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Are curved spider vanes better? And if so, why are they not standard equipment?

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The question is in the title. Are curved spider vanes better and if so then why are they not standard equipment? I do not own (or have ever owned) a reflector and have never looked through one with a curved spider. I am a beginner who would like to know why.

This astromart ad is what peeked by curiosity. http://www.astromart...ified_id=924330

There seems to be an entire industry devoted to supplying upgrades for telescopes. I have no way of knowing if an upgrade is a meaningful improvement or a waste of money. And if an improvement, then how much so? Negligible, modest, substantial, extreme? Then the issue of trying to quantify someones else "substantial" improvement. My eyes and value system might see little to nothing of value while they saw enormous. Does not mean people are always lying or being dishonest, just that we are different.

It gets really complicated.

I think it really depends upon whether you are bothered by diffraction spikes. In other respects (secondary mirror adjustment and flexure, contrast, cost, etc.) there are probably some tradeoffs depending upon the particular design.

The essential problem with curved vanes is that they cannot use tension to support the mirror; this means the vanes must be thicker to compensate, which increases total diffraction and reduces contrast.

So its a matter of choosing your problem.

A curved vane does not reduce the diffraction of the spider, it just spreads it out so it is not as apparent when viewed against a dark background.  Since it will need to greater in area since it cannot be tensioned, the overall effect on planetary contrast will be greater.

For smaller tube diameters with smaller secondaries, it makes a certain amount of sense if one is bothered by the diffraction spikes.

Myself, it believe the most important thing about a spider is that it holds the secondary in the most secure and rigid possible manner. A straight vane spider is better suited for that.

Bottom line: Curved Vane Spiders are not inherently better and potentially compromise the collimation.


Dan Perez:
I believe curved spiders are standard on teeter's sts line of scopes.


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