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09-16-2010, 10:43 PM   #31
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Thanks, so for me (optical) fisheye is fisheye, but with a circular fisheye you get full projection in every orientation on the sensor (ending up as circular picture) - which is kind of a cool gadget (but not my taste to invest into heavily).

Difference between following still not 200% clear (two Sigma lenses):
- 10mm F2.8 EX DC HSM Fisheye
- 15mm F2.8 EX DG Diagonal Fisheye

I "assume" diagonal means 180 degrees from upper left to bottom right. And "normal" means 180 degrees from left middle to right middle. But isn't that information (indirectly) already included in focal length numbers???

So about the 10-17 mm Fisheye, that is both depending on zoom?

09-16-2010, 11:07 PM   #32
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Oh, last question, how does 10 mm UWA "translate" into X mm FE?

Wait, I should be able to extract that information from lens specifications:
- Pentax UWA 12-24 mm = 99 - 61
- Pentax FE 10-17 mm = 180 - 100
- Sigma FE 4.5 mm = 180
- Sigma FE 8 mm = 180
- Sigma FE 10 mm = 180
- Sigma FE 15 mm = 180
- Sigma UWA 8-16 mm = 114.5 - 75.7 - depending on crop factor
- Sigma UWA 10-20 mm = 102.4-63.8 - depending on crop factor
- Sigma UWA 12-24 mm = 122-84.1 - depending on crop factor

Hmm, looks like Sigma UWA degrees are not really consistent...
- Also clear that FE is effectively much more wide than UWA!!!

But the post quoted above already stated that:
https://www.pentaxforums.com/forums/679474-post3.html
09-16-2010, 11:56 PM   #33
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Sometimes I go to South-Korea, maybe one day I can get this lens there (at good price):
- Samyang 8mm F3.5 Fisheye CS
09-17-2010, 05:44 AM   #34
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QuoteOriginally posted by JoepLX3 Quote
Sometimes I go to South-Korea, maybe one day I can get this lens there (at good price):
- Samyang 8mm F3.5 Fisheye CS
I got the samyang (rebranded as Pro Optic) at Adorama in NY for $279. I also use a Sigma 10-20 UWA.

the two behave very differently, and I use them both. The fisheye effect is something you have to consider, but it is all about how you line up your shot as to whether you want the effect niticible or not.

Optically the samyang lens performs well, and controls flare beyond my expectations, which for a 180 degree FOV is difficult because it is almost impossible to keep th esun out of the frame.

Note for the Sigma UWA zooms the FOV is stated for a 16x24mm ASP-C sensor but some, like canon specifically are a little different, as well as the use of these lenses on 4/3 systems

09-17-2010, 05:50 AM   #35
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QuoteOriginally posted by Lowell Goudge Quote
I got the samyang (rebranded as Pro Optic) at Adorama in NY for $279. I also use a Sigma 10-20 UWA.

the two behave very differently, and I use them both. The fisheye effect is something you have to consider, but it is all about how you line up your shot as to whether you want the effect niticible or not.

Optically the samyang lens performs well, and controls flare beyond my expectations, which for a 180 degree FOV is difficult because it is almost impossible to keep th esun out of the frame.

Note for the Sigma UWA zooms the FOV is stated for a 16x24mm ASP-C sensor but some, like canon specifically are a little different, as well as the use of these lenses on 4/3 systems
Should I start with UWA or FE?

Remark: There seem to be more people defishing FE lenses than fishing UWA:
http://www.cameralabs.com/forum/viewtopic.php?t=1280

Last edited by JoepLX3; 09-17-2010 at 05:59 AM. Reason: add remark
09-17-2010, 07:19 AM   #36
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QuoteOriginally posted by JoepLX3 Quote
Should I start with UWA or FE?

Remark: There seem to be more people defishing FE lenses than fishing UWA:
Camera Labs :: View topic - Ultra-wides vs Fisheyes? See the Difference!
I started with UWA, then FE. BUT there are a couple of considerations here.

My UWA is a zoom. the FE is a prime.

The UWA zoom is very very useful when you travel, especially if your travel is only within cities. WHen travelling (in cities) the 10-20 accounts for about 60% of my shots.

The FE is really, for me, a play toy. I use it when I believe I am in an interesting spot to make use of it, and it opens up some different possibilities, but you need to start thinking fisheye, as you walk around.

