Chasing DOF

*MightyMike* · 01-17-2009, 09:16 PM

Recently I was at a butterfly conservatory, I was using my standard macro setup, DA50-200 + Raynox 250 etc... the setup works well and provides a 2.14:1 reproduction ratio at 200mm and 1.1m on the focus ring... at that magnification i'm seeing about 1.2mm in focus @ F32 .... i thought to myself how can i get more DOF without focus stacking or losing magnification... I considered how dedicated macro lenses work, nearly identical to an extension tube... you see all the elements in a dedicated macro lens move as one back and forth to obtain focus and at 1:1 magnification the lens is approx. twice as long as it would be at infinity and therefore your effective aperture is doubled, F8 dialed in would give you F16 DOF. In contrast using the Raynox F8 is still approx F8 +/- a few decimal values under the same circumstances.

Does this mean I could use extension tubes to increase my DOF while maintaining the same magnification? some said no, but i said yes! and went out and found a set of kenko extension tubes with the AE contacts... and did the testing...

Original setup...
DA50-200mm @ 200mm and F32 + Raynox 250 = 1.2mm DOF

New Setup...
DA50-200mm @ ~115mm and F29 + 68mm of tubes + Raynox 250 = 1.8mm DOF

68mm of extension tubes give me 1.5 times more DOF at the same magnification, I did have to drop the focal length to match the magnification.

Here are some examples...

Original setup (1/2 to 2/3rds of the area between the eyes are in focus)

New Setup (the edges of each eye closest to the rest of the head are in focus)

Another way to demonstrate the difference in DOF is to show how well defined the background is for a given subject. (super close-up of a Lilliput lane house)

Original setup (but at F29 instead of F32)

New setup (notice due to more DOF the background is more well defined)

Now i have a decision to make... I have a Magnicon 3X Macro Auto Tele Converter, its meant to work with 50mm F1.4 lenses and allow a maximum of 1.4:1 magnification. its actually pretty decent quality for a 3x teleconverter... However do i keep it as is or do i take it apart and remove the glass and make it a 56mm extension tube, to go with the 68mm worth of extension tubes i already have? This will allow me to have even more DOF at the same magnification.

Some photos of the macro setup

Original... (DA50-200 @ 200mm and Raynox 250)

New Setup... (Da50-200 @ ~115mm and Raynox 250 and 68mm of tubes)

The Magnicon lens and the new setup...

So i ask again... take apart the 3x converter for more DOF or leave it as is?

**Kerrowdown** · 01-18-2009, 04:29 AM

Wow what a shot, I'm glad you mentioned macro here, otherwise that's one king kong of butterfly beastie, which I would not be in the same area as.

*MightyMike* · 01-18-2009, 05:42 PM

Originally posted by kerrowdown

Wow what a shot, I'm glad you mentioned macro here, otherwise that's one king king of butterfly beastie, which I would not be in the same area as.

Yeah just wait till i post other giant bugs

Mechan1k · 01-19-2009, 06:07 AM

I really should start playing with Macro ... I just got a set of M42 Extension tubes in the mail ... and looking forward to using them with my Super Takumars.

kristoffon · 01-19-2009, 08:53 AM

Your shots are awesome. You do realize that by using extension tubes the amount of light is also cut down so you get exactly the same effect of using a higher aperture - less light and more dof - right? So in effect your aperture is much smaller than what the lens indicates.

*MightyMike* · 01-19-2009, 12:46 PM

Originally posted by kristoffon

Your shots are awesome. You do realize that by using extension tubes the amount of light is also cut down so you get exactly the same effect of using a higher aperture - less light and more dof - right? So in effect your aperture is much smaller than what the lens indicates.

Yes i do know that, however i'd state it more like this, the tubes alter the focal length of the lens and in doing so the aperture you have dialed in is not the aperture you are actually getting... the tubes are used when my lens can't go any smaller in aperture...

**Ron Boggs** · 01-23-2009, 08:16 AM

Does sharpening in post processing "fix" diffraction problems?

With FA*200/4 Macro, f22 exhibits horrible diffraction on the small sensor digital cameras and noticeable diffraction on 35mm film. Never used it at magnifications like the original post, but at 1:1 I have to be careful of diffraction, particularly when using a digital body. This was true of the A*200/4 Macro as well. Note that both those lenses are generally considered as good as it gets for macro up to 1:1.

