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07-30-2015, 06:48 PM   #1
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Lens Rendering Discussion

First off-- I have to admit--I avoid the full frame section like the plague. I don't think much good comes out of all the redundant discussion on the same topics over and over and over again. That said I never thought I would be posting anything in here, but here goes nothing

My questions and/or topic of discussion is NOT about equivalence although I will reference angle of view to some degree.

What I am curious about is for those on the forum who are in the know to talk about a specific aspect of angle of view as it pertains to lenses.

Here is what I am asking/thinking of. Lets say I took a picture of a person standing in front of a scene with a DA21mm lens on my K3. Now lets say I never move my tripod, model, scene, or anything and I put a FF Pentax camera on the tripod with a FA 31mm lens. I am interested in how the scene would look, and the differences therein.

Would the person appear bigger or smaller in one or the other? Would there be any noticeable differences? I am not asking about sharpness, bokeh, or anything else. I am asking about a 'perspective' question....Just to keep it simple lets say BOTH lenses were set on f8 for the mythical test.

For the record the 21mm has a horizontal FOV of 59 degrees and the 31mm would have an angle of 60 degrees on each respective camera. The field of view, while not exactly identical, is still pretty close.

Bonus points if you can show an uncropped side by side comparison of the test I mentioned.

Again it's not about sharpness. It's not about rendering. It's also not about about depth of field, or resolution or any of that. It's about how the different focal lengths of the lenses will record the same scene.

Discuss.

---------- Post added 07-30-15 at 08:56 PM ----------

As a reference here is a Pentax Forum home page article.

A Guide to Perspective Distortion Review - Introduction | PentaxForums.com Reviews

---------- Post added 07-30-15 at 09:11 PM ----------

My theory is that the 31mm lens on the FF camera will bring my model out much more prominently in the same scene than the 21mm will. Not because of any sensor magic, but because it is a longer focal length.

It will make a much more prominent subject (ie the model).

I am not 100% sure on this, but what say you?


Last edited by alamo5000; 07-30-2015 at 07:00 PM.
07-30-2015, 07:24 PM   #2
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Grabbing the popcorn.
07-30-2015, 07:36 PM   #3
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QuoteOriginally posted by UncleVanya Quote
Grabbing the popcorn.
LOL!!!

I thought I would put this one in the lens section because it's much more of a lens question than anything.

I am just curious as to what others might have to say about my theory.

And the thing is... if we can find someone who has a digital body and a film body with both of the lenses mentioned... we can prove it or disprove it.

I don't know the answer... but I am seeing what people have to say.
07-30-2015, 07:50 PM   #4
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I'm not sure but it's the background size in relation to the subject that might differ..

07-30-2015, 08:07 PM   #5
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QuoteOriginally posted by UncleVanya Quote
Grabbing the popcorn.
You forgot the butter!

07-30-2015, 08:13 PM   #6
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Similar studies have been done by canikon users.

Here is one: Canon Lenses on Full Frame vs Crop | Photographers' Lounge
07-30-2015, 08:16 PM   #7
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QuoteOriginally posted by UncleVanya Quote
Grabbing the popcorn.
Sorry I got there first. You can sit in the comfy chair though.


The answer, of course is to simply go to the film section of this site where there are plenty of photos taken at multiple focal lengths of some very typical subjects. (Translation: There truly is nothing to discuss.)

BTW...when is a thread that includes the words "lens rendering discussion" not about rendering?

QuoteOriginally posted by alamo5000 Quote
It's not about rendering.

Steve
07-30-2015, 08:18 PM   #8
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QuoteOriginally posted by interested_observer Quote
You forgot the butter!

Whoops. I'd like some peanut m&m's also.

07-30-2015, 08:20 PM   #9
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QuoteOriginally posted by alamo5000 Quote
My theory is that the 31mm lens on the FF camera will bring my model out much more prominently in the same scene than the 21mm will. Not because of any sensor magic, but because it is a longer focal length.

It will make a much more prominent subject (ie the model).

I am not 100% sure on this, but what say you?

Nope


Steve
07-30-2015, 08:21 PM   #10
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FA 31 - Search Results - PentaxForums.com


Steve
07-30-2015, 08:27 PM   #11
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QuoteOriginally posted by stevebrot Quote
BTW...when is a thread that includes the words "lens rendering discussion" not about rendering?
Because I didn't know the correct words to use to express what I was trying to say.

---------- Post added 07-30-15 at 11:01 PM ----------

QuoteOriginally posted by stevebrot Quote
Nope
I am very open to the idea that I am/could be/might be/ or am wrong

I don't know the answer. That's what it boils down to.
07-30-2015, 09:05 PM   #12
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I think that depth of field is different as well as background compression, otherwise almost identical... If I remember correctly when I had Nikon FF and APS-C bodies. But sure thing that I always went for FF in regards of ISO noise difference.
07-30-2015, 09:06 PM   #13
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I promise you, with my hand on my heart, this will be just about the first things I do when I take delivery of my 36x24 Pentax.
Be patient

---------- Post added 31-07-15 at 01:45 PM ----------

QuoteOriginally posted by UncleVanya Quote
In essence then, if you use an "equivalent" f-stop, bugger all difference: as expected. The FA31 on full frame will obviously give far greater depth of field control - at the shallow end at least.

Last edited by Sandy Hancock; 07-30-2015 at 09:15 PM.
07-30-2015, 09:23 PM   #14
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QuoteOriginally posted by Sandy Hancock Quote
I promise you, with my hand on my heart, this will be just about the first things I do when I take delivery of my 36x24 Pentax.
Be patient

---------- Post added 31-07-15 at 01:45 PM ----------


In essence then, if you use an "equivalent" f-stop, bugger all difference: as expected. The FA31 on full frame will obviously give far greater depth of field control - at the shallow end at least.
Yup. I saw some other image comparisons but few gave the same perspective side by side. I'm pretty sure we can find these but this was the most promising one I found ready made.
07-30-2015, 09:40 PM   #15
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Can I add my "8mm fisheye on a Q10 vs 43ltd on FF" question to the mix?
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