Autofocus variability (1 Viewer)

I've just about completed my digiscoping kit and have been experimenting for a while taking shots of some small signs on a roof about 340 yds. from my balcony. The attached were taken with a CP4500 coupled to a Kowa Prominar TSN-823M scope using Kowa's camera adapter. Once I got the focus as good as I could see it with my reading glasses, I snapped a series of 5 shots. I did not adjust the scope on any of the shots after the first one. I did not touch the camera at all, other than to release the plunger on the cable release after each shot. Thus, the only difference between these shots should be the result of variability in the camera's autofocus. The only post-processing of these was to downsize for attachment to this message. (For the record, I have gotten shots better than the best of these, but probably no more than 10% are what I'd call even minimally acceptable. The lettering on the turquoise sign is "Non Flammable Gas." The lettering below it is "Refrigerating.")

Do any of the rest of you find variability in the autofocus on your cameras? I also have a Panasonic Lumix DMC-FZ10 that gives similar results. To what extent do you think this may account for the low percentage of decent shots?

Regards,
Bob

Hi Bob,

Just a thought, but with the distance of the sign, is there a chance that atmospheric turbulance or heat haze is affecting the sharpness of the pictures?

AndyC

AndyC said:

Hi Bob,

Just a thought, but with the distance of the sign, is there a chance that atmospheric turbulance or heat haze is affecting the sharpness of the pictures?

AndyC

Click to expand...

Hi Andy,

I don't think so. When I first took a look a scopes up at Eagle Optics, in May, it was a sunny day, about 2:00 p.m., and at higher magnifications, there were a lot of heat waves and pollen/dust clearly visible, so I know what to look for. I don't see any of that today, just looking thru the scope (i.e., without the camera attached).

Regards,
Bob

Try setting the camera on continuous, and shoot 5 shots without releasing the shutter. Then try again, another series of five. I think you will find that there is both a variability of focusing and a variability of air transparency (the CP4500 does not adjust focus between shots in continous mode). A third source of variation could be wind or other shaking of the telescope - did you use a remote control or self timer?

HTH
Niels

njlarsen said:

Try setting the camera on continuous, and shoot 5 shots without releasing the shutter. Then try again, another series of five. I think you will find that there is both a variability of focusing and a variability of air transparency (the CP4500 does not adjust focus between shots in continous mode). A third source of variation could be wind or other shaking of the telescope - did you use a remote control or self timer?

HTH
Niels

Click to expand...

The wind was calm and I was using a 10" cable release carefully, so there was no shaking of the camera or scope to speak of. It's dark now. I'll try a series of continuous shots tomorrow. Thanks for the suggestion.

Regards,
Bob