Tuesday, May 4, 2010

Pentax DSLR : Phenix 50mm F1.7 Review

Today i just want to make a short review about my favourite manual prime lens..the details are below :

1. Specifications

Image Circle : 35mm Full Frame
Focal Length : 50mm
Max Aperture : F1.7
Min Aperture : F22
Diaphragm Blades : 6 Blades
Angle of View : 47 degree
Front Element Rotation : No
Closest Focus : 0.45m
Filter Size : 52mm
Weight : 210 grams
Dimension : 63mm x 31mm

2. Build Quality

This lens build is par with pentax K, M, and A series prime lenses. It build with very tought metal. It is fully metal except the aperture ring and some part of the mount (see pic below). The focusing ring is very smooth and easy to rotate. It is very comfortable while focusing. The focus ring rotate 180 degree from minimum distance to infinity. This will make this lens is easy to facus and accurate. The lens barrel is not rotating when focusing and there is no problem using a CPL filter with this lens. The lens extand around 10mm when focusing (see comparison pic above)

3. Image Quality

Image quality is not much different when compare to FA50.4. FA50.4 are more contrast than this lens. This lens are design to use at wide aperture, so the sharpeness at wide open is very good. Add 1 or 2 stop more, the sharpness is excellent. The bokeh is quite acceptable and not much different with FA50.4 at F1.8 but FA50.4 still better. Below some sharpness sample at various aperture and bokeh comparison against FA50.4.

Bokeh test and comparison (Phenix 50.7 vs FA50.4)

In term of creamy bokeh, FA50.4 easily beat Phenix 50.7 but in term of sharpness, Phenix 50.7 win. (Phenix at F1.7, FA50.4 at F1.8 )
4. Distortion and Vignetting

Being a prime lens, this lens not show any visible distortion (maybe slightly) and vignetting also not visible (see using naked eyes) at all. So it has no problem with distortion and vignetting.

5. Chromatic Abberations (CA)

This is really surprising me. This lens control CA better than the FA50.4 lens. You can see it from the bokeh comparison above.

6. Conclusion

For conclusion, this lens is really stunning and excellent for what i have paid. I'va paid only USD30 for this lens and is great value for money. The only cons i found in this lens is this lens doesnt have auto focus (AF). That all. Other than that, EXCELLENT !!!!

7. Rating

1. Optical Quality ★★★★☆
2. Build Quality ★★★★☆
3. Value for Money ★★★★★

Thursday, April 29, 2010

Pentax DSLR : Transform M Lens Into FA Lens

I have done this transformation about 6 months ago. For this transformation, I used Phenix 50.7 lens and FA28-80 lens. I have changed the Phenix 50.7 mount with the FA mount. Sorry I dont snap a picture during the process to show you.

Here is how the final image look like:

And here aare some test result at various aperture. Aperture was changed via body setting.

Monday, April 26, 2010

Pentax DSLR : DIY Split Screen for Pentax K-7

I have found very interesting DIY tutorial on how to make your own split screen for Pentax K-7. The working flow is quite easy and i think everyone can make it. Before you start you need :
  • 1 split screen from slr film camera (you can buy it new from store or use split screen from unused slr camera).
  • 1 original Pentax K-7 focusing screen for measuring purpose.
  • Scissors
  • Ruler
  • Knife
  • Sand Paper
  • Blower
  • Fiber cloth
  • Pencil
Pentax DSLR

Ok, now we already have all the tools to start the. Then we can move to the first step.

Step 1. Take your Pentax K-7 focusing screen and put it on the split screen. Use the Pentax K-7 focusing as a marker and then draw line using a knife on the split screen. Make sure you draw it properly.

Pentax DSLR

Step 2. After you finished draw line on the split screen, cut it using scissors. Make sure you dont cut it through the line. Cut it outside the line and do it properly.

Pentax DSLR
Pentax DSLR

Step 3. Ok, now we have one split screen that size a lil bit larger than the original Pentax K-7 focusing screen size. Now we can move to the next step. Clean the tip of the cut using sand paper. Clean it until it size exactly same as the size of your Pentax K-7 focusing screen.

