My first days with the Canon A640 (1 Viewer)

erniehatt · Apr 17, 2007

Your welcome Johan, let me know what you come up with, any improvements etc. Malcs tests were very well done, and quite conclusive, for his setup, but I have tried this with two different scopes and the results are not the same, the reason for this is the scopes are all of a different focal length, so DOF changes, so the answer is to do the tests on the equipment you have. When you use a long prime lens the DOF is easier to work out because there is only one focus unit, but when you have two unatached items that have there own fucusing mechanism's things become harder. Hope that makes sense. Ernie

Johan van Rensburg · Apr 18, 2007

Feathered one said:
Johan

Take a look here for discussion and some target tests I did on depth of field. The target pictures are about half way down the page.

http://www.birdforum.net/showthread.php?t=75378&highlight=cardboard

Malc

Hi Malc.

I have read this thread and your posts on the subject before. It was an eye-openner. Your test results serves to teach me that my understanding of the concept is still extremely vague.

I have experienced the A640 changing (on it own accord) the position of the focus area without me touching the focus on the scope. In other words - the slice of in-focus area moves forwards and backwards (further away or closer to the equipment position) due to the machanics of the camera. I would not have thought this as possible. Obviously as Ernie mentions, having an unconnected optics train (that were not designed to be a unit) complicates matters. One hell of a challenge to get to grips with. I will have to experiment a lot more with camera set-up and settings. But the set-up part must come first. I am getting a fixed (30x) eyepiece later today and will start working on Ernie's adapter as soon as I have the dimentions of the new eyepiece. I know that most of my troubles stem from my current adapter that only allows semi-decent images at full optical zoom (4x). According to my calcs the lense of the camera is (after my most recent alterations when I shortened the adapter by 3.0 mm) still another 4.5 mm short of touching the eyepiece. I have not tested the train since shortening the adapter. Will post some results in a while. I first want to get the new ideas with Ernie's adapter up-and-running.

jourdaj · Apr 19, 2007

Johan,

In terms of an adaptor, I used the Canon LADC58 plastic adaptor on my Canon A620. Putting a strip of velcro (male side only) along the inside rim made for a snug fit when pressed onto the 20-60X eyepiece of my Zeiss 85T*Fl. I've gotten some wonderful images with my setup, and did it all hand-held. My advice is to brace yourself against the scope and camera, and shoot continuous mode. If your focus indicator shows a green box then some of those pics will come out very sharp. Best of luck,

Jerry
www.pbase.com/jourdaj

Johan van Rensburg · Apr 19, 2007

jourdaj said:
Johan,

In terms of an adaptor, I used the Canon LADC58 plastic adaptor on my Canon A620. Putting a strip of velcro (male side only) along the inside rim made for a snug fit when pressed onto the 20-60X eyepiece of my Zeiss 85T*Fl. I've gotten some wonderful images with my setup, and did it all hand-held. My advice is to brace yourself against the scope and camera, and shoot continuous mode. If your focus indicator shows a green box then some of those pics will come out very sharp. Best of luck,

Jerry
www.pbase.com/jourdaj

Thanks for the suggestion, Jerry. I doubt that it will serve me - I am an unsteady and shaky old fart - your set-up requires a steady hand! I will probably fall over, camera, scope, tripod and all :-O

Neil · Apr 22, 2007

I finally got my new adapter for the A640. I have found a guy in Hong Kong who can make them and he made me new adapters for the Canon A640 and the Nikon 8400. They are about 1/4 inch shorter than the normal adapters so that the lens can get closer to the eyepiece (the camera lens has to be set up off the scope). I tried the new A640 adapter on the Swarovski 20-60 zoom (at 20x ) and the Sw 30x . Now I'm able to use the camera lens more wide open with no/little vignetting. It seems to suit the 30x eyepiece best (20 mm of eye relief ) and I can find a position around 30% into the zoom which is unvignetted. I hope to test in the field tomorrow and will post results asap.Neil.

Johan van Rensburg · Apr 22, 2007

Neil said:
I finally got my new adapter for the A640. I have found a guy in Hong Kong who can make them and he made me new adapters for the Canon A640 and the Nikon 8400. They are about 1/4 inch shorter than the normal adapters so that the lens can get closer to the eyepiece (the camera lens has to be set up off the scope). I tried the new A640 adapter on the Swarovski 20-60 zoom (at 20x ) and the Sw 30x . Now I'm able to use the camera lens more wide open with no/little vignetting. It seems to suit the 30x eyepiece best (20 mm of eye relief ) and I can find a position around 30% into the zoom which is unvignetted. I hope to test in the field tomorrow and will post results asap.Neil.

Promising news, Neil. As you probably know, I am currently building a new adapter for my A640 based on Erniehatts design. It is taking longer than expected, but your possitive experience with the lense closer to the eye-piece has given my hope... Lets get back to the workshop!

Johan van Rensburg · Apr 26, 2007

I am battling a bit to get the Ernie version adapter done, mostly the swing-away facility that I am adding is keeping completion up.

