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02-25-2012, 09:35 AM   #331
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QuoteOriginally posted by Frogfish Quote
Anyone into digiscoping can tell you there are some fantastic ED scopes giving superb, sharp and CA/PF free photographs and that are fully WR. If it's anything like them I'll be a happy bunny as I was on the verge of buying one.
I beg to differ.

The Pentax PF-100ED for $1700 is the scope which is as close a reference as it gets. It is a superb ED triplet and gets top notch reviews from birders AFAICS. And it is even water-proof, not water-resistant (you can submerge 1m deep into water ...).

But there is no doubt that scopes can't match the better photographic tele lenses when it comes to resolution. The angular resolution of a sensor (~image diagonal/6000 for the K-5) is much higher than that of the human eye (~image diagonal/2000). And scopes are made to outresolve the eye, not a digital sensor.


Last edited by falconeye; 02-25-2012 at 09:42 AM.
02-25-2012, 11:51 AM   #332
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QuoteOriginally posted by falconeye Quote
I beg to differ.

The Pentax PF-100ED for $1700 is the scope which is as close a reference as it gets. It is a superb ED triplet and gets top notch reviews from birders AFAICS. And it is even water-proof, not water-resistant (you can submerge 1m deep into water ...).

But there is no doubt that scopes can't match the better photographic tele lenses when it comes to resolution. The angular resolution of a sensor (~image diagonal/6000 for the K-5) is much higher than that of the human eye (~image diagonal/2000). And scopes are made to outresolve the eye, not a digital sensor.
Interesting Falk. Though I may have used the wrong term is saying 'scope'. I was referring to telescopes such as the superb Skywatcher Black Diamond 80ED (which I've seen some stunning shots from). Does the same still apply ?

TELESCOPE SUPPLIERS - SKY-WATCHER TELESCOPE
02-25-2012, 04:08 PM   #333
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QuoteOriginally posted by Frogfish Quote
Interesting Falk. Though I may have used the wrong term is saying 'scope'. I was referring to telescopes such as the superb Skywatcher Black Diamond 80ED (which I've seen some stunning shots from). Does the same still apply ?

TELESCOPE SUPPLIERS - SKY-WATCHER TELESCOPE
First, let me clarify that while spotting scopes may not fully match a photo tele lens, my argument based on the human eye's capabilities are not accurate. In practice, a Pentax PF-100ED (630mm) may be paired with an eyepiece such as the splendid Pentax XW20 eye piece, yielding a 32x magnification which would translate to ~1500mm focal length on 35mm or 1000mm on APSC (using 50mm as 1x). The XW20 was reported to look good visually. So, at 500mm on an APSC body, it may not be as bad as my initial comment would suggest. Because the eye sees a magnified image of what the sensor sees.

Wrt astronomical telescopes, I already made a comment earlier in the thread. I linked to a source where it looks like the better 4 element telescope designs may actually outresolve a photo tele lens in the center but become worse quickly off center.
02-25-2012, 05:41 PM   #334
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QuoteOriginally posted by GordonZA Quote
A bit of fun speculation for you all..
If you look carefully at the photos of the sample lens where the DA 560 F5.6 is you will notice some tape to hide additional lettering...
What if this is actually a super zoom?

Maybe it's actually a DA 560 F5.6 - 800 F8.0..... With a push-pull type construction similar to the Canon 100-400mm... That would make this a "cheap" super zoom that would be completely unique and different?

Note that the name of the lens given on the Pentax Japan site is tentative... Ie not yet final...

Just some fun for you all....
Maybe the lettering is different to a normal zoom. Maybe it is just not a standard zoom, but a lesn with two settings. So it is either 560mm/f5.6 or wen retracted 800mm/f8 and notting in between. I guess that is the cheapest way. Could be very nice.

