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Subject: Digiscoping with Lumix GH1 and 20mm f1.7 [Print This Page]
Author: cwchan    Time: 11/12/2009 16:54     Subject: Digiscoping with Lumix GH1 and 20mm f1.7

Special thanks to Mandy who gives her GH1 and 20mm f1.7 pancake lens for my digiscopic testing.

All the test shots here were taken on 10.12.2009 at Mai Po.
A very hazy day

The setting
ISO 100,
Taken in RAW, converted to TIFF and then to JPG by using Silkypix (recommended by Panasonic) and Photoshop respectively.
Using the original electric shutter cable release to reduce human vibration.
A-mode (aperture priority)
Lens ( the pancake 20mm f1.7) setting at its f2.8 for all the shots.

Pros
Fast and able to get precise automatic focus with my 30X scope.
Light weight ( about the same weight of my old Nikon 8400).
Bright electric view finder. It brightens automatically at dim situation.
High-eye points, very usefully for spectacle wearers as we need not to come too close to (to touch) the view finder which may cause vibration.
The shutter vibration is not so obvious (most probably due to the presence of the long-plate to support the system).

Cons
Noticeable shutter release time lap.
The 20mm lens is not so sharp as expected.

Suggestion for improvement of the lens in field usage
The focusing design of the 20mm f1.7 lens is a front glass moving. My DCA has to be connected to the front ring of that focus lens directly. When the lens goes to get for focus, it goes in and out. That means, when the camera is placed on the scope via the DCA, the automatic focusing mechanism (inside the lens) carries the whole weight of the GH-1 and the lens while focusing. It will certainly slow down the automatic focus movement and, in some degree of extent, overstress the focusing gears inside, eventually causing rapid wear and tear of the lens.

If a coupling ring is made with one end connecting the DCA directly and the other end to the barrel of the lens as per photo No.3 (the green sketch), it functions like an internal focus lens, the weight is transferred via that coupling ring to the DCA without affecting the movement of the focusing mechanism, then the problem mentioned above will be solved.


No.1 The setup


No.2


No.3


No.4 At the far away side of Bird hide No.9


No.5


No.6


No.7


No.8


No.9  The original uncropped image


No.10  The 100% cropping of No.8 above


[ Last edited by cwchan at 11/12/2009 18:26 ]
Author: puppymic    Time: 11/12/2009 19:02

Your testing report is very detail. Thanks
I also think the Panasonic 20mm len is not quite sharp, whether it is because too large aperture？
Author: fneil    Time: 11/12/2009 20:51

Nice report on this camera.
I agree the 20/1.7 is not as sharp as it could be but it is acceptable for the average user up to 30 meters in good light.
The Nikon 20/2.8 D does a much better job, as does the Olympus 50/2.0 Macro although this magnification is very high for most situations.
I have just bought a Nikon 28/3.5 AI and a Nikon 24/2.8 D second hand which I'll be trying out on the G1 and GF1 this week.  These are manual focus only of course.
Neil.
Author: Robbin    Time: 11/12/2009 21:38

The camera lens may not be as sharp as expected, but the photos look ok to me, I say it's value for money.

And thx for the detail report.

[ Last edited by Robbin at 11/12/2009 21:49 ]
Author: cwchan    Time: 25/12/2009 19:03

Its big image sensor always has its advantage that the small dc could not give you the detail like the photo below.

Author: cwchan    Time: 5/01/2010 16:49

I am happy to try out this gear again after having installed with the 52mm adaptor ring. With this adaptor ring in place , it solved the problem mentioned above.
I can take the photo with  my eye  touching the EVF and get the  focus automatically controlled by the dc itself, which is just similar to common dslr .



The following sample photos were taken on January 4, 2010 at Mai Po, boardwalk.
Setting at ISO100, A-mode, f4, EV compensation to -2EV (After trial and error, I get this value for the right exposure, I don't know the reason why?)





The original uncropped image


Portion of above shot (about 95%)


[ Last edited by cwchan at 6/01/2010 08:31 ]
Author: lwingkay    Time: 5/01/2010 22:01

Quote:
Original posted by cwchan at 5/01/2010 16:49
I am happy to try out this gear again after having installed with the 52mm adaptor ring. With this adaptor ring in place , it solved the problem mentioned above.
I can take the photo with  my eye  tou ...
How much space on the barrel does the lens have for mounting the adaptal ring?

In your case, the lens is fixed in focal length, 20mm. Is it possible to mount an adaptal ring on the standard zoom lens of this camera?

Ricoh's latest product, GRX, is a good choice for digiscoping. One of the lenses that serves this camera is the 24-70mm zoom lens in which is housed a sensitive CCD of a size much larger than Nikon CP8400's. A higher ISO can be used for shooting and it is obvious that the quality of the lens is much improved as well, judging by the price that Ricoh is asking, around $3000 for the lens itself. Together with another $3000 for the camera body, the whole setup is pretty substantial in price. If problems with vignetting are resolvable, the investment is worth it for it is difficult to find a good camera for digiscoping purposes. Besides, the camera has an external EVF to allow for DSLR-like shooting.

Regards,
Peter

Postscript: The camera is provided with an extension tube for mounting wide-angle and telephotographic lenses. The tube can serve the purpose of linking the camera with the telescope.

[ Last edited by lwingkay at 5/01/2010 22:36 ]
Author: cwchan    Time: 5/01/2010 22:54

There is not much space for mounting the adapter ring, the space is about 3mm only, therefore the ring must be very good fit.
I don't think it is necessary for making this kind of ring for its (Lumis) standard zoom lens as this zoom lens is already internal focus type, it does not move externally while focusing.

Ricoh GRX 24-72 (S10 module)'s CCD is only 1/1.7 while Nikon 8400 is 1/1.5, 8400 equipped with the biggest ccd ever make in the dc market.
The 10 mega ccd being used in Ricoh should be better than 8400 in terms of noise and detail.
I have reservation on the optical quality of this Ricoh lens, the ED lens for the 8400 is really super indeed.
Author: kwingkai    Time: 6/01/2010 11:27

Very nice adaptor! It is a custom-made one? Would you please let me know where could I buy one and what is the cost?
Author: cwchan    Time: 6/01/2010 17:19

It is a custom-made adaptor specially requested by a friend.
I don't recommend this adaptor to be installed by the user himself due to the technical difficulty.

[ Last edited by cwchan at 6/01/2010 20:38 ]
Author: puppymic    Time: 9/01/2010 21:39

終於自己拎個GH1去玩下，未掌握得好，不過幾好玩

Swarovski STS-80HD + 30x + GH1





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