Swarovski 10x50 EL question (1 Viewer)

[etc]

I want to go from the 8x42 Zeiss SF configuration to the 10x50 EL as I like the improved low-light performance that you get with a bigger objective.
Problem is, out of the EL family, 10x50 EL is the only that does not have sufficient diopter correction at infinity for me. I am -5.5 (equal in both eyes) and 8.5x42, 12x50, etc. are all 7 diopters and 10x50 is only 5 diopters. What were they thinking?

The question is, would Swarovski rebuild a 10x50 EL giving it 7D of correction at infinity like the other members of the EL family? Is this something that's even possible? I know this is a very long-shot and pretty doubtful but thought I would ask anyway.
Can swaro do such a mod without fees, as repair fees would make it pointless (I can just keep using my 8x42 SF or 10x54 HT as they both go to 7D at infinity and pretty much do what I want). Just that I prefer 10x50 versus 8x42 at this point but it's a slim margin.

The 54mm objective is an absolute delight to use in low-light, 50mm can't be much worse.

 

[dries1]

Nothing wrong with asking Swarovski, at least then you would know for sure.

 

[Swedpat]

I want to go from the 8x42 Zeiss SF configuration to the 10x50 EL as I like the improved low-light performance that you get with a bigger objective.
Problem is, out of the EL family, 10x50 EL is the only that does not have sufficient diopter correction at infinity for me. I am -5.5 (equal in both eyes) and 8.5x42, 12x50, etc. are all 7 diopters and 10x50 is only 5 diopters. What were they thinking?

The question is, would Swarovski rebuild a 10x50 EL giving it 7D of correction at infinity like the other members of the EL family? Is this something that's even possible? I know this is a very long-shot and pretty doubtful but thought I would ask anyway.
Can swaro do such a mod without fees, as repair fees would make it pointless (I can just keep using my 8x42 SF or 10x54 HT as they both go to 7D at infinity and pretty much do what I want). Just that I prefer 10x50 versus 8x42 at this point but it's a slim margin.

The 54mm objective is an absolute delight to use in low-light, 50mm can't be much worse.

I can't see 10x50 would provide improved low light performance. 8x42 actually provides 10% brighter image than 10x50 at dim conditions, at a given light transmission.

 

[[email protected]]

I can't see 10x50 would provide improved low light performance. 8x42 actually provides 10% brighter image than 10x50 at dim conditions, at a given light transmission.

You will see more detail though in low light with the 10x50 than the 8x42 because of the Twilight Factor. The 10x50 has a Twilight Factor of 22 and the 8x42 has a Twilight Factor of 18. Magnification helps you in low light the same way it does in bright light. You are correct that the apparent brightness of the 8x42 would be slightly higher than the 10x50.

 

[WildPhotographer]

I use Swarovski 12x50 on. a daily basis. They are slightly heavier, but superb in low light (twilight factor 24.5). Swarovski are extremely helpful and it may be possible to have the diopter correction modified.

 

[Tringa45]

Here is a thread I (as John Russell) started 8 years ago on focus overtravel: Focus Overtravel (compatibility for the near-sighted)
Swarovski's specifications are fairly conservative and my 10x42 EL SV had dioptre compensation of +/-9 dioptres (+/-5 d spec.) and a focus overtravel of 15,5 dioptres (8 d spec.) although there was then no room for a further negative dioptre compensation on the right barrel (see post #18).

AFAIK there has been no change to the focus mechanism on the 50 mm ELs as there has been on 42 mm versions, so with a close focus of 2,50 m there should be ample room to extend the focus overtravel, if indeed this is at all necessary.

A friend of mine has a 10x50 EL FP, so if you're interested I could borrow it and do some measurements.

Btw, there's a solid technical reason why the 12x50 has more focus overtravel than the 10x50. With the same focussing mechanism the objective images can be placed proportionately further inside the focal planes of the shorter focal length eyepieces.

John

 

[Swedpat]

You will see more detail though in low light with the 10x50 than the 8x42 because of the Twilight Factor. The 10x50 has a Twilight Factor of 22 and the 8x42 has a Twilight Factor of 18. Magnification helps you in low light the same way it does in bright light. You are correct that the apparent brightness of the 8x42 would be slightly higher than the 10x50.

Still there is an important difference between relative brightness index and twilight factor.

RBI is a physical term based on the optical law: providing light transmission is equal every optical instrument with same exit pupil provide exactly the same brightness. This because same exit pupil means same light amount per area.
This is a fact and not even disputable, in the same way it's a fact that power = force x speed.
Twilight factor however, is a bit subjective formula created in an attempt to describe twilight performance. It has its strong limitation and must not be given the same validity as RBI.

 

[Swedpat]

Still there is an important difference between relative brightness index and twilight factor.

RBI is a physical term based on the optical law: providing light transmission is equal every optical instrument with same exit pupil provide exactly the same brightness. This because same exit pupil means same light amount per area.
This is a fact and not even disputable, in the same way it's a fact that power = force x speed.
Twilight factor however, is a bit subjective formula created in an attempt to describe twilight performance. It has its strong limitation and must not be given the same validity as RBI.

What I mean is that it's misleading to say: "You will see more detail though in low light with the 10x50 than the 8x42 BECAUSE of the Twilight Factor. The 10x50 has a Twilight Factor of 22 and the 8x42 has a Twilight Factor of 18".

What if we compare to a 50x50 which has a twilight factor of whopping 50! Still a 1mm exit pupil will not work good in low light...
Therefore twilight factor cannot be used to measure low light performance in the same way as the exit pupil.

 

[etc]

Here is a thread I (as John Russell) started 8 years ago on focus overtravel: Focus Overtravel (compatibility for the near-sighted)
Swarovski's specifications are fairly conservative and my 10x42 EL SV had dioptre compensation of +/-9 dioptres (+/-5 d spec.) and a focus overtravel of 15,5 dioptres (8 d spec.) although there was then no room for a further negative dioptre compensation on the right barrel (see post #18).

AFAIK there has been no change to the focus mechanism on the 50 mm ELs as there has been on 42 mm versions, so with a close focus of 2,50 m there should be ample room to extend the focus overtravel, if indeed this is at all necessary.

A friend of mine has a 10x50 EL FP, so if you're interested I could borrow it and do some measurements.

John

Yes, please do. I would appreciate that.

Are you sure about 10x42 EL having 15.5 D of overtravel? I've had the 8.5x42 EL model and it had based on my assessment only 6D of overtravel. I am at -5.5D eyesight-wise and it had barely enough and then a tiny bit more, I don't think it hits 7D. But that's 8.5x.
If 10x50 EL can do 7D, it would be enough for it not to be a deal-breaker.

 

[etc]

I've noticed that the larger the objective is, the brighter it is, with the power being a distant second.

I think 8x50 would be brighter than 10x42, even though the TI would be 20.5 and 20.5 in both cases.

 

[mwhogue]

I've noticed that the larger the objective is, the brighter it is, with the power being a distant second.

I think 8x50 would be brighter than 10x42, even though the TI would be 20.5 and 20.5 in both cases.

Not arguing and no expert here but my subjective experience is 8x56 Zeiss Night Owls "look very bright" in the dark but I can make out much more detail on, or even i.d., a specific object or animal with Canon 12x36 IS III or Vortex 15x56 HD. This difference is much greater in the dark than in daylight. Comparing models of the same quality, it's the same result with the 8.5x42 EL SV and the 12x50 FP.

Again just my subjective experience.

Mike