Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-25-2013, 11:49 AM   #1
Moderator
Man With A Camera
Loyal Site Supporter
Racer X 69's Avatar

Join Date: Jun 2010
Location: The Great Pacific Northwet
Photos: Gallery | Albums
Posts: 24,739
Field Of View With Macro Bellows

I dug around a bit on the existing threads, and didn't really find the answer to the question I am posing here. RioRico posted an excellent writeup CHEAP MACRO -- Buying or exploiting a lens for ultraclose work, which was very informative and helpful, but doesn't cover the question I am presenting here today.

I recently entered the macro side of photography with the acquisition of a bellows setup and some extension tubes. I have a Pentax M 40~80 Macro lens that so far has worked quite well during the first attempts at shooting. The images come out clear and sharp, the colors just as expected.

The one thing that became apparent immediately though was the field of view is extremely narrow. I know that shallow depth of field and a narrow field of view is going to be part of the macro world, but I found myself wondering if a wider angle lens would give a field of view that is at least a tiny bit wider in the macro setup, before I go and buy another lens.

Does anyone have useful input on this subject?

As always, thanks in advance for your input my fellow Pentaxians!

Cheers,
Racer

03-25-2013, 12:11 PM   #2
Inactive Account




Join Date: Jul 2010
Photos: Gallery
Posts: 328
Hi

Works the opposite way on bellows, you have to get closer to the subject with a wider lens. For a wider view you have to reduce magnification ( Move lens closer to camera )
If you have an old 135mm try that.
03-25-2013, 12:12 PM   #3
Moderator
Man With A Camera
Loyal Site Supporter
Racer X 69's Avatar

Join Date: Jun 2010
Location: The Great Pacific Northwet
Photos: Gallery | Albums
Posts: 24,739
Original Poster
QuoteOriginally posted by bobpur Quote
Hi

Works the opposite way on bellows, you have to get closer to the subject with a wider lens. For a wider view you have to reduce magnification ( Move lens closer to camera )
If you have an old 135mm try that.
So the longer the focal length the wider the field of view?
03-25-2013, 12:25 PM   #4
Site Supporter
Site Supporter




Join Date: Mar 2010
Location: Frankfurt am Main
Posts: 1,239
I am not sure what you mean by field of view.

The focal length determines the angle of view. The angle of view defines the size of the plane captured at a given distance (let's say the distance where everything is in focus).

If you move nearer to a subject (and would keep the focal length constant or nearly constant --> angle of view stays constant), the size of the plane in focus will be smaller. However, the needed change of the extension by bellows or tubes will change the focal length, increasing it makes the angle of view smaller.

This is adding a tele effect. Using a shorter lens as a base would not make it different for 2-dimensional objects. For 3-dimenional objects the perpective will change a bit, but, considering the shallow depth of field I am not sure it would give you the effect you seem to want.

03-25-2013, 01:37 PM   #5
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
@RKKS08

The size of the plane captured that you talked about is what's called the "field of view"
Like you say it also depends on the focus distance so in reality it's all over the place and actually not useful fo directly comparing lenses.
AOV is indeed the correct one but i believe many mean AOV but use FOV since they think it's actually the correct term for it.

There are so many things with photography that are getting twisted this way.
03-25-2013, 01:39 PM   #6
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
Racer sorry for going off topic, needed to rant about it.
Nothing meant personally or in a negative way to someone.
03-25-2013, 02:28 PM   #7
Loyal Site Supporter
Loyal Site Supporter
baro-nite's Avatar

Join Date: Aug 2011
Location: North Carolina, USA
Photos: Gallery | Albums
Posts: 5,166
QuoteOriginally posted by Racer X 69 Quote
The one thing that became apparent immediately though was the field of view is extremely narrow.
If I'm understanding you correctly, this is the whole point of macro -- to narrow the angle of view, i.e., fill the frame with something small, i.e., increase the magnification. If you want less magnification, set the bellows to less extension.

The shorter the focal length, the less extension needed to reach a given magnification.

Or do you mean working distance, the distance from subject to front of lens?

03-25-2013, 02:52 PM   #8
Moderator
Man With A Camera
Loyal Site Supporter
Racer X 69's Avatar

Join Date: Jun 2010
Location: The Great Pacific Northwet
Photos: Gallery | Albums
Posts: 24,739
Original Poster
Well I never. I start a thread so I can capitalize on the knowledge and experience of my fellow enthusiasts, and they start to argue with each other. Come on guys.

What I mean by field of view may well be the angle of view, I don't know. I guess I don't really know the correct terminology.

Let me express it another way.

A 80mm lens will provide an image that is so many millimeters wide, by so many millimeters high and "x" distance from the front of the lens.

A 50mm lens will provide an image that is so many millimeters wide, by so many millimeters high and "x" distance from the front of the lens.

A 28mm lens will provide an image that is so many millimeters wide, by so many millimeters high and "x" distance from the front of the lens.

All of these lenses will produce a different sized result at the same distance from the front of the lens to the point of focus.

If you put any of these lenses on the front of a bellows or extension tube the size of that resulting image will be reduced, correct?

