Sigma 100-300F4 (w & w/o TC) V 150-500HSM - Focus speed

jeallen01 · 03-30-2015, 02:15 AM

I have both of the above lenses, but have been surprised to find the that HSM lens appears slower to focus than the older screw-drive lens, and so I thought you guys might find the following to be of interest:

At the recent "The Photography Show" in the UK, I talked to the Service Supervisor at Sigma Imaging UK about this and then - at his invitation - sent him the following question to forward to Sigma in Japan:

"Further to our interesting discussion on the above issue at The Photography Show on Sunday 22 March, I have the following two lenses, both of which have been with yourselves at the Welwyn Garden City site in the last couple of years for checking over:

- Product : AF 100-300 / 4,0 APO EX DG (PENTAX) Serial Number: 502XXXX - Sigma Invoice 000XXXXX, dated 14/06/2013
(this lens had no particular issues but was sent to you merely for a general check-over and service)

- Products AF 150-500 / 5,0-6,3 APO DG OS HSM, Fitting: Pentax - Serial Number: 109XXXXX - Sigma Invoice SRXXXXX dated 4/9/2014
(this was brought to you because it appeared to be pretty slow to focus as compared with the 100-300)

These lenses have been tried and used on two Pentax bodies,
- K-5 (not the later II or IIS versions) S/N XXXXXXX
- K-3 S/N XXXXXXXX

Both bodies have always had the latest Pentax firmware available at the time, and neither have exhibited any obvious focusing speed issues with the 100-300, or with the other lenses I regularly use (an early non-HSM/ non-Macro Sigma 70-200 F2.8 EX, a non-HSM Sigma 10-20 F4.5-5.6 EX DC, and a Pentax 18-135 F3.5-5.6 DA WR).

However, the 150-500 HSM (bought s/h in late 2013, but in excellent general condition, and, reputedly, not having been used very much according to the previous owner) consistently focuses more “lethargically” on both the K-3 and K-5, both before and after it came into yourselves – in fact, it is noticeably the slower than the 100-300 on the K-3 (which has a more powerful lens motor than the K-5), and is still slower on the K-3 as against the same body with the combination of the 100-300 and Sigma 1.4 EX T/C fitted.

Therefore, based on our discussion and the above additional info, I would be grateful if you could take the matter up with Sigma in Japan and see what they might have to say about the issue:

PS: As we both know and acknowledge, Pentax bodies are not fast-focusing compared with some equivalent Canon/Nikon bodies, and so that is not the issue – it’s just why is it that the 150-500 HSM lens appears to be slower than the much older screw-drive 100-300?".

This was the reply that I received today:

"Dear Mr Allen

Japan have said that the lens is to standard and the difference in speed is due to the different AF mechanisms involved and the difference in the angle of the scale ring rotation.

If you still wish us to check it please send it to the address below."

I declined the latter invitation to send the HSM back for further investigation because I don't think they could actually do any more than they have already (complete service and HSM motor replacement - at no charge, which was great customer-service for a s/h lens!).

Moral/Request - SIGMA - PLEASE bring back the screw-drive 100-300 F4 in Pentax fit!!

jeallen01 · 03-30-2015, 01:47 PM

Well, does anyone have any comments on their own experience with these lenses?

Srhphoto · 03-31-2015, 03:02 PM

I have the 150-500 and use it on a K3. It is the slowest focusing of all the lenses I have.

I think the slowness (particularly at 500mm) is down to the lenses maximum aperature of f6.3. As far as I know, all focusing takes place with the lens wide open and it only stops down to whatever it is set at as the shutter is pressed. At f6.3 there's reduced light hitting the AF sensors compared to f4 on your 100-300mm lens. I think it's this and not how the lens is driven that's causing the speed difference.

Simon.

jeallen01 · 03-31-2015, 03:10 PM

Simon
I agree w.r.t. the speed of the "HSM" `150-500 - and that's why I have been (so far, at least) disappointed with this lens.

Maybe it's a matter of the type of application that is suited to this lens, and that the "HSM" moniker is actually misleading to many purchasers

Srhphoto · 03-31-2015, 10:39 PM

Originally posted by jeallen01

Simon
I agree w.r.t. the speed of the "HSM" `150-500 - and that's why I have been (so far, at least) disappointed with this lens.

Maybe it's a matter of the type of application that is suited to this lens, and that the "HSM" moniker is actually misleading to many purchasers

Personally I have no problem with the HSM moniker - it is after all how the lens is driven and in that regard is completely accurate. I believe the relative slowness is induced by the cameras AF module as it tries to deal with an f6.3 maximum aperature. The camera is trying to trade speed for AF accuracy.

Simon.

jeallen01 · 04-01-2015, 12:01 AM

Maybe it's also a perception issue - people read reviews that say it's quite fast, and yet those reviews rarely make objective comparisons with other lenses of generally similar focal lengths.

I think that's why I was quite surprised with how slow the 150-500 is relative to the 100-300, and thought that the one I acquired was faulty in some way, but in fact it appears that it is not - I was just expecting something better!

