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06-19-2013, 08:17 AM   #31
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QuoteOriginally posted by interested_observer Quote
Using that approach, if I am use to using my trusty DA 60-250/f4 on my K5, and I go out and acquire a brand spanking new Nikon D800, and I want to maintain a similar focal length range (read angle of view) for it, what do I look for. Again, 60/1.5 = 40mm and 250/1.5=166mm (rounded). Stepping back and trying to look at this objectively, I am going from a smaller sensor (APS-C) to a larger FF sensor. Essentially I am loosing the "cropped" angle of view extension (factor), that the APS-C sensor afforded me. Bottom line, the FF sensor is going to be shooting "shorter" than the same lens on the APS-C sensor.
I believe the crop factors (1.5x for APS-C, 2x for micro 4/3) are so that they give an idea of the angle of view a lens provide compared to classic 24x36mm format. So, if you look through a 50mm mounted on a APS-C body, youīll get the same field of view as if you looked through a 75mm lens mounted on a FF camera (film or digital)
If you mount the 50mm on a micro 4/3 body, it will give the same field of view as if you looked through a 100mm lens mounted on a FF camera (film or digital).

Same applies to other formats, 645 for example, I donīt know itīs crop factor but I guess it is less than 1 becouse itīs sensor is bigger than 24x36. The thing is each crop factor, calculated for each format, makes reference to 24x36 format. I guess this is because the 24x36 was the most popular format not so long ago, so it makes for a good reference. More so knowing that "50mm is normal, shorter is wide, longer is tele".
So if you mount the DA60-250 on a film camera, it will give you the field of view of a 60-250mm lens. Crop factor for 24x36 format, aka FF: 1x
(disregarding vignetting, because the lens is for APS-C, which has a smaller image circle than FF)

06-19-2013, 08:36 AM   #32
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QuoteOriginally posted by interested_observer Quote
Morning Bossa and Falk,

Perhaps my thinking is flawed, backwards and all wet (it would not be the first time according to my wife). In comparing APS-C to FF, the APS-C with the smaller sensor, on the telephoto end of the spectrum has the smaller angle of view, when discussing a single specific focal length. In the nominal conversation, the 1.5 crop factor came into being when folks who were use to using a FF film body, wound up using a cropped APS-C digital sensor. "Suddenly", their FF film lenses had a "new" angle of view, that was 1.5x of the focal length they exhibited on film. A film photographer using their 100mm film lens on their "new" APS-C digital sensor, saw their lens exhibit an angle of view of a 150mm lens, courtesy of the smaller sensor's crop factor (1.5 * focal length = cropped apparent focal length).

Now we find ourselves here in Pentaxland, with the possibility / potential of a full frame digital sensor out on the horizon. With Canon, Nikon and Sony already having theirs on the market, Pentax shooters have either migrated or are using dual system to shoot both APS-C and FF bodies. With this in mind, folks who have been shooting with the APS-C cropped sensor focal length of say 100mm, in order to maintain the same angle of view, should see the reverse. If I mount a 100mm on my APS-C body, what focal length would I need to mount on my FF body to maintain the equivalent angle of view. I would think that it would be 100mm / 1.5 = ~66mm (rounded).

Using that approach, if I am use to using my trusty DA 60-250/f4 on my K5, and I go out and acquire a brand spanking new Nikon D800, and I want to maintain a similar focal length range (read angle of view) for it, what do I look for. Again, 60/1.5 = 40mm and 250/1.5=166mm (rounded). Stepping back and trying to look at this objectively, I am going from a smaller sensor (APS-C) to a larger FF sensor. Essentially I am loosing the "cropped" angle of view extension (factor), that the APS-C sensor afforded me. Bottom line, the FF sensor is going to be shooting "shorter" than the same lens on the APS-C sensor.

That is my thought process....

Bottom line is that I think that Pentax Australia's website is incorrect. They are just adding another 1.5x crop factor on to the APS-C, when in fact they should be dividing it out. Hence, moving from FF to APS-C multiply by 1.5 then moving from APS-C to FF divide by 1.5.

Then again, I am here in Arizona and today its going to be 110 out in Tumbleweed country.

Sorry, but it is the opposite. The crop factor basically means that you get the field of view of a 1.5x longer lens on full frame as compared to APS-C. So 60mm on APS-C is bascially same field of view as 90mm on full frame.

