Camera image never in focus with PST

[JB80]

Hi all,

This problem is driving me batty but no matter what I try I just can't seem to get a good focused image from my PST. I'm using a canon 450D which I know isn't ideal but when looking at other peoples pictures using the same method they are managing to get it in focus at least.

I have tried every method at my disposal from eyeballing it in the viewfinder(which was the one and only time I had success), foucusing via live view and have tried a couple of programs like APT and Digital photo pro all with little success.

I get a nice crisp and clear image in the eyepiece so it's not an issue with the PST, it's not shake either as I am careful about that.

I don't know what's going on, when using capture programs or the live view it seems easy enough to get in focus but it's like what I'm seeing as clear focus is not actually in focus.

My sweet spot is in a pain of a spot though I'm not sure if that is part of the problem.

I'd of liked to of sorted this problem out before I went for a DMK as I don't know if the problem is going to transfer to the next camera, it's making me second guess getting a CCD and even any future PST mod.

Does anyone have any ideas?

The only thing I can think of trying is getting out the 20D and seeing if it still is a problem.

Jarrod.

[Helen]

Getting focus with a camera with a PST can be tricky. I've never tried with a dslr, but with a webcam/DMK you either need to use a shorter nosepiece or a barlow. With a short nosepiece a DMK and PST is a killer combination :-) and if you can afford it I'd say do it sooner rather than later as its much less frustrating than using a normal camera!

Helen

[JB80]

That's the thing though, it can be tricky but it's not impossible except if I'm doing it. With the dslr and hyperion zoom I can easily achieve focus it's just that focus never translates back to the camera image.

I do want a DMK but if I'm going to have the same issue then I really don't know.

[Photosbykev]

A DSLR and Hyperion zoom EP does focus on the PST without any other mods as you've already found out.

You need it connected to a laptop to get the maximum image size to check the focus on Pibbles. Using liveview, even at x10, is a marginal way to do it. APT or even EOS utilities will give you a good sized image to work with that you can zoom into.

The problem doesn't go away with the DMK etc but it is helped by the camera sensitivity and the ability to play with the gamma to give you a high contrast image to check the focus on. Like any other scope critical focus is hard to achieve and you need to keep tweaking the focus to get the best result from any system

Switching to a DMK41 and 2.5x Powermate was the best thing I ever did to improve my solar imaging.

[JB80]

Even with APT it still feels like it's impossible though, it's just so frustrating. I'm sure it's me and not the equipment but I can't work out why it seems that what is on screen as perfect focus never actually is in the image taken.

[LukeSkywatcher]

I have owned my 450D for a couple of yrs now and even now when i am outside taking images and everything looks perfectly in focus on screen...........when i upload to my pc it rarely is. The camera is not faulty because i can focus to perfection in daylight.

I assume you are using the live view 10X zoom to focus?. If not............give it a go.

I think Kev is right. You need a screen bigger then on the 450D to be 100% sure of the focus.

[JB80]

I have used the laptop and it doesn't seem to make much difference.

Maybe it's a 450D issue but I know it's probaly just me. I did think it could be related to the diopter adjustment but that should just be restricted to the viewfinder and shouldn't effect what is seen on the laptop screen, should it?

[Helen]

This might not help at the moment, but I thought it might still be worth posting (original idea from Ken - Merlin)..the marmite trick for focussing... This involves sacrificing a jar of Marmite (as I hate the stuff I was very happy indeed to do this!) so that you can have the lid.... Make a hole in it just big enough to go over the PST focus knob, you then have much finer control of the focus mechanism...

Helen

[Photosbykev]

I have used the laptop and it doesn't seem to make much difference.

Maybe it's a 450D issue but I know it's probaly just me. I did think it could be related to the diopter adjustment but that should just be restricted to the viewfinder and shouldn't effect what is seen on the laptop screen, should it?

viewfinder diopter adjustment has no effect unless you use the viewfinder to focus.

I'm wondering if this might be an issue with capturing in Raw mode, if you do? Raw mode has no sharpening applied nor does it have any other adjustments made to it so you have to apply them all in post processing. Canon raw images do look soft with low contrast and saturation before processing.

Apologies for the audio but this tutorial goes through my digital workflow http://www.photosbykev.com/wordpress/tips-and-trick/image-processing-tutorial/

[JB80]

Marmite? Bleugh.....

