Using a full frame in DX mode


Senior Member
When I got the new 200-500 tele to use on my Z5, I was thinking that if I needed more reach, I could just mount it on my D3400 body, and would have an effectively longer lens. I realize that there are advantages of the full frame sensor beyond MP, but both the half and full frame sensor are around 24 MP. I then got to thinking the other day, that I could just put my full frame into DX mode without having to drag out the second body and swap lenses. Sure, I would probably loose some detail compared to FX, or the 24 MP crop frame, but it would be quick and painless.

Now I'm wondering if just leaving the full frame in FX mode and then cropping 50% in post processing would end up with the same resolution.

My suspicion is that using the 24 MP crop body would give me the best resolution to get the extra 50%. Logic says the full frame in DX mode would give the same resolution as leaving it in FX mode and cropping?

Yes, I could go out this morning and take a series of photos and compare. I did do a FX vs DX mode comparison yesterday.

It wasn't terribly scientific. I should use exactly the same subject, image size of the object in the viewfinder and carefully ensure that magnification is identical in post processing. This was more an off the cuff.

I shot a squirrel (no blood was spilled) in FX mode. While I was changing modes, the squirrel skedaddled. Here is the result.

Squirrel, FX mode.


Squirrel, magnified.


Crepe myrtle, DX mode.


Crepe Myrtle, magnified.


Files in DX mode were less than half the size of FX mode with both in RAW. I was pleased with the resolution of the DX mode, although it definitely isn't as good as the FX. I was able to enlarge the FX to a higher magnification before losing detail, than the DX.

Discuss, and let me know your experience, and opinions.

BF Hammer

Senior Member
If both DX and FX bodies are 24MP sensors then the DX will have a great deal more detail in the image if you drop the FX image down. There are twice as many pixels recording data. It gets closer to even if you have 16MP DX sensor such as when I was using a D7000 as my 2nd camera to my D750, but still more detail in the crop sensor.

Fred Kingston

Senior Member
There is another option today... Shoot in Full Frame, up-size the image with either Adobe's Enhance feature, or Topaz's GigaPixel (better) and then crop


Senior Member
I haven't tried the enhance feature yet. Have you had good luck with it? I like that Gigapixel is a buy vs rental. Since I have Lightroom and PS, I probably should try that first and switch if I like what I see and want more.


I tried the enhance in LR. It obviously is hardware intensive and bogs down LR on my computer, which admittedly isn't the fastest. It also works. From this single example, I wouldn't call it an extreme improvement, but it definitely smooths out some of the noise, most notably in the areas above the head, and in the ears. I'm sure it would make a real difference in the print-ability of a large blow-up, or tight crop.

Here is a before and after of a blown up portion of the first photo.





So Fred, is Gigapixel a lot better than enchance in LR?
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