You are over thinking it. Basically if you mount a 50mm lens on full frame you see a wider angle of view which is then restricted (making it look like a longer lens) when you mount it on APS-C.
06-20-2013, 12:37 AM   #33
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I stand corrected - not enough coffee after waking up.....

06-20-2013, 06:26 PM   #34
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QuoteOriginally posted by Mallee Boy Quote
I am a little frustrated with Pentax at the moment in so far as they are not giving us a lot of info on the top end of their range and any planned upgrades or new products.
How does this affect your shooting with your present gear?

06-20-2013, 06:43 PM   #35
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weak spot isn't so weak ;)

QuoteOriginally posted by falconeye Quote

I do agree with bossa that 300mm currently is a weak spot in the Nikon lineup (old lens, no VR, not as sharp as the newer ones).
I'll have to disagree with this ^^ regarding sharpness. I have the older autofocus 300 f4 (AF but not AF-S) and it shows remarkable sharpness even wide-open. I have not compared it directly to the DA 300 f4, but Klaus (photozone) has the AF-S version bumping into 'excellent' in the center wide-open, while the DA stays 'very good' (for what that's worth.)

My 300 f4 is sharper than my Sigma 100-300 f4 @ 300mm, and that Sigma is a very sharp zoom.

It does lack VR, though, so it could be considered weak in that regard, and a candidate for update by Nikon.... But it's very sharp, and has great bokeh.

.
06-20-2013, 06:55 PM   #36
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QuoteOriginally posted by Class A Quote

Consider this comparison:
Sigma 18-35/1.8, fastest zoom in the world, 17 elements in 12 groups, 5 of which are special low dispersion elements and four of which are glassmold aspherical lenses. Reliable HSM. Price: $799.

Pentax 70/2.4, 6 elements in 5 groups, no special elements. Screw drive. Price: $696.95.

The Pentax lens is much cheaper to build and almost a stop slower, yet costs almost as much as the superb Sigma.
Something isn't right here.
It means Pentax is making a nice per-unit profit with the huge-margin 70, while Sigma might be selling much closer to break-even with that 18-35.

I'm still amazed at that price, and I suspect Sigma is looking for mindshare as much as (or more than) profits there...
06-20-2013, 08:11 PM   #37
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QuoteOriginally posted by stormtech Quote
How does this affect your shooting with your present gear?
Doesn't help when trying to plan ahead with filling in gaps in my "arsenal" or capability. example: I'm not happy with the results I get with the Sig 135-400 (for commercial purposes) and I acknowledge I have a shortcoming in providing quality images above 200mm. So does one go with the DA* 300 or Sigma 300 f2.8, at the current pixel count (crops off a 24 or 36mpx shot are handy) of 16....or does one bite the bullett and make the leap to the 24 or 36 brigade.? Thats the frustration. If I knew Pentax had plans to provide something in the forseeable future it would be a no brainer.
06-20-2013, 10:13 PM   #38
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QuoteOriginally posted by jsherman999 Quote
I'm still amazed at that price, and I suspect Sigma is looking for mindshare as much as (or more than) profits there...
Sure, I agree on both counts.

QuoteOriginally posted by jsherman999 Quote
It means Pentax is making a nice per-unit profit with the huge-margin 70, while Sigma might be selling much closer to break-even with that 18-35.
If we can believe everything that has been said regarding the UPP/MUP/MAP fiasco then we also know that dealers make obscene margins on many Pentax lenses (not so long ago the 70/2.4 was "just" $544.95" and a 60-250/4 was $1295.95 instead of $1999.95; the latter is a $704 or 54% difference!). I'm not sure whether these dealer margins are the same for Sigma products.

Obviously Pentax thinks that high dealer margins are necessary to bring back their products into (no longer existing) mom&pop stores but perhaps Sigma does not need to enforce the same margins because they still get store presence.


Last edited by Class A; 06-20-2013 at 10:23 PM.
06-20-2013, 10:48 PM   #39
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QuoteOriginally posted by Mallee Boy Quote
Doesn't help when trying to plan ahead with filling in gaps in my "arsenal" or capability. example: I'm not happy with the results I get with the Sig 135-400 (for commercial purposes) and I acknowledge I have a shortcoming in providing quality images above 200mm. So does one go with the DA* 300 or Sigma 300 f2.8, at the current pixel count (crops off a 24 or 36mpx shot are handy) of 16....or does one bite the bullett and make the leap to the 24 or 36 brigade.? Thats the frustration. If I knew Pentax had plans to provide something in the forseeable future it would be a no brainer.
Ok - that makes me understand the "why" then.

