Tony Northrup

Tony Northrup

Lives in United States Waterford USA, United States
Works as a Photographer/author
Joined on Jan 6, 2002
About me:

Check out my book, "Tony Northrup's DSLR Book: How to Create Stunning Digital Photography":


Total: 7, showing: 1 – 7
On Opinion: Bring on the 70-200mm equivalents article (342 comments in total)
In reply to:

JoEick: This article is very misleading.

If the point of the article is to tell the reader how a 50-150 works similar on APS-C to 70-200 on full frame, then there needs to be more thought put into equivalent apertures.

You need f2.8 on crop to roughly equal f4 on full frame. The Fuji f2.8 zoom has no meaningful size or weight savings over a Canon 70-200 f4.

Until we see more f1.8 and f2.0 zooms for APS-C, there is nothing that compares in light gathering for full frame f2.8.

There is no free lunch when it comes to light, physics, and lenses.

Love the article! I'm with Joe; give me an APS-C 50-150 f/1.8 or MFT 35-100 f/1.4 so I can truly get FF equivalent results. I know it'll have to be big...

Direct link | Posted on Sep 20, 2014 at 13:48 UTC
On Fujifilm announces weather-resistant XF 50-140mm F2.8 article (224 comments in total)
In reply to:

attomole: Suspect the equivalence brigade will be out gunning for this, There is still nothing that sucks up light like the big 2.8 zooms for full frame that have been the backbone of professional photographers kit for years, and in comparison this is bit big and a bit expensive.

Yeah, came here to say this. The article says, "essentially equivalent to a popular 70-200mm telephoto zoom on full frame," and that's true, but it's equivalent to the popular 70-200 f/4 in terms of depth-of-field (important for the portraiture this will be doing) and total light gathered... it's not equivalent to the much more popular 70-200 f/2.8 lenses.

Still, I love Fuji, and we're getting closer to my dream 50-150 f/1.8 APS-C lens that will let me finally toss my DSLRs...

Direct link | Posted on Sep 10, 2014 at 11:48 UTC

After your excellent article on equivalence, I'm surprised to see that you're still showing the 35mm equivalent focal length without applying the crop factor to the f/stop number. Obviously this tiny lens isn't equivalent to a 21mm f/2.8.

By all means, list the physical f/stop and focal length. If you apply the crop factor to the focal length, however, you should also give us the equivalent f/stop.

Here's a good explanation:

Direct link | Posted on Aug 29, 2014 at 14:26 UTC as 8th comment | 4 replies
On What is equivalence and why should I care? article (2132 comments in total)
In reply to:

Death89: Not sure myself why this causes so many issues. Even before my purchasing an FZ200 for its F2.8 throughout the zoom I was aware of the equivalence of the dual nature of F numbers, etc. so I knew a 1/2.3 sensor equipped f2.8 superzoom was never going to reach the levels of DOF/Low-Light greatness of a full frame camera.

Really enjoyed reading the article though and now have a better idea of how it all works!

fredrious, that FZ1000 video is maddening. I wish they hadn't disabled comments. Evil marketing.

Direct link | Posted on Jul 7, 2014 at 12:32 UTC
On What is equivalence and why should I care? article (2132 comments in total)

Great article! Now, if we can just get manufacturers and press to list the full-frame equivalent apertures any time they list the full-frame equivalent focal length, we'll make camera and lens shopping much more honest.

One point: You're right that equivalent ISOs (found by using the crop factor squared) aren't as perfect as equivalent focal lengths or apertures. But, when comparing similar sensor technology, they're pretty similar. In my tests, crop factor accounted for 99.2% of the differences in ISO, and only 0.8% was attributable to differences in technology.

It seems to be > 99% accurate when comparing Sony, Nikon, and MFT sensors. Canon is a bit behind, but the crop factor squared formula still holds up when comparing Canon sensors to other Canon sensors.

Direct link | Posted on Jul 7, 2014 at 12:25 UTC as 394th comment | 2 replies
On Panasonic Lumix DMC-FZ1000 First Impressions Review preview (1267 comments in total)
In reply to:

pgphoto_ca: Be's not a f2.8-f4 with this sensor (2.7x crop)'s f5.6-f8 or more.......the crop factor need also to be apply to the aperture :)

A real 400mm much bigger ! :)

For those of you who think f/2.8 gathers the same amount of light on both a big sensor and a small sensor--it's the difference between *light intensity* and *total light gathered*. The light intensity is the same, the total light gathered isn't.

If you want to figure out the total light gathered, which my tests determined is the primary factor for image noise (with differing sensor technology amounting to 0.2%), then multiply the aperture by the crop factor. That allows you to calculate both depth-of-field and total image noise--easy!

Direct link | Posted on Jun 12, 2014 at 11:53 UTC

Perhaps you guys could start providing the full-frame equivalent apertures if you provide the full-frame equivalent focal lengths? This video explains why.

The SH-1 has about a 5.5x crop factor. The lens is physically 4.5-108mm f/3.0-6.9, so the 35mm equivalent is 25-600mm f/16-38 in terms of total light gathered by the sensor, light gathered by each pixel, and depth-of-field... all the factors that impact final image quality.

Direct link | Posted on Mar 31, 2014 at 15:57 UTC as 14th comment | 9 replies
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