D2x+105mm+2xTC+Woody's diopter

[yahsemtough 0]

Are you sure it is the aperature and not the shutter speed potentially taking away the resolution?

 

Remember he was shooting at 1/25 I think whereas I guess your shot to be about 1/100 to 1/160. Maybe a little shake on firing the trigger and the slow shutter is capturing that?

[Rocha 0]

I also think that the apparent lack of sharpness was caused by slow shutter speed. I just looked at the exif of Rand's pictures, and the first was at a shutter speed of 1/25, the second was at 1/20, I think this is too slow for a 100+mm lens. Herb's was at 1/200.

[segal3 0]

Remember too, that the only reason that the entire frame is not blurry is because with those settings (F/29 or whatever translated is, F45?), when the flash fires in 1/400s or 1/500s or whatever it is, that that's where the majority of your light is coming from, 'freezing' the subject.

 

But yes, I agree that a higher shutter speed is necessary regardless, and I merely theorize on why it worked period.

 

~Matt Segal

[randapex 0]

Herb, thanks for the comparison and the pics.

 

The main difference between yours and mine, besides the the fact you were using a 1.4 instead of the 2x, which we can put aside for now, (Some say the 1.4 is sharper) is that the Woody's diopter, was also attached. As to what affect it has/had on overall sharpness, I'm not sure. Enough people complain that by it'self, the Woody's isn't all that sharp.

 

I'd like to thank everyone who's contributed as it's given me some ideas, answers and more questions. So, very productive.

 

What I'll try next time:

 

Shutter speed needs to be pushed up.

 

Open up the aperture a bit. Maybe trying around f18-f20. The Mosshead Warbonnets in Port Hardy are larger than the blennies but have the same fringes on top so DOF will still be an issue. I'd love to fill the frame with one of those guys. They're about the size of your little finger.

 

Perhaps push the ISO up a little. See how that affects the exposures. And find out if the overall image quality is still acceptable.

 

Look at strobe positioning and see if it's possible to move them forward a bit

farther.

 

Rand

[herbko 0]

Are you sure it is the aperature and not the shutter speed potentially taking away the resolution?

 

Remember he was shooting at 1/25 I think whereas I guess your shot to be about 1/100 to 1/160. Maybe a little shake on firing the trigger and the slow shutter is capturing that?

<{POST_SNAPBACK}>

 

That may be part of it. If the light is mostly coming from the strobe, then the slow shutter speed should not blur the image. As I commented on before, in Rand's case a significant part of the light is probably coming from the spotting light, so slow shutter can affect the image. I think at 1/25 motion blur should be directional, that is the lens is panning in some direction, but I don't see that in Rand's shot. I still think the very small aperture, F/58, is the primary cause of lost resolution.

[james 0]

Rand,

 

His aperture is set on the lens at f22 or whatever he used. It's the aperture that results in the diffraction I think, due to light passing through a small hole.

 

The aperture and focal length are also what affect depth of field.

 

Effective f-stop is influenced by the teleconverter and the bellows effect.

 

Does that sound right gang?

 

What I'm trying to say is that setting the aperture on the lens below the cut-off for diffraction spreading light between two pixels may be all that's necessary, and perhaps that's not affected by the TC or diopters.

 

Cheers

James

[segal3 0]

To clear up some ideas being thrown around here...

 

Given a perfect optical lens, a camera captures the most resolution (resolving power) when the aperture is wide-open, and the least resolution (losing inherent sharpness and ability to see detail) when stopped down, due to diffraction and the fact that you're taking a picture of a scene through a tiny hole (as compared to a larger one that will allow more light through, etc).

 

Now, when given a real-world lens, the same applies, but you are limited by the lens at the widest apertures (look at MTF charts for the variances). This is why it is usually taught to stop down 1 or 2 stops to get the best balanced resolution (resolving power, ability to see detail) from any given lens and camera.

 

When shooting at extremely tiny apertures, no matter what you do, even though you gain DOF, the amount of the image in focus will not be as sharp as that taken at a lower aperture.

 

On a separate note, in response to Rand's comment about the Woody's diopter, I have seen no reports from any individual that the addition of Woody's diopter leads to any noticeable (real-world) loss of sharpness (resolution).

 

~Matt Segal

[randapex 0]

Herb, I've been meaning to ask if you have any idea of reproduction ratio achieved with the combonation of 105mm, 2xTC and the Woody's??