So my question is, if I wish to achieve a wider resulting image using a bellows or extension tube, would I want to use a lens of shorter or longer focal length than what I already have? I mentioned that I have the M40~80 Macro. When I used it I tried it at the 40mm setting, the 80mm setting, and then placed it in the macro setting which can only be used with the lens at the 80mm focal length. What I found is that the area from side to side and top to bottom was extremely small (well it is macro, right?).

So if I want to get macro photos with a wider resulting area within the field of focus available using the bellows or extension tubes, do I want to get a lens with a focal length longer or shorter than 80mm? I know that any resulting increase in size may be marginal, but it would be nice to have a little more room to work with. I did some work with the setup mentioned yesterday, and found that with the exception of insects and other tiny things, there was not much to shoot.

Here are 2 images. The first is with the bellows, the second without. Both are using the M40~80 lens.





Obviously there is is a difference in the area to work with. If it is possible to get the kind of close up shots like the first one only with more width and height, using a different focal length lens I would like to explore that.
03-25-2013, 03:06 PM   #9
dms
Site Supporter
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 2,133
The term to think of is magnification. No matter what the focal length, the field of view will be the same for the same magnification. The perspective will be somewhat differerent (i.e., the near and far relationships) but not the field of view at the plane of focus. And the magnification will be differenet for different lenses on your bellows. There should be a description for your bellows--of magnification range (min to max) for a given (typical) focal length lens.
03-25-2013, 03:21 PM   #10
dms
Site Supporter
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 2,133
Hopefully the following will help.

For a given lens focal length--adding an extension (the bellows) equal to the lens focal length will yield magnification (m) of 1. on a full frame sensor (or m=1.5 on Pentax dslr).

If the lens is 200 mm and you get 200mm extension with the bellows--you have m=1.5. But with a 100mm focal length the same extension (200 mm) gets you twice the magnification (m=3), and with a 50 mm you get m=6 with the same 200mm extension.

Put another way for the same magnification you need less extension with a shorter focal length.

But the other problem is with a short focal length lens you have the object very close to the lens--so lighting is a problem (and the perspective also may become problematic).
03-25-2013, 03:33 PM   #11
dms
Site Supporter
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 2,133
My apologies--what I said about full frame vs dslr is wrong.

The magnification is 1--if you add the extension equal to the lens focal length--no matter what the sensor size.

Since I am always thinking of "same print size"--I always think of printing larger with smaller sensor.cropped sensor--and thus my misstatement.
03-25-2013, 04:21 PM   #12
Veteran Member
VisualDarkness's Avatar

Join Date: Nov 2011
Location: Uppsala, Sweden
Photos: Gallery
Posts: 4,438
Yeah, the DOF is going to be the same regardless of the focal length if the subject is the same size in the pics. The only thing that will change is the perspective as you will capture the scene at an wider angle, making the scene behind the subject more compressed. At 1:1 magnification the image projected on the sensor will be exactly the same scale (size) as the subject is in real life, if an ant is 2 mm then the ant projected on the sensor will be 2 mm.

Name:  DOF.jpg
Views: 2842
Size:  43.5 KB
03-26-2013, 03:16 AM   #13
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
QuoteOriginally posted by VisualDarkness Quote
Yeah, the DOF is going to be the same regardless of the focal length if the subject is the same size in the pics. The only thing that will change is the perspective as you will capture the scene at an wider angle, making the scene behind the subject more compressed. At 1:1 magnification the image projected on the sensor will be exactly the same scale (size) as the subject is in real life, if an ant is 2 mm then the ant projected on the sensor will be 2 mm.

Attachment 165000
Your drawing has a little fault, what is named field of view is angle of view.
The width of the frame at the focus point is the FOV, but like DMS said that is the same for the same magnification.
03-26-2013, 03:19 AM   #14
Veteran Member
Anvh's Avatar

Join Date: Sep 2011
Posts: 4,616
Glossary: Picture Angle: Digital Photography Review
03-26-2013, 07:02 AM   #15
Moderator
Man With A Camera
Loyal Site Supporter
Racer X 69's Avatar

Join Date: Jun 2010
Location: The Great Pacific Northwet
Photos: Gallery | Albums
Posts: 24,739
Original Poster
Thank you for the link to the definitions. I apologize for the confusion that my poor choice of terms may have caused.

So I still am not clear on the question I posed.

If I used a lens with a shorter focal length, on the bellows or extension tubes, will it net a wider angle of view, or a narrower angle of view, given the distance from then front lens element remains unchanged from one lens to another?
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
bit, field, field of view, input, lens, macro, question, setup, tripod, view
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quick question regarding field of view - FF vs APS-C glass? Julie Pentax SLR Lens Discussion 5 12-23-2012 05:33 PM
DA 10-17 FE - Field of View - Horiz & Vert interested_observer Pentax SLR Lens Discussion 14 09-25-2012 04:48 AM
15mm vertical field of view? Dr_who Pentax K-5 & K-5 II 10 06-10-2011 01:23 PM
Lens' field/angle of view MK-x Troubleshooting and Beginner Help 11 06-06-2011 10:24 PM
Field of view with small sensors Spring Creek Troubleshooting and Beginner Help 7 07-24-2010 06:48 AM



All times are GMT -7. The time now is 04:58 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top