[BigMackCam]

I figured that’s what he was saying, but I wanted to clarify a bit for the OP.

A big part of the reason I switched to Pentax was I was shooting film alongside digital. I wanted to be able to have one set of lenses for both. After banging my head on the wall a few times figuring out the crop factor, I realized it didn’t really matter. Just frame the shot you see in the viewfinder and change lenses when necessary.

Whilst I agree that crop factor and equivalence can be detrimental to understanding, I do think it can be helpful when switching between formats, or figuring out what will work when you've permanently moved from one format (such as 35mm film) to another (such as APS-C digital).

If I'm shooting my full frame gear, I know that I'll probably want my 24-70 f/2.8 for general walk-around photography. If I'm shooting APS-C, I know that I'll need my 17-50 f/2.8 (that's equivalence right there, even if we don't like the term) for the same applications due to the field of view range... but I know I'll also be more restricted in terms of shallow depth of field (if required) because of the focal length plus aperture relationship.

Similarly, if I'm going to shoot portraiture on full frame, I might go with my 85mm f/1.4, whilst on APS-C I'll probably pick a fast 50mm, or maybe my 28-75 f/2.8 set to appropriate focal length... but again, with shallow depth-of-field limitations to consider.

Then again, if I'm going to shoot birds at the local wildfowl park, I'll know that I could take my full frame camera and 150-600mm lens, or my APS-C camera and 60-250 plus 1.4x TC.

If you're only ever shooting one format, then I agree that you only need to become familiar with the field of view offered by your lenses. If you're shooting more than one format, though, or if you've recently moved from a different format, understanding crop factor and equivalence does - in my opinion - have some use and value if referenced sensibly. It certainly helped me - to begin with, at least.

---

Last edited by BigMackCam; 11-04-2018 at 04:15 PM.

[twilhelm]

Whilst I agree that crop factor and equivalence can be detrimental to understanding, I do think it can be helpful when switching between formats, or figuring out what will work when you've permanently moved from one format (such as 35mm film) to another (such as APS-C digital).

If I'm shooting my full frame gear, I know that I'll probably want my 24-70 f/2.8 for general walk-around photography. If I'm shooting APS-C, I know that I'll need my 17-50 f/2.8 (that's equivalence right there, even if we don't like the term) for the same applications due to the field of view range... but I know I'll also be more restricted in terms of shallow depth of field (if required) because of the focal length plus aperture relationship.

Similarly, if I'm going to shoot portraiture on full frame, I might go with my 85mm f/1.4, whilst on APS-C I'll probably pick a fast 50mm, or maybe my 28-75 f/2.8 set to appropriate focal length... but again, with shallow depth-of-field limitations to consider.

Then again, if I'm going to shoot birds at the local wildfowl park, I'll know that I could take my full frame camera and 150-600mm lens, or my APS-C camera and 60-250 plus 1.4x TC.

If you're only ever shooting one format, then I agree that you only need to become familiar with the field of view offered by your lenses. If you're shooting more than one format, though, or if you've recently moved from a different format, understanding crop factor and equivalence does - in my opinion - have some use and value if referenced sensibly. It certainly helped me - to begin with, at least.

I agree with you completely here. Regardless to what format you shoot, it is good to know what would be considered a "normal" lens as compared to a "portrait" lens.

My K55 1.8 is one of my favorite portrait lenses on my aps-c cameras, whereas the FA 77 is my go-to for 35mm.

[photoptimist]

Whilst I agree that crop factor and equivalence can be detrimental to understanding, I do think it can be helpful when switching between formats, or figuring out what will work when you've permanently moved from one format (such as 35mm film) to another (such as APS-C digital).

If I'm shooting my full frame gear, I know that I'll probably want my 24-70 f/2.8 for general walk-around photography. If I'm shooting APS-C, I know that I'll need my 17-50 f/2.8 (that's equivalence right there, even if we don't like the term) for the same applications due to the field of view range... but I know I'll also be more restricted in terms of shallow depth of field (if required) because of the focal length plus aperture relationship.

Similarly, if I'm going to shoot portraiture on full frame, I might go with my 85mm f/1.4, whilst on APS-C I'll probably pick a fast 50mm, or maybe my 28-75 f/2.8 set to appropriate focal length... but again, with shallow depth-of-field limitations to consider.

Then again, if I'm going to shoot birds at the local wildfowl park, I'll know that I could take my full frame camera and 150-600mm lens, or my APS-C camera and 60-250 plus 1.4x TC.

If you're only ever shooting one format, then I agree that you only need to become familiar with the field of view offered by your lenses. If you're shooting more than one format, though, or if you've recently moved from a different format, understanding crop factor and equivalence does - in my opinion - have some use and value if referenced sensibly. It certainly helped me - to begin with, at least.

Exactly!

Understanding focal length equivalence across formats also helps interpret and learn from other people's photos. For example, you might see a nice style of portraiture that someone has taken with a 25 mm on an M4/3 camera and want to replicate that "look" on a FF camera. Using the differential crop factor between the two formats of 2X suggests that you need a 25X 2 = 50 mm lens to get the same field of view and relative perspectives between near and far objects.

Even if one never uses different formats, other photographers do. And relating their work to your own requires understanding equivalence.