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buzz

Current wisdom on best EOS choice for Astro?

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I normally use CCD's for imaging but need to do a project with a normal DSLR.  At one time the old EOS 40D and the 1100D had liveview and good SNR performance and I seem to recall that the later models with higher pixel counts were not as good.

I have been out of this camp for a while and wondered what the perceived wisdom is on the best choice for an EOS body? APS-C is fine, since I doubt my imaging field will cover a full frame.

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The later models have improved and to be honest higher pixel counts are not a problem but depends on the FL of the scope.

If using a refractor then a flip out screen is a big bonus not so much with a reflector, cameras with the digic 5 processor tend to have lower noise at higher ISO than the earlier ones.

Alan

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I vote for the Canon 40D... pixel size & sensitivity vs noise I found is was the best when comparing to a 7D same ISO and exposure time. I think the bigger pixels on the sensor do help a lot with SNR. Add to that the ability to use with APT and Live view and I think its a winner.

I also have a modded 300D as a backup and again the big pixels do seem to be more sensitive and less noise ISO and exposure time comparison to a 7D. Only draw back on the 300D is no APT control, no live view and the 12bit ADC, but does that really matter when you stack 10+ subs? But this one is only a backup.

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I have a 600D Modded works well.......3 minute single image mounted on a Star Adventurer.....

 cygnus-300-800-100mm.jpg

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There's 3 cameras i'd recommend.

1100D is cheap and pretty good.

600D is better and has smaller pixels so works better for shorter focal lenghts.

6D is really great with very low. A lot more expensive, but worth it. Some objects are great even with a single exposure if not too faint.

6Da 60s single epxosure @ 1000mm f/5 

6112721ee634aa1cdc6804939fb6275f.1824x0_

Edited by Xplode
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Ole, that 6d shot looks amazing - there is also a 60Da on Amazon right now that is winking at me.

Edited by buzz
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A single 30 second sub on a modified Canon 6D at ISO1600, admittedly this was at f/2...I have also got a modified Canon 650D which I like because of the touch and twisty-out display.

17284784414_359af1ffc4_b.jpg

Crux - The Southern Cross by Stuart, on Flickr

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Some lovely pics here.

But the question asked at the top of the thread is one I keep going round and round.

There are quite a few different modified Canon cameras on offer from the three (is it?) suppliers of modded DSLRs.

How to choose between them? Is there much difference between them noise wise?

Or should I have my olde 450D modded? I don't fancy DIYing it. But it's 6 or 7 years old now so how much life is there left in it? Might it be a waste of money?

Or why not spend a bit more than on a moderately high-end DSLR and buy a QHY10 (say) single-shot cooled colour CCD?

I keep going round and round this circle and never coming out the other side ... if that makes sense geometrically. :-)

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The 6**D series do offer some genuine benifits for astro work.

Proper mirror lockup function, this does help if shooting lunar planetary

Inbuilt ultrasonic sensor clean routine does help in controlling dust motes

Flip out screen when used with a refractor means an end to contortions of course you can use tethering but this adds another load of kit to be carried if using a lightweight widefield rig away from home.

In general noise performace gets better with cost and the version of the cameras internal processor the difference can be significant.

Alan

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Has someone compared noise levels quantitively for different DSLRs?

I can see the mirror lock up could be useful. I tried it on my 450D to minimise scope shake, but I seemed to get more amp glow. I understand this can be less of a problem in other models. Is that right?

A flip out screen would be really useful with a Newtonian too. The camera usually starts out being nicely accessible at the start of an imaging run. An hour and a half later and you find yourself precariously atop a flimsy plastic garden chair trying to make adjustments.

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Gary Honis has a comprehensive review here http://dslrmodifications.com/DSLRcomparison.html.

I cant vouch for other models but with mine mirror lockup is a seperate function unrelated to live view and hence from what I have seen does not cause amp glow.

I had never thought that reflectors might have issues with the screen ending up at odd angles but It must do during an imaging run.

Alan

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But the question asked at the top of the thread is one I keep going round and round.

<snip>

Or should I have my olde 450D modded? I don't fancy DIYing it. But it's 6 or 7 years old now so how much life is there left in it? Might it be a waste of money?

<snip>

Or why not spend a bit more than on a moderately high-end DSLR and buy a QHY10 (say) single-shot cooled colour CCD?

<snip>

Only you or the OP can answer that...depending on your budget and expectations...ask 100 people for an opinion and you will get 100 different answers.