I used it somewhat for church interiors on a recient trip to prague budapest and vienna, and also a few scenics, but no where as much as my 10-20.

I have not "de-fished" any shots or done comparison shots to evaluate the "de-fished" shots and the resulting equivelent focal length, although my software (PSP X3) allows for this, so I don;t know where it would put you if you went fisheye.

Both are good lenses, and I think you may need to plan out your kit a little before you take the plunge either way.

If you go back a few pages, I think I posted that you need a backbone kit of zooms covering 10-200mm with a path to 400 if you want wild life. You can then fill in specialty needs with primes. I still believe that to be true.

I guess I am saying go UWA zoom first.
09-17-2010, 02:34 PM   #37
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QuoteOriginally posted by JoepLX3 Quote
Thanks, so for me (optical) fisheye is fisheye, but with a circular fisheye you get full projection in every orientation on the sensor (ending up as circular picture) - which is kind of a cool gadget (but not my taste to invest into heavily).

Difference between following still not 200% clear (two Sigma lenses):
- 10mm F2.8 EX DC HSM Fisheye
- 15mm F2.8 EX DG Diagonal Fisheye

I "assume" diagonal means 180 degrees from upper left to bottom right. And "normal" means 180 degrees from left middle to right middle. But isn't that information (indirectly) already included in focal length numbers???

So about the 10-17 mm Fisheye, that is both depending on zoom?
I believe that the DA 10-17 is 180 degrees diagonal. I have to admit that I have never really looked into it, since I got it. I used it as a walking around lens the first day I had it. I learned a LOT. Its a specialty lens, however I do like it. It has always been sufficiently wide enough for me and my use, so I never really pursued it.

QuoteOriginally posted by JoepLX3 Quote
Oh, last question, how does 10 mm UWA "translate" into X mm FE?

Wait, I should be able to extract that information from lens specifications:
- Pentax UWA 12-24 mm = 99 - 61
- Pentax FE 10-17 mm = 180 - 100
- Sigma FE 4.5 mm = 180
- Sigma FE 8 mm = 180
- Sigma FE 10 mm = 180
- Sigma FE 15 mm = 180
- Sigma UWA 8-16 mm = 114.5 - 75.7 - depending on crop factor
- Sigma UWA 10-20 mm = 102.4-63.8 - depending on crop factor
- Sigma UWA 12-24 mm = 122-84.1 - depending on crop factor

Hmm, looks like Sigma UWA degrees are not really consistent...
- Also clear that FE is effectively much more wide than UWA!!!

But the post quoted above already stated that:
https://www.pentaxforums.com/forums/679474-post3.html
There are two types of UWA lenses, Fish Eye and Rectilinear, and this deals with how the light is collected and then through the lens projected on to the sensor.

Once a couple of years ago, I used a optical calculator to compute focal length based on angle of view, i.e., using a FE field of view, to calculate a rectilinear focal length. If I remember correctly, using 180 FoV it was something like 0mm. Go down to the Angular Field of View Calculator section and plug in various focal lengths and get the corresponding field of view in degrees (rectilinear).
Now you need to compare FE to FE and Rectilinear to Rectilinear, with respect to focal length. Comparing FE to Rectilinear in terms of focal length - you are comparing apples to pineapples.

Also, to tell you the truth, I do not know how to explain a difference in focal length for a 8mm FE to a 10mm FE where each has a FoV of 180 degrees. I believe the easiest way is to compare an image of the same setting from each lens. Apples to Apples.

In terms of Rectilinear UWA you need to compare lenses based on the same crop factor. You could change crop factors, however that is similar to comparing camera prices across US dollars, Euros, and Yen when you are going to buy in Fiji.

QuoteOriginally posted by JoepLX3 Quote
Should I start with UWA or FE?

Remark: There seem to be more people defishing FE lenses than fishing UWA:
Camera Labs :: View topic - Ultra-wides vs Fisheyes? See the Difference!
To tell you the truth, knowing what I know now - I would suggest to get the UWA first, because that may satisfy you. If you got the FE first, you will also get a UWA. I also believe that the UWA is more useful, be used more. Personally, I am very happy to have both, and I use both - however that is me.

