Effects of crop factor on working distance for macro? Lens suggestion for D70?

[scottconners]

Ok this question is somewhat involved.

 

I love shooting macro on film, and my film setup is my Nikkormat EL

with a Nikkor-P 105 2.5 on tubes, ranging from 15-100+mm of extension,

lit by a Vivitar 283 hand held off camera with the thyristor on the

camera shoe, shooting to Velvia and Provia mostly.

 

However, now I'm moving to a D70 and looking to make a macro setup.

Obviously the first option that jumps to mind is the 105 2.8 AF micro,

but I've been thinking hard about my needs and am looking for suggestions.

My ultimate lens choice right now is the Nikon 70-180 Macro zoom,

which would extend the range of my kit lens while also getting me

respectable macro function (1:1.31) and extending the kit lens' reach,

giving me coverage from 18-180 in two lenses, plus a very good macro.

However, this lens is $1000 new, and I've been unable to find any used

ones at all.

My budget really can't afford this lens, so I'm looking either for a

similar off-brand lens, or an inexpensive macro prime (85mm or longer)

while I save for it. I could spend ~$500 on a similar lens, or I'd

like to spend ~$100 on a stopgap lens while I save. Other stopgap

measures I've explored are Kenko tubes with the kit lens, or offbrand

diopter(closeup) filters on the kit lens. Opinions on these options

are welcome.

 

From my understanding of it, the crop factor on a DSLR is going to

give me a longer working distance than the lens would on 35mm,

correct? Is it going to multiply by 1.5 as well?

 

That means that the 105 is going to suddenly give me the distance of a

157.5, or the 1:1 WD of 12" is going to become 18". Generally this

would be a good thing. However, I was looking hard at the Sigma 150

and 180 Macro 2.8 AF HSM lenses, as I'd love to have a nice telephoto

that was also a macro, and these are both highly rated and use the HSM

(SWM) focusing which I love. KEH has a used 180 for $499, which I am

drooling over. However, I'm worried that the 18" working distance is

going to become 27", which is probably too much for some of my shots.

 

So basically, should I look at something like the Tamron 90mm macro to

replace my 105 setup, or go all out on the Nikon zoom/similar offbrand

zoom? How much working distance at 1:1 is too much? Your suggestions

are most welcome.

[vivek iyer]

The confusion factor from the puny APS C sized sensor, DOES NOT:

 

1. Change the focal length

 

2. Change the working distance

 

3. Change the magnifications

 

You just get a smaller sized (cropped) image. That is it.

[kaiyen]

I spent about 6 weeks in a futile battle on this topic on dpreview several months ago.

 

As Vivek says, working distance doesn't change. However, it's important to think of working distance as the distance required to get 1:1, not as the distance required to get a particular composition that seems like 1:1. Let me explain.

 

If you define your picture as "the whole flower" rather than "whatever shows up in the viewfinder at 1:1," then it'll seem like your working distance changes. If you think of it as the whole flower, then the distance required to fill the frame with the flower with 35mm film is going to be shorter than the distance required to fill the frame with a DSLR with the crop factor.

 

If you think of it purely as achieving 1:1 magnification, then the working distance is exactly the same.

 

Perhaps the distinction seems obvious to you and I am wasting my time with this post. But it is apparently a common perception to think of working distance changing _if_ you define your macro work by the composition, rather than the magnification ratio.

 

allan

[scottconners]

Vivek, I know that in actuality it doesn't "change" anything, but in practice won't I have to be farther away for the same image? My thinking:

 

On 35mm film I have a picture of a stamp that fills the frame exactly at 1:1, from 12" away.

 

On Digital(1.5x sensor) with same lens, I have to be 18" away from the same object(stamp) to get it to be framed exactly the same, correct? This has the effect of giving me a 1.5x working distance for the same shot.

[richard_cochran]

If you hold the reproduction ratio constant, that is, if you still

shoot at 1:1, the small sensor just crops the image. There's no

change in working distance.

<p>

But if you hold the final image constant, that is, if you fill

the frame with the same sized subject, you will NOT hold the

reproduction ratio constant.

