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multiply by 1.5 on lenses

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I think the whole confusion is all the talk about what it "looks" like and "crop factor" and "Field of View".

I for one am new to this whole thing and also am not stupid, yet after reading this whole thread, I still am not totally clear.

I personally don't care about "focal length" and what each lens has stamped on it. I hate going into a store and saying, "im looking for a 70-300", and the salesperson says, well....you then really just need a 45-200...and i say, no, "i want a 70-300"....and then they say, "well, you know that means 105-450"......

gaaahh!!!

What i want to know is this....when I look through a lens that says 70-300 and i have it set ot max focal length of 300, am i really zooming in like it was 450mm or am i really just seeing something similar to taking a picture in PS and blowing it up to 150%? Is the object that was zoomed in at 300mm really closer when snapping the shot on a D70 then on a noirmal 35mm camera?
Daz_Genetic said:
This is just one of those things that some people are going to have
a hard time understanding. I personally don't see a problem but
people's minds work in very different ways.
NickL said:
People do seem confused by this 1.5x conversion. I know I was.

Perhaps, rather than trying to work with "equavalence" on a 35mm or
full frame, we should talk about angle of view?

I wonder if that would clarify things?

Cheers,
Nick.
Click to expand...
Click to expand...
 
Well, I saw you saw my reply further down this thread, so I guess you got it sorted, but to repeat:

You cannot say a 50mm is a 75mm on a film SLR, as the focal lengths have to do with optics. The focal length doesn't change. You can say a 50mm gives the same field of view as a 75mm on a film SLR.

For medium format cameras, the 'normal' lens is about 80mm, for 135 film SLR's it's 50mm. Now there's the DSLR's in the Nikon range, where a normal lens is between 28mm to 35mm (depends on your definition of a 'normal' lens. It doesn't matter much though).

Thomas.
 
...or just learn that your 'normal' lens with a 'normal' FOV is now a 35mm. Anything lower is a wide angle, anything higher is a tele lens.

Thomas.
DonAvebury said:
Here's the deal.

It's now time to forget focal length.

It's all about field of view. When considering a lens, you want to
know what its field of view is on your camera.
Click to expand...
 
thomas1973 said:
Well, I saw you saw my reply further down this thread, so I guess
you got it sorted, but to repeat:

You cannot say a 50mm is a 75mm on a film SLR,
Click to expand...
what I'm saying in my previous post is that whatever the lens is on a film camera is irrelevant and not of interest to me. ditto whatever the focal lenth of the lens is sitting unattached or attached to any othter camera not called a Nikon D70.

The focal length of the lens doesn't change and that's a technically accurate statement no matter what you do with the lens.

But you can pile technically accurate statements about the D70 on top of technically accurate statements with more technically accurate state thrown in for good measure and actually move further and further away from what would be practical and easily understandable.

The discussion is about the D70 and what the focal length conversion is for lens that one might use on the D70.

On the D70 a 35mm lens effectively acts like a 50mm lens. A 35mm lens is a normal lens on a d70, everything above that is a tele and everything below that is a wide.

That's very easy to understand... even for me. lol!

But everytime someone says "well a 35 is a 35 is a 35" or anything like that... it only adds confusion to the discussion about D70s and the 1:5 lens conversion issue because hey... a 35mm lens is a wide angle lens and if you put it on a D70 it's now a normal lens so that's really the only thing you have to know about the whole matter and everything else is confusion....

although it's technically accurate confusion.
 
NickL said:
People do seem confused by this 1.5x conversion. I know I was.

Perhaps, rather than trying to work with "equavalence" on a 35mm or
full frame, we should talk about angle of view?

I wonder if that would clarify things?

Cheers,
Nick.
Click to expand...
Not if you're really looking to clarify things... which I'm sure you are.

I think this is actually the problem. Nikon adapted, it seems to me, referring to the issue as a "angle of view" in the manual and I walked away from that scratching my head as I'm sure so many others did and do.

It's because "angle of view" is maybe an even less common concept to the neophyte photog than the idea of what a 28mm lens.

I think DO say this but they needed to lead with the concept in bold that a 35 lens functions on the D70 as a 50mm.

They also needed to and didn't address the fact that the focal length markings on the lens barrel that they sell kitted with the D70 as well as the focal lenth information as recorded in the camera is all EFFECTIVELY wrong... ON THE D70*

IN A PRACTICAL SENSE if not a factual sense. (please with the facts already I got that part)

My point is that it's really simple to expain this to anyone who a) has even a slight experience with 35mm lenses and cameras or b) someone who, even though they don't have any experiences with 35mm lenses, still has to live in that world because even the KITTED lens sold with the D70 has focal length information that is from the 35mm world.

Right?
 
MarkmyShots said:
...
What i want to know is this....when I look through a lens that says
70-300 and i have it set ot max focal length of 300, am i really
zooming in like it was 450mm or am i really just seeing something
similar to taking a picture in PS and blowing it up to 150%?
Click to expand...
Your confusion may be the result of not understanding the fundamentals of how this works.

To answer your question: Yes-you are zooming in at the maximum optical range--which is still only 300mm. But because the frame size of 35mm film is 1.5 larger than the frame size of the D70's CCD, the real estate available for exposure is only 1/1.5--or 3/4 the frame area of 35mm film. In other words, you have the same crop as a 450mm lens provides you if you were using 35mm film.

But forget about all that. All you need to know is that one rule applies. WYSIWYG. And what you see on a 35mm camera with a 300mm lens is a wider crop than what you see on the D70's CCD (a narrower-tighter crop). The narrower crop will always look closer than the wider crop.