De-fishing - bottom line, you have to play around with it to understand the various "projections" and why you get them. Its essentially a geometry problem. You will enjoy the problem if you have a Math, Physics, Computer Science or Engineering degree... Essentially, you are taking an image of a curved surface and going to make it lay flat by some means - similar to a map. Here is a good overview...
hope this helps....

Last edited by interested_observer; 09-17-2010 at 02:43 PM.
09-17-2010, 03:43 PM   #38
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QuoteOriginally posted by Lowell Goudge Quote
I started with UWA, then FE. BUT there are a couple of considerations here.

My UWA is a zoom. the FE is a prime.

The UWA zoom is very very useful when you travel, especially if your travel is only within cities. WHen travelling (in cities) the 10-20 accounts for about 60% of my shots.

The FE is really, for me, a play toy.
...
I guess I am saying go UWA zoom first.
Thanks for background info, think you are right!!!
- And before FE, I might also need to go for some portrait prime (50 / 85 mm) or zoom (50 - 135/150).

09-17-2010, 04:16 PM   #39
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QuoteOriginally posted by interested_observer Quote
...
Short fisheye means more wide and not only 180 from corner to corner (longest diagonal line) but also left to right and at very short even top to bottom.

This link is very good!!!
Using a fisheye as a regular rectilinear wide-angle lens · David Kennard Photography
- He defishing a 13 mm still results in some usable UWA, beyond that it is "hard-core" fisheye

Thanks for you efforts to help me (and others) out on this subject.
09-18-2010, 04:33 AM   #40
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Going after a Pentax M 50 mm F1.4
- Selling party is asking 70 Euro, I am offering 60 Euro (and checking if lens includes covers, hood and casing, probably only covers, so I expect to get it for 60 Euro)

After this lens I have to go after some AF prime / Fast AF zoom addressing (candid) portrait applications.
09-18-2010, 04:58 AM   #41
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Hey, Joep. I see that you do not plan on this, but you might want to consider the 1.7 AF TC while you are in Japan. The best teleconverter money can buy, and lets you use your MF primes for long glass in the 80mm range to 200 plus and beyond . . .

Just a thought. I understand that the wide end has been more of a focus recently.
09-18-2010, 05:22 AM   #42
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QuoteOriginally posted by Impartial Quote
Hey, Joep. I see that you do not plan on this, but you might want to consider the 1.7 AF TC while you are in Japan. The best teleconverter money can buy, and lets you use your MF primes for long glass in the 80mm range to 200 plus and beyond . . .

Just a thought. I understand that the wide end has been more of a focus recently.
Can you also effecitively use that on 50 mm F1.7?
- And 35 mm F2.4 (with autofocus)?

So far it is only interessting for 135 mm en 200 mm (~60 Euro investment) and to my understanding this AF TC isn't cheap...
- In the future I will probably maintain connections to get it "imported"

Wait, what if I would buy a Sigma 50-150 mm F2.8?
- Or should a go for a fast MF tele zoom...
09-18-2010, 05:31 AM   #43
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QuoteOriginally posted by JoepLX3 Quote
Can you also effecitively use that on 50 mm F1.7?
- And 35 mm F2.4 (with autofocus)?

So far it is only interessting for 135 mm en 200 mm (~60 Euro investment) and to my understanding this AF TC isn't cheap...
- In the future I will probably maintain connections to get it "imported"

Wait, what if I would buy a Sigma 50-150 mm F2.8?
- Or should a go for a fast MF tele zoom...
I have used mine on my A 50/1.7 and on my FA35/2; it will also work fine on a 35/2.4 or 135/2.8. I believe the TC will work on the Sigma 50-150 zoom, but this time I can't vouch for the IQ (since the TC will exaggerate any limitations of the original lens). I haven't done it myself, but am more confident that it will perform well with the Pentax 50-135.
09-18-2010, 05:51 AM   #44
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Then this AF TC starts to become realy interesting already owning: 28 mm F2.8, 50 mm F1.4, 135 mm F3.5, 200 mm F4
- Even to just find out which portrait prime I want and sell (for big money) in Europe afterwards...

FYI: Just offered 65 Euro to "break the ice" on the 50 mm F1.4
09-18-2010, 06:37 AM   #45
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He wants 70, so I doubt I will buy it...
- coming 1-2 weeks I will try to find one cheaper here in Japan, preferably an A version.
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