[claytoncramer]

I am photographing the Moon, prime focus, 17.5" f/4.5. K-2S. LiveView focuses really nicely. When I take a picture it is definitely not as sharp a focus. I turn off Live View and focus through the view finder and the focus point is slightly different. Any ideas? I would prefer using LiveView.

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Last edited by claytoncramer; 09-16-2021 at 11:44 AM.

[Bob 256]

Liveview will show the image just as the sensor sees it so it's the ultimate in obtaining correct focus. If the focus through the viewfinder differs, then your camera is not focusing where it should using the VF system. It could be that a camera adjustment (backfocus adjustment) for individual lenses is allowed (e.g. the K-1) which would address this.

Focus peaking is often used in Liveview so the image will appear sharper on the LCD screen while focusing than it will after the shot is taken. This can be handled in post-processing by enhancing some of the details using sharpening, so no worries.

For the purpose you describe, Liveview is definitely the way to go and use magnification if you have it to get a critical focus.

[Gerbermiester]

It is unlikely that live view is giving you an incorrect focusing information. When you focus using live view, you are focusing directly onto the camera's imaging sensor. While there may be a discrepancy between live view focus and viewfinder focus, I can't imagine that the live view is misaligned or incorrect. It is much more likely that there is another issue causing these results.

Since I don't know much about your setup, or how long you have been practicing photography for, I can only suggest the following simple solutions:

Mount your camera on a tripod and point your lens at the moon. When using long focal lengths, your camera and lens may still wiggle slightly after being touched.
Put your camera's drive mode into 12 second timer mode.This will help remove any camera shake from your photo by giving your gear time to stop 'wiggling'.
From here, make sure that you have turned shake reduction off. SR can introduce wobble into your photos when mounted on a tripod giving you apparent blurriness.
Next, if possible, you may want to close down your lens' aperture somewhat to ensure that you will get the sharpest images possible.
Finally, keep your shutter speed as fast as you can without hiking up your ISO value to the point that it creates visible house in your images. Try to keep your shutter speed around 1/100 or faster for best results.

Best of luck to you! I hope this helps you get to the bottom of your issue.

[AstroDave]

For the purpose you describe, Liveview is definitely the way to go and use magnification if you have it to get a critical focus.

Yes!

And, make sure camera autofocus is OFF (unless you are working on a high contrast crater rim or similar!)

[othar]

I am photographing the Moon, prime focus, 17.5" f/4.5. K20D. LiveView focuses really nicely. When I take a picture it is definitely not as sharp a focus. I turn off Live View and focus through the view finder and the focus point is slightly different. Any ideas? I would prefer using LiveView.

Maybe some kind of movement (camera shake) you don't get when using the OVF? Do you take the picture on a tripod or handhold?

As mentioned can the image in LV appear sharper than the resulting RAW file, have you processed the image already?

The moon is very bright so you can use a narrower aperture than f4.5 (f5.6 - f11, depending on the lens you use, will probably give you better results)

[FozzFoster]

Maybe double check your diopter hasn't moved which shifts focus in the viewfinder?

[MossyRocks]

When ever I am shooting images of stuff in space it is manual focus always. For things like the moon live view autofocus and regular autofocus (with the AF fine focus adjustment done properly) produce generally about the same results for me. However some times they can be fairly far off. The moon is really bright and even with a longer lens, say a 300mm f/4, it is still pretty small in the scene. Add in that unless you are lucky and get autofocus to focus (either one) on the edge of the moon it is fairly low contrast. Add it that it is pretty bright (start point of exposure is the loony 11 rule or ISO 100, f/11 1/100s) and it is fairly fast moving and getting a good autofocus is mostly a crap shoot.

So what I would do if I were you is instead is find a bright star or, if using a wider lens, planet (Jupiter is up now and should be fairly close to the moon tonight) and use magnified live with the camera pointed at that bright point light source with focus peaking turned off. Now manually adjust focus until you have minimized the star or planet (only use a planet if using a lens wider than 100mm) and you will generally be very close to a perfect infinity focus. After that recompose on the moon and shoot away. If you are serious about astro shooting I suggest getting some bahtinov masks that will work for you lenses as you can easily achieve a real perfect infinity focus with them. For regular camera lenses I have these (in all 3 sizes), and yes they do work. They are inexpensive but we know how to take care of things right? The fine grill/mess on them is what allows them to produce good results with short lenses and I have used them with a lens as short as 35mm and still gotten visible spikes in magnified live view.

