Stephan Paukner :: syslog

It appears to be very difficult to decide what lens could be optimal for one’s needs. There’s so much to choose from, so many different parameters and prices, but the price is not always a good indication for quality. You really have to search for lens tests, because the lens parameters alone only provide some basic data.

As I secretly wished that the Canon EOS 40D would already get an FF sensor, I planned to take the Canon EF 24-105mm f/4.0 L IS USM lens, what Sobotka lists at a price of €999. The lens got a recommendation in the 09/2006 issue of the German DigitalPHOTO magazine. As telephoto lens I wanted to take the Canon EF 100-400mm f/4.5-5.6 L IS USM at a later time, and Sobotka lists it at handsome €1,649. That should have been enough for some time, as I plan to do landscape photography primarily, and 24mm is already a reasonable wide angle focal length. Whereas DSLR camera bodies might get renewed after some years, the lenses are usually intended to be kept for some generations. Therefore I’d rather buy good lenses in the first time and keep it for several years, and so I’d intend to keep them usable for a possible future FF sensor.

However, as the EOS 40D now has an APS-C sized sensor with a crop factor of 1.6, this means that the 24-105mm lens would correspond to a 38-168mm, and this is not in the wide angle range anymore. If I really want to insist on it, then I’d need a separate dedicated wide angle lens to cover the region between 24 and 38mm, what corresponds to a real focal length between 15 and 24mm. The Canon EF 16-35mm f/2.8 L USM could do this at a high cost, corresponding to a 25-56mm on APS-C. But the 10/2006 issue of the German ColorFoto magazine gives no recommendation for using it on FF sensors. Maybe the 2nd edition of that lens is better, but it’s even more expensive (€1,649). Sigma’s 12-24mm f/4.5-5.6 EX DG HSM could be used on FF sensors (ColorFoto 08/2007), and on an APS-C sized sensor it’s a 19-38mm, but it doesn’t allow filters, and polar filters are essential tools for landscape photography. Anyway, that lens got a bad rating in ColorFoto 08/2007 for use on APS-C, but others say it’s quite useable there (DigitalPHOTO 05/2007). The Canon EF-S 10-22mm f/3.5-4.5 USM seems to be a little better choice, although ColorFoto 08/2007 doesn’t give a recommendation either. It corresponds to a 16-35mm and would even outrange the 24mm of the mentioned lens on FF sensors, but it also costs €759 and I don’t really want to buy two lenses at once, as everything becomes too expensive and impractical.

Of course, Nikon didn’t sleep and placed some serious competitive products on the market. First of all, they also have a full-frame DSLR now, the brand-new Nikon D3 with 12.1MP for €4,850. So, Canon isn’t the only provider of FF sensors anymore.

And they placed their Nikon D300 against Canon’s EOS 40D, just as it previously was with Nikon D200 vs. Canon EOS 30D. They equipped the D300 with interesting design parameters. Besides the MP count, it has a higher light sensitivity of up to ISO 6400, whereas Canon only provide up to ISO 3200. Canon also have a little higher crop factor of 1.6, whereas Nikon only have 1.5, what is better.

The Nikon’s viewfinder covers 100% of the lens view, whereas the Canon only covers 95%. But at least Canon have a magnification of 0.95, whereas Nikon only have 0.94, but I doubt this is of relevance.

A major difference is in their 3.0″ TFT-LCDs. The Nikon’s LCD has a resolution of 920,000 pixel, whereas the Canon only has 230,000 pixel.

The D300 has a shooting rate of 6 fps, and the EOS 40D has 6.5 fps, but if one equips the D300 with the optional battery grip, then it raises to 8 fps. And the Nikon manages a burst of 100 JPEG images, whereas the Canon can only do 75.

Nevertheless, the Canon system appears more friendly to me, and I already possessed some of their compact digicams, so the EOS 40D really will be it.

Finally! Canon announced the successor of the EOS 30D today: The Canon EOS 40D. Unfortunately, it doesn’t have a full frame sensor, what I had wished secretly, but it seems that these haven’t reached a reasonable price range yet. So, it still crops the view with a factor of 1.6, but I’ll try to stick to the better EF lenses anyway rather than just using EF-S. Nevertheless, the main enhancements to the 30D are:

• 10 MP instead of 8 MP,
• 14-bit processing instead of 12-bit,
• DIGIC III processor instead of DIGIC II,
• Dust reduction by filter vibration instead of nothing,
• Interchangeable viewfinder screen instead of a fixed one,
• ISO sensitivity icon in the viewfinder instead of no indication,
• 3.0” TFT LCD instead of 2.5”,
• LCD Live View,
• Multiple exposures on mirror lock-up,
• 3 custom user modes instead of none,
• Continuous shooting with a rate of 6.5 fps instead of 5.0 fps, and a burst of 75 JPEG or 17 RAW images instead of 30 JPEG or 11 RAW images.

Wanna have! This one will be it. Expect it in my possession at the winter family days (vulgo Christmas) this year.

Update 08/21: Some Austrian vendors already list the EOS 40D at a price of €1,299. My vendor of choice will be Foto-Video Sobotka in Vienna, as I already bought my PowerShot A710 IS there and I got some vouchers for their shop. My first lens might be the Canon EF 24-105mm f/4L IS USM, what Sobotka lists at a price of €999.

