settings of the camera to give more priority to certain colours. I have yet to play around with dark frames - but once I exceed 30 second shots that is a must do.
The camera seems to have plenty of quality, its just learning curve I face now!
was to have the camera on the mount directly, no scope, with the 200mm lens. The cameras settings were 30 seconds in manual mode F5.4 (the smallest amount the lens would goto at 200mm) and had the timer on. so I clicked waited then exposed, then waited for the noise reduction to stop then looked... In the settings you have to turn on the long exposure noise reduction. I also shot in RAW.
Hi all,
I also just bought a 400D. Awsome! I tried my first astro pic on McNaught. I set shutter priority, ISO 800 and compensation to +2, which was probably a bad Idea, as i got a lot of noise, even with noise reduction on. I popped it piggy back on my 8" Newt and set a 10 second exposure. The image was RAW.
I've also got a remote shutter release on order as well.
A couple of q's, though;
How do you focus without any realtime LCD display? I found the experience a bit daunting, as I really want to get into deepsky imaging.
Second question;
What are dark frames? That's something I've not heard of.
Anyhoo, here are the results of my first foray into the world of 400D!
Hi all,
I also got a 400D last week, I haven't tried it on the scope yet. I've just been taking terestrial shots at the moment figuring out all the options, lots of stuff to learn, but it takes great pictures. I'm making my own serial cable, then probably buy a USB to serial adapter to use with it later.
Marc - you focus roughly on a very bright star - like Sirius - using the LCD, then via a PC hook-up I guess, take a shot, adjust and repeat until your focus is great - then away you going imaging.
I believe a dark frame is a shot with the lens on - so any bright bits are likely to be permanent electronic noise you can subtract out of all your real shots.
Marc - you focus roughly on a very bright star - like Sirius - using the LCD, then via a PC hook-up I guess, take a shot, adjust and repeat until your focus is great - then away you going imaging..
thanks for the update, but the 400D doesn't allow realtime update (ie focusing) via the LCD - it's just for settings and playback. if there is a custom setting that I have yet to discover that would be great! I think I'm going to have to get an off-axis guider...(can you get those for Newts?)
Quote:
Originally Posted by g__day
I believe a dark frame is a shot with the lens on - so any bright bits are likely to be permanent electronic noise you can subtract out of all your real shots.
So what you do is take a shot with the lens cap on, and subtract any values above RGB=0 from further shot in post processing, is that how it goes? I heard that you can determine the signal to noise ratio by doing this, but I thought that was it.
How do you focus without any realtime LCD display? I found the experience a bit daunting, as I really want to get into deepsky imaging.
Use a program called DSLRFocus, it takes images from the camera in realtime and compares them to either autofocus or help you manually focus depending on your setup. It also does a lot of other stuff, read all about it here: http://www.dslrfocus.com/
I guess you can do both (dark frame and in-camera noise reduction.
Interestingly reading a book on astro-photography last week (Rod Woz) it said if you are doing a 3 minute capture, spend the same amount of time doing darks (for each and every shot you do) plus flats and bias... I guess that is to push the equipment as far as it can go. The longer your shot - the more noise you are exposed to so the longer your darkframe should be to replicate exactly that same electronic function.
Bias I presume is adjustment for the CCDs over or under emphasis of Red, Blue and Green (more reading yet to do). I presume flats are to address off axis error (where stars in the centre of view are lovely little circles, but stars towards the edge are less focused football shapes (unless you own an expensive APO or true RC type tube.
All this assumes you will import your shots into MaximDL or CS Photoshop etc to process the raw information and darks / flats / bias.
Marc the other part of your question on achieving critical focus - and everyone says over do it, and adjust as the night progress and your gear is subject to thermal expansion or contraction and/or mirror flop. I focus on say Sirus - roughly thru the view finder, then snap 5 - 10 second exposure checking the focus until its as good as I can get. DSLR Focus can likely help this by checking and minimising the size of a designate star/s - meaning you have obtained optimal focus.
