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09-11-2007, 11:44 PM   #1
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x1.7 SMC AF Adapter Compatibility

I recently picked one of these up on eBay for a great price. It hasn't arrived yet but I'll need to expand my manual focus lens collection to take full advantage of it.

As I understand it, there are certain lenses which can't be used with it due to their physical construction. Does anyone know where I can find information about which lenses to steer clear of?

09-12-2007, 12:01 AM   #2
dbh
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I stumbled across one of these today (see while on vacation post).
According to the manual,
Page not found[1].7X.pdf

you can't use these lenses:
A 15mm f3.5
M 24-35mm f3.5
Pentax 15mm f3.5 and 18mm f3.5

However the manual is old and predates a few others I'd be worried about,
DA-14, and the fisheye for example. It also says not to stack the adapters.
There are no doubt others here with examples of lenses that are known to work fine
with it from their first-hand experience.
Enjoy.
--
dbh

Last edited by dbh; 09-12-2007 at 12:03 AM. Reason: message parser complained about the URL for the manual. Best do a search on pentaximaging.com if this link fails.
09-12-2007, 02:19 AM   #3
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QuoteOriginally posted by susanc Quote
I recently picked one of these up on eBay for a great price. It hasn't arrived yet but I'll need to expand my manual focus lens collection to take full advantage of it.

As I understand it, there are certain lenses which can't be used with it due to their physical construction. Does anyone know where I can find information about which lenses to steer clear of?
I don't know about specific exclusions that some members have posted, specifically with respect to short lenses (but you may need to check the possibility for interference between lens back element and the movable elements of the adaptor.

I bought mine new to use with my PZ-1 in 1991, and the manuals even then said if can only be used with F/2.8 and faster lenses.

Fortunately neither the adaptor or cameras seem to be able to read the manuals.

I have found it works properly in all lighting conditions up to F/4.0 lenses.

My experience to date is as follows:

SMC-Pentax 300mm f/4.0
SMC-Pentax 50 mm f/1.4
SMC-M-Pentax 100mm f/4.0 macro
Vivitar Series 1 70-210mm f/3.5 (Version 1 of lens)

It works with all these just fine.

It DOES NOT work, however, with my Vivitar 400mm f/5.6. although I did not expect it to.

I have heard some people claim it works with the Pentax 300mm f/4.5 KA mount, but you would need to check.

All the above lenses work with the adaptor on my PZ-1, *istD, and K10D, You will also find a recient thread on the 300mmf/4.0 where I have posted a photo taken using the 300mm and the adaptor
09-12-2007, 09:21 AM   #4
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>Vivitar Series 1 70-210mm f/3.5 (Version 1 of lens)

>It works with all these just fine.

That's good news for me as I have that lens, although I didn't bring it along this trip.
--
dbh

09-12-2007, 12:16 PM   #5
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Susan, you mention a great price. How much was it? Just curious, I just paid 160 euros for mine. Will arrive hopefully soon...

Cheers,
Syb
09-12-2007, 11:27 PM   #6
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QuoteOriginally posted by Syb Quote
Susan, you mention a great price. How much was it? Just curious, I just paid 160 euros for mine. Will arrive hopefully soon...

Cheers,
Syb
I reckon you go a pretty good price. The only one of these I seen recently on eBay, sold for 180.

I paid 120 for a mixed lot that included this, a Pentax FA 100-300mm F4.5-F5.6, a Z-20 35mm body, a Tamron AF 35-90mm F4-F5.6, a 500mm mirror lens and other odds and ends. It's yet to arrive, so I'm praying it's in good condition.
09-13-2007, 07:42 AM   #7
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Lowell pointed out the the applications of the AF adaptor. I have one too and about the only lens I use it with is the 4/300 (old K-version and newer A*-version). There it works easily.
I have tried it, just out of curiosity with: 2,5/135 K, 4/70-210 A and it works, as well as it does with some AF lenses, like the 2.8/28-70 FA, 1.4/85 FA etc.

It does definitely not work with my 5.6/400 A, it hunts for focus and even manual focus can't be reached.

Also, no teleconverter should be used with wide-angle lenses, so the 15 mm M or A and the like are definite no-goes. It doesn't make much sense anyway. Especially in the case of the very, very good 15 mm the last lens of the lens may collide with the AF-adapters lenses (I haven't tried!)

In the past teleconverters were used as a last resort to multiply the longest focal length at hand. Today many people use them with cheap zoom lenses of all kinds and I think, many people don't even realise the poor performance they get. The only zoom lens, which I use with tc is the Sigma 2.8/80-200, because the 1.4 x Sigma converter is optimised fot this lens and the results are very good (with the 2 x tc, the results are poor).

regards
Ben
09-16-2007, 05:25 AM   #8
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Mine has arrived. In broad daylight, it works well with the M42 SMC-takumar 300mm/4 (after placing some foil on the contacts). However, it does not do the focosing all the way. One needs to focus manually a little behind the target, and then the adapter will do the rest.

That must be a thing to get used with.

AF speed is pretty quick on my K10d. I think I am going to love this thing, because it combines two things that really interest me... looking further and focus!

Syb

09-16-2007, 09:26 AM   #9
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QuoteOriginally posted by dbh Quote
I stumbled across one of these today (see while on vacation post).
According to the manual,
Page not found[1].7X.pdf

you can't use these lenses:
A 15mm f3.5
M 24-35mm f3.5
Pentax 15mm f3.5 and 18mm f3.5

However the manual is old and predates a few others I'd be worried about,
DA-14, and the fisheye for example. It also says not to stack the adapters.
There are no doubt others here with examples of lenses that are known to work fine
with it from their first-hand experience.
Enjoy.
--
dbh
it wuld seem than an extender is hardly appropriate for an extreme wideangle---sort of self defeating.

