Jason Tube Upgrade

[Tawhano]

I’m contemplating getting either an Orion 100 or 120mm Refractor Tube Assembly to replace the Jason 80mm tube on my damaged rig. The tripod is very sturdy and although the scope was disappointing the tripod held up well when I attached a Pentax 35mm SLR camera to it. I mainly want to take photos of the moon and planets, single shots no long exposures. For DSOs I’m getting the Orion SkyQuest XT10 but not to take photos.

What visual difference would I notice between the two tubes? Say for example I’m looking at Jupiter, will the disc be significantly bigger in the 120mm than the 100mm; that sort of thing.

The first problem I see is that the Jason attaches the tube assembly to the EQ mount via a circle clamp that wraps around the tube. The Jason tube is 3 ½” in diameter. Anyone have the Orion tubes and can tell me the diameter of the tube?

The second problem is the length of the tube. The Jason tube is almost three foot long whereas the Orion 100mm tube is about two foot. Will that play a part in being able to set the scope up to align the EQ mount? I’m guessing it won’t but want to be sure.

[iceman (Mike)]

Hi there

What type of mount is it?

Also, why would you not want to use the 10" dob for planets (eg: Jupiter) as well as deep-space objects?

The 10" dob will give much more pleasing views of both Solar System objects and deep-space objects. Aperture rules, especially when you have correctly collimated, allowed the mirror to cool down and have decent seeing.

The refractors are good for lower power wide field views, and are great for photography of deep-space objects.

For photography of the moon and planets, your best bet is to get a webcam rather than the single shot from an SLR or DSLR. You'll get much better and more consistent results.

You can use the webcam for solar system photography on your 10" dob, but the best results are achieved with tracking. Either an EQ platform under your dob, or put the 10" OTA on an EQ6.

Webcam solar system photography with an ED100 or 120 is also possible, it's just that the image scale and resolution will be much less than what you'll get with a 1250mm FL 10" newt.

[Tawhano]

The Jason mount is an equatorial mount.

I hope to get a webcam in the future but for now I will have to be content with my old Pentax SLR.

I have been reading where a dobsonian is not the best choice for photography so that is why I want to upgrade my refractor. I hope to get a better EQ mount in the future with a tracking motor to take photos. Finances dictate that I make do with what I have and upgrade when I can.