[Mikesul]

Thank you for that but there is a great heap of discards to get that one. This one is at 400mm

I am sure there were but getting even one good one like this is special. I did not have the patience or skill. Keep it up!

[GUB]

I am sure there were but getting even one good one like this is special. I did not have the patience or skill. Keep it up!

Awww now you have enthused me to go out and have another wander around! Yesterday was with a monopod - today a tripod. The view was at 600mm - can't remember the others. K400 - 600mm mirror on the K1. There is a thread nearby which asks if it is foolish to buy a K1 to use only old glass on. I think this answers that!

[pepperberry farm]

[marcusBMG]

Godwits, snipe and wagtails provided the opportunity to test drive a recently acquired Rubinar 500mm f8 mirror.



I habitually use my NX20 with mirrors, the facility to magnify the viewing image 5x or 7x in the evf is my best opprtunity to get the focus. F8 (actually T10'ish) by eye through an OVF proves to be just too hit and miss with the emphasis on miss - at least for me. These were taken using a bean bag. The godwit pics were at waters edge and backlit by the reflection off the water - mirrors just don't like any sort of unfavourable light like that IME - and didn't turn out very well. It was actually the images of the frustratingly skittish wagtails that came out best, due to being closest. Mirror lenses just aren't as sharp as refractive lenses so being able to resize more makes the difference. All big crops in any case except #1.
The castle from the bird reserve. I find mirrors struggle to preserve detail in these circumstances - see crop.



1:1 pixel peep crop.


At the RSPB:

[tim60]

Godwits, snipe and wagtails provided the opportunity to test drive a recently acquired Rubinar 500mm f8 mirror.



I habitually use my NX20 with mirrors, the facility to magnify the viewing image 5x or 7x in the evf is my best opprtunity to get the focus. F8 (actually T10'ish) by eye through an OVF proves to be just too hit and miss with the emphasis on miss - at least for me. These were taken using a bean bag. The godwit pics were at waters edge and backlit by the reflection off the water - mirrors just don't like any sort of unfavourable light like that IME - and didn't turn out very well. It was actually the images of the frustratingly skittish wagtails that came out best, due to being closest. Mirror lenses just aren't as sharp as refractive lenses so being able to resize more makes the difference. All big crops in any case except #1.
The castle from the bird reserve. I find mirrors struggle to preserve detail in these circumstances - see crop.



1:1 pixel peep crop.


At the RSPB:

I have the 1000/10. Your pictures are of a quality like I typically get but I have had a few that have worked out much sharper. There is probably more capability in your 500 than what you got.

[marcusBMG]

I have had a few that have worked out much sharper

What do you think made the difference?

[tim60]

What do you think made the difference?

I think actually getting focus right. The focus action is very heavy, at least compared with Takumars. And also getting no movement.

[GUB]

The Pentax Q sure strained the heck out of the Samyang 500 f8 !! - It is like cropping the centre 1/6th of area of a FF sensor and enlarging that out to size.
And in terms of field of view this is like 3000mm on my K-1.
Absolute hell to use!!
Images raw pped as best I can.
I think my lens is an early model - it has a T-mount - but is presumably the same generic lens as MarcusBMG's one above. Mine has terrible contrast compared to my Pentax K 400 - 600mm.
I agree with tim60 above - getting focus right and no movement are the issues and lady luck has a lot to do with that occasional good one!!

[smf]

I invested two hours at a wetland in Midland County, Michigan on Monday evening to capture more images of great egrets with my Tokina 500mm f/8 mirror lens on my tripod-mounted K-S2. Few birds were visible when I arrived, but at least 50 were there when I left.

[marcusBMG]

presumably the same generic lens as MarcusBMG's one above.

No, the korean made samyangs have no connection to the Russian made Rubinar. The Russian/old soviet mirrors have a pretty good rap.

I hope you don't mind too much my remarking that your results with the Q are what I would have expected with that lens - ugh.

I just did a bit of a browse in the adapted lenses to Q thread , there are a number of contributuions with some mirrors, most showing up that mirrors generally IME won't stand up to that pixel density very well. I know I've seen some better than expected images with the tamron 500mm however, posted by pacer IIRC, but can't find them.

getting focus right

+1 !!!! I would think focus is 95% of the challenge with the 1000mm f10 (and probably thats T16'ish). Do you use live view?

Further usage of the rubinar reinforces my impression I don't think it's a very good one. Not bad but...well I'll post the comparison pics against the tamron in due course.

[GUB]

No, the korean made samyangs have no connection to the Russian made Rubinar. The Russian/old soviet mirrors have a pretty good rap.

My bad - they look so similar! I see the PF reviews have an entry for your lens but no reviews - you should do one.

I hope you don't mind too much my remarking that your results with the Q are what I would have expected with that lens - ugh.

Yep that is for real! But I got my figures wrong last night and it would be about 1/36 th of the area of FF. In fact if your castle image was from FF (I am aware it is apsc) then your turret crop is a pretty good indicator of what the Q would use. The difference being in the Q it is 12mp but in a K1 crop it would be 1 mp. (Hope I have the sums right this time)

[tim60]

My bad - they look so similar! I see the PF reviews have an entry for your lens but no reviews - you should do one.


Yep that is for real! But I got my figures wrong last night and it would be about 1/36 th of the area of FF. In fact if your castle image was from FF (I am aware it is apsc) then your turret crop is a pretty good indicator of what the Q would use. The difference being in the Q it is 12mp but in a K1 crop it would be 1 mp. (Hope I have the sums right this time)

Also the viewing device on the Q shows the 'croped' bit as the full frame, making get good focus easier than when it is a fragment of the frame.

[tim60]

No, the korean made samyangs have no connection to the Russian made Rubinar. The Russian/old soviet mirrors have a pretty good rap.

The Rubinar 1000, at least, came out of Leningrad No. 3, a factory making lenses for KGB, where the priority was to get them good. The now commercial maker got the IP of the design for a song in the sell off of state assets.


My impression of the mirror lens talk in the early 80s was that they were designed to be smaller and cheaper than standard lenses of the same FL, with emphasis on cheaper, so people of ordinary wealth could get into long lenses.

[GUB]

Also the viewing device on the Q shows the 'croped' bit as the full frame, making get good focus easier than when it is a fragment of the frame.

Not sure I agree with the calculator and its choice of cocs (005 vs 03 Q vs K1) but this would suggest the Q is much harder to focus!
(Had to use the D800 for FF coz the K1 is not there !) Online Depth of Field Calculator

[marcusBMG]

I was surprised to see the rubinar wasn't listed GUB, so I listed it that's my lens in the pics. It's a nice one actually, with original case, filters etc. and cyrillic user manual/certificate.

The DoF calculations merely emphasise the tightness of the focus. The practical issue is seeing it, which IME I can't do well enough in my OVF's, only by using magnification in an EVF or on screen, and then millimetrically tickling the focus to try to nail it.
It just isn't easy with mirrors.
The rubinar for some reason is particularly ticklish, I find I'm to-ing and fro-ing a lot, and end up trying to land on a middle position (I wonder if there's a bit of slack in the helicoid - check - yes I think there is). The tamron is significantly better - more clear cut oof-in-oof as I move the focus.