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Zenitar 16mm/2.8 Fisheye

March 30th, 2014

For $200 you can get a capable fisheye for Nikon Canon (and perhaps other mounts). I got mine via ebay from a seller named rus_camera, delivery took less than a week.

Before buying I read through many confusing articles that questioned the optical quality, etc. One common “defect” is that the lens is delivered without the rear-end filters. The standard Zenitar comes with 4 filters made out of 2mm glas (1 UV, green, red, yellow-greenish). The lens is adjusted for these 2mm glass being in the optical path - if missing the lens will front-focus.

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Standard primes

February 9th, 2013

The hunt for the standard prime is over, I was struggling with the Nikkor AF-S 50mm 1.4G and the Nikkor 35mm 1.8G DX, both had something to it, but none could convince me on a D800e. I was so desperate that I tried to adapt the DX lens to the FX sensor with the Kenko 300 DGX. Not bad, but not really what I was looking for.

I prefer the 35mm FoV, I feel it is closer to the perspective we get with our vision (might be subjective), so I 35mm was called for. The Nikkor 35/1.4 has some issues with strong LoCA, the old 35/2.0 was simple not sharp enough on a D800, so recently the Nikon version of the Sigma 35mm 1.4 DG came out and here it is:

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Nikkor 35mm 1.8G with Kenko 1.4x

November 10th, 2012

As promised, I ran the 35/1.8G with the Kenko 1.4x DGX TC against the Nikkor 50mm 1.4G

The 35mm is a DX lens, it has a rather large image circle, but still at longer distances it visibly vignettes and literally cuts corners when stopped down. With the TC (tele converter) the vignetting is history, but how much will the resolution suffer?

My test was to shoot with a D800e at the same distance of ~2′ with mirror lockup and live-view focus both optics.

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Teleconverter Kenko 300 DGX 1.4x

November 10th, 2012

After a frustrating week I had to do some compulsive shopping and I found myself a Kenko 300 DGC 1.4x. It got good reviews and for €215 - why not?

Main use of a tele-converter (TC in the following, I type slowly) is to increase the focal length to get a higher magnification.

I am not a big fan of such crutches, but I had another good reason (or two): My Tamron 60mm f/2 is a DX lens and it vignettes heavily at larger distances, I wanted to give it a second life on my D800e. Also I wanted a bigger magnifaction than 1:1 without reducing my working distance.

Last but not least there was a discussion on flickr if a high-resolution body like the D800 wouldn’t put an end to to TCs in general.

Well, there the TC delivered more than I expected:

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Moving to FX, experiences and thoughts

October 16th, 2012

I used to sing the high tune on DX cameras, well I still do, but now I shoot exclusively FX.

My main reasons to switch was that my good old D90 eventually succumbed the sea-water accident I had some years ago and I couldn’t get myself into buying a true replacement. D400 still not here and the D7000 feels awkward for me, most importantly I wanted the focus system of the D300 …

Forget it, the D800 does its job.

So how is FX different from DX?

Main issue DoF: Compared to DX you have to stop a FX one stop down to get the same DoF. Compare this with a base ISO of 100 compared to the 200 of the D90-300 you find yourself at four times longer shutter speeds. You need more light and/or a better technique to pull this out.

Real challenge: The D800 is a high-res body, diffraction is an issue. Shoot it f/11 or less and say good-bye to pixel-level sharpness. This creates real problems when shooting landscapes when you discover that f/5.6 at 14mm is not just “set to 1.5m and everything is sharp”. Next on my shopping list is a Tilt/Shift lens (I am eyeing on the Samyang 24 T/S) to solve this problem.

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D800e first impressions

July 7th, 2012

This is not a review, there are tons of reviews out there. I just like to share the impressions I got after “upgrading” from D80/90 to this camera.

Size and weight. It doesn’t feel that big. The weight is relative, with a 70-200/2.8 it actually handles better than a smaller body with such a lens. With the 24-85 VR it is noticebly bulkier than a D90 with a 35/1.8, but barely different from a D90 with a 17-50 Tamron.