I was in a similar position a while back - frustration of selection of longer lenses. After a thorough evaluation, I ended up staying put. The cost to arrive at my current lens line up with Nikon was kind of expensive - I tried to be realistic when looking at what the market was paying for used lenses, and also looking at the fact that I might have had to buy some of the Nikon lenses new instead of used. Then what really swayed me to stay was looking at the accessories I had that were Pentax specific (flash, etc) and it made it look even worse.

I had some excellent coaching from a couple members here who had recently made the switch which was great in helping show me the benefits along with some draw backs to making a big jump like this. In the end some might see it as "settling" by staying put, but I simply put it in my mind to work with what I have. At the end of the day, it is more about the operator than the equipment. Can't get a longer lens? Get closer.

I guess I was hoping that your reason for thinking of switching wasn't just due to the fact of rumors (or lack thereof?).
06-21-2013, 12:38 AM   #40
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Stormtech: No, I am not a "follower of fashion", I tend more to do what suits me and my style, so believe when I say I do not want to leave Pentax. I will probably end up going after a DA* 300 after reading another post this afternoon and live in hope that Pentax wont be too far behind in releasing something that fits the bill.
I, like you, have had a pretty good look at Nikons offerings and do not relish the cost of making a change.
Cheers
Grant
06-21-2013, 01:00 AM   #41
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Regarding my original post, I made the decision to switch to Nikon, and bought a D7100 new a few days ago. I felt the switch was further validated when I picked up a second hand Nikon 70-200/2.8 VR1 for $1500NZD, and have also seen (for example) a Nikon AF-s 300/4 going second hand for as low as $1200. I have yet to see any quality long secondhand Pentax lenses on the same trading site. As some previous posters have mentioned, the cost of switching system is limiting factor, but luckily I had only invested around $1900NZD in all my Pentax gear, and was able to sell this second hand without too great a loss. Also, the availability of second hand Nikon lenses will likely counter this loss in the long run.
With regards to getting closer to the subject rather than getting a longer lens, there are times when this is simply not possible. For example, I work at sea, and if I tried to get much closer to the albatrosses I would probably end up in the trawl net . In saying that, I agree that the 'get closer' argument will be applicable as many times as not.
06-21-2013, 05:17 AM   #42
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Looks like you made the right decision for your needs and your good feeling.

Congratulations!
06-21-2013, 06:17 AM   #43
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QuoteOriginally posted by Snipsnap Quote
Regarding my original post, I made the decision to switch to Nikon, and bought a D7100 new a few days ago.
Congratulations! That should be an awesome camera.


I'm interested in this thread as I'm looking to switch as well, but for different reasons.

1) daughter is disenchanted with her K-X focusing, and she's a photo major. Probably the modern K5 II/s does better, and we have a good supply or Pentax glass.
2) however, she can borrow Nikon equipment from her school, not Pentax. And the studios are set up mainly to support Canikon.
3) I have to take my needs into consideration as well. I have a good selection of Nikon manual focus lenses, and some AF that require a higher end Nikon. Hence D7000 or D7100 appeal.
4) Daughter will likely end up taking one of the F100's to school, just like in the past she's taken a Pentax film camera -- for the possibility of swapping lenses etc.
5) I'm tired of APS-C cropping, I'd love to see my 24mm be 24mm in digital. Hence the idea of a D600. But if I spend the extra ~600 over a D7000 kit for a D600 body, how likely am I to lend it to daughter for long periods

I'm more into wide-normal-short tele than into long telephoto shooting. Purely selfishly, I would love a FF digital camera.

But here's a thought: I can get the D7000 kit, AND a Pentax K30 for less than a D600 body.
06-21-2013, 09:53 AM   #44
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QuoteOriginally posted by Snipsnap Quote
Regarding my original post, I made the decision to switch to Nikon
Maybe, come back after a while and share some of your experience with your new setup. I would appreciate it.
06-21-2013, 01:38 PM   #45
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QuoteOriginally posted by falconeye Quote
Maybe, come back after a while and share some of your experience with your new setup. I would appreciate it.
Definitely. I will be going back to sea for around 6 weeks shortly so will be able to see how the handling and autofocus of the D7100 stands up to the K30 with regards to seabirds in flight, and hopefully have some more photos to post!
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