<p>

Imagine using the D-70 to duplicate

some slides (not that that's the best way to copy slides, but it's

a fair way to illustrate a point). Remember that, to duplicate slides

in 35mm, you'd shoot at 1:1, and your final image would be an exact

copy of the original, neglecting issues like contrast build-up and

imperfections in the process.

<p>

But using the D-70, if you shoot at 1:1, you'll

get a cropped version of the original slide -- the portion of the

slide you captured will be the same size as the D-70's sensor.

If, on the other hand, you fill the frame with the original slide's

image, you'll have to move the slide further away, and change focus.

You would no longer be shooting at 1:1, but instead you'd want to

shoot at about 1:1.5.

<p>

The same is true of photographing any other macro subject. If

you want to make a frame-filling image of a flower, a stamp,

etc., keeping the image constant, you'll back up with the D-70.

If you keep the distance constant, the D-70 will get a cropped

version of the image the 35mm camera would have captured.

<p>

Keeping the image in the frame constant, the working distance

will increase with the D-70, but the precise percentage of the

increase depends on the particulars of the lens. Since working

distance is measured from the front of the lens, the distance between

the front of the lens and its optical center is an issue. Also,

some lenses change their effective focal length as they focus (the

105mm f/2.8 micro does this), which confuses the issue somewhat.

[scottconners]

Thank you Allan! That was the answer I was looking for. I mis-used the term "Working Distance" and caused confusion. <BR><BR>

 

What I meant by it was the distance required to frame the same image. In this case, I <em><b>do</b></em> need to back away from the object 1.5x to get the same framing, correct?

[kaiyen]

Yes. And as richard says, you'll lose 1:1 reproduction.

 

Another reason why it gets confusing is that if you fill the frame in both scenarios (35mm at 12" working distance and D70 at 18" working distance, for example), and print _both_ to 8x10, it should look like you've achieved 1:1 in both scenarios. Bringing the issue of print size was one of the main reasons why I couldn't seem to convince anyone on dpreview that the working distance technically stayed the same. What's technically happening is that you've changed your enlargement ratio on the print. Anyway.

 

So working distance stays the same. The "distance required to get the same composition" does change. And so does your reproduction ratio, of course.

 

allan

[scottconners]

Thanks Richard, great explanation.

 

This taken into account, I'm still looking for suggestions for offbranded macro lenses to substitute for the Nikon 70-180, or primes in the 85-105 range.

[mark_chappell]

Yes (you do have to 'back off' to get the same framing on a DSLR as on film, using the

same lens for both).

 

In much macro work, at least with flowers, insects, etc., it's generally best to go with a

long focal length instead of a short focal length, if you have the choice. This gives you

more working distance, making it easier to get good light on the subject, less risk of

scaring it (if it's scareable), etc. So I'd give the 150 or 180 lenses serious consideration (I

had the Sigma 180/3.5 HSM and it was excellent, but don't forget the Tamron 180/3.5

which may be even better).

[scottconners]

Thanks mark. I was ready to hit the "buy" button on KEH last night, but got scared when I thought about trying to work 27" away from my subject. Hand holding a flash off camera lets me get the light way out to the side for shadows that give depth (I've used on camera + side-held as well with good result) and I dont think I could get the flash at nearly the same angle from over 2 feet away, but I may have to just experiment to be sure.

[mark_chappell]

Hey, Scott, if you like strong side lighting, you do have a point about focal length. With a

short focal length you have little choice: your flash HAS to be off to the side to keep the

lens barrel from shading the subject. I guess I prefer light that's either pretty diffuse or

more or less in line with the lens axis, to give fairly shadowless results.<P>

 

Going to extremes: here's a close-up made with a REALLY long 'macro' lens (500 mm +2x

+ extension tubes): no problem with working distance but the setup is a little awkward!

<P>

 

<P ALIGN=CENTER>

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<IMG SRC="http://biology.ucr.edu/personal/MACphotos/arthropods/

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<BR>varigated meadowhawk

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[craig_bridge]

Before you buy a lens, why not try your 105P setup on a D70 first?

