Pixels, noise and cropping - Upgrade advice!

motso

motso

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Tom
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Hi All,

I have been pondering upgrading my Sony A55 (16MP) to the A77 (24MP). I predominantly shoot wildlife and hence often need to push ISO up as much as I dare (I don't like going above 400 on the A55), but also sometimes need to crop heavily.

In my head it makes sense that a higher MP count will retain more detail/IQ in my crops and noise would be reduced as a result of the better ISO performance of the A77.

Obviously the A77, also has a number of other benefits, but is there anything I am missing when it comes to the IQ of cropped images?

Hope this makes sense!

Tom.
 
The same sensor is in the A65, and ISO performance on both bodies are the same.
I bought an A65, thought it was the one for me - shadow IQ even at ISO100 was dire!
Where the A65 would do well is fast burst rates, but when compared on DP Review's RAW noise tests (using graph mode) I noticed the Pentax K5 was significantly better with, again, the same Sony sensor as in the A57, which is Sony's best ISO performance in RAW format.

So, I'd say either go for the A57 (new or pre-owned) or sit tight for a bit more and see what happens to the A65/A77 models.
I'd say there has to be an A67, that at least matches the performance of the A57's ISO, if not betters it to be as good as the Pentax's.

The alternative, depending on what lenses you have already bought into, is switch to the Pentax K5-II or even AA-filterless IIs (for similar money as A77) or a K30 and some good lenses.
The K30 beats the K5's ISO above 800 and this is matched with the new K5-II's.

I wanted to love the Sony, really wanted the A77 with its bigger body and top LCD, but the Pentax K5 is compared to the Nikon D7000 as equivalent, the Sony doesn't get a look-in, so for the price, my money would be on a K5-II, which gets you the top LCD and twin scroll wheels for aperture and shutter, not to mention buttons for the ISO/WB/etc which the Sony lacks, even with a sort of quick access menu feature.
The Pentax is just the better camera and menu/settings design - weatherproof (even on the cheap K30, which also has twin scroll wheels, but no top LCD) too, like the D7000 - but won't be quite as fast on the burst rate, at 7-8 fps.
The Pentax also does 14-bit conversion (like the D7000) whereas the Sony is 10-bit.

So sorry to have to say, but I'd switch to either a Pentax or pre-owned Nikon D7000.
 
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The switch 16mp to 24mp is not as big as it seems. In fact you'll only get about 20% more pixels on each axis. Too few to make a day and night difference. Further more most likely you will be limited by your lens.

Also iso performance is not that much better on A77. DxOmark says only about 1/3 stop.

Don't expect significant IQ difference. Some handling aspect might be better on A77 though...
 
A58 is due to be announced in days & supposedly has a further improvement in ISO.
The SLTs are always going to be ~0.4-0.5 stops behind a conventional swinging mirror DSLR body using the same sensor - it's the nature of the tech.
I'm surprised that you stop at 400ISO on an A55 though.

The Pentaxs use NR in RAW at high ISO which helps them but of course you can do the same in post-processing.
 
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heidfirst said:
The Pentaxs use NR in RAW at high ISO
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Where is that confirmed as the case?
I've read (here?) that Sony use sharpening in RAW files, but I didn't go off and check for validation as I was already heavily disappointed in the shadow noise enough to realise the A65 wasn't for me, so the proof was purely academical as the brand was no longer of interest.
 
PJ S said:
Where is that confirmed as the case?
I've read (here?) that Sony use sharpening in RAW files,.
Click to expand...
DxO.
On the other hand I've never seen it suggested that Sony uses sharpening in RAW (what a Sony will do is tag the RAW file with in-camera settings which something like IDC may use as a starting point if you let it).
 
motso said:
Hi All,

I have been pondering upgrading my Sony A55 (16MP) to the A77 (24MP). I predominantly shoot wildlife and hence often need to push ISO up as much as I dare (I don't like going above 400 on the A55), but also sometimes need to crop heavily.

In my head it makes sense that a higher MP count will retain more detail/IQ in my crops and noise would be reduced as a result of the better ISO performance of the A77.

Obviously the A77, also has a number of other benefits, but is there anything I am missing when it comes to the IQ of cropped images?

Hope this makes sense!

Tom.
Click to expand...

You need incredible lenses to make a full use of those resolutions of APS-C sensor. Therefore that 24MP practically becomes a marketing gimmick, but according to SONY consumers want bigger numbers. Only fast mega primes would benefit.