On the other shoe, AF quickly deteriorates in lens combinations where the maximum aperture is smaller than f5.6. Given the inherent speed loss
associated with using an extender you could expect the 'happy zone' for this product to be F4 and faster normal to tele lenses.

I can't see using it with a normal lens because unless you have to pack extremely light, almost everyone who has multiple lenses at all has some sort of a telephoto.

Toss out most of the telephoto zooms as they are too slow usually to work very well, and may have quality issues with an extender,
and the list gets down to moderate primes: Namely the 135mm and 200 mm SMC-A primes are the two most suitable lenses for this product.

For my part, I've never owned a 135mm lens, preferring to substitute a 100 mm macro for that category. I do own an SMC-A 200 mm F4 prime which would be an excellent target for use with this teleextender, but for the fact that I have an 80-320 FA zoom which will effectively do anything that the 200 SMC-a prime plus the FA extender will do--probably better.

Thus I own the FA 1.7 /af converter/extender and it is shelf ware.
09-16-2007, 09:48 AM   #10
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QuoteOriginally posted by Syb Quote
Mine has arrived. In broad daylight, it works well with the M42 SMC-takumar 300mm/4 (after placing some foil on the contacts). However, it does not do the focosing all the way. One needs to focus manually a little behind the target, and then the adapter will do the rest.

That must be a thing to get used with.

AF speed is pretty quick on my K10d. I think I am going to love this thing, because it combines two things that really interest me... looking further and focus!

Syb
This is sonething you need to consider with the AF TC, it only has a limited range of focus ability, and the longer the lens, the less range it has.
09-17-2007, 01:15 PM   #11
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There is another thing to consider, especially if using the 1.7x AF adapter with a zoom lens and SR turned on. That is the SR will want to know the focal length to assume when you switch on the camera. You need to multiply whatever the zoom is set to by 1.7 and select the best match in the camera. If/when you change fl, you will need to repeat this - so what you gain in convenience by now having AF with your previous MF lens, you may lose in other areas of operation.

I took the DA21, DA70 and the 1.7x AF adapter down to the big celebration festivities at Prince Rupert last week. A couple of coat pockets were all I needed to store this stuff and let me grab nice shots of the stage shows and the huge container port equipment on display.

Light-weight options are often valuable. Of course I could have done nicely with a single 21-120 zoom lens. But alas I had not one on me.
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09-17-2007, 01:46 PM   #12
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QuoteOriginally posted by dbh Quote
There is another thing to consider, especially if using the 1.7x AF adapter with a zoom lens and SR turned on. That is the SR will want to know the focal length to assume when you switch on the camera. You need to multiply whatever the zoom is set to by 1.7 and select the best match in the camera. If/when you change fl, you will need to repeat this - so what you gain in convenience by now having AF with your previous MF lens, you may lose in other areas of operation.

I took the DA21, DA70 and the 1.7x AF adapter down to the big celebration festivities at Prince Rupert last week. A couple of coat pockets were all I needed to store this stuff and let me grab nice shots of the stage shows and the huge container port equipment on display.

Light-weight options are often valuable. Of course I could have done nicely with a single 21-120 zoom lens. But alas I had not one on me.
--
dbh
You need to watch the fact that for modern lenses, where the information is available for focal length, the camera gets this transmitted through the TC without change, and in fact gets it wrong because it does not account for the change in focal length. I have reported this to pentax
09-18-2007, 10:19 AM   #13
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QuoteOriginally posted by Lowell Goudge Quote
You need to watch the fact that for modern lenses, where the information is available for focal length, the camera gets this transmitted through the TC without change, and in fact gets it wrong because it does not account for the change in focal length. I have reported this to pentax
Good point. It does correctly report the effective aperture range, though.
Except with the Bigma. I also had to dial in -2 exposure comp when I used it on the Bigma. Which reminds me, this adapter's construction is quite robust - a good thing when connecting a fairly heavy camera to a super-heavy lens.
--
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09-18-2007, 12:09 PM   #14
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QuoteOriginally posted by dbh Quote
Good point. It does correctly report the effective aperture range, though.
Except with the Bigma. I also had to dial in -2 exposure comp when I used it on the Bigma. Which reminds me, this adapter's construction is quite robust - a good thing when connecting a fairly heavy camera to a super-heavy lens.
--
dbh
Be careful, on the Sigma APO 70-200 f/2.8 DG (non macro version) the 1.4x TC does not change the "effective apature" from F/2.8 to F/4.0 it remains at f/2.8

Metering is not impacted only because, the TC reduces light. The camera does not care about the actual F Stop, only where it thinks it is and where it thinks it is going. That is all about the ratio of light i.e. change in f stops
09-19-2007, 07:38 AM   #15
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QuoteOriginally posted by Lowell Goudge Quote
Be careful, on the Sigma APO 70-200 f/2.8 DG (non macro version) the 1.4x TC does not change the "effective apature" from F/2.8 to F/4.0 it remains at f/2.8

Metering is not impacted only because, the TC reduces light. The camera does not care about the actual F Stop, only where it thinks it is and where it thinks it is going. That is all about the ratio of light i.e. change in f stops
Must be something incompatible in Sigma's implementation because the Sigma 50-500 also looks like it can be set to f2.8 when plugged into the 1.7x tc!
However my DA70 seems to work as expected wrt f-stops.

It's been 30 yrs since I bought my only other TC, a meter-coupled 2X thing for my SRT-101. It was so bad in every respect I swore off TCs. Now I may be able to see fit to give them another shot.
--
dbh
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