Trains.com

A 500mm Camera Lens … and the Twilight Zone

3440 views
17 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    July 2010
  • 351 posts
Posted by ns145 on Thursday, July 6, 2023 8:12 AM

croteaudd
Steve Otto (Moderator):
 
You brought up different ways of looking at things, and when a group is not on the same wavelength, problems can thus result.  On that 500mm lens, I think where one starts at is key.  My Nikon is a DX, and conveniently we can use 200mm and 300mm as benchmarks.  An FX view at 300mm is equivalent (for all practical purposes) to a DX view at 200mm.  That is with a start at the DX point, i.e., 200mm.  So, a 300mm DX lens is equivalent to a 450mm FX lens.
 
It one combines an FX lens and a DX camera, the math and results are drastically different (and where you start at), as demonstrated by the numbers you posted.  Without an explanation of the premises involved, the numbers seem contradictory and dizzying.   Of course, then there is a DX lens and an FX camera.  Thus …
 
Someone at Kalmbach may want to tackle the numbers and subject, and the math when looked at in DIFFERENT WAYS and different starting points, and very different results for each.  It would be a real education article and save there resulting in confusing threads as this one.
 
Thanks.
 

 

This Nikon article explains all the basics regarding DX and FX series cameras and lenses:

https://www.nikonusa.com/en/learn-and-explore/a/products-and-innovation/the-dx-and-fx-formats.html#

There is also a nice explanatory Vimeo video at the bottom of the article.  At the very end of the video the presenter shows how an FX series camera can have its settings altered to shoot with a DX crop factor even with an FX series lens.

I think that all of the interchangeability that Nikon engineered into the two camera and lens series is what is causing all of your confusion.  To a seasoned DSLR pro its all great, well thought out, and useful.  To people just starting out in the DSLR world it is a veritible nightmare of apparent contradictions.

Moderator
  • Member since
    May 2009
  • From: Waukesha, WI
  • 1,764 posts
Posted by Steven Otte on Wednesday, July 5, 2023 4:28 PM

croteaudd
Steve Otto (Moderator):
 
You brought up different ways of looking at things, and when a group is not on the same wavelength, problems can thus result. ...  
Someone at Kalmbach may want to tackle the numbers and subject, and the math when looked at in DIFFERENT WAYS and different starting points, and very different results for each.  It would be a real education article and save there resulting in confusing threads as this one.
 

 
Although I moderate all the Tracks Group Forums, I work for Model Railroader magazine. If you would like to suggest an article for Trains Magazine, please contact their editor, Carl Swanson, at cswanson@kalmbach.com.
 
And my name is spelled Otte.

--
Steven Otte, Model Railroader senior associate editor
sotte@kalmbach.com

  • Member since
    January 2002
  • 4,612 posts
Posted by M636C on Wednesday, July 5, 2023 6:09 AM

While there are quite legitimate points made in this thread, I have Nikon DX and FX cameras with the same resolution, 24 megapixels. For the same image, the FX camera has a "cleaner" appearance. The DX image has higher "digital noise" but this is only apparent in very large enlargements of the image. A feature not mentioned so far is that if you wish, you can take DX images on an FX camera. By selecting this image area, you can see an image frame in the viewfinder which shows the image area you have selected. Apparently (I've never tried it) you can fit a DX lens to an FX camera and again, a frame will appear to indicate the image area. In the case of my cameras, 24MP, the reduced image area is only 16MP. Of course you could just crop an FX image to get the same effect, but doing it live does allow you to frame the image at the time.

Strangely, you can crop the image the same way on a DX camera, again getting a reduction to 16MP resolution.

Of course, if you were out with your FX camera and didn't have an FX wide angle lens, you could fit an 18-55 DX lens and get a 16MP 18mm image (assuming you had that lens but no DX camera, of course).

While FX and DX cameras are generally similar in size and weight, DX lenses are usually much lighter if you are going to be carrying one all day.

Peter

  • Member since
    February 2023
  • 11 posts
Posted by Erie Limited on Monday, July 3, 2023 9:45 AM

Backshop
Maybe I'm not understanding you correctly.  YMMV, but my experience is if you put 500mm FX lens on a Nikon DX camera, it is the equivalent of a 750mm lens on an FX camera.  It's a great combo to stay on public property and get a shot deep in the RR yard. 

