April 24, 2014, 10:49:10 PM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Topics - Efka76

Pages: [1]
Dear colleagues,

shortly I will describe my experience in lens calibration. I hope that this story will be useful to someone who wants to calibrate lenses but never done that before.

1-2 years ago I bought Canon 7d and number of lenses. My shots seems quite Ok for me. I did not notice any back / front focus issues. But that was due to the fact that I did not have  a knowledge how to notice such things. But after spending some time in Canon rumours and reading various things about lens calibration I finally decided to try that.

My setup was following:

1) For lens calibration i bought Reikan Focal plus. Of course, Pro version is better but I thought that Plus version is sufficient as it allows fully automatic and semi-automatic calibation as well calibration target validation. Pro version is almost twice expensive as Plus version.

2) Photo studio - if you have option to do testing in bigger space, do that. My studio was almos 6 m long and of course it would be better to have bigger in order to test 200 mm lenses at x50 focal length. I selected studio for testing as it is controllable environment (light, no wind, it is easy to put calibration target on a wall.

3) Cheap tripod - it was not very convenient but for testing purposes this tripod was quite ok. During testing I target was not lost due to movements in tripod head. If you have good and expensive tripod it will be easier.

4) Calibration target  - printed on laser jet on standard (lightweight) paper (Focal manual recommends using Matte Heavyweight paper, print should be performed on Inkjet). My target worked really ok in testing but if you have ability do everything as manual says :)

5) Camera settings: AV mode, eye piece covered, etc. as indicated in manual.

6) Light level in all cased was higher than EV 8 (during my testing it was EV 8.2 - 8.9). For lighting I used halogen lights, background was lit by natural light from window and fluorescence lights. Of course such mix of lights was not very good but I tried to achieve higher EV. Light in terms of Kelvin was 5200.

The testing:

1) Target validation  - it was quite easy with all lenses; I just followed visual instructions and fixed tripod head when there was ok sign on computer screen. You just have to make sure that tripod  / head / target are not moved during testing.

2) Canon 70-200 mm 2.8L II IS USM: very good test results achieved. Based on Neuro advice I tested zoom lenses at various focal lenghts (FL). The following FL were used: 70 mm., 100 mm, 140 mm and 200 mm. Focal Plus calculated the following AFMA adjustments for the above FL: +1 ; +3 ; +1 ; -1. Testing results show really very good quality of lenses. Due to the fact that only one AFMA value can be entered into Canon 7D i left AFMA as -1 but currently thinking to change it to 0 (mid value between min and max FL).

3) Tamron SP 24-70 2.8 VC. I really like these lenses, they are my walkaround lenses and I thought that they are quite sharp. Test results were the following: 24 mm (AFMA +1), 35 mm (AFMA +9), 50 mm (AFMA +13), 70 mm (AFMA +6). In camera AFMA +6 was written. Despite the fact that difference between both FL is only 5 I was unpleasantly surprised that in between of min and max FL sharpness is reduced quite dramatically :( However, I now know what defficiency such lenses have and AFMA +6 at least will help me to have sharper images comparing to previous shots before calibration.

4) Canon 100 mm 2.8L IS Macro - I did 2 testings: @ x25 FL AFMA +7 and @x50 FL (recomended by manual) AFMA + 4. I entered +4 into camera. I was a bit surprised that i got 2 different AFMA values at different distances.

5) Canon EF-S 18-135. Due to the fact that thes lenses ar kit lenses I did not expect great results :) Results are following: 18 mm (AFMA +13) and 135 mm (AFMA +6). In camera I entered AFMA +9. In testing it was very obvious that after AFMA adjustment images were much sharper.

6) Canon 50 mm 1.4: I was really struggling with these lenses testing. At x25 FL distance I got AFMA +3, however, when I wanted to do testing @ x50 FL Reikan Focal Plus had issues: it performed many shots, however, was not able to collect reliable data for exact AFMA determination (indicator was red). I then tried test few more times at different distances from target. In few cases software was not able to collect reliable data, in one case I've got AFMA +4 (indicator was yellow, not green). I am wandering how to interpret such testing results. Does that indicate issues with my lenses or due to the fact that lenses are 1.4 it is much harder to obtain reliable results (light conditions were very good in all cases, EV 8.9). From testing I saw that AFMA values were in range of 3-5, accordingly I left AFMA +3 in camera.

Anyway, I have intentions to sell Canon 50 mm 1.4 and buy a new Sigma 1.4 Art series, when it is released. I really hope that Sigma will be much better than old design Canon lenses.

I hope that this my story will be helpful to some future testers :) Also, I would appreciate if someone knowledgeable could comment on Canon 50 mm 1.4 testing results interpretation.


Dear colleagues, I just recently acquired Reikan Focal Plus software for lens calibration. It is perfectly clear how to calibrate fixed focal length lenses, however I need your advice on zoom lenses calibration. If I understand correctly there are these options:

1) Full manual calibration - to make a lot of manual shots on both end of the zoom and import all such data in Reikan focal. Then software will show what AFMA numbers are for both ends of zoom lenses. I do not like this method as it is very time consuming and there might be some differences due to manual shots.