Vegemite is where it's at

Actually Ken gave me a spare vegemite lid which I have been using, It definitely makes it easier. I think something like that should be the first thing done with a PST it's that useful.

[JB80]

I'm wondering if this might be an issue with capturing in Raw mode, if you do? Raw mode has no sharpening applied nor does it have any other adjustments made to it so you have to apply them all in post processing. Canon raw images do look soft with low contrast and saturation before processing.

This could be a point, I do notice there is a difference when using RAWs but never even considered it would make difference to the sharpness, I always though it'd make it better if anything.

I usally don't do anything to the pic in the RAW viewer, I do it in PS after I have seperated the red channel.

Maybe I should change some settings in the RAW editor first?

[Photosbykev]

leave any sharpening until the end Pibbles or you will find you could be increasing noise. Export the image from your Raw software as a 16bit Tiff file and then load that into PS for processing.

Also I would suggest using the Canon DPP software to do the conversion, it isn't the best out there but it is alot better than some of the freebie quick convertors

[JB80]

I only had DPP as a trial unfortunately, I did quite like it though. I normally open it as a CR2 file in PS then save it as tif later. But I can save it as a tif in PS raw viewer and then open it in PS if that's the same thing.

[Photosbykev]

I only had DPP as a trial unfortunately, I did quite like it though. I normally open it as a CR2 file in PS then save it as tif later. But I can save it as a tif in PS raw viewer and then open it in PS if that's the same thing.

DPP as a trial ??? The full software package comes with the camera.

The PS Adobe Raw convertor is ok, nothing special but as good as DPP or better http://www.photosbykev.com/wordpress/2010/05/24/canon-7d-noise-handling/ . I use Phase One Capture One Pro normally but that's overkill for most users.

[RikM]

I find for white light solar images with my DSLR, I have to use much higher ISO and shorter exposures than you might expect. What might seem like poor focus could simply be the seeing blurring the image. I take 40 or so shots at ISO 800 and 1/1000sec or so and stack them in Registax. It sounds totally the wrong way to do it, but it is the only way I have found to get sharp images.

[JB80]

DPP as a trial ??? The full software package comes with the camera.

The PS Adobe Raw convertor is ok, nothing special. I use Phase One Capture One Pro normally but that's overkill for most users.

Ahh, sorry I got my software mixed up. I meant 'dslr remote pro', I never did get DPP as my cameras have been second hand and never came with it.

What would be the best way to sharpen the images then, I never see much of a difference in wavelets. I mean there is a difference but it's still all blurry. I'm sure I have some old shots I can play around with.

Maybe I'll just try in jpeg mode to see if it makes a difference.

[Photosbykev]

Ahh, sorry I got my software mixed up. I meant 'dslr remote pro', I never did get DPP as my cameras have been second hand and never came with it.

What would be the best way to sharpen the images then, I never see much of a difference in wavelets. I mean there is a difference but it's still all blurry. I'm sure I have some old shots I can play around with.

Maybe I'll just try in jpeg mode to see if it makes a difference.

You shouldn't need to play with wavelets although they can be useful but more suitable for images from avi. Try this workflow as best you can especially step 10 Photography Tips and Tricks - Digital Workflow . Please stay away from jpg images except when finally uploading to the web, you will never get the best quality.

DSLR Remote Pro is only used to capture the images rather than process them, it's a good program for timelapse and tethered work personally I prefer GBTimelapseEOS which can force a Canon DSLR into bulb mode even if the mode dial is on Manual or AV

What is your typical shutter speed for the solar work?

[michael8554]

I think RikMcRae's point about blurred seeing is worth checking.

Take a load of fast exposure shots in rapid succession and look for any with good focus.

If there aren't any you can discount that thought.

Are you processing an RGB image or just one colour?

Splitting the image into R G and B and examining each may show that G is sharpest and has good contrast (you can convert G back to a greyscale colour image and tint it the usual yellowish-red in your photo software)

Cheers

Michael

[Photosbykev]

there should be very little usable signal in the Green and Blue channels when photographing through a PST, all of the information is in the Red channel. PST Solar Imaging PhotosbyKev

[JB80]

You shouldn't need to play with wavelets although they can be useful but more suitable for images from avi. Try this workflow as best you can especially step 10 Photography Tips and Tricks - Digital Workflow . Please stay away from jpg images except when finally uploading to the web, you will never get the best quality.

