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Forum: Pentax Medium Format
03-10-2020, 09:08 AM
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Did not see this thread before. I have an RAF adapter for P645. It fits the camera nicely, without problems, although I have never really needed to use it.
My telescope has a P67 adapter made by the telescope manufacture. Then I use Pentax's own 67-645 adapter to hook up my 645z. Earlier Stevein mentioned about Astrobin search results. The majority of 645z images you can find on Astrobin was taken by me. And this is my Astrobin gallery.
To be able to to use 645z on a telescope, the adapter is just one of the equations. There are two additional requirements, both of which are more difficult to meet than getting an adapter:
1. The telescope needs to be able to project a flat image circle that's large enough for a 44x33mm sensor. Not many telescopes can do this. It typically requires a large focuser, and a large, dedicated corrector lens (focal reducer, field flattener, or coma corrector, depending on the type of telescope). Most telescopes in the market are designed for APS-C or FF, and they don't have a focuser and a corrector lens large enough for P645.
2. The optimal focus point should be far away from the last lens element of the corrector lens, far enough to accommodate the humongous 71 mm flange-back distance of P645 plus whatever length for the adapter. Among all 645 cameras, P645 has the largest flange-back distance, and not just large, unreasonably large. Pretty much only telescopes that are designed for P67 (very few) can offer this kind of back-focal distance for P645. If we are talking about Fuji GFX here, things will look much better. There are some very nice telescopes that can accommodate GFX but cannot accommodate P645, because of the very stringent requirement on back-focal distance.
The OP wanted to hook up his 645D to C4.5. There is just no hope he can do it, and no point for him to do it. C4.5 does not have the kind of large back-focal distance for P645. Even if it somehow magically has, its focuser is way too weak to support 645D's weight. Even if the weight is not an issue and even if it can reach focus, C4.5 cannot illuminate a 44x33mm area with good image quality from center to corners. If it is an 8inch Newtonian instead of 4.5inch, then it starts to look feasible. It is possible to find a strong focuser to be put on an 8+inch Newtonian with a coma corrector that can accommodate P645 (TV BIG Paracorr).
645z is absolutely a powerful camera for astrophotography. Unfortunately only few telescopes can go along with 645z.
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Forum: Pentax Medium Format
12-01-2018, 05:42 PM
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Just before we start an statistics war...
1- a film shooter will be more appealed with a CCD sensor than a CMOS, although, as has been said, today's CMOS sensors do their best to get the same colors than CCD's, but you must pay a price for those CCD colors, and it's the ISO
2- for landscapes you don't care about high ISO, much less if you use tripods, maybe your "sometimes portraits" can be more difficult to get in low light situations, BUT MF's defocus is far better than FF (I believe it, because I made some comparisons, although it maybe pure suggestion)
3- I've been said (I'm not a nikonist, although I have a D700 -with a bit of luck tomorrow I'll have not- ) there are a lot of differences between the 700 and the 850; I think you must read further about them before an upgrade: the 700 was the most praised sensor from all time Nikon, at least on my circles
4- why not to try to find a rent? Just for a weekend, rent a Z and feel it... maybe it will raise your purchase cost a bit (the rent's one), but if you don't like it, you will save a lot of money and frustration
I've had the K-5, the K-5IIs, I played with a K10D, a K-3, a K-1, and a lot of other K's, and I ended with an *istDS just because the sensor. Yes, I cannot shoot birds with it (my fault, probably), and I had to get used to noise when shooting concerts, but I did it pretty well, if you can life with "a bit" of noise
 Big Mama
The results with the 645D are pretty better, I guess
 Ster Wax i Pablo Sanpa
(both hand-held with manual focus lenses)
Do you really think you'll have worse lighting shooting landscapes?
But I always though my relationship with my cameras is more about "the touch" (how I feel them) than about "the statistics", so maybe I'm not the best one to give advice... except to NOT consider only the statistics.
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Forum: Pentax Forums Giveaways
06-30-2018, 05:10 PM
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I think there are people from Australia who entered the raffle.
I have a really fast internet connection, top of the line of what you can have in France believe me, and despite this and me doing the refreshing monkey I couldnt enter the 1st raffle....I see all this as being lucky that's it.
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Forum: Pentax Forums Giveaways
06-30-2018, 04:24 PM
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Do all these posts count towards the running total for next months giveaway of a gold Rolex?
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Forum: Pentax Forums Giveaways
06-29-2018, 10:50 AM
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This thread will open at 11pm UTC on June 30th. The first 50 people to post a reply (1 entry per household) will receive one raffle entry toward the K-1. The winner will be selected at the end of the day, based on the 100 entries from this thread and the other one.
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Forum: Pentax Medium Format
05-02-2018, 05:39 AM
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This is all I see:
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