[GUB]

I don't. But you do not even seem to have bothered to read the "basic design" section on page 2 - 3.

You mean you need me to explain that sentence for you? It said the original lens needs to be for a larger format for this to work.

[Fogel70]

It seems you need to read the whole document.

[GUB]

It seems you need to read the whole document.

Well there is these - what else do you want to draw my attention to?

[PDL]

I think equivalence is good in explaining exposure, and especially what effect exposure have on images from different formats. That exposure isn't universal between formats when it comes to resulting images using same perspective, FOV and DOF.

I have even heard stange things like people believing that it is only pixel noise that detiermines total image noise.

Yes, f-stoppers has some nice articles about equivalence.

Crop factor only concerns field of view - nothing else.

If crop factor was all that important, then all of the hand held light meters would have a sensor size input. Guess what, they do not.

Edit:
As for differing fields of view quickly accessed - here is a blast from the past. A FOV equivalence by film format from 1975 "Kodak Professional Photoguide" pg. 28. Please note the important part THE INFOGRAPH DOES NOT SAY A THING ABOUT EXPOSURE OR LIGHT "GATHERING because that is not effected by crop factor.

---

Last edited by PDL; 01-09-2020 at 06:24 PM.

[MarkJerling]

This thread just keeps getting better and better.



I've not learnt this much since grandma got her you know what stuck in the wringer.

[GUB]

This thread just keeps getting better and better.



I've not learnt this much since grandma got her you know what stuck in the wringer.

I wish there was a way we could charge admittance!

[GUB]

Thing is Mark I am learning too - I hadn't bothered to research speedboosters up to this point --- Now I know enough to know they are not much use for the K-1!.

[MarkJerling]

Thing is Mark I am learning too - I hadn't bothered to research speedboosters up to this point --- Now I know enough to know they are not much use for the K-1!.

But what about all that extra light!

[GUB]

But what about all that extra light!

Yep you can never have too much light!!
Brew up time in Nepal.
What do you reckon -- f-stop f0.5 ?

[GUB]

Actually where would the optical centre of this be to measure the focal length from?

[dbs]

Actually where would the optical centre of this be to measure the focal length from?

Hi Gub

I don't know ...but...it looks like the lens hood for a A20.

Dave

[Photobill]

Hi Photobill

I'm a "happy snapper " not a photographer and any seemingly 'easy' question just evolves into a lively discussion.
I have noticed that the question is answered on the first page

Yes it was. I had to have my thought confirmed about exposures being the same from one format to another and a little info to win my bet with a buddy.

It does make for some interesting reading though....hence the popcorn comment.

VERY interesting indeed. I had to run to the store to pick more popcorn up. 😀

Enjoy your photography persuits I certainly am.
This forum is a good educational tool.
I hope you have enjoyed youre last year here and many more to come.

Dave

THANKS Dave its the only group/forum I belong to and enjoy it very much.

[GUB]

Hi Gub

I don't know ...but...it looks like the lens hood for a A20.

Dave

Is that something like a bonnet for an A35 ? (Austin)

[Photobill]

Thing is Mark I am learning too - I hadn't bothered to research speedboosters up to this point --- Now I know enough to know they are not much use for the K-1!.

But sure they are just shoot in crop mode. OK I'm just funnin about the crop thing.
But as you, I think I'll do a little research into them as most of my Pentax lenses are FF and I'm using aps-c body's. "Knowledge Is Power" is what the bumper sticker said.

[dbs]

Is that something like a bonnet for an A35 ? (Austin)

Hi Gub

Nah the A35 s bonnet is curled more om the edges.
So they can't be inter-changeable
But they both let in more light when open.

Dave