So to answer your question, you should really look at LONGER and FASTER lens. I am not sure SONY offers such a choice, so maybe it is time for Canon or Nikon.
 
daugirdas said:
So to answer your question, you should really look at LONGER and FASTER lens. I am not sure SONY offers such a choice, so maybe it is time for Canon or Nikon.
Click to expand...
that was my first thoughts too but looking at his camera bag profile he's probably using a 70-200/2.8 & there is no mention of a TC. If that is the case then any improvement in Canon, Nikon or Sony systems is likely to be several £k (e.g. 300/2.8, 400/5.6 or better).
 
heidfirst said:
that was my first thoughts too but looking at his camera bag profile he's probably using a 70-200/2.8 & there is no mention of a TC. If that is the case then any improvement in Canon, Nikon or Sony systems is likely to be several £k (e.g. 300/2.8, 400/5.6 or better).
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200mm even on crop is a bit short for wildlife. I am guessing OP is on 75-300 5.6 which is not stellar. The Sigma 70-200mm f/2.8 with TC wouldn't win any resolution competition either.

Even a 300mm f/4 IS would be a big step forward, but ideally a 300 f/2.8 and TC, or 400, 500mm. Unfortunately, it gets very expensive very quickly, but then there are a lot more expensive hobbies around.
 
mpe said:
The switch 16mp to 24mp is not as big as it seems. In fact you'll only get about 20% more pixels on each axis. Too few to make a day and night difference. Further more most likely you will be limited by your lens.

Also iso performance is not that much better on A77. DxOmark says only about 1/3 stop.

Don't expect significant IQ difference. Some handling aspect might be better on A77 though...
Click to expand...

True.

daugirdas said:
You need incredible lenses to make a full use of those resolutions of APS-C sensor. Therefore that 24MP practically becomes a marketing gimmick, but according to SONY consumers want bigger numbers. Only fast mega primes would benefit.

So to answer your question, you should really look at LONGER and FASTER lens. I am not sure SONY offers such a choice, so maybe it is time for Canon or Nikon.
Click to expand...

Also true.

Just adding pixels will not necessarily increase sharpness, unless your lenses are upgraded to the same standard. Increasing pixel density makes the lens work much harder and need to be exceptionally good if you're to see the benefit.

If your lenses are already high grade and still the images are not good enough, then you either need better lenses yet, like a super-prime, or full-frame, or both.
 
motso said:
In my head it makes sense that a higher MP count will retain more detail/IQ in my crops and noise would be reduced as a result of the better ISO performance of the A77.
Click to expand...

Noise will be increased with a higher pixel count. This is because the space for each pixel is reduced, therefore its light gathering properties are reduced too. To make up the shortfall, the signal is amplified a bit more and that increases the noise as background levels of noise are also amplified.

An analogy would be recording audio on tape. A studio machine with wide tracks on 1" or 2" tape has good signal to noise ratio. Reduce it to the tiny width of tracks on a cassette tape and the signal to noise ratio goes up. Usually heard as a hiss on cassettes (for those of us old enough to remember them!).


Steve.
 
Steve Smith said:
Noise will be increased with a higher pixel count. This is because the space for each pixel is reduced, therefore its light gathering properties are reduced too. To make up the shortfall, the signal is amplified a bit more and that increases the noise as background levels of noise are also amplified.
Click to expand...
This only applies when you are trying to drag the signal out of the noise - for example in astrophotography. For a well exposed image, it's really the overall size of the displayed image that matters. You will get similar noise levels out of a 10Mpix APS-C camera as you would from a 30Mpix APS-C camera blowing up the complete sensor image to the same image size.

Where you will see the differences is if you crop to the same pixel dimensions and then print to the same size (i.e. crop to 1000 x 1000 - the higher pixel density image will have to be blown up more so the noise becomes more visible).
 
Thanks for all the interesting replies, I guess its not as clear cut as I'd hoped! At the moment I primarily use a Sigma 70-200mm 2.8, I chose this over a longer zoom (Sigma 150-500) with a smaller aperture as I found my old Sony 75-300 5.6 (a pretty poor lens) to be extremely limiting in most situations. I love the speed of the Sigma but am missing a bit of zoom and the purchase of a 1.4x teleconverter is imminent. In the future I may opt for the 150-500 Sigma but don't think I will be spending thousands on lens any time soon.

I have also made the choice to stay with Sony, I generally really like their cameras.

From these comments it would seem that I am probably better off sticking with what I have at the moment, are there any rumours of a A77 replacement?