 

Rand

[scorpio_fish 5]

Given a perfect optical lens, a camera captures the most resolution (resolving power) when the aperture is wide-open

 

Not true

 

I believe Rand must have hit the limit of the strobes in order to require a slower shutter speed. It may be solved by positioning (remember that icky inverse squares thing).

 

He didn't have the problem with just the diopter. That extra 2-stops is a killer.

 

Assuming that f/29 is the actual f-stop then one can easily assume a loss of sharpness due to diffraction. As a matter of fact, it looks that way to me just based on my own experience.

 

In the old film days, we would physically adjust the camera aperture. The LED in the viewfinder would give the effective aperture on Nikons, not the actual. It varied by camera as to actual vs. effective being displayed. It was weird seeing the readout f45. It is the actual aperture that causes diffraction (i.e. the physical opening), not the effective aperture.

 

Anyway, time to get some manly strobes instead of those boy toys.

[james 0]

Some stronger Inon strobes would be nice, eh? Watch this space.

 

FWIW, I was able to shoot 5:1 (35mm equivalent) with the Z220's set at -1 when I had my strobes pointed correctly. I had my lens set at f22

 

I don't know the exact number/math, but I'm guessing they could do effective f32

 

Cheers

James

[herbko 0]

I go off to a meeting and come back to find all this confusion.

 

Some of it is I think caused by my careless use of the word "effictive", so I'll try to clear it up.

 

The aperture is the ratio of the lens diaphram opening to the focal length. Adding a TC increases the focal length, so if the opening is unchanged the aperture is reduced (larger F number). I 've read that some camera and TC combination will adjust for this automatically: if you add a TC and set the same aperture the opening will be bigger to compensate. You should find out if your's does by the simple test I described on my first post. I know that mine does not. The shot I posted had aperture set to F/16 by it is REALLY F/22, and I wrote F/22 for the aperture even though the camera setting was F/16 as you can see in the EXIF.

 

Becasue of diffraction small apertures will limit resolution even for an ideal lens. Lens imperfection will limit resolution for large apertures. That's why most of the resolution tests you see for cameras at sites like dpreview is shot around F/8. For the 1.6x cropped 6Mpixel sensor 300D, at around F/16 diffraction starts to eat into the resolution and becomes the limiting factor not the number of pixels. I do not expect the 12Mpixel sensor on the D2x to have much better resolution than the 300D at this REAL aperture and smaller. That's the theory. I asked Rand for the 100% crops to see if it's consistant.

 

Rand, your lens by itself has maximum magnification 1:1, with a 2x TC it should be 2:1. You can just fit an 11mm subject in the frame at max magnification. I'm not sure what your diopter will do as I have not tried that one.

 

James, Mark has given hints about a higher powered Inon strobe. Have you any details you can share. Brighter strobes are on my list just ahead of the 5D.

[james 0]

Hi Herb,

 

I'm confused. I thought an aperture was a mechanical opening (a small hole) and small holes (as well as slits, like we used in physics class) creat diffraction.

 

I though a F-stop depends on the size of the aperture and the focal length.

 

But I could be wrong.

 

RE the Inon's. I'm just making hopeful guesses based on what Mark has posted on various message boards.

 

Cheers

James

[randapex 0]

Thanks for the explaination Herb. I'll test that out tonight and see how the camera responds. I do seem to recall getting some high f stop readings, ie f45.

 

Also at one point, of having the camera read with a strange symbol: <f7 and it wouldn't change with the aperture wheel being turned. Some of my shots read f0 so I'm not sure if I've got a faulty connection with the TC or some other issue. After the dive, I removed the TC put the 105mm back on and the f stops read correctly.

 

As for the Woody's. I'd taken some shots with and without the diopter and I'd say that with it, the subject was roughly 50% bigger than without. Perhaps getting me in the area of 3-1. Thanks for the calculation.

 

Rand

[herbko 0]

Hi Herb,

 

I'm confused.  I thought an aperture was a mechanical opening (a small hole) and small holes (as well as slits, like we used in physics class) creat diffraction.

 

I though a F-stop depends on the size of the aperture and the focal length.

 

But I could be wrong.

 

Cheers

James

<{POST_SNAPBACK}>

 

I think technically you are right. But I think in photography the term has come to mean F-stop. When someone asks you what aperture you set on a shot, you never respond with 5mm. It may be fun to do to see the reaction.

[acroporas 0]

I am confident that the lack of sharpness is from using both teleconverter and diopter and it is not just because woody's is a low quality diopter.

