97 replies to this topic

[Tom_Kline]

In the good old days of manual focusing most macro lenses (e.g. 55/3.5, 105/4, and 200/4 Micro-Nikkors) only focused to 1:2 (half life size) so special extension tubes were sold to match to the focal lengths so as to yield 1:2 to 1:1 focusing range for some lenses. For example the Nikon PK-13 ring is 27.5mm long and was designed for the 55 whereas the PN-11 was for the 105. These two lenses also focused to 1:2 simply by racking out the lens elements, the extension tube carried this out for another increment equal to that intrinsic to the lens. When the 200 came out, it had internal focus (IF) and no extension tube came out for it. My recollection was the that the TC-300 teleconverter (TC; a.k.a. doubler) was recommended to bring the 200 to 1:1 but the PN-11 could be used too but less than 1:1 resulted. The IF enables lenses to compensate for lens aberrations induced by change in focus distance. This would be lost if an extension tube was used but would be conserved if a TC was used.

The bellows correction factor (due to loss of light by the extension) was engraved on the barrel of some MF macro lenses, two scales on some for use with and without the 1:1 tube. With the advent of TTL metering and TTL flash, the bellows correction factor was all but forgotten since the metering system took care of it. Interestingly, the 50 macro lens for the Nikonos RS has an automatic compensation so that as the lens is focused to 1:1, it opens up a tad. Therefore, f/22 remains T/22, (T-stop, not f/stop) but the DOF is that of the compensated aperture, i.e., less DOF. I criticized this 'feature' in my review of the RS that I did for the AAUS a decade or so ago. This is good for some folks, but DOF is sacrificed as a result.

The main problem of using an extension or TC UW is that one may have to use special lens gears; unless you have one of those ports that incorporates focusing and have a port extension tube that is the same length as your lens extension tube. Alternatively, you would have to do your dive at a fixed focus distance, like in the days of Nikonos (I to V) extension tubes and framers (remember them?).

BTW, I believe the EOS Canon 50 macro lens only goes to 1:2 and needs a tube to go to 1:1 like many MF focusing macros.

Tom

[Tom_Kline]

ps. forgot to mention that there are formulas for calculating the bellows correction factor, DOF etc. but are not to practical for UW use, one needs to know the total extension (tube plus amount due to lens focusing) and focal length and use a calculator. I recall one even includes pupillary magnification. One would need more input data.

[Kasey]

However, i do find that the filters do work with a 60mm, this is an example of 60mm with a +4.  True, i had to get right on them to get this full frame but..it worked...luckily they were turned this way

<{POST_SNAPBACK}>

I don't think that this shot demonstrates magnification beyond the native 60mm micro - unless those are pygmy mandarinfish

[MikeVeitch]

Well, in order to get them to fill that much of the frame (its full frame, no crop) i needed to be right on top of em, regular 60mm won't get you that full of a frame without the diopter (might have been a +2 as opposed to a +4...) but definitely more than just the regular 60 could do, believe me i tried on many occasions. Then i bought the 105.... much less frustrating that way, mandarins don't like it when you're port is only 3 inches away, ruins their sex drive...

[Chris Bangs]

I like the limited DOF it gives and i think is an easy way to go, without having to worry about extra length on your lenses and ports.
Too bad Chris Bangs doesn't seem to post on here these days, he has some great examples of using all sorts of combinations as that is one of his specialties (guess he is too busy taking photos of children!!!! )

However, i do find that the filters do work with a 60mm, this is an example of 60mm with a +4. True, i had to get right on them to get this full frame but..it worked...luckily they were turned this way

<{POST_SNAPBACK}>

[/quote]

Very Funny Manta breath!

sorry about the long hiatus. The peak kiddy shooting season is over, now I can get back to concentrating on UW stuff.

I found that using (+) filters on the 60mm reduced my working distance too much when shooting at max reproduction. I have used such filters with the 105 mm with decent results.