DSLR Remote Pro is only used to capture the images rather than process them, it's a good program for timelapse and tethered work personally I prefer GBTimelapseEOS which can force a Canon DSLR into bulb mode even if the mode dial is on Manual or AV

What is your typical shutter speed for the solar work?

Fair enough about the wavelets, I'll leave them alone from now on. Thanks for the link too, lots of stuff in there that I can try. I had always wondered what that bar in your sig represented, now I know and I have always stayed away from the unsharp mask tool so I'll give that a try too.

The only reason I was going to try the jpeg was to see if it was the softening effect of the RAWs that is causing the issue, maybe in RAW the focus point appears different than what I think it should be.

I just want to check I guess but maybe going through some of the process' in your link will help.

I only trialled remote pro simply for trying out the capture part, it did look good but had a pricetag to suit, maybe one day I will feel the need to get it. But yeah, I had my program names confused earlier.

Generally I batch my speeds, for the proms 1/15 to 1/25 and for the surface 1/320 to 1/500 sometimes I do a few shots past those but I normally get something out of those settings. Normally at iso 200 as well.

edit: Also what Kev said above, I split the channels to use just the Red one. Blurred seeing could be an issue but I this is the same all the time.

It may just be me being rubbish at processing too, because I had a couple of good early results but I can't remember what I did to achieve it.

[michael8554]

Quote PhotosbyKev: "there should be very little usable signal in the Green and Blue channels when photographing through a PST, all of the information is in the Red channel."

Apologies for the error, I must have been thinking back to pre-PST when I did white-light imaging.

But thankfully you confirm the RGB split advice :->

[Photosbykev]

Pibbles, could you upload a Canon raw file that you are concerned about so we could check the original data. Mediafire would be ideal, it's a free file hosting site.

Your exposures sound similar to mine when I used a 5D MkII, can you see any difference in softness between the proms and surface detail images? That might point to a vibration problem if the proms are softer.

Using jpg mode so that the camera does all the work might be useful, but only for a trial.

[JB80]

I couldn't get mediafire to work for me but megaupload did. This is one of the better ones. Maybe there isn't anything wrong with it and it's just the processing that's letting me down, at least I'd know then. I'd be happy if it was that.

MEGAUPLOAD - The leading online storage and file delivery service

I hoped that link works.

To be honest I thought the proms where fairly good but I just don't know anymore. I try my best to not have any vibration, but I guess it could be when the shutter is working. I have a sturdy mount with sturdy legs and most of the time it's on the grass, so it could be actual camera shake.

Yeah I just wanted to test the theory, I was hoping to today but the clouds have come in.

[Photosbykev]

Hi Pibbles,

a quick play of the CR2 file.

Converted from Raw to 16-bit tiff without any adjustments

Imported into PS, split into channels and discarded G and B.

Selected the disk and ran a colouring action I use and then reselected the disk again and ran an unsharp mask over it 3 times. Cropped and resized for the web.

Two things that immediately spring to mind, the focus is off so that needs some work and also looking at the histogram of the CR2 file you have underexposed the disk by at least 1 stop, you've used a shutter speed of 1/500sec@iso 200 I would expect this to be nearer 1/200 or 1/160 @ iso 200. I'm not really sure what's happening in the sky around the sun, it's very noisy so I delibrately left that as it was.

The sun was also off centre in the frame which is why the hot spot of the PST isn't centred on the solar disk

[JB80]

Thanks for taking a look

I have found that 1/320 is generally a bit more user friendly but this was the first one I found that demonstrates what was going on with focus, all my Sun pics have the same focus issue. But I will try a tad longer exposure and probably iso400.

The noise I have no idea about either, if it's in the sky then is might be over the Sun too. Also interesting as I had got some very noisy widefield shots once stacked with darks added but I am led to believe that was using high iso with a CLS filter but I don't know what is normal or not. It's probably unrelated though but I hope it's not an issue with my camera.

About it being off centre my sweet spot is off centre so I try to get as much as I can in the sweet spot, I have no idea if it's necessary to do that though.