From there when shooting the moon start with exposure similar to loony 11 and you will find that you my need to add 1 to 2 stops of exposure but it is a good starting point. Stick things on a big tripod and use the 2s mirror up delay shooting and a remote release. Beyond that shoot lots of shots of the moon as the atmosphere is rather turbulent so by shooting lots of shots you can pick the best or combine the best parts of each to get a really great shot.

[UncleVanya]

I’m pretty sure the OP is using the camera on a telescope. The keyword: prime focus

The Prime Focus Method (Astrophotography)

The focusing is done via the telescope focuser manually. This isn’t an autofocus operation.

To the OP:
The viewfinder on any SLR can differ from the actual recorded image due to small differences in the optical path. Fine tuning of this can be done along with diopter correction. If it looks out of focus optically but the LCD looks in focus I would check the diopter adjustment first by looking at the in viewfinder data displayed. If this is clear and the image is not then it is clear that the distance to the eyepiece is out of adjustment to the length of the path to the sensor. This can be adjusted with shims, or for lenses with autofocus or the use of catch in focus the focusing can be biased via fine adjustment to match. If the text data in the viewfinder is not clear try adjusting the diopter settings until the text is clear.

Ultimately the rear lcd based live view should be the most accurate.

[pschlute]

When I take a picture it is definitely not as sharp a focus. I turn off Live View and focus through the view finder and the focus point is slightly different. Any ideas

They are two entirely different auto-focus systems.

[MossyRocks]

I’m pretty sure the OP is using the camera on a telescope. The keyword: prime focus

Completely missed that. and that it is a 17.5" f/4.5 which should have clued me it too. In that case then using a bahtinov mast really becomes essential. Also at about 2 meters focal length the moon really will be trucking across the scene and atmospheric distortion will be very visible when it happens. Even at 800mm in bad conditions the atmospheric distortion from turbulence is very visible. Also being at ~2m and APS-C the moon will overly fill the frame so for that I would let it drift across the frame and take several videos and from that use software to get the best out of it.

[UncleVanya]

They are two entirely different auto-focus systems.

See my earlier post. I don’t think he is talking about autofocus at all. I think he is saying if he uses live view to manually focus, and the images made that way are not in focus (not sure if that is true or if it is a misreading). Further it differs from the focus achieved by using the viewfinder. That seems nuts. But that’s what I’m reading.

[Bob 256]

See my earlier post. I don’t think he is talking about autofocus at all. I think he is saying if he uses live view to manually focus, and the images made that way are not in focus (not sure if that is true or if it is a misreading). Further it differs from the focus achieved by using the viewfinder. That seems nuts. But that’s what I’m reading.

He was saying he wasn't observing as good a focus with a taken picture as with Liveview (assuming this is on the LCD screen). I know this to be well and true since Liveview uses video peaking which makes a Liveview image appear (considerably) sharper than the same on the screen right after taking a photo. This can be made up for in post. Secondly, he states that the VF focus doesn't agree with the Liveview. This could be due to diopter issues if using the visual sharpness of the VF image for a reference, but it is most likely due to variability in the VF focusing system (if using AF) which may be reading the "sweet spot" differently than Liveview, the latter of which is absolutely correct since it is taken directly from the sensor. As AstroDave suggested, the OP should be using manual focus and is better off using Liveview as a reference.

[claytoncramer]

Thanks for the suggestions. I am MF. I have no idea how autofocus could work without a lens. Diopter adjustment could be an explanation of the difference but I would still expect LiveView to be correct focus. I used GIMP to improve the image.

[claytoncramer]

12 second delay. There is no motion on the screen. This is not a tripod. This is a 17.5" diameter reflector telescope.

[UncleVanya]

12 second delay. There is no motion on the screen. This is not a tripod. This is a 17.5" diameter reflector telescope.

Are you turning off SR (shake reduction?

I can't recall if the K-70 mirror flaps down and back up differently on 2 sec vs. 12 sec. Some cameras (I think the K-50 was one) drop the mirror in liveview before firing the shutter. If I recall the drop happens at the start of the 2 second timer, and just before the shot on the 12 second timer. I could be misremembering - on the K-3 and similar the shutter doesn't have to drop the mirror to fire and wasn't as different.

Earlier someone suggested that in liveview the sharpening applied is higher than on the actual shot. So you may be experiencing that. Is the result just a little softer or worse? Can you share shots with us? Is viewfinder focus worse or better in the end result?