Let me throw a spanner in here... I too shoot with a D90, 35 F1.4G and Zeiss 100 F2. really great fun. I have been thinking about upgrading to a D7000, but noticed the other day the D700 is only about $600 extra, So here's the question.
Is it better to shoot a DX camera with Higher MP or an FX camera with lesser MP (12MP for the D700) -especially considering the 2 primes.?
...just another thought for people getting into DSLR purchases.
Knowing what I know now, I would never have purchased DX lenses. 20/20 hindsight!
I have just made the move from a D300s to a D800E ( I still have the D300S. Not giving that up without a fight!). I have been investigating lens options for the FX format.
Not too sure if I have been mislead by sales staff (through their own ignorance or something else) or no-one has ever explained the whole 'crop factor' story to me correctly.
I still have to think slowly about what is happening and what the conversions really mean when going fro a FX to DX and back to FX because I had been lead to believe something different.
I have asked at several camera stores about the crop factor and had several differing explanations...so here goes, i think I have finally worked it out!
FX lenses and DX lenses are essentially the same beast when discussing ....MM magnification from a DX point of view, so a 100mm FX lens will produce the same result in the viewfinder on a DX body as a 100mm DX lens on a DX body.
I had been lead to believe that if you put a 100mm FX lens on a FX body and you compare the viewfinder image to a 100mm DX lens on a DX body, you would see the same thing. Not so. the 1.5 multiplier applies to ALL lenses on a DX body, even DX classed lenses.
To prove this to myself i put a DX lens set at 100mm on my D300S (DX) and a 150mm (FX) on my D800E(FX) and yikes, same image in the viewfinder. This comparison is the reverse of what most people are concerned about but when migrating to FX format, everything you thought applied to DX format might be suddenly turned on it's head.
This crop factor can be confusing , especially when you have been lead to believe something totally different for a number of years.
I recently purchased a Tokina 11-17mm DX f/2.8. I had an option of a Tokina 16-28 FX f/2.8. the sales staff knew that I was also about to go FX but still steered me towards the 11-17 stating the 16-24 wouldn't be as suitable for the type of photography I was into totally due to it being a 16-24mm, not wide enough. The truth is they roughly produce the same image in the viewfinder if connected to their respective bodies (the 11-16 mm will produce an equivalent 16.5-36 mm in the DX viewfinder).
Before you make any purchases be aware of crop factor and it's implications in a couple of years when you decide you might want to go FX. If you are happy to have your FX camera auto crop your images when you put on a DX lens, and loses one third of your pixels go for it. DX lenses are cheaper (quality is not compromised) because they don't have to cater for the extra sensor size.
FX lenses can be a much larger investment but if you are considering a new lens purchase, consider future proofing yourself. Paying more than $1,200.00 a couple of years ago for a great piece of glass now feels like wasted money knowing that (as an example only) a 50mm FX lens would have produced exactly the same results as a 50mm DX lens on my DX, D300S.