02-25-2012, 06:22 PM   #335
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QuoteOriginally posted by RonHendriks1966 Quote
Maybe the lettering is different to a normal zoom. Maybe it is just not a standard zoom, but a lesn with two settings. So it is either 560mm/f5.6 or wen retracted 800mm/f8 and notting in between. I guess that is the cheapest way. Could be very nice.
If that was the case and it was $2500 that would be the deal of the century! (no sarcasm) Knock me right off the fence and into buying land!
02-25-2012, 08:12 PM   #336
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A 560mm f5.6 lens on a Pentax K5 is equivalent to 840mm in 35mm full frame terms. A Nikon 200-400mm f/4 zoom on a D300S has an equivalent 840 mm only with the use of a 1.4X converter. And at 840mm with the 1.4X, it is a f5.6 lens just like the Pentax. However the Nikon autofocuses with the 1.4X. The difference between the two lenses is that the Pentax is a prime at 840mm with full autofocus while the Nikon is a zoom at all focal lengths. No lens slower than f4 of any brand will reliably autofocus with a 1.4X converter. You have to manual focus. So what I am saying is that a Pentax 560mm f5.6 could be a great lens to use.
02-25-2012, 08:33 PM   #337
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QuoteOriginally posted by fredok1 Quote
No lens slower than f4 of any brand will reliably autofocus with a 1.4X converter. You have to manual focus.
I did not get it. Even DAL 55-300 autofocus with 1.4X TC and 1.7X AFA up to f/8 (on the lens). And I expect the 560/5.6 to autofocus with such TCs easily.
02-25-2012, 09:15 PM   #338
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QuoteOriginally posted by Greyser Quote
I did not get it. Even DAL 55-300 autofocus with 1.4X TC and 1.7X AFA up to f/8 (on the lens). And I expect the 560/5.6 to autofocus with such TCs easily.
But it's a struggle with the 55-300, a real struggle !

02-25-2012, 09:16 PM   #339
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QuoteOriginally posted by falconeye Quote
First, let me clarify that while spotting scopes may not fully match a photo tele lens, my argument based on the human eye's capabilities are not accurate. In practice, a Pentax PF-100ED (630mm) may be paired with an eyepiece such as the splendid Pentax XW20 eye piece, yielding a 32x magnification which would translate to ~1500mm focal length on 35mm or 1000mm on APSC (using 50mm as 1x). The XW20 was reported to look good visually. So, at 500mm on an APSC body, it may not be as bad as my initial comment would suggest. Because the eye sees a magnified image of what the sensor sees.

Wrt astronomical telescopes, I already made a comment earlier in the thread. I linked to a source where it looks like the better 4 element telescope designs may actually outresolve a photo tele lens in the center but become worse quickly off center.
Thank you for the clarification Falk. In that case the telescope sounds like it could be an excellent birding lens !
02-25-2012, 10:31 PM   #340
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I use the Pentax PF80ED scope with the CA-35 DSLR scope adapter. Whilst it does still allow the focus beep to work on centre spot focusing (on my K10D), it is a difficult combination to focus! The focus wheel on the scope adjusts the focus by quite a large amount with only a small turn of the focus wheel. Using the spot focus beep I can get some pretty decent shots... The nice things about this new lens over a scope:
1. The AF
2. Fine manual focus control
3. Aperture!!! F5.6 as opposed to F13.5!!!

Still hoping it turns out to be a zoom though....
02-26-2012, 09:18 AM   #341
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QuoteOriginally posted by GordonZA Quote
3. Aperture!!! F5.6 as opposed to F13.5!!!
The Pentax PF-80ED is 504mm f/6.3.
02-26-2012, 10:11 AM   #342
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Here are the specs from the Pentax site:
http://www.pentax.jp/english/products/binoculars/scope/pf-ca35/spec.html

I got it wrong, with the ca-35 it is a F12.5 not F13.5...

With the PF-80ED it's a 1530mm on APSC...
02-26-2012, 11:18 AM   #343
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QuoteOriginally posted by GordonZA Quote
Here are the specs from the Pentax site:
PF-CA35 : Spotting Scopes : Binoculars / Spotting Scopes : PENTAX

I got it wrong, with the ca-35 it is a F12.5 not F13.5...

With the PF-80ED it's a 1530mm on APSC...
I talked about the PF-80ED (and before, the PF-100ED) and the focal lengths I referred to are correct.

You talk about the PF-CA35. This obviously is a 2x teleconverter which also has a mount to adapt SLRs. But you still cite wrong properties for the PF-80ED as such. If you used a so-called focal-plane adapter, you'd see the native properties of the PF-80ED.


...

But the PF-CA35 being a 2xTC is interesting. It allows a good test of the lens optical performance. Do you have any 100% crops (1:1 pixels) you can share with us?
02-26-2012, 11:37 AM   #344
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Not sure what the specs on the scope alone are but take your word for it... The combination gives you what I mentioned. Having that eyepiece adapter is awesome!

These were taken using my K10D, PF-80ED and CA-35...

I did crop and slightly sharpen these, would have search my laptop to find the originals but at least these should give you an idea... The gull has taken handheld in a howling Cape Town South Easter!
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02-26-2012, 11:51 AM   #345
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By the way handheld shooting with a scope is very difficult... You have to hold your breath otherwise your chest rising and falling with each breath takes you way off your target...

Also it is extremely difficult to focus....
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