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Forum: Pentax K-1 & K-1 II
07-26-2017, 01:26 PM
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Thanks once again for all the useful info Bob. I noticed that Samyang/Rokinon sells a 500 mm CAT. Given the good quality of the prime lenses made by Samyang perhaps the quality of the CAT would be superior to most others. Or perhaps not? I wonder if Samyang actually manufactures theirs - all of them sound very much alike in the descriptions.
Do you think there is any reason to not use pixel shift, other than the large file sizes which won't be a problem for me as I will have some large capacity cards? Thanks again.
Btw, do you live in the zone of totality? I noticed you live in Idaho as I do and I am in the zone, although not in the center.
Mike
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Forum: Pentax K-1 & K-1 II
07-25-2017, 08:41 AM
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Thanks Bob. I looked on B&H and didn't find any lenses labled Matsukov but did find several f8 fixed aperture 500 mm mirror lenses with different brand names. I assume that's what you meant.
On Amazon and B&H I also found many non-mirror f8 - 32 manual lenses in 500 mm and several of these include a doubler for 1000mm reach for a bit less than $100. A description is below (I assume these are all made by the same manufacturer). These would seem ideal for the eclipse but I wonder about the IQ. When a 500 mm standard type lens from Sigma, etc. costs $5-6000 it's difficult to imagine a $90 lens would provide much quality. I'm not knowledgeable about optics and have no idea what "catadioptic mirror lens" or " achromatic refractor design" mean. The description:
"This is a 500mm / 1000mm f/8 Manual Focus Lens is a classic refractor-style T-mount lens, with an aperture diaphragm in the middle of the lens body to stop down the aperture when necessary. However, it is assumed that much of the shooting with such a lens will be at its maximum f/8.0 aperture, with a tripod, monopod, or other such support. The included 2x doubler converts this 500mm lens into a 1000mm.
This lens' sophisticated achromatic refractor design yields images with pleasing peak contrast and well controlled flare. It can be used at maximum aperture on a very bright day for some images of moving subjects.
- Achromatic refractor 500mm f/8 lens in T-mount
- Multicoated optics
- Knurled focus ring to the front of the lens
- Accepts 67mm filters on the front of the lens
- Fixed tripod collar"
I know you said you don't have any personal experience with such a lens but, given the design of these lenses do you think either of these lens types might give decent IQ, or at least IQ comparable to a telescope?
I've never done any astrophotography and I greatly appreciate your input on this. Thanks.
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Forum: Pentax K-1 & K-1 II
07-24-2017, 08:04 PM
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Bob, you recommend a telescope on the camera over a lens. Do you have any specific recommendations for a telescope? Price is a consideration, especially since this will be a one time use. This will be for a K-1 which I would think would allow a substantial amount of cropping.
Thanks.
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