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Skywatcher 150P and SPC900 WebcamFocus Problem

tmartin

By tmartin
in Discussions - Cameras

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tmartin

tmartin

Posted
Posted

Hi Folks,

I'm suffering from information overload in trying to search for an answer to my webcam focusing problem and am in great need of help!!

I've recently purchased a Philips SPC900 series webcam, to go with my Sky-Watcher 150P Dobsonian and I'm having problems focusing it. I was looking through a Sky at Night magazine's back cover disk's 'Hot Spots' section and saw a full picture of the moon, citing the same equipment that I have, which gave the 'apparent' view as if seen through a 25 mm eyepiece; which enthused me to start astro-imaging. However, when I set mine up, the view was as if I was looking through a 10 mm eyepiece, i.e. looking close up (just the Mare Imbrium), with the added problem of the 'rack and pinion' focusing at the end of its travel and being unable to focus the image.

I'm at a loss to work out this conundrum and would greatly appreciate your help and guidance.

Thanks in anticipation,

Tom

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Dazza121

Dazza121

Posted
Posted

I have a 130eq with the philips cam and i can only get about 1/5th of the moon in the frame so reckon yours would be even less. I have been told that this is usual and to get a pic of the whole moon you need to do a mosaic (which ive not been able to try yet as there is no moon to view).

Dont have any focusing problems so cant help you there unfortunately.

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Parus major

Parus major

Posted
Posted

I've got the F8 tube as well, what you might find is that during collimation the mirror might be a bit far up the tube. Try tightening the bolts back to pull the mirror down the tube and re-collimate.

You can also try it in the daytime by removing only the wee cap from the cover and aim at something far away.

I must admit to being a little puzzled at this since with mine the focal point with the camera only is about 9mm out from fully racked in.

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tmartin

tmartin

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Many thanks for those that have commented, much appreciated.

If I can respond in turn:

Dazza121 - I've read that the mosaic is a solution for this type of set up, in capturing a full moon on a webcam and I don't have a problem in principle ... Photoshop works wonders!! I'm just very surprised that this is how such a relatively small scale photo was collated, as it would take a considerable number of processed images to make the final photo.

the 5th race - Am I right in thinking that this reducer will effectively allow the eyepiece's focal point to 'travel' further in down the eyepiece holder for the same physical position of the rack? One thing I've been told is that the eyepiece is too far back in the housing and that some form of adapter is needed to change the 1.25" current housing, thereby allowing the eyepiece to be located closer to the secondary mirror. Would this be fitted before or after the IR filter?

Parus major - I don't have a problem with collimation, as everything appear to be as tight as it should be and nothing seems to have migrated. Certainly the secondary looks to be nicely lined up on the cross hairs. I've a solar filter, so have been experimenting by day, but cloudy skies have thwarted my efforts of late! Perhaps the focal reducer will allow me that last little bit of adjustment.

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martindf3

martindf3

Posted
Posted
Hi Folks,

I'm suffering from information overload in trying to search for an answer to my webcam focusing problem and am in great need of help!!

I've recently purchased a Philips SPC900 series webcam, to go with my Sky-Watcher 150P Dobsonian and I'm having problems focusing it. I was looking through a Sky at Night magazine's back cover disk's 'Hot Spots' section and saw a full picture of the moon, citing the same equipment that I have, which gave the 'apparent' view as if seen through a 25 mm eyepiece; which enthused me to start astro-imaging. However, when I set mine up, the view was as if I was looking through a 10 mm eyepiece, i.e. looking close up (just the Mare Imbrium), with the added problem of the 'rack and pinion' focusing at the end of its travel and being unable to focus the image.

I'm at a loss to work out this conundrum and would greatly appreciate your help and guidance.

Thanks in anticipation,

Tom

I have just got a 0.6 focal reducer and screwed it on the end of webcam adapter and I too cant get the webcam focused. Tried removing all my TAL 150p Focusser fitting and still it wont come in to focus . Didn't quite understand the explanation you were given allthough I can collimate my scope without problem . Question does the reducer have to be closer to webcam sensor or whole webcam be closer to the secondary mirror ?
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Viv

Viv

Posted
Posted

I had the same problem with my original 200p.

have you tried using the standard barlow that came with it ?? That's what worked for me.

You need to increase the focal length (think), this is the way to do it.

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tmartin

tmartin

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Cubemaster ... just thinking, my Philips SPC900NC webcam came with a 1.25" eyepiece adaptor (plus IR filter) as part of the kit, are you suggesting an extension tube to add onto the screw in adaptor as supplied?

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  • 4 weeks later...
tmartin

tmartin

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Thanks everyone, I tried and failed in trying to change the housing from 1.25" to 2", with an adaptor last night, where the aim was to reduce the distance between the webcam and the primary.

I'm still working on the problem, so all thoughts welcome.

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tmartin

tmartin

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Cubemaster, thanks for the link, but it looks exactly like the one that came as part of the kit. The problem is that the webcam sits level with the holder, regardless of how long the adaptor is.

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