I'm still not sure what you mean by "similar to taking a picture in PS and blowing it up by 150%." If you mean the field of view--yes. If you mean the quality--no. The former is optical, the latter interpolated through software.
MarkmyShots said:
Is the object that was zoomed in at 300mm really closer when snapping
the shot on a D70 then on a normal 35mm camera?
Click to expand...
I would hope the object is the same distance. Neither closer nor further away.

Once again, the WYSIWYG is different on both cameras. On a 35mm, it will record a wider crop because there is more photo-sensitive real estate to record the subject. On a CCD, the crop will become tighter (more narrow) as there is less photo-sensitive real estate to record the image. Therefore, the tighter crop on the CCD looks like it was taken by a longer focal length lens compared to 35mm film. That makes the subject look closer. To crop the image to the same size as that recorded on the D70's CCD--you'd require a focal length of 1.5x using a 35mm film camera.

In your example

35mm--> 300mm lens---> crop size = X
D70----> 300mm lens----> crop size = X/1.5

in order for the 35mm camera to get a crop size equivalent to the D70's, you need to multiply the focal length on a 35mm 300mm lens by 1.5x so that it is 450mm.

If you are still having trouble understanding this, I'd suggest you do a search on the following terms:

focal length
field of view
aspect ratio
crop size

best of luck ...

the born 2 design
design guy
 
This and all the similar threads is better than watching Abbot and Costello act out the classic "Who's on First" baseball routine.
Thanks for the entertainment. LOL
Jim
jammerbirdi said:
NickL said:
People do seem confused by this 1.5x conversion. I know I was.

Perhaps, rather than trying to work with "equavalence" on a 35mm or
full frame, we should talk about angle of view?

I wonder if that would clarify things?

Cheers,
Nick.
Click to expand...
Not if you're really looking to clarify things... which I'm sure
you are.

I think this is actually the problem. Nikon adapted, it seems to
me, referring to the issue as a "angle of view" in the manual and I
walked away from that scratching my head as I'm sure so many others
did and do.

It's because "angle of view" is maybe an even less common concept
to the neophyte photog than the idea of what a 28mm lens.

I think DO say this but they needed to lead with the concept in
bold that a 35 lens functions on the D70 as a 50mm.

They also needed to and didn't address the fact that the focal
length markings on the lens barrel that they sell kitted with the
D70 as well as the focal lenth information as recorded in the
camera is all EFFECTIVELY wrong... ON THE D70*

IN A PRACTICAL SENSE if not a factual sense. (please with the
facts already I got that part)

My point is that it's really simple to expain this to anyone who a)
has even a slight experience with 35mm lenses and cameras or b)
someone who, even though they don't have any experiences with 35mm
lenses, still has to live in that world because even the KITTED
lens sold with the D70 has focal length information that is from
the 35mm world.

Right?
Click to expand...
--
http://www.pbase.com/JungleJim
 
Understand that it is cropped and the lens is what it say the focal length is.

After that, do use the 1.5X multiplier to convert to 35mm std for the D70.

You need to reference to a standard like 35mm so you can relate to other photographers who have a different multiplier, ie. 1.3X, 1.6X, 1.7X, APS, etc.

Simple.
Michael Paul DiOrio said:
Hi folks

I'm just wondering if people are remembering to multiply the focal
length any lens on a digital camera by 1.5 ?
for example an 80-400, I believe would be a 120-600mm lens.
I think it's more important to remember that when dealing with wide
angles. There's a big difference in the look of a picture taken
with a 24mm lens on a film camera and a 24 mm lens on a digital
camera. The chip size on the digital camera basically makes it a
35mm lens.
just a tthought.
Michael DiOrio
Click to expand...
 
One more minor point on this....

I totally understand the field of view issue, in which a 20mm lens on a DSLR has the same field of view as a 30mm (film) SLR lens.

However, if I take a tight photo of a person with a 20mm lens verses a 30mm lens, BOTH on a film SLR, the proportions are different- the classic example is the "big nose" syndrome.

Am I correct that a 20mm lens on a DSLR will image the same big nose as the 20mm lens on the film SLR? It will be the same big nose, just cropped down.

It seems to me that the perspective issue has been lost in these discussions...

Thanks,
Neil
 
Not really true, as if you have a 20mm mounted on your D70, you will use it as you would use a 30mm on a film SLR. So you would back off a bit, thus redusing the 'big nose' issue.

Remember, the focal length does not change the perspective, the distance to your object does.

Thomas.
NRothschild said:
One more minor point on this....

I totally understand the field of view issue, in which a 20mm lens
on a DSLR has the same field of view as a 30mm (film) SLR lens.

However, if I take a tight photo of a person with a 20mm lens
verses a 30mm lens, BOTH on a film SLR, the proportions are
different- the classic example is the "big nose" syndrome.

Am I correct that a 20mm lens on a DSLR will image the same big
nose as the 20mm lens on the film SLR? It will be the same big
nose, just cropped down.

It seems to me that the perspective issue has been lost in these
discussions...

Thanks,
Neil
Click to expand...
 
One way to look at it is draw a 35mm negative say 1.5 inches by 1 inch. inside the rectangle draw a smaller rectangle representing the d70 sensor, say 1 inch by 3/4 inch centered. That is the portion of the image the d70 shows giving the impression of a larger photo causing the confusion.
 
rchalacy said:
One way to look at it is draw a 35mm negative say 1.5 inches by 1
inch. inside the rectangle draw a smaller rectangle representing
the d70 sensor, say 1 inch by 3/4 inch centered. That is the
portion of the image the d70 shows giving the impression of a
larger photo causing the confusion.
Click to expand...
 
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