100mm macro v's 150mm?

swag72

swag72

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I have fallen in love with my 100mm macro lens following the purchasing of a flash. I am finally getting the sorts of pics I have been after for a year.

Anyway - I have spent a holiday with the 100mm and 430EXII stuck on the end of the 50d and I've got some dragons that I am happy with. While I have been honing my commando stealth techniques, I can't help thinking that a 150mm macro or even a 180mm would be easier and would ensure that opportunities weren't lost due to a cracking twig etc.

So ................ If we assume that I am happy with my current set up (ie Canon and Speedlite) - What pros and cons do I need to know about if I look at a longer focal length macro?

Will my flash still be as effective as I'll be further away? Will the chances of more camera shake be a problem with a longer FL?

Would welcome your comments.
 
the 150mm will give you a extra 44mm working distance at 1:1 , your flash will work OK (as long as you don't use the hood ) the two main disadvantages are the extra weight 295g extra for the sigma 150mm and 365g for the Canon 180mm, also with the extra focal length you will get a shallower DOF.
 
Camera shake shouldn't be a problem if you're relying on the flash. But it's likely to feel a much heavier lens, especially if you go for the Canon 180mm. Daft as it sounds even if you do go for the 180 L I wouldn't expect a huge increase in IQ. It's not that the 180 is bad, but rather that the 100 is so good for the price.

But where you will gain is in working distance from the subject. I suppose it depends what you're shooting really.

cheers
 
Dogfish_magnet said:
the 150mm will give you a extra 44mm working distance at 1:1 , your flash will work OK (as long as you don't use the hood ) the two main disadvantages are the extra weight 295g extra for the sigma 150mm and 365g for the Canon 180mm, also with the extra focal length you will get a shallower DOF.
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44mm not a huge difference I guess.
A shallower DOF :eek:
 
I recently tested a Sigma 105 macro alongside a Sigma 180 macro - the longer working distance was handy for some insects, though the even shallower DOF means you need to stop down a lot if you want all the subject in focus. I didn't find the extra weight to be an issue, I preferred the handling of the 180, the tripod mount made it easy to use on a tripod/monopod. I prefer the 105 for shots of static subjects, but like the 180 more for live stuff.
 
swag72 said:
44mm not a huge difference I guess.
A shallower DOF :eek:
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It's the benefit of greater working distance and slightly narrower field of view (if indeed you think they are benefits) against weight and cost.

Depth of field remains the same at the same magnification and f/number.
 
HoppyUK said:
It's the benefit of greater working distance and slightly narrower field of view (if indeed you think they are benefits) against weight and cost.

Depth of field remains the same at the same magnification and f/number.
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Although the physics say this my eyes tell me there is a difference when i use my MP-e65 / 105 /150 :cautious: .....

Have a read of this article it would also suggests that

Depth of field remains the same at the same magnification and f/number

may only be true for lens of a certain physical design. :thinking::shrug: and i may be confusing DOF with background blur...:)
 
You should also consider the new canon 100mm L IS now (I think it is f2). it seems quite certain it will be released later this year. Price might be very high though.
 
Dogfish_magnet said:
Although the physics say this my eyes tell me there is a difference when i use my MP-e65 / 105 /150 :cautious: .....

Have a read of this article it would also suggests that

Depth of field remains the same at the same magnification and f/number

may only be true for lens of a certain physical design. :thinking::shrug: and i may be confusing DOF with background blur...:)
Click to expand...

DFM, that's a good link which I've read before (y) It takes a practical approach to some quite extreme science, and is written in plain-ish English. It's a good read I think :) And it does say quite clearly that for all practical purposes that if subject size remains the same then so does DoF, which is what I was picking up on.

When you get into the minutiae of the mathematics and start changing various parameters, small shifts in DoF happen all over the place in theory. But TBH I am much more interested in what photographs actually look like, and what is relevant - if you can't see it, it doesn't matter. Basic DoF science is there as a guide, but ultimately it's the picture that counts. Of course, physics can explain everything if you go into enough detail, but basic DoF calculations are just that and if you move the goal posts far enough they need to be reassessed - extreme macro is one area, fish-eye lenses are another, mirror lenses too.

With that thought in mind, your comment about the Canon MP-e65 is a good one. It is not a 'regular' lens at all and when you focus it, it's more like a zoom. It does not behave like ordinary macros and the article makes reference to different lens designs changing the rules a bit (re exit pupil).

Having said that, I am not aware of any significant DoF shifts particular to this lens. What may be more relevant is the effect of working distance on perspective and field of view - that makes a big difference to how much background is visible, how cluttered or plain it looks, and how that affects stand-out of the main subject. It's not a DoF effect, but it does much the same thing when you look at a photograph.

So in that respect, I would say the main difference between conventional 100mm and 180mm macros is not DoF, but the change in field of view due to working distance.

Cheers.

Edit: There is a way to get both a longer working distance and more depth of field. Just move back a little with the 100mm lens, and crop. What you are doing then is effectively using a smaller sensor format, which delivers greater DoF. If you enlarge the image 1.4x, you will gain one f/stop of extra DoF. Of course, you will also take a hit on image quality but if that's an acceptable trade off, the option is there.
Another thought: Kenko Pro 1.4x fits a Canon 100 macro, giving you a 140mm f/4. I used that combo quite a bit to gain working distance and it's surprising how much difference only a few cm makes. Image quality was pretty good, at least at mid-range apertures - I never seem to shoot macro at low f/numbers for DoF reasons.
 
HoppyUK said:
Another thought: Kenko Pro 1.4x fits a Canon 100 macro, giving you a 140mm f/4. I used that combo quite a bit to gain working distance and it's surprising how much difference only a few cm makes. Image quality was pretty good, at least at mid-range apertures - I never seem to shoot macro at low f/numbers for DoF reasons.
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That is something that I have considered, and now will probably go back to the idea. A £100 Kenko TC is cheaper and easier than changing a lens and will probably achieve pretty much what I'm after (y)
 
Bit naive this one but wouldn`t a 1.4 converter on a 100mm lens on a 50d actually give you almost 230mm ?? as its a cropped camera of 1.6 anyway ??. Have i got that roundabouts right??. Just food for thought ?. Take care . Ron
 
mavron said:
Bit naive this one but wouldn`t a 1.4 converter on a 100mm lens on a 50d actually give you almost 230mm ?? as its a cropped camera of 1.6 anyway ??. Have i got that roundabouts right??. Just food for thought ?. Take care . Ron
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Not quite Ron, but I get where you're coming from ;)

A 100mm f/2.8 with 1.4x telecon actually becomes a 140mm f/4 lens. If fitted on a Canon 1.6x crop body it will then have the equivalent field of view of a 224mm lens when fitted to a full frame or film camera.
 
HoppyUK said:
Not quite Ron, but I get where you're coming from ;)

A 100mm f/2.8 with 1.4x telecon actually becomes a 140mm f/4 lens. If fitted on a Canon 1.6x crop body it will then have the equivalent field of view of a 224mm lens when fitted to a full frame or film camera.
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Thanks HoppyUK . I knew there was summat in it . So i must be improving my camera education thanks to you guys in TP . Take care all .And Sara . Love you`re Macro work anyway . Why change?.
 
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