2) To run full automatic calibration 2 times (for minimum and maximum focal length of zoom lenses). In this case I will get 2 AFMA values. Then there is a question which value should i input into the camera? Its a pity but my camera (canon 7d) does not support input of 2 AFMA values for zoom lenses.

In my opinion, are the following options:

a) to input AFMA value, which is determined based on long end of zoom lenses (such advice I found in Focal testing guide.

b) To input mid value of both AFMA numbers

c) to run additional test in mid of the zoom and input that value into the camera.

I would really appreciate your advice as tomorrow I will be performing that testing and your advice would be very helpful to me.

Canon General / Developments in technology
« on: January 04, 2014, 01:27:47 PM »
Dear colleagues,

I would like to hear your thoughts about developments in photographic technology and reasons why such developments are so slowly implemented. When I look at digital photography and prices it is obvious that the first digital cameras were extremely expensive and not affordable to general public. However, during the last decade there were quite significant developments in digital cameras (increased MP, better DR, ability to shoot with higher ISO). I understand that 5-7 years ago FF cameras were very expensive due to the fact that FF sensors were very expensive. Accordingly, cheaper (crop) sensors were invented in order to make digital cameras more affordable to general public.

I still do not understand why after so many years FF cameras are so expensive as sensor production should be much much cheaper (R&D costs already amortised, mass production is already in place). Also, I can not understand MF camera costs, which rocket to the sky :).

Also, there are not so many improvements in Canon's digital cameras technology. As far as I understand in digital camera the most important things are sensor and processor. If you take a look at computer area you can notice very significant improvements in processors speed, their architecture and etc. Canon, for example, still produces 5 year old 7D, which is based practically on outdated technology (I admit that 7D is superb camera, however, it could be even better). So, why is it so hard to photographic companies to try harder and develop better sensors and image processors on a yearly basis. They ear sufficient profits, which could be invested in R&D. Of course, I understand that improvement in optics are very costly and even slight improvement is very hard to achieve. That's why we are still using lenses , which were developed 10y (or even more) ago.

The same applies to MF cameras. I can not justify their costs. In my opinion (maybe I am wrong) the difference between MF and FF is the sensor, processor capabilities and larger lenses. If MF sensors are produced as mass production their costs should be much lower and MF cameras would be more affordable. I have impression that Canon and Nikon are basically milking the same cows for many years and do not try very hard to due to lack of real competition.

Any thoughts on that matters?

Lighting / Speedlite resource
« on: February 21, 2013, 01:53:39 PM »
I am wondering what is speedlight (especially Canon 580 EXII) resource and whether it is possible to see how many shots were already made.

Software & Accessories / Photo storage facility
« on: January 29, 2013, 08:06:53 AM »
I just noticed that Nikon released service, which provides free 2GB of storage space to everyone and free 20GB if you have Nikon camera. Link is here: http://info.nikonimagespace.com/en_00/welcome.html.

It is interesting whether Canon is going to release such service as well? Currently Canon and Nikon are almost equal competitors, but they are competing in gear area. I always considered Canon as more superior comparing to Nikon, however, I am a bit disappointed that Canon is starting to slightly loose competition to Nikon as it seems that Nikon's marketing guys have more brains. I would really expect Canon to make more investments in R&D, review their pricing strategy and start to remember that we are living in internet age (it seems that Nikon understood that firstly).

It is always better to be market maker and form trends rather than to be simple follower. What is your view on such matters?

Canon General / Why did you choose Canon?
« on: January 26, 2013, 01:42:42 PM »
It is interesting to hear stories why people choose Canon when there are a lot of other firms? Nikon, Pentax, Sony...

I personally was always interested in photography and was shooting quite a lot when I was young with analog cameras Smena and Zenit- E (Soviet type cameras). My first digital camera was P&S Sony bought in 2004, however, i was not satisfied with its quality (at that time analog cameras quality was much better than digital).

In 2007 I acquired Canon G7 which was able to produce better quality photos comparing to other P&S cameras. Finally in 2012 I decided to buy DSLR and definitely choose Canon as they had more attractive design comparing to Nikon and much bigger variety of lenses (I always admired L class white lenses, which in my mind was always associated with superb quality). I never Pentax, Sony or other firms. Currently I am happy with my EOS 7D, however, have plans to move to FF (of course, that would by 5D Mark III). That's why my almost all lenses (except for EF-S 18-135) are compatible with FF cameras.

It would be interesting to hear your stories why you choose Canon.

Software & Accessories / Reikan FoCal not compatible with Win 8
« on: January 13, 2013, 07:29:37 AM »
I had intentions to buy Reikan FoCal for my lens calibration, however, by reading descriptions in their website I found out that this software is not compatible with Windows 8 version. Here it is extract from Reikan's official website:

"At present FoCal is only available for computers running Windows XP (SP3) and Windows 7 operating systems.

Windows 8 is not officially supported but does work with Nikon cameras.  We will be testing with Windows 8 very shortly and assuming the manufacturer driver support is operational we hope to have a release formally approved for Windows 8 by Early 2013."

Previously i noticed in some tread (which somehow I could not find) that people were complaining that Reikan FoCal software is not working in 8 platform. It seems taht all of us will have to wait until release of new and compatible software version. I hope that this information will be useful to some of you.

Pages: [1]