FX vs DX for long shots

So i can use my D300 (DX body) with my 70-200 (FX lens) to replicate a longer focal length. (1.5 x 200 = 300mm). If i bought an FX body and used the same lens, it would be a 200mm focal length for real, but if i only used the 'center' of the image it would effectively be a 300mm image.

But what about the IQ?

The D300 has 12 million pixels. The new d300 (FX) has 24 million pixels, but in the example about, I'd only be using 'some' of them. IF i'm counting correctly, the DX sensor is about 43% the size of the D600 sensor (371 sq mm vs 862). If i use 42% of the larger sensor on this hypothetical image, that is 10.3 million pixels. So would I be correct to conclude that 10.3 million for the FX setup would be lower quality than the 12.3 million for that far away shot?

I realize for most of the work done using the full frame of both, there's no comparison.

thanks,

Neil

If your lens is kept constant and you compare DX to FX for reach, you have to get up to the D800 before you have a greater pixel density than the D300.

It is pixel density (pixels per mm on the sensor) that determines how many pixels you can get on a far away subject with the same lens. As you have calculated, the D600 cropped to DX gives you ~10MP.

The greatest reach you can get is actually with the D3200 (24MP DX), but we are expecting other DX 24MP upgrades at some point in the future.
--
John
Gallery: http://jfriend.smugmug.com

Indeed, to match the image size produced from a 24mp DX sensor from an FX sensor image when cropped to match focal length, the sensor needs to be 57mp

There are those that argue "get a bigger lens" however decent 500mm plus fixed lenses cost multiples of the cost of a DX body. A Sigma 50-500 OS (which is an awesome lens and relatively inexpensive) attached to a 24mp D400 would be a deadly combination.

To reach the equivalent image on a FX body without cropping would require either a 700mm or 800mm lens.

If you have the money kicking about for a decent one of these, please donate it to me.

Thanks! ;-)

Andy

--
Aviation Photographer, http://www.evansaviography.co.uk

Examples of my work:
http://www.airliners.net/open.file/0839507/L/
http://www.airliners.net/open.file/0992198/L/
http://www.airliners.net/open.file/0937722/L/
http://www.airliners.net/open.file/0946396/L/
http://www.airliners.net/open.file/0878142/L/

I took this with my D800 and 70-200 vrII. I was in the end zone ,2nd level, about 120 yards away, hand held. It's about 100% cropped. I don't have any experience with D300 having upgraded from a D70 so I can't make a valid comparison between dx and fx.

Andy Evans said:

Andy Evans wrote:

Sigma 50-500 OS (which is an awesome lens and relatively inexpensive) attached > to a 24mp D400 would be a deadly combination.

Andy

Click to expand...

The high MP sensors do show the limitations of your glass much faster than the lower MP sensors. The 50-500 by all means is a huge compromise, but the judgements are highly subjective for sure.

The general comments against other (often more expensive) lenses is that it lacks detail/micro contrast and sharpness, sometimes color is off or flat, and its long and heavy. Some say it's mono or tripod only. The latter is however very debatable, cause this conclusion comes from testers/reviewer using the lens the first time.

If you look for reports from regular users, they often tell us they 'learned' to use the lens without mono- or tripod, e.g. using stabilizing gear like the waist support systems, or just muscles and technique.

Sharpness and detail complaints are often related to the edges. On APS-c cameras you will not notice that much of this.

Than there is the focus off with changing focal length issue. Which means thatif you are framing somwhere between 50-500 mm you will be refocussing the lens constantly. This may cause the battery to run out of juice constantly. My tip: frame as much as you can even with the picture become slightly unsharp and only finally focus only with AF-on if you've got the framing right.

I think you will learn a lot about this lens when you read the following user report. Remember, it's tested on a Canon FF (a good one..):

http://darwinwiggett.wordpress.com/2011/06/21/sigma-50-500mm-f4-5-6-3-apo-dg-os-hsm-lens-review-a-field-test/

All in all, if you buy it, do post some examples cause it's one the lenses on my list as well.

lock

Lock,

By asking for the money, I was asking for the money for a 700 prime lol

Nice write up, I have owned and used the OS version for two years and taken many of my best shots with this lens. All my 2011 and 2012 flying shots have been taken with this lens on my website and flickr ( http://www.flickr.com/evansaviography )

Beforehand I owned the original 50-500 and can say the image quality from the OS version is much better, taking it from an ok lens to the lens of choice for Nikon aviation shooters that can't afford the 200-400.

Andy
--
Aviation Photographer, http://www.evansaviography.co.uk

Examples of my work:
http://www.airliners.net/open.file/0839507/L/
http://www.airliners.net/open.file/0992198/L/
http://www.airliners.net/open.file/0937722/L/
http://www.airliners.net/open.file/0946396/L/
http://www.airliners.net/open.file/0878142/L/

If you are concerned with sports for your reach, the problem is that no current FX camera is as fast as your D300 except the D4!

First off the new is a D7000(FX) sort of, not even close to a D300(FX), that would be the D4 if at all, quite a stretch.

nbg70 said:

The D300 has 12 million pixels. The new d300 (FX) has 24 million pixels, but in the example about, I'd only be using 'some' of them. IF i'm counting correctly, the DX sensor > is about 43% the size of the D600 sensor (371 sq mm vs 862). If i use 42% of the larger > sensor on this hypothetical image, that is 10.3 million pixels.

Click to expand...

This following would be true only if you assume the FX pixels are inferior to the DX pixels.

nbg70 said:

So would I be correct to conclude that 10.3 million for the FX setup would be lower > quality than the 12.3 million for that far away shot?

I realize for most of the work done using the full frame of both, there's no comparison.

thanks,

Neil

Click to expand...

--
Everything happens for a reason. #1 reason: poor planning
WSSA #44

In general, the larger the front aperture of a lens used for sunlit near-ground level shots, the greater the disturbance from atmospheric "noise" (boiling/rippling) becomes. This can be subtle, but is observable. Astronomers call this atmospheric disturbance issue "seeing". You can make up the difference with higher ISO if possible. Something no larger than 3.5" is about maximum before "seeing" significantly degrades the view. About f5.6 on a 500mm focal length. Smaller is even better.

Of course, in good seeing conditions, there's no substitute for inches of good glass.

If you need clarity, a smaller front aperture may have benefits not obtainable with larger glass. The issue becomes, does someone make a good, small aperture long lens?
--
Wayne

See more at:

http://www.flickr.com/photos/turbguy/