Pentax DSLR

Step 4. After clean the tip of the cut, use blower to blow the dust. Then use fiber cloth to clean the split screen. Now our own split screen size is clean and ready to use.

Pentax DSLR

Step 5. Then take a ruler measure and devide the split screen into 3 x 3 or 4 x 4 square depends on you. After measure, mark it with a pencil. After finished marking the split screen, draw a line through the mark using knife and ruler.

Pentax DSLR
Pentax DSLR

Here we are. Our own DIY split screen for Pentax K-7 is finish and ready to use. Now you can try it and have fun manual focusing using your Pentax K-7.

Pentax DSLR

Thursday, February 4, 2010

Pentax DSLR : Pentax K-X blur/soft focus problem report

Lately a lot of new Pentax K-X users reported that pictures come out from their K-X is not sharp or blur. There are still no accurate answer related to this problem. It could be problem from the hardware or firmware. But some forumers reported that the problem solved after they upgrade the firmware from v1.01 to v1.01.00.07. Apparently, after do the firmware upgrade, most of them still facing the problem.

There are two possibility that cause the problem. First, Shake Reduction (SR) mechanism problem and the second one is from the in-camera setting menu. Some said the problem occur due to the unaccurate SR mechanism. I dont know how true is it but from the specifications, the K-X SR mechanism should be better than previous pentax model.

Friday, November 27, 2009

Pentax DSLR : Pentax DA17-70 F4 AL [IF] SDM Review

Pentax SMC DA 17-70mm F4 AL [IF] SDM offers the most attractive combination of range, speed, technology and price - on paper at least. It is a dedicated APS-C format lens with a field-of-view equivalent to 26-107mm (full format).

The DA 17-70mm f/4 features the new near-silent Supersonic (ultrasonic) Dynamic Motor (SDM) AF. Unlike the DA* 16-50mm f/2.8 SDM it does not offer the old AF drive screw for legacy DSLR support but that's forgivable by now.

This lens is using KAF3 mount which means only can AF with SDM support body. With non-SDM body, only manual focus available.


Image Circle: APS-C
Focal Length: 17-70mm
35mm Equivalent: 25.5-105mm
Max Aperture: F4
Min Aperture: F22
Diaphragm Blades: 7 Blades
Lens Construction: 17 Elements in 12 Groups
Angle of View: 79 to 23 degree
Focus Details: Internal, SDM with quick-shift focus
Front Element Rotation : No
Zoom System: Rotary
Closest Focus: 0.28m/0.92ft.
Magnification Ratio: 0.31x/1:3.2
Filter Size: 67mm
Dimensions: 93.5mm x 75mm / 3.7 in. x 3.0 in.
Weight: 485g / 17.1 oz (without hood)

1. Build Quality
The build quality is really good and comparable with DA* series. It feel very solid in my hand. The weight is on the average side which is not too heavy and not too light. Zoom ring is quite bigger(approx 35mm long) and it is very comfortable. It is also tight and this prevent lens slip off or extend when camera facing down.

This lens extend when zooming. It is feature with Internal Focus[IF] which means the lens not extend and rotating while focusing. The picture below show the size comparasion of the lens when extend.

2. AF Mechanism
SDM MotorAF respond is very fast as expected since it use SDM focusing. But the AF speed not much different with non-SDM lenses. About the accuracy, this lens focus accuracy is good but sometimes it give up when no proper contrast detect and need to refocus.

This lens also feature a quick-shift focusing mechanism means it can give you fully manual control and you can easily manual focusing without changing focusing mode.

During the focusing, this lens does not making any noise like screw dirven AF lenses. Thank you for the SDM feature which make this lens silent during focusing.

3. Image Quality(IQ)
IQ is comparable with DA* series. This lens reported use the same glass as the DA* series. Flare and CA control are very good and seems better than DA*16-50. This lens also quite good at macro at 70mm. Minimum focus 28cm at the whole facal range give this lens maximum magnification around 1:3.2 at 70mm. This sharpeness is good at whole range. Quite soft wide open at 70mm but good if increase 1 or 2 stop.