There is a misunderstanding here. Any given lens, regardless of its focal length, projects an image onto the camera's sensor. The image does not change if you move the lens from an FX to a DX camera. The smaller sensor sees less of the image. It does not bring you closer. Imagine having a print with its subject in the center. You can crop away one third of the outer area of the print and the subject remains the same. It is the same going from FX to DX. If that 500 mm lens won't get you the shot, putting it on a DX camera won't help. You need either a longer lens or a position closer to the subject from which to shoot. 

  • Member since
    July 2016
  • 2,631 posts
Posted by Backshop on Sunday, July 2, 2023 4:25 PM

rrnut282

Maybe I'm not understanding you correctly.  YMMV, but my experience is if you put 500mm FX lens on a Nikon DX camera, it is the equivalent of a 750mm lens on an FX camera.  It's a great combo to stay on public property and get a shot deep in the RR yard.  

 

I agree.  From what I've read, the difference is the size of the sensor in the camera. Since the DX has a smaller sensor area, each focal length increase (or decrease) will have a bigger difference. Think of it (for us old folks) as the difference between a 24x36mm 35mm camera and a 110 13x17mm frame size. The lens isn't different, just the "effective" focal length.

  • Member since
    March 2016
  • 349 posts
Posted by croteaudd on Sunday, July 2, 2023 4:04 PM
Steve Otto (Moderator):
 
You brought up different ways of looking at things, and when a group is not on the same wavelength, problems can thus result.  On that 500mm lens, I think where one starts at is key.  My Nikon is a DX, and conveniently we can use 200mm and 300mm as benchmarks.  An FX view at 300mm is equivalent (for all practical purposes) to a DX view at 200mm.  That is with a start at the DX point, i.e., 200mm.  So, a 300mm DX lens is equivalent to a 450mm FX lens.
 
It one combines an FX lens and a DX camera, the math and results are drastically different (and where you start at), as demonstrated by the numbers you posted.  Without an explanation of the premises involved, the numbers seem contradictory and dizzying.   Of course, then there is a DX lens and an FX camera.  Thus …
 
Someone at Kalmbach may want to tackle the numbers and subject, and the math when looked at in DIFFERENT WAYS and different starting points, and very different results for each.  It would be a real education article and save there resulting in confusing threads as this one.
 
Thanks.
  • Member since
    May 2003
  • From: US
  • 25,292 posts
Posted by BaltACD on Saturday, July 1, 2023 7:15 PM

tree68
 
zugmann
most people carry one around in their pocket already.  

My cell phone has better resolution than my Canon Rebel DSLR.  Granted, I've had it for a while.

About the only advantage to the DSLR for day-to-day photography is the controls I have on the DSLR and the ability to change lenses.

My cell phone camera has different focal length lens on it.  Close up to wide angle.  No telephoto lens however.

Never too old to have a happy childhood!

              

  • Member since
    December 2001
  • From: Northern New York
  • 25,020 posts
Posted by tree68 on Saturday, July 1, 2023 6:41 PM

zugmann
most people carry one around in their pocket already. 

My cell phone has better resolution than my Canon Rebel DSLR.  Granted, I've had it for a while.

About the only advantage to the DSLR for day-to-day photography is the controls I have on the DSLR and the ability to change lenses.

LarryWhistling
Resident Microferroequinologist (at least at my house) 
Everyone goes home; Safety begins with you
My Opinion. Standard Disclaimers Apply. No Expiration Date
Come ride the rails with me!
There's one thing about humility - the moment you think you've got it, you've lost it...

  • Member since
    January 2002
  • From: Canterlot
  • 9,575 posts
Posted by zugmann on Saturday, July 1, 2023 6:29 PM

croteaudd
Maybe camera manufacturers will finally get wise and start producing simple cameras that take sharp photos.

most people carry one around in their pocket already. 

It's been fun.  But it isn't much fun anymore.   Signing off for now. 


  

The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any

  • Member since
    March 2016
  • 349 posts
Posted by croteaudd on Saturday, July 1, 2023 6:16 PM

seppburgh2

$5000 for a camera?  Gee, I'll stick with my old Argus hocky puck camera.  With a little practice, use to be real fast on the click shutter, wind shutter, advance film for those here it comes, there it is, get that going away shot!

seppburgh:
 
Yes, you seem to speak with a bit of sensibility and wisdom.  Some years ago, I purchased a low end 24MB Nikon digital.  I have need of a 45MB Nikon but have concluded that it might be best to just wait and see what develops.  You mentioned an Argus.  That hasn’t been heard for a while.  Maybe camera manufacturers will finally get wise and start producing simple cameras that take sharp photos.  Steinheimer and Adams used the simplest of cameras, not ones that take a lifetime just to read the reference manual!
  • Member since
    May 2003
  • From: US
  • 25,292 posts
Posted by BaltACD on Saturday, July 1, 2023 2:55 PM

tree68
One wonders if good old film will make a resurgence.