Since your shots do not appear to have significant diffraction issues at very small apertures I am curious as to why...sharpening actually fixes diffraction? Raynox diopter effects diffraction? Regular--nonmacro--lens have any impact on diffraction at high magnification? Is this a case against true macro lenses for high magnification imaging?

Just curious, though unlikely to play with high mag. myself...

Very nice work by the way!

falconeye · 01-23-2009, 11:05 AM

The OP got it exactly right.
As said in some other post, the effective focal length f' at a given magnification m is:
f' = f * (1 + m)
as long as magnification is reached with focussing, extension tubes or tele converters, or any combination thereof.

However, not applicable for a Raynox front lens adapter.

Originally posted by Ron Boggs

Does sharpening in post processing "fix" diffraction problems?

Diffraction stays challenging. I am sure that the original images (not downscaled for the web) aren't sharp. On the one hand, the Raynox lenses don't match the quality of SLR lenses. On the other hand, one should stay below f/8 for razor-sharp m=1:1 macro images as this corresponds to f/16 at infinite distance where diffraction is already visibly limiting the resolution on a K20D.

For razor-sharp macro images and significant DoF, there is no other way than focus stacking.

Igilligan · 01-23-2009, 11:17 AM

Your Raynox 250 looks very different from mine. Mine has what looks to be a smaller lens inside a clip-on piece... I am confused by how much different/larger yours looks. How does it attach to the 50-200?

Are there different model of this lens?

pingflood · 01-23-2009, 11:56 AM

Those are some great shots, and thanks for sharing what you've found out. Had never thought about it, but what you say makes perfect sense.

I would love the Canon MPE-65 macro lens (1x-5x) but do so little macro I think I'll stick with reversed lenses and extension tubes for now.

01-17-2009, 09:16 PM	#1
MightyMike Marketplace Reseller Join Date: Nov 2008 Location: Canada Posts: 9,322	Chasing DOF Recently I was at a butterfly conservatory, I was using my standard macro setup, DA50-200 + Raynox 250 etc... the setup works well and provides a 2.14:1 reproduction ratio at 200mm and 1.1m on the focus ring... at that magnification i'm seeing about 1.2mm in focus @ F32 .... i thought to myself how can i get more DOF without focus stacking or losing magnification... I considered how dedicated macro lenses work, nearly identical to an extension tube... you see all the elements in a dedicated macro lens move as one back and forth to obtain focus and at 1:1 magnification the lens is approx. twice as long as it would be at infinity and therefore your effective aperture is doubled, F8 dialed in would give you F16 DOF. In contrast using the Raynox F8 is still approx F8 +/- a few decimal values under the same circumstances. Does this mean I could use extension tubes to increase my DOF while maintaining the same magnification? some said no, but i said yes! and went out and found a set of kenko extension tubes with the AE contacts... and did the testing... Original setup... DA50-200mm @ 200mm and F32 + Raynox 250 = 1.2mm DOF New Setup... DA50-200mm @ ~115mm and F29 + 68mm of tubes + Raynox 250 = 1.8mm DOF 68mm of extension tubes give me 1.5 times more DOF at the same magnification, I did have to drop the focal length to match the magnification. Here are some examples... Original setup (1/2 to 2/3rds of the area between the eyes are in focus) New Setup (the edges of each eye closest to the rest of the head are in focus) Another way to demonstrate the difference in DOF is to show how well defined the background is for a given subject. (super close-up of a Lilliput lane house) Original setup (but at F29 instead of F32) New setup (notice due to more DOF the background is more well defined) Now i have a decision to make... I have a Magnicon 3X Macro Auto Tele Converter, its meant to work with 50mm F1.4 lenses and allow a maximum of 1.4:1 magnification. its actually pretty decent quality for a 3x teleconverter... However do i keep it as is or do i take it apart and remove the glass and make it a 56mm extension tube, to go with the 68mm worth of extension tubes i already have? This will allow me to have even more DOF at the same magnification. Some photos of the macro setup Original... (DA50-200 @ 200mm and Raynox 250) New Setup... (Da50-200 @ ~115mm and Raynox 250 and 68mm of tubes) The Magnicon lens and the new setup... So i ask again... take apart the 3x converter for more DOF or leave it as is?

