vanderhala Loc: Los Angeles, CA

I dont understand: you cannot have it both ways.
Either the crop factor is valid, and a 11-20 wide angle zoom FX will be 16-30 , just like a 150-400 would be 225 - 500 (Nikon, crop factor 1.5) ?

SteveR Loc: Michigan

Yes, every lens used on a crop sensor camera is subject to the crop factor, whether they be dx or fx lenses. Does that clarify things?

SuperflyTNT Loc: Manassas VA

The OP asked what the advantages/disadvantages of using an FX lens on a DX body. The responder stated that wide angle lenses wouldn’t respond as expected because of the crop factor. I merely pointed out that an FX lens would respond no differently than a DX lens of the same focal length. Yes, an 18mm FX lens on a DX body would still be an 18mm lens but it would appear like a 27mm on FF. Just as an 18mm DX lens would appear like a 27mm on a FF. It also would apply to all lenses, not just wide angle.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

An 18mm lens on an FX camera would NOT appear like a 27mm - if you are referring to angle of view. But you are correct that an 18mm lens would have an angle of view equivalent to a 27mm lens. You appear to be considering the image circle, and how it is usually smaller for DX lenses. But that isn't always true - there are some DX lenses that have a large image circle.

https://photographylife.com/using-nikon-dx-lenses-on-fx-cameras

So in this case the 35mm F1.8 DX lens which when used on a DX camera provides an angle of view equivalent to a 52.5mm lens on an FX sensor, but when used on a FX camera it presents a field of view which for all intents and purposes provides an angle of view of a 35mm FX lens.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Even if the resolution is higher on the low contrast lens. The good thing is that you can increase the contrast in images taken with the hi-res, low contrast lens to have both a perception of sharpness and the capture of fine detail and texture. A high contrast lens that has lower resolution will never capture the fine details and no amount of post processing can add them back.

SuperflyTNT Loc: Manassas VA

Sorry I read that again and it BBC wasn’t clear. I meant that an 18mm DX lens on a DX camera would also give the same AOV as a 27mm on a FF. That’s what I get for posting after bedtime.

SteveR Loc: Michigan

Of course not, it's not on a crop sensor camera. There's no crop factor.

selmslie Loc: Fernandina Beach, FL, USA

Introducing a term that nobody else uses only increases the confusion.

Everyone else calls it the Crop Factor. It only applies to the size of a sensor relative the the full frame standard - 24x36mm. To account for sensors that do not have a 2:3 aspect ratio it is calculated based on the diagonal dimension of the sensor.

selmslie Loc: Fernandina Beach, FL, USA

There is no question that many of us here are smarter than TN and understand the issues better than he seems to from what he has published.

Discussions about the nature an importance of sharpness often go off the rails when you try to make them objective. Lens sharpness and sensor sharpness are abstract concepts that are hard to apply to real images because they are measured differently.

Lenses have traditionally been tested against specific targets like the 1951 USAF resolution test chart and the results expressed as line pairs per millimeter. That's fairly objective. It's where MTF curves come from.

We may take for granted that, if a sensor is specified as 4000x6000 pixels, then it has a 24MP resolution. But we must not overlook the Bayer array. The Bayer array has only 12MP of green pixels that are the primary source of luminance information. The 6MP each of red and blue pixels are used together with the green pixels as a set of overlapping RGB pixels. This tends to reduce the actual resolution to somewhere between 24MP and 12MP, closer to 17MP. The same applies to X-Trans and to color sensors with much higher nominal resolution.

A 24MP sensor without the Bayer array as in the Leica Monochrom actually has a true 24MP resolution. The new 40MP Leica M10 Monochrom Digital Rangefinder Camera will be something to to consider if anyone can afford it.

But the subject of sharpness is given too much importance. It only applies to parts of the scene where the image is close to the focus distance. That might mean something if most of the subject matter is close to infinity (landscapes if it is far beyond the hyperfocal distance) or if you are copying a flat document. But it has no significance in portions of the image that are beyond the DOF.

rehess Loc: South Bend, Indiana, USA

and we concentrate on sharpness way too much. I believe, based on my own experiments, that even 24mp digital is much sharper than we actually got from film, and we didn't worry so much about it then. Now days, often it seems like the only thing we worry about, to the cost of composition and other issues which the old masters concentrated on.

selmslie Loc: Fernandina Beach, FL, USA

Yes, it is sharper but some of the difference we see may be because we are comparing our old images with images taken today using better lenses.

I would estimate 135 film scanned with a good scanner somewhere in the 16-22MP range depending on the speed of the film.

But that's why some of us like medium format film. It provides over 3½ times as much resolution at 6x6cm as full frame, betweem 56 and 77MP.

rehess Loc: South Bend, Indiana, USA

quote=selmslie]Yes, it is sharper but some of the difference we see may be because we are comparing our old images with images taken today using better lenses.

I would estimate 135 film scanned with a good scanner somewhere in the 16-22MP range depending on the speed of the film.

But that's why some of us like medium format film. It provides over 3½ times as much resolution at 6x6cm as full frame, betweem 56 and 77MP.[/quote]In my case, I used exactly the same lens to take 16mp digital photos that I had used twenty years ago to take the slides, proving that the lens was capable of more sharpness than I had ever gotten from Kodachrome.

selmslie Loc: Fernandina Beach, FL, USA

That may depend on how you scanned your Kodachrome. My comparison is based on scanning with a Coolscan 9000 at 4000 PPI. I can see the grain in Tri-X but not in Kodachrome 25.

rehess Loc: South Bend, Indiana, USA

My scanning was done by a professional - I do not know what equipment he would have been using in 2002, but I am guessing it was rather good. I could also see grain in lower grain density film but not in the Kodachrome slides.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)