For the first time it really seems that I can keep my time plan. I try to reach page 32 today, and if I manage to keep writing one page per day, I will reach the half of the average thesis page number this week, and will indeed manage to be finished with the beginning of October. The theses at my institute indeed range over a number of about 70 pages.

I met with HGFei on Friday, and he said he can fully support my will to be finished soon. There won’t be a serious research or new results in my thesis (except for how the Gabor transform can be computed more easily for separable 2D atoms), but only a summary and visualization of the known results in the 2D case, where of course will be no surprises. Serious research is reserved for dissertations anyway. He wants the results to be suitable for talks or demos.

I proceeded with Chapter 4 about digital images and 2D frequencies rather than with Chapter 3 about finite discrete GA, as it isn’t that mathematical and I wanted to read more on the corresponding things before. I’ll soon have it finished, and maybe I’ll manage to finish the finite discrete GA in the first September week, what is 2 weeks from today.

Doris and I had a short travel to Munich and Salzburg from August 5th to 10th, 2007. This is just a brief summary providing links to the photo gallery.

We took an early ICE train from Vienna directly to Munich. I’ve never really been to Germany before. We brought our luggage to our hotel near the central station and visited the inner city afterwards. To be honest: Vienna is more beautiful than Munich. In the afternoon we visited the Olympic Park, went up the Olympic Tower and had dinner at the “Little Oktoberfest”, where I got the first Maß of beer in my life.

The next day we went to the Viktualienmarkt, after what we visited the English Garden and had lunch at the beer garden next to the Chinese Tower, where I got the first Weißwurst of my life. We had a little boat trip at a small lake in the English Garden. For dinner we went to the famous Hofbräuhaus.

On day three we went to Schloß Nymphenburg and had lunch at the beer garden Hirschgarten. In the afternoon we were shopping some delicatessen at the Dallmayr, and had dinner at the Weiße Brauhaus.

The next morning we took the train from Munich to Salzburg, where the weather became rainy. To be honest, Salzburg isn’t that overwhelming, except if you’re totally into Mozart. Salzburg is seen within one day. We rent a Smart via LaudaMotion.com and went to St. Wolfgang where we were staying in a guesthouse and had dinner at the local pizzeria.

The next day we had a short look at St. Wolfgang, but unluckiliy I got ill. Next day we were driving back to Salzburg, returned the Smart and took the train back to Vienna at noon instead of waiting until the later afternoon as originally planned.

I already got a little time panic, as I noticed that I wouldn’t make it within September. I’ll need the whole month of September, too. A problem is that Doris wanted to go on a two-week holiday. As she has to take a course anyway, we delayed it to the beginning of October. After that I only want to have to do cosmetic stuff, and no content anymore. I want to have it printed and handed in by the mid of October. And already at the mid or the end of November, there should be the Master exam. I want to be finished by my 30th birthday. This. Must. Work. I can’t afford needing more time, as January 2008 is the last possibility, otherwise I’d have to pay €6,000 back.

On the content: I looked at multi-window Gabor frames, and M. Dörfler’s PhD thesis is a good source. Maybe I can apply her results 1:1 to images, as natural images also dominate in the lower frequencies. The lower frequencies are “area-producing”, already determining the image to a very high degree. Therefore small windows are needed densely in the lower frequency area, resulting in a dense covering here, incorporating many different orientations, yielding only a rough coverage of the image space. The higher frequencies are “contrast-producing” or “border-producing”. Frequency coverage doesn’t have to be that dense here, the exact frequencies are not that interesting, but their location is important. So, a multi-window Gabor system could be of similar type in 2D as it had been taken for 1D music signals by Dörfler.

But multi-window systems shall appear rather late in my thesis. First there are a lot more other things to mention. I made a rough table of contents, giving me a good lead:

• Gabor Frames in as Section 2.3
• Chapter 3: Finite-dimensional discrete Gabor Analysis
• TF-matrices, stuff, frames in
• Gabor matrix
• GA on finite groups and general lattices
• Dual atom on general sampling sets
• Chapter 4: Frequency behavior of digital images (nix Gabor, nix shifts)
• Digital representation of images, RGB, matrix, values
• Understanding 2D frequencies, tensor product of 1D freq
• FFT2, low frequencies dominate, point to multi-windows
• Chapter 5: Image representation by Gabor expansion (Gabor stuff, experiments)
• Atoms can be separable or non-separable
• 2D PF-shifts of an atom, 4D position-freq space
• Separable atom: 2D-dual is tensor of 1D-duals
• Huge frame matrices, applying TF-matrices to image matrices for sep-atoms, proof
• Separable atom, separable lattice, separable dual
• Separable atom, non-separable lattices (1 dim only, both dims), dual
• Non-separable atom, isomorphism 1D-2D, various lattices, dual
• Unassigned
• Multi-window Gabor frames, similar to music signals
• Biological vision

Chapters 3 and 4 should be possible within August, and the rest will be in September.

It is currently completely open if there really will be some “real world” applications of GA to image processing, like serious deblurring, denoising or compression. I’d have to compare it to existing methods, actually. Currently I only plan to compare the various duals and do some thresholding of the Gabor coefficients. If there really will be some multi-window stuff, then maybe only for separable atoms, as I don’t know how I could check the frame quality otherwise.