For the intense macro up to 10:1 teleconverters are required, In the future I plan to put the 200 mm micro lens to use. I will experiment with the (+) filters when using that lens

Chris

[james]

Way to go Chris - we'll be interested to see the results from the 200mm. I'm assuming it's the newer AFS model ($$$$)

Cheers
James

[segal3]

For the intense macro up to 10:1 teleconverters are required, In the future I plan to put the 200 mm micro lens to use. I will experiment with the (+) filters when using that lens

It's awfully tough for you Nikon users to get higher magnifications...

Canon makes a lens that does 1x-5x straight out of the box...

~Matt Segal

[Chris Bangs]

Way to go Chris - we'll be interested to see the results from the 200mm.  I'm assuming it's the newer AFS model ($$$$)

Cheers
James

<{POST_SNAPBACK}>

Yes it is the AFS, I got it over 3 years ago and have yet to dive with it. may need a sherpa to carry the rig!

Chris

[Chris Bangs]

It's awfully tough for you Nikon users to get higher magnifications...

Canon makes a lens that does 1x-5x straight out of the box...

~Matt Segal

<{POST_SNAPBACK}>

snake oil I think, Matt san! I notice that this "wonder" lens is not in your line-up;-)

All the best
chris

[segal3]

snake oil I think,  Matt  san!  I notice that this "wonder" lens is not in your line-up;-)

I'm but a mere student.

Snake oil, hardly - it's proven topside. The one caveat about the lens is that it is not internal focusing, that is, the lens extends as you move towards 5:1 (5x lifesize)...this complicates port selection. I'm working on getting my hands on a copy to try and figure out the logistics.

~Matt Segal

[Chris Bangs]

I'm but a mere student.

Snake oil, hardly - it's proven topside. The one caveat about the lens is that it is not internal focusing, that is, the lens extends as you move towards 5:1 (5x lifesize)...this complicates port selection. I'm working on getting my hands on a copy to try and figure out the logistics.

~Matt Segal

<{POST_SNAPBACK}>

Hi Matt

Ok, I was only kidding,

I think all true macro lenses do not internally focus. at least all my nikon one don't!

due to the VERY narrow field of view a flat port that will accommodate the lens at its maximum extension will work. the drawback would be lighting the subject as the lens shortens at lower reproduction ratios.

My Aquatica uses a extension ring system which is great for extreme macro as this allow me to fine tune the port length to whatever lens combination I want to use. I generally try to have the front of the lens as close to the inner port face as possible in order to maximize the working distance.


James started a topic long ago where I went into detail. the thread deals with using teleconverters but most of it would apply to general super macro shooting.

http://wetpixel.com/...?showtopic=3318

I have a few small galleries on another board with some high reproduction macro images as well as a shot or two the rig I used. the link is below, just scroll down until you see the macro galleries.

http://dive.scubadiv...=3&dir_id=51925

all the best

chris

[Paul Kay]

A few comments.

Canon's 100mm usm macro lens is a true internal focussing macro lens which does not physically alter its external dimensions between infinity and 1:1. The Canon 50mm macro lens only reproduces at half lifesize without an extender, whilst Nikon's 60mm goes right to 1:1 (a Canon 60mm FF going to 1:1 is on my wish list - I know Sigma make one but I haven't had good experiences with Sigmas so far).

Most manufacturers (used) to produce tables showing magnification of their lenses with both extension tubes and their own diopters fitted - but perhaps more importantly, they also showed the recommended magnifications for each combination - that is where the combinations produced their optimum results. I'm not sure whether they still do but no doubt this information will be somewhere on the web.

One point which has not been mentioned is exposure. Exposure increases as magnification increases. For those interested the formula is E = (1+m) x (1+m) where m is the magnification. So at 1:1 E = (1+1) x (1+1) = 2 x 2 = 4, ie 2 stops shift. Practically this simply means using powerful enough flash units! The cameras show this shift in different ways it would appear, and this is why the effective stop shown is not the one set.