4. Distortion and Vignetting
Distortion is quite visible at 17mm but stil acceptable. At 24mm and above, distortion is nearly zero. At 17mm wide open, this lens show around -1EV vignetting but not really noticeble. It can be correct by using F5.6 and above.

5. Chromatic Abberations(CA)
This lens control CA quite well and it is acceptable. The weakest point is at 17mm which pronouced CA especially in wide open aperture. But it can be correct by step down one stop exposure. Beyond 24mm and above, the CA is very well control.

6. Conclusion
For overall this lens is very good for a daily use. The focal cover from 17mm to 70mm is very usefull for street shooting or travel.

Pros :
1. Better build quality, solid
2. Better CA control
3. Better accuracy
4. Fast respond and silent AF
5. IQ comparable with DA* series
6. Very good zoom ring

Cons :
1. Can only AF with SDM support body
2. Easy to give up(AF)
3. Max aperture F4
4. Price

7. Rating
1. Optical Quality ★★★★
2. Build Quality ★★★★☆
3. Value for Money ★★★☆


Tuesday, October 27, 2009

Pentax DSLR : Tamron SP AF 17-35mm F2.8-4 Di LD Aspherical [IF] Review

This Tamron's ultra wide-angle zoom lens starts at 17mm when used with a conventional 35mm SLR camera. When mounted on an APS-size digital SLR camera, it provides a focal length coverage equivalent to a 28-55mm (on a 35mm format camera), covering the desirable wide-angle to standard range.

It has maximum aperture F2.8 at 17mm and F4.0 at 35mm. Being F2.8 at wide end is an advantage for this lens compare to other wide angle lenses. It has 77mm filter which is very usefull for a wide angle lens to prevent vignetting at wide end. The spherical front element will cause some flare but can be correct easily by using a petal type lens hood that come with the lens.


Image Circle: 35mm
Focal Length: 17-35mm
35mm Equivalent: 25.5-52.5mm
Max Aperture: F2.8-4
Min Aperture: F22
Diaphragm Blades: 7 Blades
Lens Construction: 14 elements in 11 groups
Angle of View: 104 to 63 degrees
Focus Details: Internal
Front Element Rotation : No
Zoom System: Rotary
Closest Focus: 0.3m / 0.98 ft.
Magnification Ratio: 0.19x / 1:5.4
Filter Size: 77mm
Dimensions: 86.5mm x 83.2mm / 3.4 in. x 3.3 in.
Weight: 440g / 14.4 oz

1. Build Quality
The build quality is satisfied me and feel solid in my hands. The build seem better than other tamron lens and not feel plasticky. The weight and the size is quite acceptable for the wide angle lens. This lens come with a huge petal type 77mm hood to prevent flare.

This lens extend when zooming but it just extend around 1cm and not really noticable. This lens feature Internal Focus[IF] which prevent it extend or rotating while focusing. The picture below show the size comparasion of the lens when extend.

2. AF Mechanism
Lens MountThis lens AF is quite faster. The AF sound is a little bit noisy but still acceptable and not annoying me. The accuracy is good for a close range object at all focal length but sometimes it missfocus when the subject range is too far especially at 17mm and wide open.

3. Image Quality(IQ)
This lens is very sharp even at wide open and extreme sharp if you add 1 or 2 stop exposure. The center sharpness was really impressive but the corner sharpness is drop drastically but still acceptable.

Sharpness at 17mm F2.8 [Click for full resolution] Handheld 1/4s ISO400

4. Distortion and Vignetting
At 17mm, this lens show visible distortion but there is no distortion from 24mm and above.

Brickwall test at 17mm [Click for full resolution]

5. Chromatic Abberations(CA)

6. Conclusion
For the conclusion, overall I found that this lens is very worth for the money I paid. Here are some samples that I took with this lens. I will add some sharpness and resolution test in the future for reference.

7. Rating
1. Optical Quality ★★★★
2. Build Quality ★★★★
3. Value for Money ★★★★☆


Sunday, September 20, 2009