This done its onto the main game and longer duration astrophotography. I had my first play last night - scopes both aligned, focus good, bulb functioned worked - and I did 10 seconds, 30 seconds, 60 seconds, 2, 2 and 4 minute shots (guided) until yep - the clouds all rolled in!
Use a program called DSLRFocus, it takes images from the camera in realtime and compares them to either autofocus or help you manually focus depending on your setup. It also does a lot of other stuff, read all about it here: http://www.dslrfocus.com/
Martin
Hi Martin,
According to the DSLRFocus web site, the 400D is not supported at this time.
From memory, when photographing in RAW format (which gives you full 12 bit data), the camera doesn't do noise reduction. But don't quote me on that, I just seem to remember reading that somewhere in the manual.
I found the easiest way to take darks was just put the cap back on the telescope. Remember to pause for a couple of minutes after your luminace frame, to allow the chip to cool back down.
Dark subtraction is very easy in Photoshop. You just open the 2 frames (1 image and 1 dark), move the dark over the image, and select "difference" from the application menu on the right. I don't have it running here at work so I can't give precise instructions, but it is very easy. I haven't got onto bias frames yet.
My Ultrawedge just came in, so at last I can start with some longer frames this weekend w00t!!!
From memory, when photographing in RAW format (which gives you full 12 bit data), the camera doesn't do noise reduction. But don't quote me on that, I just seem to remember reading that somewhere in the manual.
That's not correct. It will always do noise reduction if:
1) You have it set (in custom functions menu)
2) Your exposure is over 30 seconds.
Use a program called DSLRFocus, it takes images from the camera in realtime and compares them to either autofocus or help you manually focus depending on your setup. It also does a lot of other stuff, read all about it here: http://www.dslrfocus.com/
Martin
Been to the site, and found that DSLRFocus doesn't upport the 400D yet - Bugger!
EDIT: Sorry, Gary already made the point. Still a bugger though...
The up-side is I got my RS-60E3 Remote release yesterday.
Last edited by Marc; 23-02-2007 at 02:20 PM.
Reason: Gary already made that point!
That's not correct. It will always do noise reduction if:
1) You have it set (in custom functions menu)
2) Your exposure is over 30 seconds.
Ahh thanks for that Mike. I only just got the thing. I don't remember where I heard that. Do you think the auto noise reduction is as good as manual dark frame subtraction? Would be a lot easier if it was!
Well interestingly I have taken a few shots this evening - ranging from 90 - 240 seconds - M42, M46, Eta Carina and Omega Cluster - and taken a few darks, two interesting observations with noise reduction switched on.
1. Darks are nearly pitch black - I see no discernible noise whatsoever
2. The bulb shot for say 120 seconds, processes for maybe 120 seconds after the lens closes before the image is composited to the LCD / PC - maybe it is doing appropriately framed darks by popping up its prism, taking a dark, then subtracting it from the last image?
Pretty smart if it was!
PS
Had to add this time to DSLR Shutter to ensure a sequence isn't chopped allowing for post image processing by the camera.
The cameras noise reduction (dark frame subtraction) takes an image for the same length of time as the image you just captured, so if you took an image of 120sec the camera will do a noise reduction for the same length of time, 120sec. Nothing moves inside the camera when the dark frame is being done it just simply captures an image whilst the shutter is closed (same as having a lens cap on) Then processes the images before writting the file (.CR2 and/or JPG). Best just to leave the camera alone during this process to prevent any missread information onto the CF card.
Hope this helps a bit..
Havent had a chance to try a few deeper exposures around Orion etc... have to waitfor the weather to clear up, but I am having fun learning about Deepsky Stacker, a neat little program that stacks quite well, both my scorpio and Orion shots were done with it... Lacks a bit of editing power, but thats what Photoshop was invented for
Oh Photoshop CS3 comes out in March.
Does DSLR shutter work on the 400D then? How do you connect from the DSLR to the program, will the supplied USB cable work?