It got an opportunity to test the shortened version of my in-line adapter earlier today. That adapter was shortened by only 3 mm and what a difference it made. In really poor light I had to crank the ISO setting to Hi and I compensated exposure by -2/3 steps. The birds were at 25 m and my Zeiss eye-piece set at 25x. Considering the poor light conditions and some cropping the results are quite pleasing to me. Pix 1 is of a black-collared barbet. Pix 2 is a hybrid red-eyed/dark-capped bulbul.

erniehatt · Apr 26, 2007

Johan, Nice results under the circumstances, The way I was going to do the swivel, was to drill the main block, and make the swing away at the angle bracket. To explain a bit better, look at the inner circle you will see a small hole, drill through there, countersink and glue in bolt.Ernie

Neil · Apr 27, 2007

I'm testing the A640 with the new adapter on the Pentax 100 mm scope and the 20mm eyepiece (43mm thread). As I mentioned recently I've had a couple of adapters shortened (about 1/4 inch )to provide an alternative zoom postion Just testing in my loungeroom window I was able to achieve "vignetting free" at 7.3 mm which is at the wide end of the zoom (35 mm ). This gives 33 x 35 = 1155 mm. A little bit of vignetting crept in as you zoomed but was manageable up to 12.6mm. Over this and the quality dropped off due to over-magnification.
With a sliding adapter as Ernie has made you would be able find more "sweet spots". With two adapters I'll be able to go wide and long as necessary. This varies a lot with different eyepieces too. Neil

erniehatt · Apr 27, 2007

Good one Neil, it's not such a bad camera with a little effort is it. I am experimenting at the moment with longer zoom cameras, have a vignette free image from the Sony f717, I have to make another bracket to suit, but it looks promising. Ernie

Neil · Apr 27, 2007

Ernie,
I still need a way to use the camera vignetting free at around 2000 mm equivalent. I now have short and long but not mid. Could you post some test images using your adapter through the zoom range? I can get a sliding type adapter made here. Neil.

erniehatt · Apr 27, 2007

Neil said:
Ernie,
I still need a way to use the camera vignetting free at around 2000 mm equivalent. I now have short and long but not mid. Could you post some test images using your adapter through the zoom range? I can get a sliding type adapter made here. Neil.

OK Neil, Let me know what eyepiece, I tend to use the 40 or 30mm , It may take a little while as my gear is packed away at the moment, due to refurbishing my household. I will set up something static in the backyard. there will of course be some difference between mine and the results you get, because of difference in focal length.I am not too sure what you mean by 2000mm equivalent please clarify for the feeble minded. Ernie

Johan van Rensburg · Jun 26, 2007

It has taken TWO WHOLE MONTHS to get my "Ernie-adapter" completed. Finished the last bracket earlier today, put the whole lot together and did some tests to see if it would deliver as I expected. A slight disappointment in that at minimum zoom I still experienced vignetting. Big improvement through the range though.

My set-up includes a 20-60x eyepiece. The new adapter allows the eyepiece zoom to be adjusted with the camera in place. What a surprise when I discovered that with the A640 lense at min zoom vignetting disappears at around the 40x setting on the eyepiece.

I have also sorted out the focussing problem by setting the camera on manual focus and fine-tuning the focus by adjusting the focus on the scope. I had my optomotrist build me as special set of glasses that has +8.5 dioptre. This works like a jewelers loupe, alowing me to see the pixels on the display much better - focussing is now too easy:t:

Below are some pix showing off the swing-away version of Enrie's adapter. When you want to "swing away" and use the scope for bird watching, you just switch off the camera, the lense retracts and VOILA! the swing-away action can be performed!

The pix of the flowers show the vignetting experienced at minimum zoom (both on camera lense and scope eyepiece) and the stage where vignetting disappears completely (camera lense still at min zoom, eyepiece at 40x)

erniehatt · Jun 27, 2007

Hi Johan,
Thats a great Job youve done there, glad my little design was of some help. I wish I had the gear to make one up myself, still my original is working fine for me. Good luck with it. Ernie

Brian Stone · Jul 5, 2007

I've been using the Nikon P4 for the past year and getting some good results but always had a bit of an issue with the noise and softness often creeping in. I also do a lot of macros photography and it wasn't as good as the 995 it replaced. So with the cost of the A640 coming right down to c.£150 I decided to take the plunge.

Really very happy indeed. Much sharper and less noisy results than the P4 and a bit faster too. The rotating screen is useful (back to the 995 days) really bright and clear. Macro performance is sensational (see my blog).

I've used a roll of tape to centre my P4 in the 20x eyepiece of a Leica APO77 scope and with a little modification this works fine with the A640. There is still vignetting at mid-range zoom settings and I can't use the final 4x zoom setting as the lens extends too far but at minimum zoom and one click back from max there is little or no vignette at all.

I'm going to miss the image stabilisation, especially as it's often so dull here at the moment but you can wind up the ISO successfully which would have been hopeless with the P4. The two shots attached were taken at ISO400 and have been run through Neat Image, sharpened a little and resized.

Hopefully more shots to come soon.

Neil · Jul 5, 2007

Brian,
I had a look at your Blog. Very nice work. I haven't tried Macro off the scope. I'll have to give it a go. Neil.

Brian Stone · Jul 5, 2007

I should also have mentioned the manual focus on the A640 is a real advantage. Set the camera to manual focus and you get a magnified section appear on the screen. You can then focus really accurately using the scope.

My first days with the Canon A640 (1 Viewer)

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