01-18-2009, 04:29 AM	#2
Kerrowdown PEG Moderator Join Date: Aug 2008 Location: Highlands of Scotland... "Hold Infinity in the palm of your hand" - William Blake Photos: Gallery Posts: 57,819	Wow what a shot, I'm glad you mentioned macro here, otherwise that's one king kong of butterfly beastie, which I would not be in the same area as. Last edited by Kerrowdown; 01-21-2009 at 12:27 PM.

01-23-2009, 11:17 AM	#9
Igilligan Guest	Mike... Big question for you Your Raynox 250 looks very different from mine. Mine has what looks to be a smaller lens inside a clip-on piece... I am confused by how much different/larger yours looks. How does it attach to the 50-200? Are there different model of this lens?

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01-18-2009, 05:42 PM	#3
MightyMike Marketplace Reseller Join Date: Nov 2008 Location: Canada Posts: 9,322 Original Poster	Originally posted by kerrowdown Wow what a shot, I'm glad you mentioned macro here, otherwise that's one king king of butterfly beastie, which I would not be in the same area as. Yeah just wait till i post other giant bugs

01-19-2009, 06:07 AM	#4
Mechan1k Veteran Member Join Date: Jun 2007 Location: Sydney, Australia Posts: 2,891	I really should start playing with Macro ... I just got a set of M42 Extension tubes in the mail ... and looking forward to using them with my Super Takumars.

01-19-2009, 08:53 AM	#5
kristoffon Veteran Member Join Date: Aug 2008 Location: Brazil Posts: 532	Your shots are awesome. You do realize that by using extension tubes the amount of light is also cut down so you get exactly the same effect of using a higher aperture - less light and more dof - right? So in effect your aperture is much smaller than what the lens indicates.

01-19-2009, 12:46 PM	#6
MightyMike Marketplace Reseller Join Date: Nov 2008 Location: Canada Posts: 9,322 Original Poster	Originally posted by kristoffon Your shots are awesome. You do realize that by using extension tubes the amount of light is also cut down so you get exactly the same effect of using a higher aperture - less light and more dof - right? So in effect your aperture is much smaller than what the lens indicates. Yes i do know that, however i'd state it more like this, the tubes alter the focal length of the lens and in doing so the aperture you have dialed in is not the aperture you are actually getting... the tubes are used when my lens can't go any smaller in aperture...

01-23-2009, 08:16 AM	#7
Ron Boggs Site Supporter Join Date: Feb 2008 Location: MT Photos: Gallery Posts: 1,349	Does sharpening in post processing "fix" diffraction problems? With FA200/4 Macro, f22 exhibits horrible diffraction on the small sensor digital cameras and noticeable diffraction on 35mm film. Never used it at magnifications like the original post, but at 1:1 I have to be careful of diffraction, particularly when using a digital body. This was true of the A200/4 Macro as well. Note that both those lenses are generally considered as good as it gets for macro up to 1:1. Since your shots do not appear to have significant diffraction issues at very small apertures I am curious as to why...sharpening actually fixes diffraction? Raynox diopter effects diffraction? Regular--nonmacro--lens have any impact on diffraction at high magnification? Is this a case against true macro lenses for high magnification imaging? Just curious, though unlikely to play with high mag. myself... Very nice work by the way!

01-23-2009, 11:05 AM	#8
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	The OP got it exactly right. As said in some other post, the effective focal length f' at a given magnification m is: f' = f * (1 + m) as long as magnification is reached with focussing, extension tubes or tele converters, or any combination thereof. However, not applicable for a Raynox front lens adapter. Originally posted by Ron Boggs Does sharpening in post processing "fix" diffraction problems? Diffraction stays challenging. I am sure that the original images (not downscaled for the web) aren't sharp. On the one hand, the Raynox lenses don't match the quality of SLR lenses. On the other hand, one should stay below f/8 for razor-sharp m=1:1 macro images as this corresponds to f/16 at infinite distance where diffraction is already visibly limiting the resolution on a K20D. For razor-sharp macro images and significant DoF, there is no other way than focus stacking.

01-23-2009, 11:56 AM	#10
pingflood Veteran Member Join Date: Jun 2008 Location: Borås, Sweden Photos: Gallery Posts: 3,169	Those are some great shots, and thanks for sharing what you've found out. Had never thought about it, but what you say makes perfect sense. I would love the Canon MPE-65 macro lens (1x-5x) but do so little macro I think I'll stick with reversed lenses and extension tubes for now.