DBK 41 reluctant to focus

[trent_julie]

Good morning everyone,

I would like to pick the forum's brain about a particular problem I encountered this morning.

I was attempting to image mars using;

ED100
DBK 41 Webcam
with and without Powermates

I have success using this method previously imaging Mars, however i was using a 1000d with movie record software.

So this has lead to me believing I'm doing something wrong with the webcam itself, I used a lot of different settings but still no detail could be wrangled out of Mars....

I had the collar both attached and removed from the DBK 41, this caused no difference,

I had attempted to use a bartinov mask to achieve focus.... and to be honest this didn't help at all.

It really seems that the DBK 41 just does not want to focus...
I am using a motor driven focuser which is capable of extremely fine adjustments so its not like I'm skipping past that elusive focus point.

Any experience / suggestions to ease my frustration would be greatly appreciated.


Cheers,

Trent

[[1ponders] (Paul)]

Try it with the star diagonal in place Trent. If it reaches focus then you will need an extension. This is the most likely cause.

Its unlikely to be the DBK unless you have the exposure set too low or the gain too high and the image is being over exposed.

[trent_julie]

Thanks for that Paul,

I'm a little confused though, As I have plenty of travel left in the tube in either direction and i can infer where the focal point wants to be, however, at no point clarity is evident.

Just as a side note seeing wasn't the excellent, however experience dictates that more detail should be expected considering under the same conditions I got polar caps and some darkened features with the 1000d.

Maybe my final exposure levels where out of wack, however I did play around until i got the best out of the camera.... which was not good at all.......

[[1ponders] (Paul)]

Ok, so if as you focus Mars gets smaller and then larger as you go through the point then its probable that it is the exposure settings. Can you focus on a star? How does it focus on the moon without and with the powermate? Have you tried Jupiter yet?

Even using the powermate with the ED100 you won't get an awful lot of detail and mars will be small and bright. Drop your gain down to about half and start your exposure at a point where you can just make out Mars when it appears slightly out of focus. As you focus, reduce your exposure time as mars becomes brighter.

If you want to use your BT Mask, find a good bright star fairly close and increase your exposure to around 5 sec or so and increase your gain to around 80-90%. Initially don't try to focus on Mars using the BT Mask. Use a nice bright star.

Hope that is useful.

[trent_julie]

Thanks Paul,

I will try the method of setting the exposure level tonight for imaging Jupiter, I will be using a 16inch lightbridge as well to get a bit of a comparison. Thanks for your comprehensive assistance, I will post tomorrow with my results,

Thanks again

Trent

[[1ponders] (Paul)]

Your welcome Trent. Hope it comes together for you. Definitely post results. Best way to get feedback around here.

[Irish stargazer (John)]

Hi

Does your camera have an IR cut filter installed? Focus can be awkward without one.