Resolution. The angular resolution is at the level of a D7000, so keeping the speeds at the level where I was comfortable with worked out. Using Auto ISO the D800 adjust the speed to 1/focal length. Due to the good grip and the well designed shutter button I get enough 100% sharp pictures out of it (you can still tune this in the settings)

Dynamic range: Mindblowing. In Lr4 pull down Highlight by 100 and pull up shadows by 100 - no visible degradation, not color shifts.

High ISO: Auto ISO works really well, but shooting at 6400 is still OK. At pixel level the results are like a D90 at 1600ISO, scaled down it equates a D90 at  ~ 1000ISO. For normal usage (web, small prints) perfectly OK.

AF: I never used Auto selection, but the D800 changed that. When shooting a face it locks on the nearest eye. Perhaps in 98% of the case it makes the same decision I made only faster. I can concentrate more on the composition and let the camera figure out the rest.

Moiré: Yes, it exists. But the Moiré brush gets rid of it. I customized this brush by adding +12 saturation and after a quick swipe with this tool it is gone. It is important that you know where to find it, otherwise you might miss it.

Exposure: Very different from the D90. Spot metering is spot metering, you have to be very careful to pick the right spot. Matrix metering looks a bit underexposed sometimes, but it is not a flaw: It tries to preserve highlights and thanks to the excellent noise characteristics you can pull up shadows to almost no end.

File-size: I always shoot RAW, current setting 14-bit lossless compression. This gives you ~90 pictures on a 8GB card. I will experiment a bit with these settings, perhaps using uncompressed files to speed up post-processing.

Still, it is not a beginner camera, you need a good shooting technique, good glass and a solid understanding of the principles of photography. The camera is so good, it mercilessly shows you your mistakes. It will make you a better photographer.

Nikkor AF-S 24-85mm 1:3.5-4.5 VR review

July 7th, 2012

I needed a standard zoom, but I wanted something compact for landscape and general use. The 24-70 was out for this reason, too heavy and 2.8 aperture was low on the list of needed features. VR was more desirable to capture motion and low-light work where no tripod is at hand.

I researched a bit the Tamron 24-70, but 82mm filter size, a flimsy hood and pronounced onion patterns in highlights made me drop that thought.

The recently announced  AF-S 24-85mm 1:3.5-4.5 VR fits the bill. I would have preferred weather-sealing and a constant f/4 aperture, but for $/€600 not all wishes will come true. It has a rubber seal on the mount.

This brings me to the features:

  • Rubber seal at mount (full metal)
  • M -M/A (fulltime manual focus override)
  • VR

Build

  • Full plastic, Made in China
  • Focus / zoom feel a bit rough, but operate precisely
  • dual cam tube, no wobbling
  • 72mm filter

Heck, why 72mm filter thread? (this went up from 67mm of the non-VR model)

AF-speed is good, slower than the 24-70. I’d say 2/3sec from close focus (38cm) to infinity. Barely audible when 1m away, very reliable, no hunting.

Vignetting, very little, less than 1 stop wide open and almost none at f/5.6

Distortion, slight barrel at 24 (12 in Lr4 correction), even slighter pincushion from 35mm upwards.

CAs need correction in Lr, but this is a one-click.

Pretty flare resistant, dead sharp in the center. Borders very good at f/5.6, some additional sharpening brings corners to center level. It seems to have some field curvature that prevents it from performing better in the corners, but not too pronounced.

Close focus, don’t expect too much, it doesn’t have near field correction, results are good, but nothing to write home about.

VR - 4 stops - no way. I’d give it 2 stops on the wide end and 3 stops on the long end. Note that this gives more handholdabilty than the 24-70.

Summary, good deal for the asked price. As I don’t shoot wide open much, this lens gives me everything I need for a third of the price of  the 24-70 (sorry for mentioning it so often, but it is simply the reference in this focal range). The small size and low weight make it preferable for landscape work: Better balance on the tripod and smaller profile in windy conditions. If you capture moving objects you would like to have a lens that is faster, but I ask if a 50/1.4 would do there an even better job

Sample images

Why many pixels really help

March 4th, 2012

The new Nikon D800 has a 36MP sensor. Bummer

Well it is relative. When you compare it to a D7000 - the pixel-density is the same: Crop-factor 1.5 yields 2.25 the surface and 16*2.25 =36).