[Chris Bangs]

Thanks Paul

learned a little about Canon today.

Thanks for the formula. My solution on stuff greater than 8:1 iwas add more narrow beam strobes and fine tune with strobe to subject distance. with film this was an expensive trial and error techneque. Digital as made it a one dive job. also having the ability to adjust ASA is a very welcome feature

[UWphotoNewbie]

Interesting lens. Thanks for posting Matt. Fill a 35mm frame with a grain of rice....hmmm.

Has anyone actually used this one underwater? The internal focusing is a non-issue for underwater use. All lenses are "internally focusing" once you add the port--sized to the maximum extension.

I have my doubts though if this would be a practical way to get beyond 1:1 underwater. AS I read it, this is basically a 60mm with a very close focus. So the problems of getting beyond 1:1 with the 60mm are the same here (think 60mm with a huge diopter). The minimum focus distance is 0.78"(5x) to 1.02"(1x). By the time you add in the port I can't imagine getting closer than 1" from the subject and lighting it is another matter. So perhaps its better just to use the 105mm/100m and get 1:1 at 12" which is a reasonable distance to light the subject and not spook it. I think if you are planning to go beyond 1:1 in a practical sense you need to start with a long focal length (via teleconverters or long lenses) then bring in the close focus with a diopter. Perhaps this is why I haven't heard of anyone here using this lens?

Opinions?

[james]

Yes, that's correct. Eric and I have both looked at this lens and rejected it because it has no working distance. It's made for scientists photographing static subjects, not nature photographers.

But it sure is cool.

Cheers
James

[Jolly]

The extension tubes will allows closer focusing resulting in higher magnification, this without loss of opticall quality ...

<{POST_SNAPBACK}>

Extension tubes can be seen as a slide projector put further away from the wall/screen. The image circle becomes bigger but darker. You loose light with extension tubes because just a part of the bigger image circled is captured. Further more, every little error in image quality is magnified too. Extension tubes are often considered to have no influence on light and image quality because there is no optical element inside. But extension tubes strongly intervene into the optical system resulting in light loss and image quality degradation. I’ve experienced that image quality becomes more critical with internal focusing lenses and zoom lenses.

Teleconverters increase magnification but different to extension tubes you still can shoot at infinity. OK, different thing, but if you don't want to shorten working distance a teleconverter might be more interesting.

Here is a nice comparison between different Teleconverters. Kenko 1,5x looks really good:
http://www.traumflie...erter_check.php

The site is in German but the pictures say a lot.

Julian

[Alex_Mustard]

Note that Sigma has just announced two new Teleconverters:

http://www.dpreview....econverters.asp

Alex

[Jolly]

I think decent image quality far beyond 1:1 can be obtained by turning around the lens. But difficult to house and working distance is around camera’s flange focal lens. This would require a macro ring strobe and lots of port / gear modification.

The second image (uncropped) is around 6mm x 4mm in reality. Please don’t evaluate contrast and noise, I’ve tried with ISO3200.



Julian

[Jolly]

Note that Sigma has just announced two new Teleconverters:

http://www.dpreview....econverters.asp

<{POST_SNAPBACK}>

Sigma converters work similarly to the Canon ones. They are specifically designed for long tele lenses (protruding element). I think the only Sigma macro you can use with these converters is the 180mm macro. Or you can try with an extension tube leaving enough space to mount another macro lens.

Basically the Kenko (or Tamron) converters are mechanically compatible to all lenses. And they are not bad at all.

Julian

[Arnon_Ayal]

Here is a nice comparison between different Teleconverters. Kenko 1,5x looks really good:
http://www.traumflie...erter_check.php

The samples with the 2X converters are terrible
In samples I sow with the Kenko 2X its looks much better, but that was with prime lens. If I remember correctly its mentions that thus converters are best with prime lens.