 

I have experimented with using both with my Canon 1.4X and Canon 500D diopter on the following lenses: canon 300/4, canon 100/2.8 and sigma 150/2.8 (I had to use an extension tube to make the macros compatible with the 1.4x)

 

I found that with all the lenses at any aperature, more detail was captured by using teleconver or diopter than with both.

 

Can anyone post an example of a sharp 100% crop that utilized both a diopter and a teleconverter?

[mrbubbles 0]

I used a woodys diopter extensively with a 105 on my recent trip to the solomons. See post here of soft coral crab a few days ago. I remember being in mabul malasia about 8 years ago. At that time it was the place to go for macro,like suawaysi is now. I remember all the japanese had housings with diopters and teleconverters. The set ups blew us away. They were taking pics of gobie eyeballs and such. Their shots were amazing, altho with slide film the depth of field was nothing like digital. There was a dive master there named yoshi, who had a book of his work out. Im not sure of his last name?hirata? You guys might want to check out his old stuff, just to see their work, it was facinating.

[randapex 0]

Herb, FWIW, the D2x doesn't adjust f stop # if the TC is on, I can add or remove it at f20 for instance and it won't change. What I did find, is the max aperture will drop from f40 to f32 as you zoom.

 

Rand

[acroporas 0]

Rand, testing it at f/20 doesnt tell you anything because the lens is capible of f/20 in both cases.

 

See if the camera will let you set the aperature to 2.8(or what ever is normally wide open without the teleconverter) with the teleconverter on. If it will let you set it to 2.8 then it is not correcting for it, if it will not let you set the aperature to 2.8 then it is correcting for it.

[herbko 0]

Rand, testing it at f/20 doesnt tell you anything because the lens is capible of f/20 in both cases.

 

See if the camera will let you set the aperature to 2.8(or what ever is normally wide open without the teleconverter) with the teleconverter on.  If it will let you set it to 2.8 then it is not correcting for it, if it will not let you set the aperature to 2.8 then it is correcting for it.

<{POST_SNAPBACK}>

 

Yes. That's a good check. I would double check by spot metering a subject at a fixed distance. If putting on the TC does not change the EV, then it is adjusting. If it does not the EV should drop 2 stops with the 2x TC added.

[james 0]

It might also depend on whether you are using a Nikon TC made for that lens or a Kenko Pro TC. I'm making a big assumption here but I'd assume Nikon's TC would at least have a better chance of "talking" to the camera.

 

Cheers

James

[Kelpfish 15]

Hi all,

 

I have done a fair amount of super macro using the Nikon 105, with a screw on +2 diopter and a 2X converter. The picture below is a tiny hermit crab way inside of its shell. The trick with slow shutters is, of course, stabalization. Even at a 60th or even 125th shutter, the shallow working space requires one to make sure their housing is pinned between some rocks, as in a make-shift tripod. The slightest movement can cause blur and not only that, it is damn near impossible to compose unless you are stable and not moving around. Also, at slow shutter speeds your light has time to bounce back from the negative space, thus giving you the lighted background you discuss, especially at 1/25th. This pic was shot at F22 at 1/60th using Ikes Substrobe 50, two of them pinned against my port. My housing was wedged between 2 rocks.

 

Spectacular images can be had once you get the hang of using this kind of set up. I am even contemplating this same set up with the addition of a Macro Mate, but I will probably use my DS125's for more light.

 

Great thread.

 

Joe

[randapex 0]

I did the test and it will stay at 2.8 with the TC added so I'm fairly certain, it's not recognizing it. And it is the Kenko TC.

 

Joe, thanks for posting that shot. The eyes are incredibly sharp. Your point is well taken on stablizing. I've found that supporting the port by cradeling it in my open left palm really helped. The real positive on this type of shooting is fantastic air consumption

[james 0]

Joe,

 

One thing to consider when purchasing macro strobes is the amount of light that they direct to the center of their spread. Since the field of view is so small (hopefully less than 36mm across, no?) you aren't always served well by a wideangle strobe like the DS125 or SS200.

 

I tried using my SS200's in Bali for macro, but I was happier with the Inon's for this type of shooting.

 

According to tests I've seen, Ike SS50's throw more light (higher reading on a flash meter) at a small subject than do the DS125's.

 

Cheers

James

[Kelpfish 15]

That is correct. I have tubes that I put on both my macro and WA strobes to funnel the light. But you have to be accurate when aiming.

 

Joe

[james 0]

Joe,

 

Can you post a photo and perhaps a description of your snoots?

 

Cheers

James