[scottconners]

Unfortunately both my 105 2.5 and my extension tubes are pre-AI, so they wont mount to the D70 without damaging it.

Also, the D70 will not meter at all without a "chipped" lens, nor will the TTL flash work, which is one of the things I am eagerly looking forward to.

[rw]

Scott,

 

Normally a ring flash will solve the problem. or a custom made bracket which position the flash just above the front element aiming down at say 30 degree. These set up will take the length of the lense barrel out of the equation.

 

But the D70 needs DX flash to support TTL, so the SB 29 (ring flash) is out if you need TTL. This leave you with the custom made bracket option, but hanging out a large DX flash on top of the lense is a bit awkard especiality if you have a long lense, like the Micro 200 mm AF f4 i own. I think it is probably not too bad .....

 

That's why I like about my S2 pro, I can use a old model small Nikon flash to get TTL. My current set up is a SB23 (which is small) with a SC-17 cord mounted on custom made bracket which I fabricated myself. Sometime, if I am a bit lazy, I just use the SB26 mounted directly on the hot shoe and tilt it down a bit to suit the situation.

 

Lense recommendation: Micro Nikor 200 mm AF f4 or Nikon Micro 105mm f2.8 in order of preference.

[hayward]

<p align="center">This question comes up frequently - you may want to search. I have tried dipters and tubes and reversed lenses and nothing works as well for me as a good macro lens. I flat out love my Tamron 90mm macro and have been using it lately with a Tamron SP 1.4x teleconver for pictures like this one. The 90mm macro was $300 in used mint condition and the TC was $180 new.

 

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<img src="http://d6d2h4gfvy8t8.cloudfront.net/2749235-lg.jpg">

<br>

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</p>

[richard_hedges2]

I use a Tamron 90mm micro & kenko extension tubes for nikon/af for my D100. The combination works very well for micro. you can not go wrong.

[david_h._hartman]

<em>Effects of crop factor on working distance for

macro? --Scott Conners<br>

</em><br>

Considerable If you dont think it out. 1:1 on 6x6 or 6x7cm

isnt nearly as impressive as 1:1 on 24x36mm. It could be a

rude surprise. 1:1 on 4x5 in (9.5x12cm) isnt much and 1:1

on 8x10 is much less. I found close-up photoraphy with a

Hassleblad, 80/2.8 Planar and set of three tubes somewhat

frustraing at first. With a Nikon and 55/3.5 and M2 tube I was

used to infinity to half life size with no change in tubes. The

Hassie only achived the effect of half lifesize (as I recall)

with all three tubes. I had to quicly learn which tubes I'd want

and not guess<br>

<br>

OK, its not really the working distance at a given

reproduction ratio. Its that you need a greater

reproduction ratio to fill a larger format. Working distance is

greatly effected by the focal length so if you want more use a

longer focal.<br>

<br>

In the case of the smaller DX formats you need less. An AF 70~180/4.5~5.6D

ED Micro-Nikkor is a great lens for the DX formats. It only

achieves 0.75x at 180mm but thats fine for DX in many

situations. That 180mm is more like 105mm at 0.75x. The lens also

makes a good, if slow, general purpose telephoto lens. The lack

of grain or noise at 200~400 ISO is helpful in using the slower

lens. The lens is not slow as a close up lens as focusing closer

does not reduce illumination at the film or sensor as with the AF

60/2.8D or AF 105/2.8D Micro-Nikkors.<br>

<br>

The effect on a D2H of the 70~180/4.5~5.6 Micro is similar to a

160mm lens on 24x36 and 0.75x is much like 1:1 or a little better

for filling the frame. Make no mistake, the crop factor

does not change reproduction ratio and working distance but you

will likely chose sorter lenses and use lower reproduction ratios

with the DX formats.<br>

<br>

Its like a new language. Its best to learn to think

in the new language as soon as possible.<br>

<br>

Regards,<br>

<br>

Dave Hartman.