Jump to content


Pentax XW 7mm


Recommended Posts

Hello. I had been looking for a planetary eyepiece, and high magnification eyepiece of quality for sometime. As the small field of view and tight eye relief on the higher magnification plossl did start to make me wish for a more relaxed eyepiece viewing experience. And as around the 6 to 7mm mark seems to be going to be probably the most used high power eyepiece due to the seeing conditions and atmosphere conditions we have in this country then it seemed sensible to concentrate the maximum budget for a quality reasonable wide view eyepiece about this 7mm mark.

So when a Pentax appeared on the market place an interesting and possibly worthwhile route to explore. My knowledge on these eyepieces was limited, I had read a few articles were the pentax did get a mention in the same sort of sentences of the TV delos but I could not remember the outcome of this but I did remember these were thought of as quality eyepieces. Therefore a  decision to buy was made and the deal was done. 

A few days later the package arrived and there was the 7mm Pentax. My first impression was that it seemed a bit of a funny looking eyepiece and did not have a similar weight and feel to it as I was expecting. I was expecting a TV nagler sort of feeling but this was more of a lightweight and plastic outer coating sort of offering. As for the eyepiece itself the caps were removed and the eyepiece seemed in very good condition, which is always nice when the previous owner has obviously cared and treated their eyepieces with respect. Therefore my initial thoughts were lovely condition eyepiece but bit of a strange appearance.

As always with new kit I do try and set up in the daytime if possible to avoid mishaps in handling unfamiliar items in the dark when it's more likely that damage can occur by using unfamiliar kit. Also especially with eyepieces i do find daytime conditions very useful for judging the quality of the optical performance. Therefore the AZ4 mount was set up and the equinox 120ed apo was placed on it. The William Optics dielectric diagonal was placed into the focuser. The pentax comes in a very well designed plastic bolt type case which does help protect the eyepiece very well. After removing the eyepiece from the bolt case it was places into the diagonal and it's top protective eye cap was removed. The initial test is a neighbouring chimney and therfore the scope was pointed in the appropriate direction. Looking through the pentax eye lens the focuser was moved until an image started to appear. The first thing that struck me was the very good eye relief of around the 20 mm mark. If you are used to an Ortho or plossel in  a 7mm ,then you are in for a shock and treat of how relaxed and comfortable the extra eye relief brings to your viewing position. But I also noticed with the pentax that your eye placement seemed to have to be very accurate to stop black outs to your viewing experience. On gaining focus of the neighbouring chimney the views were very sharp and crisp indeed. The type of view that met me was that of a very good quality Ortho and the Optics do seem very high quality and in a top draw for the type of planetary eyepiece that I was looking for. With the crisp sharp views was the incredible field of view. At around 70 degree then the fov was a very nice aspect and such a sensible place to be. Enough field of view to make it useful and very pleasant,but not overwhelming which sometimes you get with very wide field of views eyepieces, to which sometimes in my experience you have to move your head or eye position to get the benefit available. With the pentax xw you get the advantage of the 70 decree apparent field of view while able to maintain your eye and head position. The views of the neighbouring chimney was the sharpest and most relaxing eye position that I have used to this point. When you get a high power eyepiece that is both sharp and clear , to the point you can pick out individual grains of sand in the mortar then you know your eyepiece and scope and beginning to work as a great combination. The scope was then pointed to a tree in a near by field . The tree was  sharply defined and the leaves just full of colour Therefore my initial impression on the pentax was very favourable indeed.

