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Old 22-08-2013, 12:24 PM
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Occulta (Chris)
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Full frame camera comparison

Gizmag has done a comparison of the following full frame cameras:

* Canon EOS 6D
* Nikon D600
* Sony SLT-A99
* Canon EOS 5DIII
* Nikon D800/e

The review can be found here:

http://tinyurl.com/ks6cqln

Chris
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Old 26-08-2013, 10:22 AM
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He doesn't conclude much. Often reviewers say "the best camera is the one that suits you the best" - well you knew that before you read the review right?

D600 is a good camera but it has the dust/oil issue which as far as I know has not yet been solved. That means you have to clean the sensor often because there is a defect in the shutter mechanism that is causing bits of paint or dust or oil to flick onto the sensor. This is discussed ad nauseum on the camera forums.

It stopped me from considering one.

They all have their pluses and minuses and often buyers are already brand loyal so reviews mean little when that occurs. Often buyers have invested heavily in one brand of lens and their choice now is gone and are locked in from an earlier decision (which they may be entirely happy with).

Another factor reviewers don't look at it that astrophotographers do is QE. QE is very much higher with the current Nikon cameras.

Also the Nikon hot pixel noise suppression applied prior to saving to RAW was very bad in early Nikon models but has been greatly improved in later models and appears to no longer be an issue.

I did read a report where one guy used a D800 for deep sky astrophotography and he complained about something being non linear. I am not sure what he meant by that but he found a way around it. The resulting image was pretty spectacular even by CCD standards. But DSLRs are still a long way off from challenging a cooled high quality CCD.
Its that whole mono every pixel counts thing.

DSLR sensors are probably really sensitive these days but they have so much stuff on top of them only a fraction of the light is getting through.

Here is a list of common cameras QE performance (not sure how accurate it is but its probably a guide);

http://www.sensorgen.info/

Also of interest coming up in the near future. Fuji has developed and patented a process of a light sensitive organic coating for sensors that increases light sensitivity and results in the highest dynamic range sensor at 88db. That should be in Fuji cameras at the end of next year earliest perhap 2015.

A full frame Sony Nex camera is expected very soon. That could be of interest to astrophotographers as well as it may be easier to cool as the sensor most likely has been pushed against the back wall of the camera body.

Greg.
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Old 26-08-2013, 04:26 PM
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Hi Greg - any chance you could scare up a link to the D800 being used for Deep sky?
cheers,
Andrew.
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Old 26-08-2013, 05:27 PM
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Here you go Andrew:

http://tech.groups.yahoo.com/group/d...message/158253

What he was referring to was nonlinear were his flats with a D800. He is saying that the RAW can shift.

I am not sure about his flat fielding techniques, they seem a little odd to me so perhaps he is right perhaps he is simply doing his flats in an odd way. Its hard to tell. So that may or may not be an issue.

Certainly the resulting image is very good. So his work around was good.

Flats was a topic I found out more about at AAIC and found a few tips on it that may help.

Firstly he recommends to rotate your instrument to get rid of gradients - I have never heard of anyone else ever doing that so he must be using a very uneven source of light for his flats. Secondly he subtracts a number for bias instead of an actual bias shot. I don't think that would be ideal either why subtract a theoretical when you can have the actual?? So, keep that in mind.

Greg.
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Old 26-08-2013, 05:59 PM
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Thanks Greg - very interesting read, and he definitely has some stunning images from the modified D800 - I've been waiting for someone else to do it!
cheers,
Andrew.
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Old 26-08-2013, 06:05 PM
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That's right Andrew. I couldn't see myself ripping out the UV/IR filter on a $3600 camera! Its an impressive result and his work around for the flats is a workable approach in case what he says is true.

Greg.
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Old 26-08-2013, 06:38 PM
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Something I noticed on a recent photography trip where we were all shooting in manual and comparing exposures - I often had to increase my exposure by a stop with my D800 vs those shooting Canon 5D MkII.

Not sure why, but it would appear that ISO values aren't equivalent between manufacturers. Greg mentioned this in his presentation at AAIC - something about how it is measured.

DT
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Old 27-08-2013, 08:23 AM
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Yes if you look up ISO in Wikipedia it goes into it.
Fuji is similar. ISO6400 in the Fuji is about ISO4000 in the Nikon.
For a standardisation it appears the manufacturers have a fair amount of leeway. Perhaps they have different approaches to implementing the ISO and its not as sinister as it sounds.

Greg.
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Old 28-08-2013, 04:01 PM
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Quote:
Originally Posted by DavidTrap View Post
Not sure why, but it would appear that ISO values aren't equivalent between manufacturers. Greg mentioned this in his presentation at AAIC - something about how it is measured.
The DSOMark site measures ISO against stated camera settings and it neever seems to be spot on. Even the amount it differs for each ISO setting on a single camera is non-linear. Very good site to get info on measured comparisons.
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