I realize many people here use autofocusers, however I am sure most beginners are using manual focus.
I’d like to discuss different ways of optimizing manual focus with SGP.
Right now this is my procedure:
After a rough manual focus that allows plate solving and getting to my target.
I use the frame/focus and start looping short 3-4 second exposures.
I then crop an area usually where there are some brighter stars near the center if possible.
I click the HFR star icon to get star calculations
I now start moving the focus to see smaller HFR calculations (Usually every 2nd frame due to vibrations)
sometimes it’s hard to keep track of which star’s number I am focusing on - sometimes they disappear.
There’s also the image statistics window that gives me the HFR value for the ~300 stars in the whole view. I am not sure if it’s better to use this number exclusively as it’s easier to work with and not look at the cropped image star numbers.
have you ever tried a bahtinov mask? there’s freeware for windows called “bahtinov grabber” that can analyze the diffraction pattern and tell you when you are in the critical focus zone. although it requires placing and then removing the mask from the telescope, it’s super accurate.
as for what you’re doing now, i’d think that taking the average number would be better, just to avoid the problem of the star you were concentrating on going missing in the HFR calculation…
I’d second the above from @pfile - without auto focus, using a bahtinov mask and bahtinov grabber is a really easy and effective way of getting quick and accurate focus. It works best with a bright star, and if you are plate solving you can use sgp’s focus and target positions to slew to and from a suitable star from your target - the help file has the details of how to do this.
Thought I would mention… I also prefer the Bahtinov Mask, but a while ago we added a feature into SGPro where you can turn on “Image History” and start the Frame and Focus loop. When history is enabled, the HFR for your current focus position will be displayed on the image itself (prominently in the upper left corner). In addition to this, the image history module will record the lowest HFR it has seen so far (with a focus controller, also the position it was obtained at…) with a manual focuser you will need to do a little guessing.
Not sure if it makes a difference whether you’re using a CCD or a DSLR. I only use a DSLR and prior to coming to SGP, I used BackyardEOS with my Canon T5i. I still prefer using BYE for focusing using its ‘Live Preview’ / Frame & Focus feature and once focused on a star, shut it down and switch over to SGP.
I think SGP has a ‘Live Preview’ feature too, but haven’t spent time looking at it yet to see if it can wean me off BYE completely.
I’m still trialing SGP, and loving it, but find manual focusing (without a B-mask) not very user friendly and find myself doing the same as rj above - I just use BYEOS, which is very facile, fast and accurate. I would love to see a manual focus feature similar to BYEOS implemented in SGP.
Can you not use this HFR tool/stat on a single brighter star? I’m too coming from BYEOS, but now have a CCD, I also have no intention of purchasing an auto focuser because I’m generally always outside in the observatory when imaging anyways. The added cost, weight, is not worth it to me. With as great as software can be now, I prefer not to fiddle with a B-mask, I just want to slew to a star, and manual focus while I watch the monitor for the lowest ##. I’m super new to SGP but I’m starting to get the feeling it’s not very user friendly to those without a fully automated observatory
Focusing is fine manually and also still very useful software if you aren’t fully automated - I am not fully automated one of my scopes has autofocus the other I focus manually.
I use frame and focus to capture a short exposure e.g. 5 sec depending on filter and watch the hfr on frame and focus, I make an adjustment and if better try to refine it, if worse I move the focuser in the other direction - I don’t normally loop the frames as touching the scope makes it judder a bit and confuses the situation. You don’t need to slew to a bright star to do this - if using narrowband filters you may have to use longer exposures depending on the filter
If you don’t want to use a Bahtinov Mask you can use the image history module while taking a loop of images. This will show you the hfr of your last few images so you can see if you’re getting closer to focus or moving away from it.
thanks - trying SQP and was really hoping to find something like BYE for focus. REALLY do MOST people have auto focus? I’m part of a large club and I don’t know of any members with auto focus. This program intimidated me away… but a demo video from a noob drew me back in. Still I don’t want to load other programs just to focus. My lowly laptop is already more apps than it can really comfortably handle.
CCD’s are always in live view. (they have no shutter). Using sharpcap and it’s fast shutter/exposure setting you do get a live view. I often use it for day light testing. It’s a shame most other software capture has a max exposure of 1 or even .5 seconds. With sharpcap I can set 1/500th for day time (live view) and test captures.
Would be nice if SGP could add these faster exposure options too.
Many CCDs actually do have a physical shutter. I would say the lack of a shutter is actually a fairly new thing, mostly found with CMOS cameras. Almost all CCD based cameras do have a physical shutter.
You can type in whatever you want for the exposure. Our minimum is the minimum that the camera reports it can capture through the ASCOM driver.
As far as how to manually focus I would recommend pulling up the Image History module and running the frame and focus utility. This will give you a large readout of your current HFR on the image as well as show the trend line for the HFR and star count in the Image History module. Should make manual focusing fairly easy to hit your best HFR.
I stand corrected - thanks - Never seen one with a shutter, though I’m quite new to this. I’m trying to learn your software during the day when it’s tolerably warm here. (Michigan). And it’s been limited by not allowing me to test which higher exposures. I will look for what you suggested!
Making progress with the help of this support area. THANKS. I have setup in garage (looks like rain here in Michigan) surely cloudy at noon). I found another post that said “image history and uncheck enable” this stopped the pause after a test shot while it was looking for stars (during the day there are none). I can enter daytime exposures of 0.05 thanks for pointing out I can enter anything. Since no stars - I loaded a star image, says needs to be grayscale 16bit. I’ll go make one. Making progress with SGP.
Not so fast buddy -
so I take a star image, I change it to 16bit in photoshop and change mode to greyscale in photoshop. I save as a .tif. I go to load it in SGP to experiment with and it says open image error. Value cannot be null. (which value is empty?) then says parameter name: dib. ?
That brings up another question. Say I’m shooting frame and focus shots… my camera is a 071MC. (color) F&F wants 16bit grey for HFR). In other software I can set the capture to RGB or 8 or 16bit raw. But I don’t see any such option in SGP? How do I force it’s required 16bit-grey format and then change back to RGB for my actual color captures?
SGPro can only open uncompressed, single layer tif images. We don’t really recommend this workflow as it strips all of the header information out of your image.
SGPro only ever takes 16-bit grayscale images. Color is only needed during post processing steps.