03-30-2015, 02:15 AM	#1
jeallen01 Pentaxian Join Date: May 2008 Location: London, UK Posts: 1,697	Sigma 100-300F4 (w & w/o TC) V 150-500HSM - Focus speed I have both of the above lenses, but have been surprised to find the that HSM lens appears slower to focus than the older screw-drive lens, and so I thought you guys might find the following to be of interest: At the recent "The Photography Show" in the UK, I talked to the Service Supervisor at Sigma Imaging UK about this and then - at his invitation - sent him the following question to forward to Sigma in Japan: "Further to our interesting discussion on the above issue at The Photography Show on Sunday 22 March, I have the following two lenses, both of which have been with yourselves at the Welwyn Garden City site in the last couple of years for checking over: - Product : AF 100-300 / 4,0 APO EX DG (PENTAX) Serial Number: 502XXXX - Sigma Invoice 000XXXXX, dated 14/06/2013 (this lens had no particular issues but was sent to you merely for a general check-over and service) - Products AF 150-500 / 5,0-6,3 APO DG OS HSM, Fitting: Pentax - Serial Number: 109XXXXX - Sigma Invoice SRXXXXX dated 4/9/2014 (this was brought to you because it appeared to be pretty slow to focus as compared with the 100-300) These lenses have been tried and used on two Pentax bodies, - K-5 (not the later II or IIS versions) S/N XXXXXXX - K-3 S/N XXXXXXXX Both bodies have always had the latest Pentax firmware available at the time, and neither have exhibited any obvious focusing speed issues with the 100-300, or with the other lenses I regularly use (an early non-HSM/ non-Macro Sigma 70-200 F2.8 EX, a non-HSM Sigma 10-20 F4.5-5.6 EX DC, and a Pentax 18-135 F3.5-5.6 DA WR). However, the 150-500 HSM (bought s/h in late 2013, but in excellent general condition, and, reputedly, not having been used very much according to the previous owner) consistently focuses more “lethargically” on both the K-3 and K-5, both before and after it came into yourselves – in fact, it is noticeably the slower than the 100-300 on the K-3 (which has a more powerful lens motor than the K-5), and is still slower on the K-3 as against the same body with the combination of the 100-300 and Sigma 1.4 EX T/C fitted. Therefore, based on our discussion and the above additional info, I would be grateful if you could take the matter up with Sigma in Japan and see what they might have to say about the issue: PS: As we both know and acknowledge, Pentax bodies are not fast-focusing compared with some equivalent Canon/Nikon bodies, and so that is not the issue – it’s just why is it that the 150-500 HSM lens appears to be slower than the much older screw-drive 100-300?". This was the reply that I received today: "Dear Mr Allen Japan have said that the lens is to standard and the difference in speed is due to the different AF mechanisms involved and the difference in the angle of the scale ring rotation. If you still wish us to check it please send it to the address below." I declined the latter invitation to send the HSM back for further investigation because I don't think they could actually do any more than they have already (complete service and HSM motor replacement - at no charge, which was great customer-service for a s/h lens!). Moral/Request - SIGMA - PLEASE bring back the screw-drive 100-300 F4 in Pentax fit!!

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03-30-2015, 01:47 PM	#2
jeallen01 Pentaxian Join Date: May 2008 Location: London, UK Posts: 1,697 Original Poster	Well, does anyone have any comments on their own experience with these lenses?

03-31-2015, 03:02 PM	#3
Srhphoto Forum Member Join Date: Aug 2014 Location: North Yorkshire Posts: 51	I have the 150-500 and use it on a K3. It is the slowest focusing of all the lenses I have. I think the slowness (particularly at 500mm) is down to the lenses maximum aperature of f6.3. As far as I know, all focusing takes place with the lens wide open and it only stops down to whatever it is set at as the shutter is pressed. At f6.3 there's reduced light hitting the AF sensors compared to f4 on your 100-300mm lens. I think it's this and not how the lens is driven that's causing the speed difference. Simon.

03-31-2015, 03:10 PM	#4
jeallen01 Pentaxian Join Date: May 2008 Location: London, UK Posts: 1,697 Original Poster	Simon I agree w.r.t. the speed of the "HSM" `150-500 - and that's why I have been (so far, at least) disappointed with this lens. Maybe it's a matter of the type of application that is suited to this lens, and that the "HSM" moniker is actually misleading to many purchasers

03-31-2015, 10:39 PM	#5
Srhphoto Forum Member Join Date: Aug 2014 Location: North Yorkshire Posts: 51	Originally posted by jeallen01 Simon I agree w.r.t. the speed of the "HSM" `150-500 - and that's why I have been (so far, at least) disappointed with this lens. Maybe it's a matter of the type of application that is suited to this lens, and that the "HSM" moniker is actually misleading to many purchasers Personally I have no problem with the HSM moniker - it is after all how the lens is driven and in that regard is completely accurate. I believe the relative slowness is induced by the cameras AF module as it tries to deal with an f6.3 maximum aperature. The camera is trying to trade speed for AF accuracy. Simon.

04-01-2015, 12:01 AM	#6
jeallen01 Pentaxian Join Date: May 2008 Location: London, UK Posts: 1,697 Original Poster	Maybe it's also a perception issue - people read reviews that say it's quite fast, and yet those reviews rarely make objective comparisons with other lenses of generally similar focal lengths. I think that's why I was quite surprised with how slow the 150-500 is relative to the 100-300, and thought that the one I acquired was faulty in some way, but in fact it appears that it is not - I was just expecting something better!