Bahtinov mask spikes missing.

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goldstar
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Bahtinov mask spikes missing.

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Post by goldstar »


Something I have noticed on Baht focusing with my modified Canon XS. Using a SW 80 ED.
I use either of two DSLR's for AP. A stock Canon 3 Ti or a modified XS.
Until now I have preferred the 3 Ti because of the convenience of the flip screen. However I did some basic tests that showed that as expected the XS picks up more photons per exposure time than the 3 Ti in R.G and B. I know I can expect more in R. I can halve the exposure time for the same result on the XS. Presumably since the pixel size is greater (20 Mpx v 10 Mpx).
So sacrificing the convenience of the flip screen I use a mirror to view the fixed XS screen when at awkward angles and it works well.
However I notice that I do not see the focusing spikes as easily, if at all in the XS as I do in the 3 Ti.
I can't figure out quite why. It's no big issue as focusing just by using smallest star dot works OK.
The image brightness in both screens seem to be the same with and without mask and all camera settings the same.
The spikes largely disappear in the XS. ????
Is this pixel size? Screen resolution? Color response?
Scopes: 200mm f6 DOB:CR 6 150 mm f 7.5 refractor, SW ED 80 mm f 7.5. 2 X 80 mm f7.5 guides.
Mount: AVX.
NexGuide auto guider. Cameras 3 Ti and XS modded. I optron Skytracker.
Motley EP collection.
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