I always look to see what kit was used for a particular image that I like and go from there...

As an extension to the above post from Alan here is a post where Gary does some indoor testing, my findings are similar, i.e. the "best" camera is a full frame camera but that doesn't come for free, in cost terms and other issues like being able to get in image circle big enough:

http://dslrmodifications.com/6DReview/6DReview.html

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Interesting thanks. Good to see how well the 450D stands up. Makes having mine modded an attractive option. Maybe to be replaced by a new Canon body to go with my various lenses I use for daytime photography. Oh dear! Options, options!

Edited by Ouroboros

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Has someone compared noise levels quantitively for different DSLRs?

I can see the mirror lock up could be useful. I tried it on my 450D to minimise scope shake, but I seemed to get more amp glow. I understand this can be less of a problem in other models. Is that right?

A flip out screen would be really useful with a Newtonian too. The camera usually starts out being nicely accessible at the start of an imaging run. An hour and a half later and you find yourself precariously atop a flimsy plastic garden chair trying to make adjustments.

The 450 is a very capable camera and easily modified (but not as easy to mod as the 1100d). It's a nice DIY project as you can pick up second hand eos bodies cheaply. I highly recommend Backyard eos to save your neck and knees plus it can automate a number of processes.

I also purchased a Fuji mirror less recently and am very impressed with its TransX sensor.

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A 60Da 10minute dark frame similar to the Honis ones, approx 300 pix from the centre.

post-30455-0-56256500-1437285385.jpg

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I think you also need to consider the sky conditions you will be shooting under. If they are light polluted, then I don't think you will benefit much from a low noise camera as it will be drowned out by the sky glow 'noise'. At least, that's how I understand it from what I have read.

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I'm going to (initially) try a different route. My normal camera is a Fuji X-T1, which as some may note from prior posts, has good Ha and some SII sensitivity. I already have a T-thread adaptor and an intervalometer but wanted to do things by USB.  It has WiFi but that is a primitive app.

I just discovered that Fuji has released tethered software for the X-T1, called HS-V5, for about £80. I can do my focusing and framing with that (using a GoldFocus mask for focusing) and then switch over to the intervalometer for the imaging exposures themselves. I was never particularly convinced with liveview focusing and I think I can get round it with the mask, since GoldFocus monitors a folder for image exposures and works on those.

It might not work, but for £80 it is probably worth a go.

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I'll be interested to know how you get on with the X-T1.  Do you plan to mod it?

Answering your original question regarding the best EOS then the 7D Mk II is probably the best out there at present - see Roger Clark's review here:

http://www.clarkvision.com/reviews/evaluation-canon-7dii/

Regarding the Fuji, I wonder if it clips pixel values in dark frames to black (which Nikon are STILL doing - even with their model dedicated for astro work - the D810A).

Mark

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I just got the HS-V5 tethering software. It interfaces through the USB port and usefully allows either PC or Camera controls to prevail. I worked out that I can focus and frame using PC operation, since I only need relatively short exposures (no more than 30"). It can download frames to the PC rather than onto the card and they can be analysed by my GoldFocus software to confirm and set focus. (I could use the liveview and use the mask only)  I then turn it over to Camera control.

That is when I use the microphone socket, that doubles up as a standard release. I can set the Camera's dial setting to Bulb and use a standard trigger via serial port, or a fleabay intervalometer I bought for £20. I then save Raw files to the card, which saves on USB bandwidth.

I already had the vertical grip, and I just bought a cheap battery adaptor and a DC-DC voltage converter. I now have a 9V DC feed from my 12V distribution panel running the camera .    Just need a clear night to try it out.

I'll post some pictures.   When I compared it to my son's EOS 1100D, it was inherently less noisy on the RAW files, something that is borne out by the dpreview comparisons too. I don't think any RAW files are truly unprocessed but it was not swallowing faint stars, which is I believe a criticism of the early Nikon bodies.

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Just bought an EOS 60Da -  and evaluating bias and dark noise.   At ISO400, I measured the bias mean and SD as well as a calibrated 10-minute dark from each. 16-bit figures - no noise reduction options selected. RAW files measured in PixInsight.

Camera       Mean Bias     Bias SD         Mean Dark          Dark SD

Fuji XT1          13.7               2.84               39                       170

Eos 60Da         27                  8.3               103                      235

I think the Fuji does a dark subtract, but it cannot subtract the noise. Having said that, its bias and dark noise seems better. Just trying to work out how best to measure color response...and when the clouds part, a real comparison.

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