Due to the dismal weather conditions we are unlucky enough to have in the uk getting to use the pentax fully has been a bit of an uphill struggle. But I have had time with it enough now dodging the clouds and rain to get a reasonable overall opinion. A few weeks back Saturn was coming into view at around 10 in the evening over the neighbouring hedge. Lucky on one such evening the clouds in the south had cleared and therefore time to set up theAZ4 and the equinox 120apo. After getting the scope in the correct location the planet was centrer using my old favourite the 32mm TV plossl. It was time for the pentax to go to work. So eyepieces were swapped over . After a slight adjustment on the scopes position and adjustment on focus , Saturn started to come into view. The views of Saturn always put a smile on my face, firstly as it is such a beautiful well structured planed that it opens the mind to what stunning object's are there floating around the universe for us to discover and to try and view for the backyard astronomer. Also Saturn was the first planet I ever saw through a telescope and every time I see the planet it takes me back to that point of time in life to which I started to gain much more interest in this hobby. The pentax in the scope and Saturn in view, I was getting the atmosphere shudder which I do find very frustrating at times as getting precise focus in these conditions can be a bit of a lottery. But after a while the conditions did seem to improve somewhat so a bit more of a precise adjustment was made to the focus. In view now was a very good image of Saturn and it was to get better. Over the next 5 minutes I was getting moments the views of Saturn were the best I have ever seen. Saturn was sharp and crisp I was starting to realise that the pentax was a very good eyepiece indeed and in the equinox 120apo just seemed to be complementing each other to produce the best views of Saturn I have ever seen. A week or two later the moon was out so the frac was set up again. And the results were again very very good. The pentax allows your eye to be in a very comfortable position, to which IMO allows you to spend more time at the eyepiece and therefore increasing your viewing opportunities of your target. But your eye does have to be in a certain position to get the best out of the pentax. And on the moon the apparent field of view at 70  degree again was a very nice field of view to have . Enough fov to see the lunar landscape but not overwhelming therefore you can still concentrate on particular subjects such as the crators without being distracted. Also as I use manual mounts it means I can keep targets in view longer without the need to adjust to track. The pentax again on lunar landscape was very sharp and crisp this eyepiece certainly had been impressing me. In the refractor this eyepiece was working very well and the refractor seemed to be performing at its best with the pentax in it   .

I have managed to get the pentax in the OOuk dob also to do a limited impression on its suitability. On a couple of clear evenings  Cygnus and Cassiopeia were brought into view when cloud gaps permitted. location of  Cygnus and the binaries of albireo was located and the pentax did not disappoint. The stars were tight in the eyepiece and giving off there yellow and blue delights for the scope and eyepiece to convey to me , albireo certainly did not disappoint in the pentax. Going into Cassiopeia a few night's  later when weather conditions kindly allowed. Then initially the nagler 20mm was placed into the dob and cluster hunting began. The big w did not disappoint and a combination of the nagler 20mm and then changing over to the pentax allows the star clusters to be seen in full and then close up in detail. The pentax again served its purpose and the star clusters were sharp points of light with that lovely full star field within the clusters.

My overall opinion of the pentax was it performed the best of any eyepiece I have used to date in the refractor at around the 7mm range. It optical performance was clear and sharp with a great and useful fov of 70degree and a very nice relaxing eyerelief of 20mm. The only downside is getting correct eye position as this is important to avoid black outs. This eyepiece gave me my best view ever of Saturn through the equinox , and that in itself makes this eyepiece a worthwhile addition. In the dob the eyepiece has also performed very well giving me some great close up views of binaries and clusters. Therefore overall the  pentax 7mm will be a much used and very competent eyepiece in my collection to get the best views possible.☺









The Pentax xw 7mm ☺

  • Like 5
Link to comment
Share on other sites

Super report on a superb eyepiece :icon_biggrin:

I have 4 XW's from 3.5mm to 10mm and rate them very highly indeed. It took me a little while to find the correct eye placement as well but when you do, the rewards are generous.

Interesting thing about the XW's is that they were not designed for astro use at all apparently but for terrestrial use in spotting scopes. Goodness knows what Pentax could produce for astronomical purposes if they really put their minds to it !

I now prefer to use XW's over good quality orthos because of the viewing comfort and very similar optical qualities.

I did try a 10mm Delos for a short while and found it very, very, very similar to the XW in practically every respect.

  • Like 3
Link to comment
Share on other sites

Congrats on getting a really top class EP. I have 3 XWs: the 5, 7, and 10, and they are just superb. I got a Delos 8mm to sit between the 10 and the 7 (now with a parfocaliser ring so all four planetary EPs are parfocal), and the difference between them is minute, if not non-existent. The Delos has a tiny bit more FOV, but the XWs are just a touch more comfortable to use (for me, others may have different experiences).

  • Like 2
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.