GRDIII + GT1 - test of vignetting

[odklizec]

Last Friday, I received the step-down ring I ordered (bought here) to test the GT1 lens with GRDIII. It's made from metal, and looks well finished and durable.

Step-Down ring 43-37mm

step_down.jpg (57.94 KiB) Viewed 6794 times

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EXIF-Data

Image taken on: Sun Aug 30, 2009 9:02 pm

Focus length: 6 mm

Shutter speed: 1/9 Sec

F-number: F/1.9

ISO speed rating: 200

Whitebalance: Auto

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 1/1 EV

Metering mode: Pattern

The result is exactly what I expected it will be. There is some vignetting and it looks worse in JPEG than in DNG. I think its just the additional contrast and other JPEG processing that makes it worse. Another problem is, that the step-down ring I got is too thick (the thickness of outer part is 4mm, total thickness of ring is 6.5mm). I think it's a problem of most of step-down rings? There are some thinner rings, but they are hard to find. What we need is really thin ring that reduces the vignetting to it's bare minimum. The problem is, that there may be a problem with durability of too thin ring.

In any case, the vignetting with step-down ring is much noticeable in 4:3 and 3:2 and it's almost invisible in 1:1. Next time I will try also the sharpness

Here you can see how the GT1 vignetting looks in various aspect ratios:

4:3 with step-down ring

GT1_4_3.jpg (62.77 KiB) Viewed 6741 times

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EXIF-Data

Image taken on: Sat Aug 29, 2009 9:04 am

Focus length: 6 mm

Shutter speed: 1/55 Sec

F-number: F/1.9

ISO speed rating: 400

Whitebalance: Auto

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 3/10 EV

Metering mode: Center-weighted average

4:3 handheld - I just held the GT1 in front of the GRDIII lens)

GT1_4_3_handheld.jpg (64.2 KiB) Viewed 6769 times

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EXIF-Data

Image taken on: Sat Aug 29, 2009 9:15 am

Focus length: 6 mm

Shutter speed: 1/32 Sec

F-number: F/1.9

ISO speed rating: 400

Whitebalance: Auto

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 3/10 EV

Metering mode: Center-weighted average

3:2 with step-down ring

GT1_3_2.jpg (55.99 KiB) Viewed 6742 times

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EXIF-Data

Image taken on: Sat Aug 29, 2009 9:04 am

Focus length: 6 mm

Shutter speed: 1/52 Sec

F-number: F/1.9

ISO speed rating: 400

Whitebalance: Auto

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 3/10 EV

Metering mode: Center-weighted average

1:1 with step-down ring

GT1_1_1.jpg (95.45 KiB) Viewed 6747 times

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EXIF-Data

Image taken on: Sat Aug 29, 2009 9:04 am

Focus length: 6 mm

Shutter speed: 1/52 Sec

F-number: F/1.9

ISO speed rating: 400

Whitebalance: Auto

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 3/10 EV

Metering mode: Center-weighted average

Two real-world examples:

4:3

_1090863_sm.jpg (268.29 KiB) Viewed 4222 times

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EXIF-Data

Image taken on: Thu Apr 15, 2010 2:58 pm

Focus length: 4.5 mm

Shutter speed: 1/620 Sec

F-number: F/4.5

ISO speed rating: 100

Whitebalance: Manual

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 0 EV

Metering mode: Center-weighted average

full resolution file

3:2

_1090864_sm.jpg (260.77 KiB) Viewed 4190 times

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EXIF-Data

Image taken on: Thu Apr 15, 2010 2:58 pm

Focus length: 4.5 mm

Shutter speed: 1/540 Sec

F-number: F/4.5

ISO speed rating: 100

Whitebalance: Manual

Flash: Flash did not fire, compulsory flash mode

Camera-model: GR DIGITAL 3

Exposure program: Aperture priority

Exposure bias: 0 EV

Metering mode: Center-weighted average

full resolution file

[thelps]

Thanks for the sample images here Pavel, the vignetting seems quite graduated to my eyes - you'd have to decide image by image how much to crop. At a guess if you cropped the image it would make it about a 7Mpixel image and the resultant increase in "zoom" effect would make the 40mm lens act more like a 50mm.

Tim

[rondo]

Thank you Pavel...Flare was an issue with GT1/GRD2 and artificial vignetting was a common remedy to deal with it...My conclusion is that it is quite usable as is.

[fei]

Thank you Chief! I believe as long as the pictures are sharp at infinity I will go ahead and get it!

[cfc247]

Pavel, have you found a slimmer step down ring and tested the GT-1? Which hood did you use with the GRDIII? Do you know if any of the older hoods will work on the GR III? Thanks.

Mark

http://www.flickr.com/photos/22910881@N08/

[odklizec]

Hi Mark,

Unfortunately no, I did not find slimmer step-down ring yet. My problem is that there are no shops around me stocking the step-down rings and most of online shops do not mention the ring thickness. As for old GRD hoods, I'm afraid, they will not work with GRDIII. The diameter is different.

[cfc247]

Thanks for the info Pavel!

[Randius]

Is there really no plan from Ricoh to release a GT-1 replacement for GRD3 in the next couple of years? A little hesitant to go for the GRD3 without 40mm as the 17-40 was the primary lens on my 5D (sold) and I did use the 40mm end at times...

[oxideblu]

What about using the GRX's TC-1 on the GRD3? I think they both have the same thread/mount size.

[odklizec]

No, it will unfortunately not work. Although the thread is the same, the diameter of rear TC-1 lens is too small to be usable at 28mm. This is also why is the TC-1 usable only at 72mm (if attached on GX/GXR S10). So yes, you can attach TC-1 on GRDIII and you will get an enlarged image, but with strong vignetting. It's not usable even in 1:1 mode.