I will post a ISO400 photo tonight, perhaps I am mistaking 'noise' for something else?

Thanks

Tom.
 
motso said:
Thanks for all the interesting replies, I guess its not as clear cut as I'd hoped! At the moment I primarily use a Sigma 70-200mm 2.8, I chose this over a longer zoom (Sigma 150-500) with a smaller aperture as I found my old Sony 75-300 5.6 (a pretty poor lens) to be extremely limiting in most situations. I love the speed of the Sigma but am missing a bit of zoom and the purchase of a 1.4x teleconverter is imminent. In the future I may opt for the 150-500 Sigma but don't think I will be spending thousands on lens any time soon.

I have also made the choice to stay with Sony, I generally really like their cameras.

From these comments it would seem that I am probably better off sticking with what I have at the moment, are there any rumours of a A77 replacement?

I will post a ISO400 photo tonight, perhaps I am mistaking 'noise' for something else?

Thanks

Tom.
Click to expand...

You need a better long lens. You will still end up cropping to hell with whatever you choose. I would keep the camera and save up for a good long lens so that you can keep cropping to a minimum. One of the xxx-500 sigma if you want it on the cheap side or the 70-400 sony which I hear is a rather good lens.
 
menthel said:
You need a better long lens. You will still end up cropping to hell with whatever you choose. I would keep the camera and save up for a good long lens so that you can keep cropping to a minimum. One of the xxx-500 sigma if you want it on the cheap side or the 70-400 sony which I hear is a rather good lens.
Click to expand...

He might as well get that Sony lens, it will be worth it. There is no escaping from the fact everything will be f/5.6+ at the longer end, so good ISO performance and editing workflow will need to match it. ISO400 is simply too little for wildlife.
 
daugirdas said:
He might as well get that Sony lens, it will be worth it. There is no escaping from the fact everything will be f/5.6+ at the longer end, so good ISO performance and editing workflow will need to match it. ISO400 is simply too little for wildlife.
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Agreed. Cutting cropping to the minimum (please excuse the terrible pun) should always be the first step for wildlife. The camera is most likely fine up to 1600 when you aren't throwing away 3/4 of the image!
 
arad85 said:
This only applies when you are trying to drag the signal out of the noise - for example in astrophotography. For a well exposed image, it's really the overall size of the displayed image that matters.
Click to expand...

No, it will have the same effect on the signal to noise ratio. You may however have a signal that is so high that the noise is insignificant.
 
Some really interesting responses, very helpful. I should say I am well aware 200mm is not really sufficient for most wildlife. The reason I went for the 2.8 is that currently most of my photography is done whilst on walks and shooting handheld. The 70-200 2.8 is perfect for slinging over the shoulder and fast enough to be used without a tripod. I fully expect to have to add a longer lens to my collection in due course, however at the moment I am trying to make the most of my current set up without too much more expenditure (could probably get the A77 second hand from LCE and trade in my A55).

I think to clarify what I mean by noise at ISO400, this is when the photo is cropped, which obviously enhances noise. If I were taking a 'full frame' image then I would be confident going way above 400. This leads back to my original question which was that by having more pixels, crops would retain more detail. This however does not seem to be the case and it sounds as if any improvement would be minimal.

My long term plan would be to have the Sigma 70-200, the 150-500mm and a 1.4x teleconverter, which I think should give me a great (budget) set up. Is this sensible?

If you still think it would help if I uploaded a picture let me know, but I think the helpful responses have helped me understand a lot more.

Thanks for the responses!

Tom.
 
Tom,

Upload an image mate - I'm pretty sure if you're asking all this, your images would benefit from some additional PP that could make them look much better with the equipment you have.

Plus it will give some further clarification. It's easy to advice but more *effective* to advise against something evident.
 
I looked at some of my images and its clear that the problems are due to cropping, I guess I was hoping that having more pixels would improve the quality of my crops, but theres no escaping from the fact I need a bigger zoom. Here's a photo I posted in another thread that is not cropped that much from the original image:


DSC01318 by tomsouthall, on Flickr

This was taken at F3.2 1/500 sec and ISO400. There is something just not quite right with it, many parts of the scene seem grainy to me and this has had some sharpening and noise reduction in LR4, let me know your views..

Thanks

Tom
 
All aspects of image quality take a hit when you crop. For more reach, rule of thumb is get a longer lens, then add an extender, then crop as a last option.

