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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Fernando - your Cosina 100-300 (1 Viewer)

The TS, Antares and GSO certainly all look like the same model. I think GSO make them and other companies but their own badge on. That happens with a lot of GSO stuff. Not sure how the rotating mechanism works. I get the impression that it can rotate all the time and you just set the friction on the grub screws, not 100% sure though.

Paul.
 
Fernando - thanls for clearing that up.

Excellent links Paul - thanks.



What is the idea behind a rotational focuser ? Is the standard SW focuser i have right now a rotational focuser ?
 
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Musoman said:
What is the idea behind a rotational focuser ? Is the standard SW focuser i have right now a rotational focuser ?
Click to expand...

On the rotational type you undo one screw and the whole focuser with camera can rotate allowing you to quickly frame the subject how you wish as in vertical or landscape or anything in between. On the Skywatcher's stock focuser you have to loosen the screws, rotate the camera and then lock the screws up. I suppose there's the added danger of the camera falling out during all this so the rotating focuser is a simple and quick solution. Having said that my old William Optics scope had a rotational focuser and I never used it so I don't really miss it on the Skywatcher. I just loosen the screws, spin the camera and take the photo, quite often taking the photo without locking the screws back up. I don't think it's that big a deal. I'd only get a new focuser if mine got worn out or damaged. I know the SW is only single speed but I rarely used the dual speed on my old scope, I always found the micro adjustment wheel to be too slow which could mean a missed photo. I prefer the photo to come in and out of focus quickly so I can be in focus in a split second. It's down to personal preference.

Paul.
 
Good info Paul..

I can say a rotating focuser isnt my main criteria though I'm not against it. When i choose a replacement, it'll be more on price / quality / fit.

I prefer the look of the black focus tube on the SW ( £125 ) rather than the chrome tube on the Antares ( £116 )

I also liike the idea of not bothering with adapters. In fact i didnt know some of them require adapters. I figured they'd all just mount straight on.

Something i need to find out about i guess, before i buy
 
does the lens hood come off, was thinking of replacing it to reduce some weight. (off the SW 80ED that is)
 
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thornlv said:
does the lens hood come off, was thinking of replacing it to reduce some weight. (off the SW 80ED that is)
Click to expand...

It's a push fit so yeah, just pull it off. It doesn't weigh hardly anything though so you wont really gain from replacing it. A better mod is to make a retractable one like Fernando has done. There's a photo of his in a thread somewhere.

Paul.
 
This is an intriguing project. Maybe something like this would work for me?

My ES127 has 109 mm of focuser travel, but at 952.5 mm of base focal length that doesn't let me focus all that close (even if I set it up so that there's only a few mm of travel beyond infinity focus). It would be great if I could get another 100 mm or so of travel. Extension tubes take too much time to swap in and out; by the time I've done it, the bird is gone.

How much travel does the Cosina 100-300 have? By this I mean... what equivalent extension tube is the converted 100-300 when racked in completely, and what is it when racked out completely?

With the Televue RFL-4087 reducer, I have only about an inch of travel on the focuser beyond infinity... so I may not be able to keep infinity focus.
 
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OK, measured the cosina racked out and racked in..

Racked in its 97mm - racked out its 147...so pretty much thats 50mm of easy sliding auto extension ;)

I have, of course , the 80mm of scope focuser tube too.

Minimal extension = 97mm ( focuser tube and Cosina both racked in )

Maximum extension = 227mm ( Focuser tube and Cosina both racked out )
 
Baby Blue Jay

I'm new to the site. My family found a baby blue jay. We were told to put it in an alternative nest closest to the nesting site. We can't find the nest , so we put the baby in a bucket with grass and used a rope to put it near a tree branch. If the mom doesn't come back to feed it, what would a baby blue jay eat? We fed it water from a dropper.
 
Musoman said:
OK, measured the cosina racked out and racked in..

Racked in its 97mm - racked out its 147...so pretty much thats 50mm of easy sliding auto extension ;)

I have, of course , the 80mm of scope focuser tube too.

Minimal extension = 97mm ( focuser tube and Cosina both racked in )

Maximum extension = 227mm ( Focuser tube and Cosina both racked out )
Click to expand...
Cheers Musoman.

50mm of extra focus travel... not as much as I hoped, but still a nice improvement. And 97mm would still allow me to reach infinity focus without a reducer on my ED127.

I just ordered one. Not as good a price as you got — £16 + £10 shipping — but still good enough.

Okay, so what other ingredients will I need? Did you have to machine any parts? How did you replace the Minolta MD mount with a Canon EOS one?
 
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birking said:
I'm new to the site. My family found a baby blue jay. We were told to put it in an alternative nest closest to the nesting site. We can't find the nest , so we put the baby in a bucket with grass and used a rope to put it near a tree branch. If the mom doesn't come back to feed it, what would a baby blue jay eat? We fed it water from a dropper.
Click to expand...

The trouble with picking up baby birds is that they LOOK like they've been abandoned, when in fact they haven't. The mother would have almost certainly been about somewhere, although on a rare occasion, a baby is alone.

I'd leave it back where you found it, as long as its not any danger from local cats and stuff. Keep an eye out from a distance, so that the parent bird cannot see you.
 
David Ellsworth said:
Cheers Musoman.

50mm of extra focus travel... not as much as I hoped, but still a nice improvement. And 97mm would still allow me to reach infinity focus without a reducer on my ED127.

I just ordered one. Not as good a price as you got — £16 + £10 shipping — but still good enough.

Okay, so what other ingredients will I need? Did you have to machine any parts? How did you replace the Minolta MD mount with a Canon EOS one?
Click to expand...

Mine was cheap because it was an earlier version of the model that Fernando bought. I actually bought the Cosina because i thought thats what Fernando had done to get extra extension without having to keep changing the tube lengths by unscrewing one set and screwing in another longer set. In fact, after i bought the Cosina, not only did Fernando post that his was a later model, ( may have been better built ? ) but that he never used it as an extension at all, as all he wanted was the CPU inside the lens. ;) I didnt pay attention. But i ended up with something unique :t:
Anyways...
I almost totally dismantled it. I took all glass out, and the rear mount off. I then 2 part epoxied an EOS > M42 chipped adapter where the Minolta mount was. I also epoxied the twist to focus portion, and also cut it down a bit. Whats left is whats sticking out the front, which is enough to insert in the scope focuser tube, and get a decent amount of clamping action on it.
 
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