[Callum Potter]

Most of my experiments with a DSLR were with camera lenses on an old Canon 300d – so widefield mainly using fixed focus lenses – 8mm, 50mm and 85mm.

I found images were always better with dark frame subtraction.

I was never really sure how to do flat fields for ‘wide-field’ lenses – so never did.
I did use processing techniques for ‘synthetic’ flats, though, using IRIS.

I have a new camera, Canon 600d, now, but not done much with it so far. 
I expect it has much lower noise that the 300d, but whether it is neglible in exposures from 5s to 10s I have yet to measure.

Callum.

 

 

[Callum Potter]

Hi Jeremy,

if you select the text and use the link tool on the editor bar above (first line) you should be able to fix up the link. e.g.

http://www.britastro.org/vss/CSS%202126%20campaign_20140511%20(1).pdf

Cheers, Callum

 

[Callum Potter]

Thanks Mike – i guess for many of us of a certain age Pluto will always hold a fascination.

For those not keeping up to date with my blog here is an image of Pluto on 30 July and 1st August.

I’m not sure the orientation is right – as Martin Mobberley points out iTelescope T18 has a “weird PA”. I think North is at about 1 o’clock…

[Callum Potter]

Hi Cameron,

that’s a really nice image. I do like dso’s in their stary context like this, and you have nicely managed to capture the ‘wings’ which are often missed. Nice structure too.

Well done.

Looking forward to seeing more.

Clear skies, Callum

[Callum Potter]

I guess because they were originally made by Coronado, and they used their own tooling… Probably never been changed to use ‘standard’ Meade threads.

Maybe you could find someone with a broken PST available for spares?

Cheers, Callum

[Callum Potter]

Hi Terry,

you could see if you could borrow a Meade star diagonal or focusser and see if the thumbscrew from that fits yours – at least then you would have a screw to compare against.

Most of these thumbscrews seem to be a bit non-standard to me… Though I must admit I have never measured one.

 

Callum

[Callum Potter]

From a chromatic aberration point of view probably not – but many prefer wider fields of view, and ‘better’ eyepieces may be better constructed, with better coatings.

I usually use my TV plossls on my Lunt solar scope – i quite like the combination.

Zoom eyepieces seem to be quite popular too, though I don’t have one.

Sunny Skies, Callum

[Callum Potter]

And here is an image from Tom Boles on 23rd – 16 x 60s stacked. C14 f11. 21:55 to 22:15

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