After all, today's kids don't think us oldsters understand vinyl records...

Kodak is still making film - 

Following is part 1 of a three part series on Kodak film manufacturing.

Never too old to have a happy childhood!

              

  • Member since
    December 2001
  • From: Northern New York
  • 25,020 posts
Posted by tree68 on Saturday, July 1, 2023 2:27 PM

One wonders if good old film will make a resurgence.

After all, today's kids don't think us oldsters understand vinyl records...

LarryWhistling
Resident Microferroequinologist (at least at my house) 
Everyone goes home; Safety begins with you
My Opinion. Standard Disclaimers Apply. No Expiration Date
Come ride the rails with me!
There's one thing about humility - the moment you think you've got it, you've lost it...

  • Member since
    September 2003
  • 21,669 posts
Posted by Overmod on Saturday, July 1, 2023 12:27 PM

Much of that money is going for the larger sensor and faster, more complex parallel circuitry to record, buffer, and store a very-high-resolution image in realtime.  Unless you need 6400-dpi film-level resolution, and intend to be making oversize enlargements, much of the recent professional or even 'prosumer' improvements in still cameras may not be something that even serious preservationists need to have.

8K video, even at frame-tripled and motion-vector-steered 24fps -- that's another matter.  But it's video.

  • Member since
    January 2010
  • 399 posts
Posted by seppburgh2 on Friday, June 30, 2023 9:57 PM

$5000 for a camera?  Gee, I'll stick with my old Argus hocky puck camera.  With a little practice, use to be real fast on the click shutter, wind shutter, advance film for those here it comes, there it is, get that going away shot!

 

  • Member since
    March 2016
  • 349 posts
Posted by croteaudd on Friday, June 30, 2023 6:40 PM
What was trying to be conveyed is that there is little difference in reality between FX and DX when you put them side by side.  With FX, the circuity is sprawling, but with DX things are more crammed.  Very simple.
 
At the camera store I patronize, I asked a salesman point blank:  Which was better, FX or DX.  “They’re the same!”
 
Unfortunately, Nikon is making a clear distinction now, with cheap mirrorless all 20 MB, and the more professional mirrorless 24 and 47 MB.  It is unknow if that strategy will ultimately be good for Nikon or bring them corporate instability.  In light of camera stores dying in droves, I find it questionable that $5000 Nikons will be sold by people that have no idea about camera or care about camera inventories!
Moderator
  • Member since
    May 2009
  • From: Waukesha, WI
  • 1,764 posts
Posted by Steven Otte on Friday, June 30, 2023 1:52 PM

For the person who complained about this post... "YMMV" doesn't mean what you think it does. It stands for "Your Mileage May Vary." Meaning, although you may have experienced something different, this is what I've experienced.

--
Steven Otte, Model Railroader senior associate editor
sotte@kalmbach.com

  • Member since
    January 2001
  • From: MP CF161.6 NS's New Castle District in NE Indiana
  • 2,148 posts
Posted by rrnut282 on Wednesday, June 28, 2023 12:52 PM

Maybe I'm not understanding you correctly.  YMMV, but my experience is if you put 500mm FX lens on a Nikon DX camera, it is the equivalent of a 750mm lens on an FX camera.  It's a great combo to stay on public property and get a shot deep in the RR yard.  

Mike (2-8-2)
  • Member since
    March 2016
  • 349 posts
A 500mm Camera Lens … and the Twilight Zone
Posted by croteaudd on Friday, June 16, 2023 12:59 PM
So that nobody will be fooled here at the TRAINS Forums … Some buy a Nikkor 500mm lens with wonder!  But a 500mm “FX” lens is only a 333mm “DX” lens! (Nikon terminology.)  And the camera knows the difference and can’t be fooled!  The “conversion” factors are 1.5 and -1.5 depending on which way one is trying to go.  Hopefully, everybody at these TRAINS forums is a lot wiser now if they didn’t already know this!

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

Newsletter Sign-Up

By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy