FA 100-300 4.7-5.8 Identified as 4.5-5.6 ??

JFN · 04-19-2012, 07:33 AM

I grabbed a FA 100-300 4.7-5.8 the other day, got it in the mail today, and for some reason all my bodies (K-r, MZ-6, MZ-7) identify the aperture in "A" mode as 4.5-5,6 instead?? It's indeed the 4,7-5.8 (4,7 is marked on the aperture ring) but for some reason in "A" mode, this does not seem to be the case.

https://www.pentaxforums.com/lensreviews/data/44/SMC_Pentax-FA_100-300mm_F47-58.jpg

Anyone know what this could be about? There's another FA 100-300 that actually is 4.5-5,6, but there's no way to be wrong about this, it is the 4,7-5.8 version.

The lens is sweat and everything works perfect, I dont mind having 4.5 instead of 4.7, but I wonder what it's all about...

Confused...

Last edited by JFN; 04-19-2012 at 10:33 AM.

northcoastgreg · 04-19-2012, 07:47 AM

I suspect that Pentax cameras are programmed to only record specific f-stops (such as 4, 4.5, 5, etc.) and 4.7 and 5.8 don't fall in the pre-programmed array. With variable aperture zooms, just because the camera says 4.5 doesn't mean it's really 4.5. It might be 4.3 or 4.7.

JFN · 04-19-2012, 07:52 AM

Very interesting, I had no idea about this!

I though at first that it was the K-r that identified the lens, and did it wrong assumingly, since there actually is another 100-300 FA as well which has just precisely f/4.5-5.6, but then when I found out that my film bodies did the same, I became quite curios about what this was..

Giklab · 04-19-2012, 09:02 AM

Well, the thing is, the 4.5-5.6 is supposed to be a lower grade lens.

JFN · 04-19-2012, 09:11 AM

Originally posted by Giklab

Well, the thing is, the 4.5-5.6 is supposed to be a lower grade lens.

But that's another lens, other glass, etc. So?

Giklab · 04-19-2012, 09:29 AM

So, the camera identified it as a 4.5 instead of 4.7. I agree that the problem might lie with the "rounded" aperture values, but just pointing out since many people seem to mix them up. I know it says 4.7 on the lens.

JFN · 04-19-2012, 09:42 AM

Originally posted by Giklab

So, the camera identified it as a 4.5 instead of 4.7. I agree that the problem might lie with the "rounded" aperture values, but just pointing out since many people seem to mix them up. I know it says 4.7 on the lens.

Yeah, I bet that happess, though with this lens it's not a case of mixup.

L33tGreg · 04-19-2012, 10:19 AM - **1 Like**

Max aperture on K-mount lenses is communicated to the camera via the pins on the mount encoding a binary string. Each pin can either be shorted, or not (1 or 0). Pentax defined the combinations when the KA mount was created for the A-series lenses. The documentation is here: Features and Operation of the Ka Mount . As a result, lenses would odd max apertures can't be exactly specified to the camera. What will blow your mind even more as the bodies indication of max aperture will vary depending if the camera is setup for 1/2 stops or 1/3 stops!

doudou54300 · 11-07-2014, 01:43 AM

Hello...

i have almost the same question : a seller in ebay is selling this lens : smc FA 100-300. On the photo we can see the box with written FA 100-300 F4,7 -5,8 but on the photo of the lens : body of the lens is black and aperture ring starts at 4.5.
seller certify that it is the 4,7 - 5,8 version with black body...

this question is important because 4,7/5.8 version does not have same weight and optical performance than 4.5/5.6

Is it possible ? has anyone already had this problem ?

Thanks for your answer...

Lionel

**alfa75ts** · 11-07-2014, 02:19 AM - **1 Like**

As far as I know the 4.7 only came in silver.

Ask Yves if the photograph is of the actual lens for sale.

If he says yes, it's a 4.5. If he says no ask for a photo of the actual lens he has for sale including the side which says SMC PENTAX-FA etc..

krazykat · 11-07-2014, 03:58 AM - **1 Like**

The 4.7 also came in black, but it's a lot rarer. I have one, and I saw another one in a Shinjuku camera shop in 2012.

doudou54300 · 11-07-2014, 04:22 AM

Originally posted by krazykat

The 4.7 also came in black, but it's a lot rarer. I have one, and I saw another one in a Shinjuku camera shop in 2012.

How can you make difference between f4.5 black and f4.7black ????
Obviously on the photo in ebay i ca read on aperture ring 4.5...but seller says it is a 4.7 "black version" with a f4.7 box...strange ???

**alfa75ts** · 11-07-2014, 12:44 PM

Originally posted by doudou54300

but seller says it is a 4.7 "black version" with a f4.7 box...strange ???

Very strange.

Ask for a picture from the side:

krazykat · 11-07-2014, 01:53 PM

Originally posted by doudou54300

How can you make difference between f4.5 black and f4.7black ????
Obviously on the photo in ebay i ca read on aperture ring 4.5...but seller says it is a 4.7 "black version" with a f4.7 box...strange ???

If the photo shows 4.5 then it's a 4.5, my black 4.7 shows 4.7.

doudou54300 · 12-08-2014, 02:58 PM

Finally seller sent me mail : confirming that he made a mistake : it was a f4,5 usual black edition....and not a 4,7....we were all right !!!

Lionel

04-19-2012, 07:33 AM	#1
JFN Veteran Member Join Date: Dec 2011 Location: Golfe du Lion Photos: Gallery Posts: 362	FA 100-300 4.7-5.8 Identified as 4.5-5.6 ?? I grabbed a FA 100-300 4.7-5.8 the other day, got it in the mail today, and for some reason all my bodies (K-r, MZ-6, MZ-7) identify the aperture in "A" mode as 4.5-5,6 instead?? It's indeed the 4,7-5.8 (4,7 is marked on the aperture ring) but for some reason in "A" mode, this does not seem to be the case. https://www.pentaxforums.com/lensreviews/data/44/SMC_Pentax-FA_100-300mm_F47-58.jpg Anyone know what this could be about? There's another FA 100-300 that actually is 4.5-5,6, but there's no way to be wrong about this, it is the 4,7-5.8 version. The lens is sweat and everything works perfect, I dont mind having 4.5 instead of 4.7, but I wonder what it's all about... Confused... Last edited by JFN; 04-19-2012 at 10:33 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
For Sale - Sold: Pentax FA 100-300, FA 70-200, M 28mm; Sigma EX 28-70, Apo 70-300; Tamron Di LD 70-300	stillnk	Sold Items	17	04-08-2012 11:39 AM
How are lenses identified for EXIF?	Edgar_in_Indy	Pentax SLR Lens Discussion	4	09-06-2011 06:28 PM
Silver fa 100-300 ot the DAL 55-300?	RickB52	Pentax SLR Lens Discussion	8	07-25-2011 09:53 PM
Nikon D7000 + 70-300 VR vs. Pentax K5 + Sigma 100-300	highyellow1	Canon, Nikon, Sony, and Other Camera Brands	41	05-06-2011 07:40 AM

04-19-2012, 07:47 AM	#2
northcoastgreg Pentaxian Join Date: Feb 2010 Location: Northern Michigan Photos: Gallery \| Albums Posts: 6,173	I suspect that Pentax cameras are programmed to only record specific f-stops (such as 4, 4.5, 5, etc.) and 4.7 and 5.8 don't fall in the pre-programmed array. With variable aperture zooms, just because the camera says 4.5 doesn't mean it's really 4.5. It might be 4.3 or 4.7.

04-19-2012, 07:52 AM	#3
JFN Veteran Member Join Date: Dec 2011 Location: Golfe du Lion Photos: Gallery Posts: 362 Original Poster	Very interesting, I had no idea about this! I though at first that it was the K-r that identified the lens, and did it wrong assumingly, since there actually is another 100-300 FA as well which has just precisely f/4.5-5.6, but then when I found out that my film bodies did the same, I became quite curios about what this was..

04-19-2012, 09:02 AM	#4
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182	Well, the thing is, the 4.5-5.6 is supposed to be a lower grade lens.

04-19-2012, 09:11 AM	#5
JFN Veteran Member Join Date: Dec 2011 Location: Golfe du Lion Photos: Gallery Posts: 362 Original Poster	Originally posted by Giklab Well, the thing is, the 4.5-5.6 is supposed to be a lower grade lens. But that's another lens, other glass, etc. So?

04-19-2012, 09:29 AM	#6
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182	So, the camera identified it as a 4.5 instead of 4.7. I agree that the problem might lie with the "rounded" aperture values, but just pointing out since many people seem to mix them up. I know it says 4.7 on the lens.

04-19-2012, 09:42 AM	#7
JFN Veteran Member Join Date: Dec 2011 Location: Golfe du Lion Photos: Gallery Posts: 362 Original Poster	Originally posted by Giklab So, the camera identified it as a 4.5 instead of 4.7. I agree that the problem might lie with the "rounded" aperture values, but just pointing out since many people seem to mix them up. I know it says 4.7 on the lens. Yeah, I bet that happess, though with this lens it's not a case of mixup.

04-19-2012, 10:19 AM - 1 Like	#8
L33tGreg Veteran Member Join Date: Jan 2011 Location: Charleston, SC Photos: Gallery Posts: 369	Max aperture on K-mount lenses is communicated to the camera via the pins on the mount encoding a binary string. Each pin can either be shorted, or not (1 or 0). Pentax defined the combinations when the KA mount was created for the A-series lenses. The documentation is here: Features and Operation of the Ka Mount . As a result, lenses would odd max apertures can't be exactly specified to the camera. What will blow your mind even more as the bodies indication of max aperture will vary depending if the camera is setup for 1/2 stops or 1/3 stops!

11-07-2014, 01:43 AM	#9
doudou54300 New Member Join Date: Nov 2014 Location: nancy Posts: 7	Hello... i have almost the same question : a seller in ebay is selling this lens : smc FA 100-300. On the photo we can see the box with written FA 100-300 F4,7 -5,8 but on the photo of the lens : body of the lens is black and aperture ring starts at 4.5. seller certify that it is the 4,7 - 5,8 version with black body... this question is important because 4,7/5.8 version does not have same weight and optical performance than 4.5/5.6 Is it possible ? has anyone already had this problem ? Thanks for your answer... Lionel

11-07-2014, 02:19 AM - 1 Like	#10
alfa75ts Loyal Site Supporter Join Date: Jun 2009 Location: Melbourne Australia Photos: Albums Posts: 1,356	As far as I know the 4.7 only came in silver. Ask Yves if the photograph is of the actual lens for sale. If he says yes, it's a 4.5. If he says no ask for a photo of the actual lens he has for sale including the side which says SMC PENTAX-FA etc..

11-07-2014, 03:58 AM - 1 Like	#11
krazykat Veteran Member Join Date: Aug 2010 Posts: 546	The 4.7 also came in black, but it's a lot rarer. I have one, and I saw another one in a Shinjuku camera shop in 2012.

11-07-2014, 04:22 AM	#12
doudou54300 New Member Join Date: Nov 2014 Location: nancy Posts: 7	Originally posted by krazykat The 4.7 also came in black, but it's a lot rarer. I have one, and I saw another one in a Shinjuku camera shop in 2012. How can you make difference between f4.5 black and f4.7black ???? Obviously on the photo in ebay i ca read on aperture ring 4.5...but seller says it is a 4.7 "black version" with a f4.7 box...strange ???

11-07-2014, 12:44 PM	#13
alfa75ts Loyal Site Supporter Join Date: Jun 2009 Location: Melbourne Australia Photos: Albums Posts: 1,356	Originally posted by doudou54300 but seller says it is a 4.7 "black version" with a f4.7 box...strange ??? Very strange. Ask for a picture from the side:

11-07-2014, 01:53 PM	#14
krazykat Veteran Member Join Date: Aug 2010 Posts: 546	Originally posted by doudou54300 How can you make difference between f4.5 black and f4.7black ???? Obviously on the photo in ebay i ca read on aperture ring 4.5...but seller says it is a 4.7 "black version" with a f4.7 box...strange ??? If the photo shows 4.5 then it's a 4.5, my black 4.7 shows 4.7.

12-08-2014, 02:58 PM	#15
doudou54300 New Member Join Date: Nov 2014 Location: nancy Posts: 7	Finally seller sent me mail : confirming that he made a mistake : it was a f4,5 usual black edition....and not a 4,7....we were all right !!! Lionel