Originally posted by colonel00
I've read through a bunch of threads on the 150-450 and it's on my long term wish list. I guess I've just never seen mention of it's APS-C equivalence of 230-690mm. But, I was watching a video today and even looked at
Ricoh's website and it lists it right there. I tried to search the forums but I didn't really see any mention of this.
I've seen many comparisons to the DA* 300 and even comparisons with the DA* 300 and 1.4TC to the 150-450 but in reality they aren't even close as far as reach goes are they? The DA* 300 is an APS-C lens so even with the TC its reach is now 420mm, correct? Where as the 150-450 is stated as being 230-690mm on APS-C and if you pair that with the TC it creeps up to just under 1000mm.
Now, I will fully admit that I try to get my head around the whole FF versus APS-C and focal view equivalence thing but sometimes it goes around and around in my head so much that I probably end up confusing myself more in the end than I was at the beginning. That poor little hamster running in my head at full speed misses a step and must gets taken for a ride much like this:
https://youtu.be/YXRH50fvHWA?t=31
Anyway, please set me straight on all of this. Am I reading into this completely wrong?
The FOV changes when you use the same lens on different formats. So for example, if that 150-400 is an aps-c lens, to get the same FOV on FF you would need a 230-690mm zoom on FF.
This doesn't mean smaller formats have more 'reach' with the same lenses, it just means that it's being cropped more when you use the same lens on smaller formats.
So the focal length can never physically change, but it's highly misleading to say "focal length is focal length, full stop" because the same focal length
on different formats gives you radically different images. (I wish people would move on from that almost-useless answer of 'focal length is focal length'. It only applies if you shoot one format your entire life )
The question you ask is valid and understanding at least the crop factor and maybe it's big-brother 'equivalence' is useful if you intend to shoot more than one format and not be befuddled while doing so.
If you only ever plan to shot one format - don't worry about crop factor, it doesn't directly apply to you.
.