So no worry about the lenses, when we disregard the border at larger apertures. Frankly, when do you need sharp corner when shooting wide open?

One inconvenience is the larger file size (up to 70MB), but considering that I bought my computer with a 500GB drive 2 years ago, and now a 2TB turns along with it - do we really have to care?

The D800 also features crop-modes that utilize only a smaller section of the frame, this will keep the file-size down when the resolution is really not necessary (beware: a DX crop transforms the D800 into a heavy D7000, it is not downsampling the whole sensor!).

Yes, it is that easy, but there are many out there who think (or don’t think at all) that so many pixel must come for a price. Indeed, they come, but the only price is the list-price of the D800(e).

Besides the storage issue, two arguments float around:

  1. The pixel density is too high, diffraction will ruin the image, it is better to shoot with a lower pixel-count
  2. Larger pixels perform better at high ISOs, better a lower pixel-count like in the D4

You know my drill, first the short answer and then the lengthy derivation:

  1. Diffraction will only compromise details a lesser sensor won’t even resolve
  2. You can downsample the file to reduce the noise almost perfectly equivalent to a sensor with larger photo-sites

Yes, I use pixels and photo-sites synonymously in this article

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Hyperfocal

September 25th, 2011

First some practical rule I use: I call it the 10/10 rule:

At f/1, 10mm the hyperfocal distance is 10m.

To get to real situations:

  1. Divide 10m by the f-number you want to use (example f/5.6 gives ~1.8m)
  2. Compute the square of your focal length and divide by 100 (example 28mm * 28mm ~ 800, hence 8 )
  3. Multiply the two results (example 1.8m * 8 = 9.6m)

This rule is reasonably exact, you can use it as well to find the right aperture (the near-field is roughly half of the hyperfocal): Say, you have a 50mm lens and need everything from 10m to infinity in focus.

  1. Multiply the min focus distance by 2 (example: the hyperfocal is then 20m).
  2. Divide the lensfactor as computed in (2) above by the hyperfocal distance (example 50*50/100=25, 25/20 = 1.25m)
  3. Multiply by 10 to get the required aperture (example 1.25*10 ~ f/13)

You can shorten this by dividing the hyperfocal distance by 10 and execute only step 2, this gives numbers that are easier to compute.

This approximation is designed for “normal” APS-C cameras with a pixel-pitch of ~5µm. To be fair this makes sense down to f/8 - for smaller apertures the diffraction will get you unreasonably long hyperfocal distances. I recommend to fix the algorithm by setting the start distance of 10m to 8, 6 or 4m for f/11, f/16 or f/22.

What is hyperfocal distance?

Glad you ask, without much ado, hyperfocal distance is the focus distance from there even objects at infinity will still appear sharp. It is computed as

H = f*f/N/c + f

where f is the focal length, N the f-number and c the diameter of the circle of confusion (CoC)

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Tele lens subject separation

September 11th, 2011

A common knowledge item in photography is that tele-lenses allow you better subject separation. I had been interested in how much we are talking about.

You have for sure noticed that the subject separation (aka DoF, Depth of Field) is more pronounced at close distances. To make things comparable we have to define comparable scenes and from a photographer’s point of view the common denominator is the magnification. In common portrait scenes you have a magnification of 1:10 to 1:100. This means that that 1cm (or inch) on the sensor will represent 10 to 100cm (or inches) of the subject.

The basic optical formula tells us that the magnification is the relation of the subject distance and the focus distance. The constant coupling these lengths is the focal length of the lens. Short: Double the focal length and all other lengths will have to double too. If you shot your friend so that the face fills the whole frame with a 50mm, your will have to step back four times as far to achieve the same with a 200mm lens.

Here two images shot at 70 (right) and 210mm (left). The magnification of the subject is roughly the same and both pictures had been taken at f/5.6:

http://www.flickr.com/photos/csaager/6137162424/

This comparison makes it easy to see the difference: The diameter of the bokeh circles on the water is three times wider. In other words: The blur that causes the subject separation is proportional to the focal length - at constant magnification and aperture!

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