It's not an absolute rule by any means but works as a general guide as to which corner of the envelope to push first. And they're all pushing one way or another, long lens wildlife stuff is not easy.
 
motso said:
I looked at some of my images and its clear that the problems are due to cropping, I guess I was hoping that having more pixels would improve the quality of my crops, but theres no escaping from the fact I need a bigger zoom. Here's a photo I posted in another thread that is not cropped that much from the original image:


DSC01318 by tomsouthall, on Flickr

This was taken at F3.2 1/500 sec and ISO400. There is something just not quite right with it, many parts of the scene seem grainy to me and this has had some sharpening and noise reduction in LR4, let me know your views..

Thanks

Tom
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Ok yes - that's past salvageable lol. Longer lens :)

I haven't used the camera myself but people make too much fuss over noise. Use a decent lens that is stupidly sharp and the detail will be retained up to whatever ISO you use. The rest is in your PP skills but you can (noisewise) clean it up to look like something shot much lower (I had a thread that showed a 25600 image cleaned up to look very similar to a ISO 1600 shot).

There is some strange artefacts going on there though - it looks like a water painting filter has been applied or something...all you did was crop??? Any sharpening, if so what was the threshold?
 
The image has been over cropped, over sharpened and then over noise reduced. Get a longer lens. If you still have a problem then a new camera body may be in order.
 
I know its bad, you don't need to re post it!! I was just using it as an example!

Another thing I've noticed is that when using large apertures, anything that gets in the way of the target (ie. branches) look terrible and completely ruins the shot. There's no crazy effects on that, but sharpening is at 80 (radius 1.3), I guess that is kind of high!

Richard, thats a really useful rule of thumb and one I've never heard before, I guess I knew cropping was destructive, but didn't realise quite how much.

I don't regret getting the 70-200, its extremely versatile, but I guess I just need to accept I need longer. Phil, I guess you wouldn't class either the Sigma 150-500 or 50-500 as 'stupidly sharp'?

Tom.
 
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motso said:
I know its bad, you don't need to re post it!!

Another thing I've noticed is that when using large apertures, anything that gets in the way of the target (ie. branches) look terrible and completely ruins the shot. There's no crazy effects on that, but sharpening is at 80 (radius 1.3), I guess that is kind of high!

Richard, thats a really useful rule of thumb and one I've never heard before, I guess I knew cropping was destructive, but didn't realise quite how much.

I don't regret getting the 70-200, its extremely versatile, but I guess I just need to accept I need longer. Phil, I guess you wouldn't class either the Sigma 150-500 or 50-500 as 'stupidly sharp'?

Tom.
Click to expand...

I think 200mm isn't very long at all... but for wildlife nothing is. I've been at 400mm thinking I needed at least 800mm!!

I had a 120-400mm which was quite sharp. Wouldn't hold a candle to any lens I currently own but it would give me quite good results so long as I wasn't cropping too heavy.

I've seen some amazing shots from the lenses stated but I'd definitely want to be trying out one before buying THAT one. Sigmas rep for QC is too big of a gamble for me...with a decent 2x teleconverter, monopod and shooting at F8 would probably get you a very decent shot.
 
menthel said:
The image has been over cropped, over sharpened and then over noise reduced. Get a longer lens. If you still have a problem then a new camera body may be in order.
Click to expand...

quite a bit...! and some heavy front focus icing on top

motso said:
I know its bad, you don't need to re post it!! I was just using it as an example!

Another thing I've noticed is that when using large apertures, anything that gets in the way of the target (ie. branches) look terrible and completely ruins the shot. There's no crazy effects on that, but sharpening is at 80 (radius 1.3), I guess that is kind of high!

Richard, thats a really useful rule of thumb and one I've never heard before, I guess I knew cropping was destructive, but didn't realise quite how much.

I don't regret getting the 70-200, its extremely versatile, but I guess I just need to accept I need longer. Phil, I guess you wouldn't class either the Sigma 150-500 or 50-500 as 'stupidly sharp'?

Tom.
Click to expand...

25-40 at r=1.0-1.2 is a more reasonable sharpening range. NR definitely less than 20 or indeed a set of water paint is a better tool.
 
In my earlier reply, I suggested to look at the Pentax K5 or K5-II as opposed to the Sony A77.
I know you've stated a preference for the Sony for whatever reason, but aside from longer zoom lens, if you do still think the body needs to change, have a serious thought about the Pentax.

Happened to stumble upon this moments ago whilst looking for info on someone else's plight here - http://www.dxomark.com/index.php/Pu...x-K5-II-Showing-the-competition-how-it-s-done
 
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