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Focus question (Pentax 65ED with Panasonic LX2)

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Old Wednesday 3rd September 2008, 03:08   #1
zack2
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Focus question (Pentax 65ED with Panasonic LX2)

Hello -

I am attempting to digiscope using my Pentax 65EDa scope and Panasonic LX2 camera.

I have a Pentax XW14 eyepiece on the scope, giving me 28x magnification. I've followed the directions which I found on a thread in this forum about the Leica D-Lux-3 camera (mechanically identical to my Panasonic), zooming in just until the '2x' readout appears in the camera viewfinder, and placing the camera lens as close to the scope eyepiece as I can get it without touching the glass (coincidentally, the front part of the LX2 lens just fits into the eyecup of the XW14 eyepiece, making handholding the camera quite easy).

There's no appreciable vignetting, and I'm able to set manual exposure quite accurately simply by judging the image on the LCD screen. However, I'm having trouble getting the focus completely sharp. Focus in my photos is almost there, perhaps marginally acceptable if viewed casually at small sizes, but definitely not as sharp as it should be. I'm shooting in bright daylight with apertures around f5.6 and shutter speeds around 1/400, so I don't think camera shake is the issue.

Am I doing something wrong? Do I need to focus my camera manually, or focus the scope using the camera LCD rather than my eye at the eyepiece? I actually tried to do the latter, but was having trouble judging critical focus on the camera LCD in bright daylight - and it SEEMED that I was coming up with the same focus point as I was by eye through the eyepiece...

Any suggestions greatly appreciated.

Thanks!
Zack
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Old Thursday 4th September 2008, 11:21   #2
mmdnje
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hi zack.why don't you post a picture, se we can see what's going on. I will be willing to bet that the main problem is camera shake. Jose
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Old Thursday 4th September 2008, 13:31   #3
zack2
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Quote:
Originally Posted by mmdnje View Post
hi zack.why don't you post a picture, se we can see what's going on. I will be willing to bet that the main problem is camera shake. Jose
Good idea! I've never posted photos to this site before, so I hope I've made good guesses about file size... Here are two test images, along with roughly 50 percent crops. All are jpegs straight out of the camera with no post-processing (except for resizing); I know I could improve things in Photoshop by increasing contrast and a bit of sharpening, but I wanted to show what is happening in the camera.

Thanks!
Zack
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Last edited by zack2 : Thursday 4th September 2008 at 19:18.
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Old Friday 5th September 2008, 01:30   #4
mmdnje
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HI Zack. the second picture shows "double edge", suggesting camera movement/shake. I have taken a few digiscoped pics (see my gallery), and the only way for me to eliminate this is iwith camera adapter, and remote release. If using a DSLR, I have to use the 2 sec mirror lock.
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Old Friday 5th September 2008, 13:30   #5
zack2
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Quote:
Originally Posted by mmdnje View Post
HI Zack. the second picture shows "double edge", suggesting camera movement/shake.
Jose
Hmmm. The 'double edge' that I'm seeing looks to me like chromatic aberration, present to some degree in my scope but made worse by the scope image being slightly out of focus.
(Incidentally, my camera doesn't have a remote release but I took the test shots using the multi-shot 'burst' feature so at least there's no additional vibration caused by my finger pressing down on the shutter release button.)
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Old Monday 8th September 2008, 13:50   #6
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Hi,

That looks like the results I get from my Kowa TSN-821, which don't have florite glass, not sure what the Pentax calls their high-end glass. Best remedy is to stay away from high contrast areas, remove some of the CA in photoshop and apply sharpening.

Since the light is scattered more in a non-florite scope the subjects will always look more fuzzy though. I got a florite scope to get around this but havent had much time to use it yet.

Btw, as close to the glass as possible might not be correct. The correct distance is when the edge of the viginetting circle is sharp. Too close or too far away darkens the image.

Regards Björn
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Old Thursday 11th September 2008, 13:41   #7
zack2
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The Pentax scope does in fact use flourite glass -- 'ED' is the designation which Pentax uses for it. The scope has a tiny bit of CA, but nothing like what I'm seeing in my digiscoped photos.

Regarding the sharpness of the vignetting circle -- good point, and something that I was wondering about. The edge of the vignetting circle is indeed fuzzy, and I haven't found any way to get it sharp. I've tried moving the camera various distances from the eyepiece, manually focusing the camera, different zoom settings on the camera, etc.

Going back to my original question, I'm still unclear what is the proper way to focus for digiscoping. Should I be focusing the scope by eye, or by looking at the camera LCD screen? (The two focus points actually seem to be close or even identical, though it is hard to judge focus on the LCD screen). Once the scope is focused, should I put the camera on auto focus or focus manually? I've tried focusing the camera manually at various distances, and strangely the results are inconsistent -- sometimes I seem to get the best results near infinity, sometimes much closer (around 3 feet). I have no idea why this would be!

Thanks,
Zack
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Old Thursday 11th September 2008, 14:12   #8
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I can never get the camera and scopefocus to be the same. If I focus the scope and attach the camera the focus is always off. I use the autofocus in macro mode on my P5100, the focus range is quite large so it doesn't matter so much how the scope is focused. If the autofocus has trouble locking on i use infinity and try to focus via the LCD, can be quite hard to get right.

Which I could help more but I'm a newbie myself, only been doing this for 6 months.

Regards Björn
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